JP2009190385A - Thermal transfer image receiving sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal transfer image receiving sheet provided with a water-based receiving layer and capable of giving a clear and high quality image and free from matting the image transferred on the receiving layer when the image is thermally transferred on the water-based receiving layer using the thermal transfer sheet provided with a dye layer and a coating liquid for forming the receiving layer to form the water-based receiving layer. <P>SOLUTION: In the thermal transfer image receiving sheet provided with at least a receiving layer on the base material sheet, a dye coloring resin which is dispersible or dissolvable in water-based solvent and has an active hydrogen-containing functional group and a crosslinking agent are incorporated in the receiving layer and the receiving layer is constituted of a three-dimensional crosslinked structure formed by crosslinking the dye coloring resin with the crosslinking agent. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermal transfer image receiving sheet used for printing by a thermal transfer system.

As a method of forming an image using thermal transfer, a thermal transfer sheet (hereinafter referred to as “ink ribbon”) having a dye layer in which a thermal diffusion dye (sublimation dye) as a recording material is supported on a substrate sheet such as a plastic film. And a thermal diffusion transfer system (sublimation thermal transfer system) that forms a full-color image by superimposing a thermal transfer image-receiving sheet provided with a receiving layer on another substrate sheet such as paper or plastic film. ing. Since this method uses a thermal diffusion dye as a color material, the density and gradation can be freely adjusted in dot units, and a full-color image exactly as the original can be clearly displayed on the image-receiving sheet. It is applied to color image formation for computers and the like. The image is of a high quality comparable to a silver salt photograph.

  The receiving layer in the thermal transfer image-receiving sheet is formed by applying a receiving layer constituting resin using an organic solvent and an aqueous receiving layer formed by applying the receiving layer constituting resin using an aqueous solvent. Broadly divided into layers. In particular, the usefulness of the water-based receptive layer has attracted attention from the viewpoint of environment or safety.

  On the other hand, as a method for forming a thermal transfer image-receiving sheet, a method in which a porous layer and a receiving layer are sequentially applied and dried on a base sheet by gravure coating, etc. There are known wet-on-wet methods, simultaneous multilayer coating methods in which a plurality of layers are simultaneously coated on a substrate sheet, and the like. Among these forming methods, the simultaneous multi-layer coating method is attracting attention because it can obtain a thermal transfer image-receiving sheet with a smaller number of steps than other forming methods.

As an example of the simultaneous multilayer coating method, for example, in the example of Patent Document 1 (production of the thermal transfer image-receiving sheet 5), a plurality of layers such as a heat insulating layer and a receiving layer are formed on the substrate by simultaneous multilayer coating. A thermal transfer image receiving sheet is disclosed. Specifically, it is described that a thermal transfer image receiving sheet is obtained by using a slide coating method as a simultaneous multi-layer coating method. Further, Patent Document 2 discloses a method for producing a thermal transfer image-receiving sheet, characterized in that an aqueous intermediate layer and an aqueous receiving layer are simultaneously applied (for example, Patent Document 2 Claim 1). Discloses an ink jet recording medium having a water-soluble resin as the outermost layer (for example, Patent Document 3 claim 1), which describes simultaneous application of an ink-receiving layer coating solution and a basic solution.

In particular, since the thermal transfer image-receiving sheet provided with the above-described aqueous receiving layer is suitable to be formed by the above-described simultaneous multilayer coating method, the thermal transfer image-receiving sheet provided with the aqueous receiving layer is also expected from this viewpoint.
JP 2006-88691 A JP-A-6-171240 JP 2006-103040 A

  However, the thermal transfer image-receiving sheet provided with the water-based receiving layer has the following problems. That is, in an aqueous receiving layer, when an image is thermally transferred using a thermal transfer sheet provided with a dye layer, the image transferred onto the receiving layer tends to be matted, sufficiently satisfying the demand for clearer and higher quality images. Sometimes it was difficult to let

According to the diligent study by the present inventors, it has been found that the problem of matting is remarkable in a thermal transfer image receiving sheet using a receiving layer having insufficient heat resistance. The printed image is matted because part of the resin constituting the aqueous receiving layer is fused to the dye layer due to heat during transfer, and the ink ribbon including the dye layer in that state is used. Since the receiving layer is pulled by the winding force of the dye, the dye contained in the dye layer is not satisfactorily dyed on the receiving layer, and a part of the resin constituting the receiving layer is further taken on the surface of the dye layer. It was guessed that this was because of this.

  Therefore, the present inventors use a crosslinkable resin as a resin constituting the aqueous receptive layer in the thermal transfer image-receiving sheet, and simultaneously crosslink these using a cross-linking agent, thereby three-dimensionally cross-linking the aqueous receptive layer. It has been found that the problem of matting can be solved by constituting the structure, and the present invention has been completed.

That is, the present invention
(1) A dye-transferable resin having a base sheet and a thermal transfer image-receiving sheet having at least a receiving layer on the base sheet, wherein the receiving layer can be dispersed or dissolved in an aqueous solvent and has an active hydrogen-containing functional group A thermal transfer image-receiving sheet comprising a three-dimensional cross-linking structure comprising a cross-linking agent and the dye-dyeable resin and the cross-linking agent,
(2) The thermal transfer image-receiving sheet according to (1), wherein the dye-dyeing resin is a styrene acrylic copolymer resin,
(3) The thermal transfer image-receiving sheet as described in (1) or (2) above, wherein the crosslinking agent is a carbodiimide-based crosslinking agent,
(4) The thermal transfer image-receiving sheet according to any one of (1) to (3), wherein a release agent is contained in the receiving layer.
(5) The thermal transfer image receiving sheet according to any one of (1) to (4) above, wherein a porous layer is provided between the base sheet and the receiving layer,
(6) A receiving layer-forming coating solution comprising an aqueous solvent, a dye-dyeable resin having an active hydrogen-containing functional group that can be dispersed or dissolved in the aqueous solvent, a crosslinking agent, and a cooling gelling agent. ,
(7) The dye-resinable resin is a styrene-acrylic copolymer resin, wherein the receiving layer forming coating solution according to (6),
(8) The receiving layer forming coating solution according to (6) or (7), wherein the crosslinking agent is a carbodiimide-based crosslinking agent,
Is a summary.

  The image-receiving sheet of the present invention has succeeded in improving the heat resistance of the receptor layer by constituting the receptor layer with a three-dimensional crosslinked structure formed by crosslinking the dye-dyeable resin and the crosslinking agent. As a result, even if the ink ribbon and the receiving layer are pressure-bonded in a high-temperature environment during printing, the resin constituting the receiving layer and the dye layer are fused, and a part of the receiving layer is taken up by the dye layer. The conventional problem has been improved satisfactorily. Thus, the dye contained in the dye layer migrates well to the receiving layer constituted by the three-dimensional cross-linking structure, enters into the network of the three-dimensional cross-linking resin, and forms a clear and high-quality image without matting. Made it possible.

  In addition, the thermal transfer image-receiving sheet of the present invention includes a water-based receptive layer, and is considered in terms of environment and safety, and when a layer other than the receptive layer is formed on the base sheet, These multiple layers have the advantage that they can be manufactured by a simultaneous multi-layer coating method with a fewer number of steps.

  In particular, in the thermal transfer image-receiving sheet of the present invention, when a styrene acrylic copolymer resin is used as the dye-dyeable resin constituting the receiving layer, there is no bleeding of ink after printing and a sufficient cross-linked structure is obtained. This is preferable because it can be realized.

  Further, in the embodiment of the present invention in which a carbodiimide crosslinking agent is used as a crosslinking agent contained in the receiving layer, a crosslinking reaction can be easily and satisfactorily caused with a dye-dyeable resin having an active hydrogen-containing functional group. preferable. In particular, a carbodiimide crosslinking agent can sufficiently cause a crosslinking reaction with the resin even at a temperature at which the aqueous solvent for dispersing or dissolving the receiving layer-constituting resin can be dried. Very advantageous.

[Thermal transfer image receiving sheet]
Hereinafter, the best mode for carrying out the thermal transfer image-receiving sheet of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic sectional view showing one embodiment of the thermal transfer image receiving sheet of the present invention. A thermal transfer image receiving sheet 10 illustrated in FIG. 1 includes a base sheet 1 and a receiving layer 2 formed on the base sheet 1. The thermal transfer image receiving sheet of the present invention is not limited to the above-described configuration, and may be provided with one or two or more different arbitrary layers between the base sheet and the receiving layer. The thermal transfer image-receiving sheet of the present invention having an arbitrary layer will be exemplarily described below.

