JP2010269583A - Thermal transfer receptive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal transfer receptive sheet which shows successful mold releasability from a dye heat transfer sheet during printing, obtains a sharp and highly light-resistant printed image, and has superb adhesion with a laminate protecting layer. <P>SOLUTION: The thermal transfer receptive sheet is constituted of a sheet-like support and an image receiving layer laminated on at least one surface of the sheet-like support. In addition, the image receiving layer contains a polyurethane resin synthesized with a polymeric component containing (A) to (C) and a releasing agent. (A) A polyisocyanate of which an alicyclic polyisocyanate and/or an aliphatic polyisocyanate account for not smaller than 90 mass%, (B) an polyol of which an aromatic diol accounts for not smaller than 50 mass%, and (C) a low molecular weight polyamine compound. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The thermal transfer receiving sheet of the present invention relates to a thermal transfer receiving sheet having good releasability from a dye thermal transfer sheet at the time of printing, providing a clear and excellent light-resistant printed image, and excellent transferability of a laminate protective layer. Is.

  The dye thermal transfer system is a thermal transfer receiving sheet (hereinafter also referred to as “receiving layer”) having a dye thermal transfer sheet (hereinafter also referred to as “ink ribbon”) and an image receiving layer (hereinafter also referred to as “receiving layer”) that receives the dye. The dye layer and the receiving layer are superposed, and the dye is transferred onto the receiving layer by heating to form an image. Heating is performed with a thermal head, and a full-color image is formed with multicolored dots. Since the dye is used, the image is clear and highly transparent, and a high-quality image usable for photographic use is obtained. In recent years, in order to prevent scratches on the printed image, sublimation thermal transfer printers that transfer a laminate protective layer after printing have become common.

  As the resin for forming the receptor layer, dyeable thermoplastic resins such as vinyl chloride resins, polyester resins, polyurethane resins, polyvinyl acetal resins, acrylic resins, and cellulose resins have been proposed. Generally, such a thermoplastic resin is dissolved or dispersed in water or an organic solvent to prepare a receiving layer coating solution, which is applied to a sheet-like support and dried to form a receiving sheet, Commercialized.

The vinyl chloride resin has high water resistance, and when used in the receiving layer, the printed matter is excellent in image storability in a high-temperature and high-humidity environment. Acrylic resins and polyester resins have the problem that it is difficult to achieve both the releasability of the receiving layer and the transferability of the heat transferable laminate protective layer. Cellulosic resins have good releasability of the receiving layer, but have a problem that the printing density is low and the image blurs in a high temperature and high humidity environment.
Regarding the polyurethane resin, a urethane resin containing 5 to 90 parts by weight of an aromatic component has been proposed as an example of a thermal transfer recording resin (Patent Document 1).
However, in order to cope with sublimation thermal transfer printers whose printing speed has been increasing in recent years, color density, image light resistance, peelability from ink ribbon, and lamination can be achieved only by controlling the content ratio of aromatic components. It is difficult to balance the required quality of transferability of the protective layer.

Patent Document 2 proposes a urethane resin synthesized from a non-aromatic polyisocyanate and a polyol. However, a urethane resin that does not contain a certain amount or more of an aromatic component has poor dyeability and is not suitable for high-speed thermal transfer printing. Further, Patent Document 2 proposes the use of an aliphatic polyol, but the aliphatic polyol has low heat resistance and is likely to cause a fusing trouble with an ink ribbon in high-speed thermal transfer printing.
In order to avoid running troubles such as sticking of the ink ribbon and the image receiving layer, proposals have been made to add a release agent to the image receiving layer (Patent Documents 3 to 5).
However, in consideration of only the releasability of