  FIG. 2 is a schematic sectional view showing another embodiment of the thermal transfer image receiving sheet of the present invention. A thermal transfer image receiving sheet 11 of the present invention shown in FIG. 2 is configured by laminating a porous layer 3 and a receiving layer 2 in this order on a base sheet 1.

  FIG. 3 is a schematic sectional view showing another embodiment of the thermal transfer image receiving sheet of the present invention. The thermal transfer image receiving sheet 12 of the present invention shown in FIG. 3 is configured by laminating a first primer layer 4, a porous layer 3, and a receiving layer 2 in this order on a base sheet 1.

  FIG. 4 is a schematic sectional view showing another embodiment of the thermal transfer image receiving sheet of the present invention. The thermal transfer image-receiving sheet 13 of the present invention shown in FIG. 4 has a first primer layer 4, a porous layer 3, a second primer layer 5, and a receiving layer 2 laminated in this order on a base sheet 1. Configured. Hereinafter, each layer constituting the thermal transfer image receiving sheets 10 to 13 of the present invention shown in FIGS. 1 to 4 will be described in more detail.

<Receptive layer>
First, the receiving layer 2 in the thermal transfer image receiving sheet 10 of the present invention will be described. The receiving layer 2 is a layer formed on the substrate sheet 1 and has a function of receiving a dye when a printed material is formed by the thermal transfer method using the thermal transfer image receiving sheet 10. The most important point in the thermal transfer image-receiving sheet 10 of the present invention is that in the receiving layer 2, a dye-dyeable resin that can be dispersed or dissolved in an aqueous solvent and has an active hydrogen-containing functional group, and the dye-dyeable resin is crosslinked. In order to form a three-dimensional cross-linked structure, a cross-linking agent is used. By realizing such a three-dimensional cross-linked structure, the heat resistance of the receiving layer 2 is improved, and matting of an image printed on the receiving layer 2 is improved satisfactorily. Further, it is desirable that the receiving layer 2 contains a release agent so that the dye layer can be smoothly peeled off after the pressure-bonding between the receiving layer and the dye layer at the time of printing.

In addition, since the receiving layer 2 is a so-called aqueous receiving layer that can be dispersed or dissolved in an aqueous solvent, the base sheet 1 and the receiving layer 2 are formed like the thermal transfer image receiving sheets 11 to 13 illustrated in FIGS. When arbitrary different layers are formed between them, a plurality of layers including the receiving layer 2 can be simultaneously applied to the base sheet 1 by multilayer coating. In particular, when the thermal transfer image-receiving sheet of the present invention is applied simultaneously in the above multilayer, it is desirable that the receiving layer 2 contains a cooling gelling agent.
The constituent materials that can be contained in the receiving layer are described in detail below.

(Dye dyeing resin)
As the resin for constituting the receiving layer in the present invention, a dye dyeable resin that can be dispersed or dissolved in an aqueous solvent and has an active hydrogen-containing functional group is used. More specifically, the receptor layer-constituting resin can be dispersed or dissolved in an aqueous solvent, which will be described later, and a combination of one or more functional groups having active hydrogen such as a carboxyl group, a hydroxyl group, or an amino group. In the above, a dye-dyeable resin containing two or more molecules in the molecule is used.

In particular, the dye dyeable resin preferably has a glass transition temperature of 20 ° C. or higher, more preferably 30 ° C. or higher, and even more preferably 40 ° C. or higher. Further, the receiving layer constituting resin preferably has a glass transition temperature of 120 ° C. or lower. It is because the heat resistance of the obtained receiving layer can be improved by using the receiving layer constituting resin having a glass transition temperature in such a range.

Examples of the receiving layer-constituting resin include, for example, a polyolefin resin, a polyvinyl resin, a polyester resin, a polyurethane resin, a polycarbonate resin, a polyamide resin, a cellulose derivative resin, or a polyether resin, and a crosslinking agent. A compound having a functional group having an active hydrogen capable of reacting with is used. In the present invention, any of these resins can be suitably used. Among them, from the viewpoint that a printed image has a high density and a clear image can be obtained, one of the polyvinyl resins is used. It is preferable to use a seed styrene acrylic resin. In addition, all of the receiving layer constituting resins exemplified below contain functional groups having active hydrogen capable of reacting with a crosslinking agent in the resin as described above, that is, there are crosslinking points in the resin. It means a resin.

  Examples of the polyvinyl resin suitably used as the receiving layer constituting resin in the present invention include, for example, vinyl chloride / vinyl acetate copolymer, vinyl chloride / acrylic compound copolymer, ethylene / vinyl chloride / acrylic acid ester copolymer, Examples thereof include an ethylene / vinyl acetate / vinyl chloride copolymer.

The vinyl chloride / vinyl acetate copolymer is not particularly limited as long as it is a copolymer composed of vinyl chloride and vinyl acetate, and can be copolymerized with these essential monomers in addition to vinyl chloride and vinyl acetate. The body may be obtained by polymerizing a small amount.

The vinyl chloride / acrylic compound copolymer is not particularly limited as long as it is a copolymer composed of vinyl chloride and an acrylic compound, and a single amount copolymerizable with these essential monomers in addition to vinyl chloride and an acrylic compound. The body may be obtained by copolymerization in a small amount.

Examples of the acrylic compound include acrylic acid; acrylic acid salts such as calcium acrylate, zinc acrylate, magnesium acrylate, and aluminum acrylate; methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and 2-ethoxy. Acrylic esters such as ethyl acrylate, 2-hydroxyethyl acrylate, n-stearyl acrylate, tetrahydrofurfuryl acrylate, trimethylolpropane triacrylate; methacrylic acid; methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, tridecyl methacrylate , Cyclohexyl methacrylate, triethylene glycol dimethacrylate, 1,3-butylene dimethacrylate, trimethylo trimethacrylate It can be mentioned methacrylic acid esters such as propane.
In the present specification, “acrylic compound” means (meth) acrylic acid and / or an alkyl ester thereof.

  The ethylene / vinyl chloride / acrylic acid ester copolymer and the ethylene / vinyl acetate / vinyl chloride copolymer (hereinafter, these copolymers are collectively referred to as “ethylene / vinyl chloride copolymer”). Is not particularly limited as long as it is a copolymer obtained by polymerizing at least three monomers of ethylene, vinyl chloride and acrylate, or three monomers of ethylene, vinyl acetate and vinyl chloride. In addition to these three types of monomers, a small amount of a small amount of monomer may be copolymerized.

  The ethylene / vinyl acetate / vinyl chloride copolymer may be a copolymer of ethylene / vinyl acetate copolymer (EVA) and vinyl chloride. As the EVA / vinyl chloride copolymer, EVA may be used. It may be a graft copolymerized vinyl chloride. EVA includes those in which all or part of vinyl acetate units in the copolymer is saponified.

In the present invention, “acrylic acid ester” constituting the ethylene / vinyl chloride / acrylic acid ester copolymer is a concept including a methacrylic acid ester in addition to the acrylic acid ester. Examples of the acrylic acid ester include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-ethoxyethyl acrylate, 2-hydroxyethyl acrylate, n-stearyl acrylate, tetrahydrofurfuryl acrylate, and trimethylolpropane triacrylate. Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, tridecyl methacrylate, cyclohexyl methacrylate, triethylene glycol dimethacrylate, dimethacrylic acid-1, Examples include 3-butylene and trimethylolpropane trimethacrylate.
In the present invention, only one type of the above-mentioned receptor layer constituting resin may be used, or two or more types having different monomer compositions, average molecular weights, and the like may be used.

  The styrene acrylic resin suitably used in the present invention is not particularly limited as long as it is a copolymer obtained by polymerizing two types of monomers, a styrene monomer and an acrylic monomer. In addition to the monomer, a small amount of a small amount of monomer may be copolymerized.

The styrene monomer is not particularly limited, and a known compound can be used. For example, alkylstyrene such as styrene, α-methylstyrene, β-methylstyrene, 2,4-dimethylstyrene, α-ethylstyrene, α-butylstyrene, α-hexylstyrene, 4-chlorostyrene, 3-chlorostyrene, There are halogenated styrenes such as 3-bromostyrene, 3-nitrostyrene, 4-methoxystyrene, vinyltoluene and the like.

On the other hand, the acrylic monomer is not particularly limited, and a known compound can be used. For example, acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-ethoxyethyl acrylate, 2-hydroxyethyl acrylate, n-stearyl acrylate, tetrahydrofurfuryl acrylate, trimethylolpropane triacrylate; Acid; Methacrylic acid such as methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, tridecyl methacrylate, cyclohexyl methacrylate, triethylene glycol dimethacrylate, 1,3-butylene dimethacrylate, trimethylolpropane trimethacrylate Examples include esters.
In the present specification, “acrylic” includes (meth) acrylic acid and / or an alkyl ester compound thereof.

In addition to the styrene monomer, acrylic acid monomer, and methacrylic acid monomer, the styrene acrylic resin may be copolymerized with known monomers that can be copolymerized with these monomers. Examples of such monomers include methyl acrylate, methyl methacrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, tert-butyl acrylate, 2-ethylbutyl acrylate, 1,3-dimethylbutyl Acrylic esters and methacrylic such as acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, ethyl methacrylate, n-butyl methacrylate, 2-methylbutyl methacrylate, pentyl methacrylate, heptyl methacrylate, nonyl methacrylate Acid esters; 3-ethoxypropyl acrylate, 3-ethoxybutyl acrylate, dimethylaminoethyl acrylate, 2 Acrylic acid ester derivatives and methacrylic acid ester derivatives such as hydroxyethyl acrylate, 2-hydroxybutyl acrylate, ethyl-α- (hydroxymethyl) acrylate, dimethylaminoethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate; phenyl acrylate Acrylic acid aryl esters and acrylic acid aralkyl esters such as benzyl acrylate, phenylethyl acrylate, phenylethyl methacrylate; monoacrylic acid of polyhydric alcohols such as diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, bisphenol A Esters or monomethacrylates; dimethyl maleate, malee Mention may be made of maleic acid dialkyl esters such as diethyl acid, vinyl acetate and the like. One or more of these monomers can be added as monomer components.

As described above, each of the receptor layer-constituting resins described above contains a functional group having an active hydrogen capable of reacting with a crosslinking agent in the resin, that is, a resin having a crosslinking point in the resin. Means. Therefore, by applying a coating solution for forming a receiving layer containing these receiving layer constituting resins and a crosslinking agent directly or indirectly on the base sheet, and causing a crosslinking reaction using heat or ionizing radiation resin, A receiving layer constituted by a three-dimensional cross-linking structure formed by cross-linking these resins and the cross-linking agent can be obtained. Moreover, since the receiving layer constituting resin used in the present invention is a dye-dyeable resin, the dye contained in the dye layer is dyed in the resin showing the above three-dimensional structure at the time of printing.

(Aqueous solvent)
In the present invention, the “aqueous solvent” used to disperse or dissolve the dye-dyeing resin constituting the receptor layer 2 refers to a solvent containing water as a main component. The proportion of water in the aqueous solvent is usually 60% by weight or more, preferably 70% by weight or more, and more preferably 80% by weight or more. Examples of solvents other than water include alcohols such as methanol, ethanol, isopropanol, and n-propanol; glycols such as ethylene glycol, diethylene glycol, and glycerin; esters such as ethyl acetate and propyl acetate; ketones such as acetone and methyl ethyl ketone. Amides such as N, N-dimethylformamide can be exemplified.

(Crosslinking agent)
The cross-linking agent contained in the receiving layer 2 may be a known one as long as it has a three-dimensional cross-linking structure together with the dye-dyeable resin constituting the receiving layer 2 and can be dispersed or dissolved in an aqueous solvent. It can use by selection suitably. The crosslinking agent used in the present invention may be a thermal reaction type crosslinking agent or an ionizing radiation reaction type crosslinking agent. In the present specification, ionizing radiation means an electromagnetic wave or a charged particle beam having an energy quantum capable of cross-linking molecules, and usually ultraviolet (UV) or electron beam (EB) is used.

For example, specific examples of the crosslinking agent include carbodiimide-based crosslinking agents (polycarbodiimide compounds derived from isophorone diisocyanate, carbodiimide compounds derived from tetramethylxylylene diisocyanate, other branched carbodiimide compounds, and carbodiimide compounds derived from dicyclohexylmethane diisocyanate, or carbodilite. V-02, V-02-L2, V-04, V-06, E-01, E-02 (all manufactured by Nisshinbo Co., Ltd.) and the like; an oxazoline compound, or Epocross K-1010E, K-1020E, Examples thereof include K-1030E, K-2010E, K-2020E, K-2030E, WS-500, and WS-700 (all manufactured by Nippon Shokubai Co., Ltd.).

Examples of other crosslinking agents include aldehyde crosslinking agents (formaldehyde, glyoxal, glutaraldehyde, etc.); epoxy crosslinking agents (diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidylcyclohexane, N, N-diglycidyl-4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc.); active halogen-based crosslinking agent (2,4-dichloro-4-hydroxy-1, 3,5-s-triazine etc.).

Examples of other crosslinking agents include haloamidinium salt crosslinking agents (1- (1-chloro-1-pyridinomethylene) pyrrolidinium, 2-naphthalenesulfonate, etc.); active vinyl crosslinking agents (1, 3, 5 -Trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, N, N'-ethylene-bis (vinylsulfonylacetamide) ethane, etc.); mucohalogenic acid type cross-linking agent (mucochloric acid, etc.); N-carbamoyl Examples thereof include pyridinium salt-based crosslinking agents (such as (1-morpholinocarbonyl-3-pyridinio) methanesulfonate); N-methylol-based compounds (such as dimethylol urea and methylol dimethyl hydantoin).

  Examples of other crosslinking agents include isocyanate-based crosslinking agents (dispersible isocyanate compounds, or Duranate WB40-100, WB40-80D, WT20-100, WT30-100 (all manufactured by Asahi Kasei Co., Ltd.), CR-60N. (Manufactured by Dainippon Ink & Chemicals, Inc.)); polymer hardener; boric acid and its salts; borax; aluminum alum and the like.

In particular, since the dye-dyeable resin used in the present invention uses a resin containing a functional group having an active hydrogen such as a carboxyl group, a hydroxyl group, or an amino group, a resin having these functional groups among known crosslinking agents. It is preferable to use a carbodiimide-based cross-linking agent having a property of being well cross-linked because it can be cross-linked well with the dye-dyeable resin to achieve a three-dimensional cross-linked structure.

The thermal transfer image-receiving sheet of the present invention is a so-called water-based sheet and can be produced by a simultaneous multilayer coating method. However, in this case, in order to form a thermal transfer image-receiving sheet provided with a sufficiently cross-linked receiving layer, there are the following problems.
That is, when an aqueous sheet is produced by the simultaneous multilayer coating method, each layer formed on the base sheet generally contains a cooling gelling agent or a binder resin that can also be used as a cooling gelling agent. Is. Usually, in order to dissolve these cooling gelling agents in the coating liquid, the coating liquid heated to an appropriate temperature is independently filled in the coating liquid tank in the slide coating apparatus, and the heat-retaining state is maintained. Under this temperature, a crosslinking agent that is a heat-reactive crosslinking agent and has a low reaction initiation temperature may start crosslinking from the state of the coating liquid before being applied onto the substrate sheet. There is a possibility that so-called deception occurs in the liquid, and a uniform and smooth receiving layer is not formed. Therefore, when producing the thermal transfer image-receiving sheet of the present invention by simultaneous multilayer coating, it is necessary to pay attention to the selection of the crosslinking agent. In contrast, the carbodiimide-based crosslinking agent does not cause a crosslinking reaction to a problem even at a temperature at which the cooling gelling agent can be dissolved in the coating solution, and is generally implemented in the simultaneous multilayer coating method. In the drying step of about 50 ° C., it is possible to cause a crosslinking reaction with the receiving layer constituting resin, so that it can be said to be a very preferable crosslinking agent.

  Further, in the simultaneous multi-layer coating method, an ionizing ray irradiation process is further added, and an ionizing radiation reaction type crosslinking agent is used in the receiving layer coating liquid. The receiving layer constituting resin and the crosslinking agent can be reliably crosslinked without being influenced.

  As described above, the receiving layer 2 includes a crosslinkable dye-dyeable resin and a crosslinking agent, and is composed of a three-dimensional crosslinked structure formed by crosslinking these. In particular, as the dye-dyeable resin, a resin containing a functional group having an active hydrogen such as a carboxyl group, a hydroxyl group, and an amino group is used, and a carbodiimide-based crosslinking agent is used as a crosslinking agent. In FIG. 2, a three-dimensional cross-linked structure is well shown, and matting of the receiving layer 2 is preferably improved.

The reason why the matting of the receiving layer 2 is improved by configuring the receiving layer 2 with a three-dimensional crosslinked structure is as follows. That is, when an image is printed on the thermal transfer image receiving sheets 10 to 13 by the thermal transfer method, both are pressure-bonded with necessary applied energy in order to dye the dye contained in the dye layer onto the receiving layer 2. At that time, since the heat of transfer is also applied, in the receiving layer 2 having low heat resistance, the resin constituting the receiving layer and the dye layer are fused, and then when the ink ribbon is wound up, the dye layer on the surface of the ink ribbon It is considered that the receiving layer-constituting resin was taken on the surface, and as a result, matting occurred. The above matting problem is particularly noticeable when printing a high density portion, and since the matting becomes prominent when a larger applied energy is required, the receiving layer structure having low heat resistance during printing is also used. It is inferred that the resin is taken on the surface of the dye layer. On the other hand, the present inventors improve the heat resistance of the receiving layer 2 by three-dimensionally cross-linking the resin constituting the receiving layer 2, thereby fusing with the dye layer and receiving it on the surface of the dye layer. It has been found that “taken” of the layer-constituting resin can be satisfactorily prevented.

  In order to particularly satisfactorily solve the problem of matting an aqueous thermal transfer image-receiving sheet by constituting the receiving layer 2 in a three-dimensional crosslinked structure, the dye-dyeing resin and the crosslinking agent constituting the receiving layer 2 are sufficient. It is desirable to be crosslinked. The degree of crosslinking of the receiving layer 2 can be indicated by the degree of crosslinking, the gel fraction, and the like. For example, from the viewpoint of the degree of crosslinking, the degree of crosslinking of the dye-dyeable resin contained in the receiving layer 2 is desirably 25% or more, more desirably 45% or more, and desirably 65% or more. Is more preferably 85% or more, and most preferably 90% or more.

(Release agent)
In the receptor layer 2 in the present invention, the release agent is not an essential component, but is preferably used as a receptor layer constituent material for the following reasons. That is, as the dye dyeable resin for constituting the receiving layer 2 in the present invention, those having a glass transition temperature of 20 ° C. or higher and 120 ° C. or lower are preferably used as described above. Here, when the glass transition temperature of the dyeing property is relatively high, the releasability from the dye layer at the time of printing may be poor. The tendency of releasability is particularly remarkable when the glass transition temperature of the dye-dyeable resin is in the range of 40 ° C. or higher and 120 ° C. or lower. On the other hand, when a release agent is used as the receiving layer constituting material, it is possible to improve the releasability at the time of insufficient printing.

Examples of the release agent used in the present invention include conventionally known ones such as silicone oil, phosphate ester compounds, and fluorine compounds. Among these, silicone oil is particularly suitable because it has good compatibility with the dye-dyeable resin used in the present invention. More specific examples of silicone oil include epoxy-modified silicone oil, alkyl-modified silicone oil, amino-modified silicone oil, fluorine-modified silicone oil, phenyl-modified silicone oil, polyether-modified silicone oil, vinyl-modified silicone oil, and hydrogen-modified silicone oil. Modified silicone oil such as silicone oil is preferred. Also, emulsified silicone can be used.

(Cooling gelling agent)
Further, according to the present invention, a cooling gelling agent can be optionally added to the receiving layer 2. In particular, when producing a thermal transfer image receiving sheet in which a plurality of layers including a receiving layer are laminated on a substrate sheet, such as the thermal transfer image receiving sheets 11 to 13, by a simultaneous multilayer coating method such as a slide coating method, the receiving layer By adding a cooling gelling agent to 2, it becomes possible to manufacture with high efficiency. Further, the inclusion of the cooling gelling agent in the receiving layer 2 not only makes it possible to produce a multilayer thermal transfer image-receiving sheet in the simultaneous multilayer coating method, but also prints on the obtained thermal transfer image-receiving sheet. When it does, it contributes also to the improvement of the releasability of a receiving layer and a dye layer. Therefore, even in the thermal transfer image-receiving sheet 10 composed of the receiving layer 2 and the base sheet 1, an advantageous effect can be obtained by adding a cooling gelling agent to the receiving layer 2.

  In addition, in any layer in the thermal transfer image-receiving sheet of the present invention such as a porous layer or a primer layer to be described later, the addition of a cooling gelling agent is optional, but in particular an aqueous system comprising two or more layers including a receiving layer. When the thermal transfer image-receiving sheet is produced by the simultaneous multilayer coating method, it is desirable that a cooling gelling agent is added to any layer.

The cooling gelling agent used in the present invention described above has a property of gelling when cooled. The cooling gelling agent is not particularly limited as long as it has cooling gelling properties. In particular, in the cooling gelling agent dissolved in water, the cooling gelling agent at 15 ° C. The viscosity of the cooling gelling agent at 80 ° C. is preferably 3 times or more, more preferably 5 times or more, and particularly preferably 10 times or more of the viscosity.

  Examples of the cooling gelling agent used in the present invention include gelatin, polyvinyl alcohol, agar, κ-carrageenan, λ-carrageenan, ι-carrageenan, pectin and the like.

  The gelatin is composed of a peptide chain obtained by denaturing collagen having a triple helix structure. The gelatin partially recovers the triple helix structure by cooling, and the recovered triple helix structure. As a starting point, a three-dimensional network is formed to show cooling gelation characteristics.

  The above-mentioned κ-carrageenan, λ-carrageenan, and ι-carrageenan are natural polymer compounds mainly composed of galactose and 3,6-anhydrogalactose having a molecular weight of about 100,000 to 500,000 extracted from red algae seaweed. It is characterized by having a half-ester type sulfate group in the molecule, and usually exhibits a gelling property by using a thickener such as locust bean gum or a metal salt compound in combination. is there.

  The pectin is a natural polysaccharide that constitutes a cell wall of a plant, and exhibits cooling gelation characteristics when used in combination with an ionic compound.

  In the present invention, any of the above cooling gelling agents can be suitably used. In the present invention, only one type of cooling gelling agent may be used, or two or more types of cooling gelling agents may be used in combination.

(Optional additive)
In addition to the constituent material of the receiving layer 2 described above, other additives can be appropriately used as the constituent material of the receiving layer 2 without departing from the spirit of the present invention. Examples of other optional components include an antioxidant, an ultraviolet absorber, a light stabilizer, a filler, a pigment, an antistatic agent, a plasticizer, and a hot-melt material.

  The thickness of the receiving layer 2 configured as described above is appropriately determined within a range in which a desired print density can be expressed according to the type of the resin constituting the receiving layer, the type of thermal transfer image-receiving sheet, the type of ink to be dyed, and the like. In particular, in the present invention, it is preferably in the range of 0.5 μm to 20 μm, particularly preferably in the range of 1 μm to 20 μm, and more preferably in the range of 1 μm to 15 μm. Is preferred.

<Coating liquid for forming receiving layer>
By adjusting the constituent material of the receiving layer 2 described above, the receiving layer forming coating liquid of the present invention is obtained. The receiving layer forming coating solution of the present invention contains at least an aqueous solvent, a dye-dyeable resin, and a crosslinking agent. Further, it is desirable that a release agent and a cooling gelling agent are contained, and in addition, other optional additive components may be included.

The blending ratio of the receiving layer forming coating solution is appropriately determined in consideration of the amount that the dye-dyeable resin constituting the receiving layer is sufficiently cross-linked within a range not departing from the purpose of the receiving layer in the present invention. Good. That is, generally, it is desirable to use an equimolar crosslinking agent with respect to the acid value of the dye-dyeable resin. More specifically, the total amount of crosslinking points of the added crosslinking agent is preferably 60% or more and more preferably 70% or more with respect to the total amount of crosslinking points of the dye-dyeable resin. It is preferably 80% or more, more preferably 90% or more.

Moreover, it is preferable that the said mold release agent is added so that it may become in the range of 0.5 weight part-30 weight part with respect to 100 weight part of dye dyeable resin.

  In addition, the content of the cooling gelling agent in the receiving layer-forming coating liquid of the present invention is not particularly limited as long as it does not interfere with the dyeing property of the receiving layer and is within a range that sufficiently provides the following effects. That is, when a thermal transfer image-receiving sheet is produced within a range that does not interfere with the dyeing property of the receiving layer, when a multilayer including the receiving layer 2 is simultaneously coated on the base sheet, the receiving layer-forming coating solution The cooling gelling agent is added to such an extent that good coating properties are ensured and drying unevenness is prevented in the drying step. In general, the cooling gelling agent is preferably in the range of 2 to 50 parts by weight in terms of weight at the time of drying with respect to 100 parts by weight of the solid content in the coating liquid for forming the receiving layer, In particular, it is preferably in the range of 2 to 30 parts by weight, and more preferably in the range of 2 to 20 parts by weight. When the blending ratio of the cooling gelling agent is less than 2 parts by weight, for example, unevenness or the like is likely to occur when the receiving layer-forming coating solution is applied and dried on the base sheet. There is a possibility that a good multilayer thermal transfer image-receiving sheet is not formed. On the other hand, when the amount is larger than the above range, for example, dyeing may be hindered during image formation, and the density may decrease. The cooling gelling agent is generally dissolved in an aqueous solvent and then mixed with the receiving layer forming coating solution. The concentration when the gelling agent is dissolved in the aqueous solvent should be adjusted appropriately depending on the concentration and viscosity of the receiving layer coating solution, or the viscosity and surface tension of other layers formed adjacent to the receiving layer. Can do.

The receptive layer-forming coating solution is prepared by dispersing or dissolving the above-described dye-dyeable resin, crosslinking agent, or any other additive such as a release agent and a cooling gelling agent in a water-soluble solvent. The The viscosity of the receiving layer-forming coating solution used in the simultaneous multilayer coating step is not particularly limited as long as it is not mixed with other coating solutions that are simultaneously coated on the base sheet in the step. Absent. In particular, in this step, it is preferably within a range of 1 mPa · s to 50 mPa · s at 40 ° C., particularly preferably within a range of 5 mPa · s to 50 mPa · s, and more preferably 7 mPa · s to 40 mPa · s. -It is preferable to be within the range of s.
The viscosity can be measured using, for example, a small vibration viscometer (VIBRO VISCOMETER CJV5000, manufactured by A & D) (hereinafter the same). The solid content concentration of the coating solution for forming a receiving layer used for forming a sheet by the simultaneous multilayer coating method is not particularly limited as long as the viscosity is within a desired range. It is preferably within the range of ˜50% by weight, and more preferably within the range of 10% by weight to 40% by weight. Each solid content is dispersed or dissolved by the above-mentioned aqueous solvent so as to have such a solid content. Is preferred. If the solid content concentration is too low, the viscosity of the solution decreases and the drying time becomes longer. If the solid content concentration is too high, the storage stability of the coating solution decreases, and the viscosity increases, which is inconvenient for coating. Is produced.

  The receptor layer-forming coating solution is prepared before the production of the thermal transfer image-receiving sheet, particularly when the crosslinking reaction initiation temperature is room temperature or a temperature close to room temperature, such as a carbodiimide-based crosslinking agent. It is desirable to complete the present receiving layer forming coating solution by adding the crosslinking agent and dispersing or dissolving it in an aqueous solvent immediately before forming the receiving layer.

<Base material sheet>
Next, the base material sheet 1 used for the thermal transfer image-receiving sheets 10 to 13 of the present invention will be described. The base sheet 1 has a function of supporting the receiving layer 2 described above.
Hereinafter, the base sheet 1 will be described in detail.

  The base sheet 1 used in the present invention has desired heat resistance depending on the printing temperature or the like when forming an image on the receiving layer 2 side using the thermal transfer image receiving sheets 10 to 13 of the present invention. There is no particular limitation as long as it is present. Specific examples include resin-coated paper, resin film base, and paper base, among which resin-coated paper is preferable.

  The resin-coated paper is usually formed by laminating a base resin layer on both sides of a base paper. Examples of the base paper constituting the base paper include natural pulp, synthetic pulp, and pulp paper made from a mixture thereof. Among these, it is preferable to use paper mainly composed of wood pulp. The base paper may be subjected to a conventionally known process such as a calendar process to be described later if necessary.

  The base paper can be produced by a known method, but a base paper that is calendered is preferable. This is because when a base paper that has been calendered is used for the base paper, the smoothness can be improved and the glossiness of the resulting thermal transfer image-receiving sheet can be enhanced. The thickness of the base paper is preferably in the range of 10 μm to 1000 μm, and more preferably in the range of 50 μm to 300 μm.

  The resin for forming the base resin layer is preferably a resin having a small neck-in and a good drawdown property. For example, a polyolefin resin, a polystyrene resin, a vinyl resin, a polyester resin, an ionomer Resin, nylon, polyurethane and the like can be mentioned, and a polyolefin resin is preferable in that a film excellent in water resistance, strength, gloss and the like can be obtained.

  Examples of the polyolefin resin include high-density polyethylene, medium-density polyethylene, low-density polyethylene, polypropylene, polybutene, and polypentene. Among these, high-density polyethylene, medium-density polyethylene, low-density polyethylene, and polypropylene are preferable, and polypropylene is particularly preferable. Is preferred.

  The base resin layer may be a film or sheet obtained by mixing one or more of the resins, and in addition to the resin for forming the base resin layer, a pigment, a filler, etc. It may be a film or sheet formed by adding Further, the resin for forming the base resin layer may be one obtained by blending an additive such as a modifier to improve adhesiveness. Examples of the modifier include olefin copolymers such as Tuffmer (manufactured by Mitsui Chemicals).

  As described above, the resin-coated paper obtained by laminating the base resin layer on both surfaces of the base paper can be produced by a known laminating method such as dry lamination, wet lamination, or extrusion. Each of the above layers can be appropriately subjected to primer treatment or corona discharge treatment for the purpose of improving interlayer adhesion. Moreover, the thickness of the base material sheet 1 which is the resin-coated paper as a whole is preferably in the range of, for example, 10 μm to 1000 μm, and more preferably in the range of 50 μm to 300 μm.

  Next, the resin film substrate will be described. The resinous film substrate used as the substrate sheet 1 in the present invention is, for example, polyester, polyacrylate, polycarbonate, polyurethane, polyimide, polyetherimide, cellulose derivative, polyethylene, ethylene-vinyl acetate copolymer, polypropylene, polystyrene. , Acrylic, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone, polysulfone, polyether sulfone, tetrafluoroethylene, perfluoroalkyl vinyl ether, polyvinyl fluoride, tetrafluoroethylene-ethylene, From resins such as tetrafluoroethylene-hexafluoropropylene, polychlorotrifluoroethylene, and polyvinylidene fluoride It is possible to form. In particular, in the present invention, polyethylene terephthalate or polypropylene resin can be suitably used as a resin for forming the resin film substrate.

As thickness of the base material sheet 1 which is the said resin-made film base materials, it is preferable to exist in the range of 20 micrometers-100 micrometers, for example, especially in the range of 25 micrometers-60 micrometers, and especially in the range of 30 micrometers-50 micrometers.

  Examples of the paper substrate used as the substrate sheet 1 include condenser paper, glassine paper, sulfuric acid paper, high-size paper, synthetic paper (polyolefin-based, polystyrene-based), high-quality paper, art paper, Examples thereof include coated paper, cast coated paper, wallpaper, backing paper, synthetic resin or emulsion-impregnated paper, synthetic rubber latex-impregnated paper, synthetic resin-incorporated paper, paperboard, and cellulose fiber paper.

  In the case of using the paper base material as the base material sheet 1, the thickness is not particularly limited. For example, the thickness is in the range of 80 μm to 400 μm, particularly in the range of 100 μm to 300 μm, particularly in the range of 100 μm to 210 μm. It is preferable to be within the range.

<Porous layer>
In the thermal transfer image receiving sheet of the present invention, at least a receiving layer is provided on the base sheet, but one or more functional layers may be provided between the base sheet and the receiving layer as necessary. The functional layer is not particularly limited as long as it is for improving production efficiency or printing characteristics in the thermal transfer image receiving sheet. Hereinafter, a porous layer will be described with reference to FIGS. 2 to 4 as an example of a functional layer that can be formed between the base sheet and the receiving layer as one of the functional layers.

  The porous layer 3 shown in FIGS. 2 to 4 is formed between the base sheet 1 and the receiving layer 2 and is configured to include at least a binder resin and hollow particles, and more preferably a cooling gel. It is comprised including an agent. The porous layer 3 is formed by transferring heat applied from the thermal head to the receiving layer 2 to the base sheet 1 or the like when an image is formed using the thermal transfer image receiving sheets 11 to 13 of the present invention. It is a layer for imparting heat insulation to the sheet to prevent loss of the material sheet. In addition, the porous layer 3 has a cushioning property by containing hollow particles, and in the thermal transfer image-receiving sheet provided with the porous layer 3, density unevenness at the time of image formation and white spots in highlight portions are prevented. Printing characteristics can be improved.

The heat insulation property of the porous layer 3 can be arbitrarily adjusted by the thickness of the porous layer 3 or the porosity of the porous layer mainly resulting from the amount of hollow particles contained in the porous layer 3. . The heat insulating property of the porous layer 3 can be appropriately adjusted according to the use of the thermal transfer image receiving sheets 11 to 13 of the present invention.

From the viewpoint of providing sufficient heat insulation to the porous layer 3, the thickness of the porous layer 3 is preferably in the range of 10 μm to 100 μm, and more preferably in the range of 10 μm to 50 μm. At this time, the density of the porous layer 3 ^is in the range of ^{0.1g / cm 3 ~0.8g / cm 3} , among them is within the range of 0.2g ^/ cm ³ ~0.7g ^/ cm 3 It is preferable.

Similarly, the porosity of the porous layer 3 is preferably in the range of 15% to 80% from the viewpoint of giving sufficient heat insulation to the porous layer 3. The porosity is as follows:
(Void ratio of hollow particles) × (content ratio of hollow particles in the porous layer)
The value represented by

  The porous layer 3 used in the present invention may have a configuration composed of a single layer, or may have a configuration in which a plurality of layers are laminated. Here, the porous layer 3 having a configuration in which a plurality of layers are stacked may have a configuration in which layers of the same composition are stacked, or a configuration in which layers of different compositions are stacked. You may have. In particular, the porous layer 3 used in the present invention preferably has a configuration in which two layers having different compositions are laminated. It is because a more functional porous layer can be obtained by setting it as such a structure.

  As an example of the case where the porous layer 3 used in the present invention has a two-layer structure, the porous layer 3 includes a porous layer A containing hollow particles a and the hollow from the base sheet 1 side. The thing which has the structure by which the porous layer B containing the hollow particle b whose hollow rate is smaller than the particle | grains a was laminated | stacked can be mentioned. By using the porous layer 3 having such a two-layer structure, the effect of improving the printing characteristics such as density unevenness at the time of printing and white spot prevention in the highlight portion can be exhibited more satisfactorily.

(Hollow particles)
The hollow particles contained in the porous layer 3 will be described. The hollow particles used in the present invention have a function of imparting heat insulation and cushioning properties to the porous layer 3. Accordingly, the hollow particles are not particularly limited as long as the desired heat insulation and cushioning properties can be imparted to the porous layer 3, and foamed particles may be used, or non-foamed particles are used. You can also. The expanded particles used as the hollow particles may be independent expanded particles or continuous expanded particles. Furthermore, the hollow particles used in the present invention may be organic hollow particles composed of resin or the like, or inorganic hollow particles composed of glass or the like. The hollow particles may be cross-linked hollow particles.

  Examples of the resin constituting the hollow particles include styrene resins such as crosslinked styrene-acrylic resins, (meth) acrylic resins such as acrylonitrile-acrylic resins, phenolic resins, fluorine resins, polyamide resins, and polyimide resins. Examples thereof include resins, polycarbonate resins, and polyether resins.

  The average particle diameter of the hollow particles is not particularly limited as long as the desired heat insulation and cushioning properties can be imparted to the porous layer depending on the type of resin constituting the hollow particles, etc. , Preferably in the range of 0.1 μm to 15 μm, particularly preferably in the range of 0.1 μm to 10 μm. This is because if the average particle size is too small, the amount of hollow particles used increases and the cost increases, and if the average particle size is too large, it becomes difficult to form a smooth porous layer.

  In the present invention, the amount of the hollow particles contained in the porous layer 3 is not particularly limited as long as the porous layer 3 having desired heat insulating properties and cushioning properties can be obtained. When the total solid content is 100% by weight, the proportion of hollow particles is preferably in the range of 30% to 90% by weight, and in particular, in the range of 50% to 80% by weight. Is preferred. If the content is too small, voids in the porous layer may decrease, and sufficient heat insulating properties and cushioning properties may not be obtained, and the content ratio is too large, and the weight ratio of the binder resin for forming a porous layer described later is too high. This is because if the thickness is too small, the porous layer becomes brittle and the moldability of the layer may deteriorate.

(Binder resin for porous layer formation)
As the binder resin used to form the porous layer 3, a so-called aqueous resin that can be dispersed or dissolved in an aqueous solvent is usually used. Examples of such water-based resins include polyurethane resins such as acrylic urethane resins, polyester resins, gelatin, polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, pullulan, carboxymethyl cellulose, hydroxyethyl cellulose, dextran, dextrin, and polyacrylic acid. And salts thereof, agar, κ-carrageenan, λ-carrageenan, ι-carrageenan, casein, xanthene gum, locust bean gum, alginic acid, gum arabic, and those described in JP-A-7-195826 and 7-9757. Homopolymerization of a real xylene oxide copolymer, water-soluble polyvinyl butyral, or a vinyl monomer having a carboxyl group or a sulfonic acid group described in JP-A-62-245260 And copolymers and the like. Moreover, you may use in combination of 2 or more types of the said resin. In the case of using a material such as gelatin, polyvinyl alcohol, agar, κ-carrageenan, λ-carrageenan, ι-carrageenan, etc. as the porous forming binder resin, these binder resins also exhibit a cooling gelling function. Therefore, it can be satisfactorily produced in the simultaneous multilayer coating method without using a cooling gelling agent described later.

(Cooling gelling agent)
Next, the cooling gelling agent used for the porous layer 3 will be described. The cooling gelling agent used in the present invention has a property of gelling when cooled, and has a thermal transfer image receiving sheet 11 having at least an aqueous receiving layer 1 and a porous layer 3 on a base sheet 1. Thru 13 can be manufactured with high efficiency by simultaneous multilayer coating. In addition, about the kind of cooling gelling agent used for the porous layer 3, it is the same as that of the cooling gelling agent used for the receiving layer 1 mentioned above.

  Moreover, in this invention, the ratio of the hollow particle contained in the porous layer 3 and a cooling gelling agent will not be specifically limited if the porous layer which has desired heat insulation property can be formed. Especially, in this invention, it is preferable that a cooling gelatinizer exists in the range of 10-50 weight part in conversion of weight with respect to 100 weight part of solid content in a porous layer coating liquid, Especially 10. It is preferably within the range of ˜40 parts by weight, and more preferably within the range of 12-40 parts by weight. It is because the porous layer 3 excellent in heat insulation can be formed when the content ratio of the hollow particles and the cooling gelling agent is within the above range.

(Optional additive)
The porous layer 3 used in the present invention may contain an optional additive component as necessary in addition to the hollow particles and the cooling gelling agent described above. Examples of the optional additive component that can be contained in the porous layer 3 include nonionic silicone surfactants, curing agents such as isocyanate compounds, wetting agents, and dispersants. .

<Primer layer>
As another example of the functional layer that can be formed between the base sheet and the receiving layer in the thermal transfer image receiving sheet of the present invention, a primer layer will be described with reference to FIGS. The first primer layer 4 provided on the thermal transfer image receiving sheets 12 and 13 shown in FIG. 3 and FIG. 4 is between the substrate sheet 1 and the porous layer 3, and the second primer layer 5 is porous. It is formed between the layer 3 and the receiving layer 2. Each of these primer layers has a function of improving the adhesion between the substrate sheet 1 and the porous layer 3 or the adhesion between the porous layer 3 and the receiving layer 4. That is, in the present invention, the primer layer is provided between the layers constituting the thermal transfer image-receiving sheet laminated on the base sheet and between the sheets, or between each layer, and is optionally formed in order to improve their adhesion. Is.

(Binder resin for primer layer formation)
The first primer layer 4 and the second primer layer 5 used in the present invention are desired to have an adhesive property between the base sheet 1 and the porous layer 3 or an adhesive property between the porous layer 3 and the receiving layer 4. There is no particular limitation as long as it can be improved to the above level. In particular, in the present invention, the resin is preferably composed of a resin that can be dispersed or dissolved in an aqueous solvent. This is because each layer constituting the thermal transfer image receiving sheet is formed of a material that can be dispersed or dissolved in an aqueous solvent, thereby enabling the thermal transfer image receiving sheet to be manufactured by the simultaneous multilayer coating method. Here, as the primer layer forming resin, the same resin as the water-based resin used as the porous layer forming binder described with respect to the porous layer 3 described above can be used. As shown in FIG. 4, when two or more primer layers are formed on one thermal transfer image-receiving sheet, the plurality of primer layers may be formed using the same binder resin, or The primer layer may be formed of different binder resins.

(Cooling gelling agent)
The first primer layer 4 and the second primer layer 5 used in the present invention preferably contain a cooling gelling agent. When the first primer layer 4 and the second primer layer also contain a cooling gelling agent, the first primer layer 4 and the second primer are formed on the substrate sheet 1 when the thermal transfer image receiving sheet of the present invention is produced. This is because the layer 5, the porous layer 3, and the receiving layer 2 can be satisfactorily manufactured by the simultaneous multilayer coating method. Here, as the cooling gelling agent, those similar to the cooling gelling agent used for the receiving layer 1 described above can be used.

  When using the primer layer forming resin and the cooling gelling agent as the primer layer, the ratio of the primer layer forming resin and the cooling gelling agent in the primer layer is as follows. When forming, it is not particularly limited as long as it is within a range in which a desired viscosity characteristic can be imparted to the primer layer forming coating solution. Especially in this invention, it is preferable that a cooling gelling agent exists in the range of 1-100 weight part in conversion of weight with respect to 100 weight part of solid content in the coating liquid for primer layer formation, and especially 20 It is preferably in the range of ˜80 parts by weight, and more preferably in the range of 25 to 75 parts by weight. When the content ratio of the cooling gelling agent is less than the above range, when the primer layer forming coating solution is applied onto the base sheet, for example, the adhesion with other layers may be reduced. Because.

(Other additive components)
The first primer layer 4 used in the present invention may further contain an optional additive component in addition to the primer layer forming binder resin and the cooling gelling agent. Examples of the optional additive component include a nonionic silicone-based surfactant, a curing agent such as an isocyanate compound, a wetting agent, and a dispersant. The curing agent is particularly effective when, for example, a thermoplastic resin having active hydrogen is used as the primer layer forming resin.

[Method for producing thermal transfer image-receiving sheet]
Next, a method for manufacturing the thermal transfer image receiving sheets 10 to 13 of the present invention will be described. The thermal transfer image receiving sheets 10 to 13 of the present invention can be generally produced using a known method as a method for producing a thermal transfer image receiving sheet. That is, the constituent layers may be sequentially laminated and manufactured on the base sheet 1 by a gravure coating method or the like. In particular, when manufacturing a thermal transfer image receiving sheet having a plurality of layers including a receiving layer on the substrate sheet 1, such as the thermal transfer image receiving sheets 11 to 13, a simultaneous multi-layer coating method in which the plurality of layers are simultaneously coated is used. It can also be manufactured. Alternatively, the thermal transfer image-receiving sheet of the present invention can be formed by simultaneously forming a plurality of functional layers such as a porous layer and a primer layer on a substrate sheet by, for example, a simultaneous multilayer coating method in addition to the manufacturing method described above. It is also possible to provide a step of applying the layer separately. However, since each of the thermal transfer image-receiving sheets 10 to 13 of the present invention is constituted by a three-dimensional cross-linking structure formed by cross-linking a dye dyeable resin and a cross-linking agent, a cross-linking step that enables the cross-linking reaction is required. And

Below, in order to demonstrate the manufacturing method of the thermal transfer image receiving sheet of this invention more concretely, it demonstrates using the manufacture example of the thermal transfer image receiving sheet 12 by the simultaneous multilayer coating method.
An application process performed by a slide coating method using a so-called slide coater will be described with reference to FIG.

(Coating process)
First, the application | coating process which laminates | stacks a some layer simultaneously on a base material sheet is demonstrated using FIG. FIG. 5 is a diagram illustrating a method for manufacturing a thermal transfer image receiving sheet 12 having a first primer layer 4, a porous layer 3 and a receiving layer 2 on a substrate sheet 1 by a slide coating method using a slide coater. It is a conceptual diagram which shows a mode that the coating liquid for forming is simultaneously apply | coated on the base material sheet | seat 1, and the multilayer sheet | seat 42 is formed.

The multilayer sheet 42 is formed by winding the base sheet 1 fed from an unwinder (not shown) around the back roll 14, and on the exposed surface side, a first primer layer forming layer 34, a porous layer forming layer 33, And the receiving layer forming layer 32 in this order. The three layers laminated on the substrate sheet 1 are the first primer layer forming coating solution 24, the porous layer forming coating solution 23, and the receiving layer, which are filled in the coating device 15 independently. The forming coating liquid 22 is simultaneously formed on the base sheet 1 and formed. When a plurality of coating liquids are simultaneously applied by a slide coater, the temperature of each coating liquid is generally adjusted within a range of 25 ° C. to 60 ° C., but in the thermal transfer image receiving sheet 12 of the present invention. Since the receiving layer 2 contains a crosslinking agent, the temperature of the coating solution needs to be determined in consideration of the crosslinking temperature of the crosslinking agent. More specifically, it is necessary to pay attention to this point because there is a possibility that the coating property of the receiving layer forming coating liquid 22 may be lowered if a crosslinking reaction is actively generated in the coating apparatus 15.

From the viewpoint of coating quality, the slide coating method is excellent in film thickness uniformity, and since there is no rotating part, quality defects due to scattering of the coating liquid are unlikely to occur, and there is no friction part, so there is no friction part. There is an advantage that loss due to cutting is less likely to occur. Also, from the viewpoint of handling properties of the coating liquid, the slide coating method can use a coating liquid that is less likely to change in concentration, viscosity, and composition of the coating liquid and that has high reactivity and changes over time. The coating liquid can be used up and waste is hardly generated, and a high solid content coating liquid can be used, and the amount of solvent used can be reduced.

  In the above-mentioned slide coating method, the coating liquid for forming the primer layer, the coating liquid for forming the porous layer, and the coating liquid for forming the receiving layer are usually mixed with a surfactant, etc. Is added so that the difference in surface tension between the two coating liquids is within a certain range.

(Cooling process)
Next, the multilayer sheet 42 formed as described above is subjected to a cooling process. In the cooling process, each layer formed on the base sheet 1 is cooled by a cooling method 1 in which cool air is blown onto the multilayer sheet 42, and a cooling zone in which the multilayer sheet 42 is adjusted to a room temperature below a desired temperature. There is a cooling method 2 or the like for passing through. As another method, the base sheet 1 that has already been cooled in the coating step is applied to the back roll 14, and each layer is cooled at the temperature of the base sheet 1 by applying the coating liquid of each layer thereon. The cooling method 3 for simultaneously performing the coating process and the cooling treatment process, or by cooling the surface of the back roll 14 carrying the base sheet 1 and cooling each layer via the base sheet 1, The cooling method 4 etc. which perform a cooling process process simultaneously may be sufficient. Moreover, you may implement a cooling process process combining the cooling methods 1 thru | or 4 mentioned above.

  In the cooling treatment step, the temperature for forcibly cooling the coating film is usually in the range of 0 ° C. to room temperature. By performing such a cooling process, the cooling gelling agent present in the multilayer sheet 42 is cooled and gelled.

(Drying process and crosslinking process)
The multilayer sheet 42 cooled in the cooling step is subsequently subjected to a drying step and a crosslinking step, whereby the thermal transfer image receiving sheet 12 is completed. As a method of drying the multilayer sheet 42, the multilayer sheet 42 can be dried by non-contact drying by blowing warm air of appropriate temperature while sequentially feeding the multilayer sheet 42 to a plurality of rolls. At this time, it is preferable to provide a drying path length of 500 m or longer, thereby preventing a rapid drying of the sheet, thereby forming a good thermal transfer image-receiving sheet free from drying unevenness.
The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

  In the drying step of the multilayer sheet 42, a crosslinking reaction can be caused in the dye-dyeable resin and the crosslinking agent contained in the receiving layer 2 by the heat of drying. That is, the thermal transfer image-receiving sheet of the present invention is characterized in that the receiving layer is constituted by a three-dimensional cross-linking structure formed by a cross-linking reaction between a dye-dyeable resin and a cross-linking agent. In addition to being produced with high efficiency by producing by the method, there is an advantage that the drying step and the crosslinking step can be carried out by the same treatment. However, the above description does not mean that the three-dimensional crosslinked structure constituting the receiving layer in the present invention is achieved only by the crosslinking step that also serves as the drying step. That is, as long as the above does not work adversely in the thermal transfer image-receiving sheet manufacturing process, a part of the crosslinking reaction in the receiving layer is in the state of the coating liquid during the manufacturing process other than the drying process or inside the coating apparatus. It does not exclude what happens.

  The drying step also serving as a crosslinking step, which is performed in the production of the thermal transfer image-receiving sheet of the present invention, varies depending on the type of crosslinking agent used, but is preferably 30 ° C to 90 ° C, more preferably 40 ° C to 60 ° C. The method of drying the coating film in the step is not particularly limited as long as the aqueous solvent remaining in the coating film can be reduced to a predetermined amount or less within a predetermined time and the crosslinking reaction can proceed. is not. About such a drying method, generally a well-known method can be used as a method of drying a coating film.

  As described above, the thermal transfer image-receiving sheet and the receiving layer-forming coating liquid of the present invention have been described by way of some embodiments. However, the present invention is not limited to the above-described embodiments. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

  Hereinafter, the present invention will be described in more detail with reference to examples. The indicated weight parts were described as solid content and diluted with pure water as necessary.

(1) Preparation method of sample Preparation method of styrene-acrylic copolymer (synthesis of emulsion 1)
In a 500 mL Erlenmeyer flask, 102 g of styrene, 54 g of ethyl acrylate, 42 g of lauryl acrylate, 3 g of acrylic acid, and 1.9 g of Aqualon HS-10 (Daiichi Kogyo Seiyaku Co., Ltd.) were stirred and mixed (hereinafter referred to as “ Called Composition A ”). In a 1 L three-necked flask, 200 g of distilled water was added and heated to 80 ° C., and about 20% of the total amount of the composition A was added and stirred for 10 minutes. Thereafter, 0.2 g of ammonium persulfate dissolved in 20 g of pure water was added and stirred for 10 minutes, and then the remaining 80% of the composition A was dropped with a dropping funnel over 3 hours and further stirred for 3 hours. Thereafter, the mixture was cooled to room temperature and filtered through # 150 mesh (Japanese woven fabric) to obtain Emulsion 1. Molecular weight 244000, Tg 50 ° C. Further, from the molecular weight of styrene, ethyl acrylate and lauryl acrylate and the amount used for the reaction, the respective molar ratios are 58%, 32% and 10%.

(Synthesis of Emulsion 2)
Emulsion 2 was obtained by synthesis in the same manner as the synthesis of emulsion 1 except that the amount of acrylic acid added was changed to 4 g. The reaction time was continued until the presence of the monomer could not be confirmed by TLC, or the abundance did not decrease.

(Preparation of receiving layer forming coating solution 1)
10 parts by weight of gelatin (RR, manufactured by Nitta Gelatin Co., Ltd.) dissolved in water with respect to 90 parts by weight of the above emulsion 1 (styrene acrylate copolymer), and a silicone-based system 10 parts by weight of a release agent (KF615A, manufactured by Shin-Etsu Chemical Co., Ltd.) was dispersed and dissolved in pure water to prepare a coating solution 1 for forming a receiving layer.
In addition, the concentration of the coating liquid 1 for forming the receiving layer is adjusted to include the total solid content of 6.2 parts by weight of a carbodiimide-based crosslinking agent (Carbodilite V-04, manufactured by Nisshinbo Co., Ltd.) added in-line in a slide coating apparatus described later. Was adjusted to pure water so as to be 25% by weight.

(Porous layer forming coating solution)
75 parts by weight of hollow particles (HP-91, manufactured by Rohm and Haas), 25 parts by weight of gelatin (RR, manufactured by Nitta Gelatin) dissolved in water (weight ratio when gelatin is dried), and surface activity 0.15 parts by weight of an agent (Surfinol 440, manufactured by Nissin Chemical Industry Co., Ltd.) was dispersed and dissolved in pure water, and diluted with pure water so that the total solid content was 17% by weight.

Example 1
Using a slide coater capable of simultaneous multilayer coating, a thermal transfer image receiving sheet was prepared as follows. Resin coated paper (STF-150, manufactured by Mitsubishi Paper Industries Co., Ltd.) is used as a base sheet, and the receiving layer forming coating solution 1 and the porous layer forming coating solution are heated to 40 ° C., respectively. The carbodiimide-based crosslinking agent was added in-line to the receiving layer forming coating solution 1 immediately before being applied to the base material sheet, focusing on the working solution tank. And two layers were apply | coated simultaneously so that a porous layer and a receiving layer may be laminated | stacked in this order on a base material sheet. Next, the obtained laminate was cooled at 10 ° C. or lower for 1 minute to gelatinize the gelatin contained in each layer, and further dried at 50 ° C. for 5 minutes to produce a thermal transfer image receiving sheet. did.
Each layer was coated such that the film thickness upon drying was 40 μm for the porous layer and 5 μm for the receiving layer.

(Example 2)
As the dye-dyeable resin in the receiving layer forming coating solution 1, the styrene acrylate copolymer was changed from the emulsion 1 to the emulsion 2, and the amount of the carbodiimide-based crosslinking agent added was changed to 8.3 parts by weight. Example 2 was prepared in the same manner as in Example 1, except that a coating solution 2 for forming a receiving layer was prepared.

(Comparative Example 1)
A thermal transfer image-receiving sheet was prepared in the same manner as in Example 1 except that the receiving layer-forming coating solution 1 was used and no crosslinking agent was used.

(Comparative Example 2)
A similar receiving layer forming coating solution 4 was prepared as the dye dyeable resin in the receiving layer forming coating solution 3 except that the styrene acrylate copolymer was changed from emulsion 1 to emulsion 2. Comparative Example A thermal transfer image-receiving sheet was prepared in the same manner as in Example 1 and used as Comparative Example 2.

  Table 1 summarizes the names and theoretical oxidation of the dye-dyeable resins contained in the receiving layer-forming coating solutions used in the above Examples and Comparative Examples, and the presence or absence of a crosslinking agent.

エマルジョン１、２：スチレンアクリル酸エステル共重合体
カルボジライトＶ‐０４：カルボジイミド(日清紡製)

Emulsions 1 and 2: Styrene acrylate copolymer Carbodilite V-04: Carbodiimide (Nisshinbo)

(Evaluation)
Using Example 1 produced as described above, an image was printed on the receiving layer side by a thermal transfer method described later, and the matting of the image was evaluated as follows. Further, Example 2 and Comparative Example 1 or 2 were similarly printed, and the matting of the image was evaluated. The evaluation results are summarized in Table 2.

<Printing method and matte evaluation>
Using the thermal transfer image receiving sheet of Example 1, a black solid image was printed on the receiving layer side of Example 1 with a sublimation thermal transfer printer CP-720 (manufactured by Canon Inc.), and the sharpness of the image at that time was as follows: Sensory evaluation was performed, and it was determined that the matte was larger as the image was not clear.

(Criteria for sensory evaluation)
A: Although the image was slightly changed, it was sufficiently clear and had no problem in practical use.
○: Change is seen in the image, but it can be put to practical use as a high-quality image.
X: Deterioration in image quality was confirmed, and it was visually confirmed that matting occurred.

As shown in Table 2, Example 1 and Example 2 in which the receiving layer was formed using the receiving layer forming coating solution to which the cross-linking agent was added were the same as the conventional case when the image was printed. Compared to that, matting was definitely improved. The reason is considered that the heat resistance of the receiving layer is improved because the receiving layer is constituted by a dye-dyeable resin and a crosslinking agent in a three-dimensional cross-linked structure.

On the other hand, in either Comparative Example 1 or 2, it was confirmed that the printed image was matted. This is a result of the receiving layer being taken up by the dye layer due to the winding force of the ink ribbon in the state in which the dye-dyeing resin in the dye layer and the receiving layer is fused by heat at the time of printing at the time of thermal transfer. It was guessed.

1 is a schematic cross-sectional view showing one embodiment of a thermal transfer image receiving sheet of the present invention. 1 is a schematic cross-sectional view showing one embodiment of a thermal transfer image receiving sheet of the present invention. 1 is a schematic cross-sectional view showing one embodiment of a thermal transfer image receiving sheet of the present invention. 1 is a schematic cross-sectional view showing one embodiment of a thermal transfer image receiving sheet of the present invention. It is a conceptual diagram which shows having formed the multilayer sheet with the simultaneous multilayer coating method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material sheet 2 Receiving layer 3 Porous layer 4 1st primer layer 5 2nd primer layer 10 Thermal transfer image receiving sheet 11 of this invention Thermal transfer image receiving sheet 12 of this invention Thermal transfer image receiving sheet 13 of this invention Thermal transfer image receiving sheet 14 of this invention Back roll 15 Coating device 22 Receptor layer forming coating solution 23 Porous layer forming coating solution 24 First primer layer forming coating solution 32 Receiving layer forming layer 33 Porous layer forming layer 34 First primer layer Forming layer 42 Multi-layer sheet

Claims (8)

In the base sheet and the thermal transfer image receiving sheet provided with at least a receiving layer on the base sheet,
The receiving layer contains a dye-dyeable resin having an active hydrogen-containing functional group that can be dispersed or dissolved in an aqueous solvent, and a crosslinking agent, and the dye-dyeable resin and the crosslinking agent are crosslinked. A thermal transfer image-receiving sheet comprising a three-dimensional cross-linked structure formed by 2. The thermal transfer image receiving sheet according to claim 1, wherein the dye dyeable resin is a styrene acrylic copolymer resin. The thermal transfer image-receiving sheet according to claim 1 or 2, wherein the crosslinking agent is a carbodiimide-based crosslinking agent. The thermal transfer image receiving sheet according to any one of claims 1 to 3, wherein a release agent is contained in the receiving layer. The thermal transfer image receiving sheet according to any one of claims 1 to 4, further comprising a porous layer between the base sheet and the receiving layer. A receiving layer-forming coating solution comprising an aqueous solvent, a dye-dyeable resin having an active hydrogen-containing functional group that can be dispersed or dissolved in the aqueous solvent, a crosslinking agent, and a cooling gelling agent. The receiving layer forming coating solution according to claim 6, wherein the dye-dyeing resin is a styrene acrylic copolymer resin. The receiving layer-forming coating solution according to claim 6 or 7, wherein the crosslinking agent is a carbodiimide-based crosslinking agent.

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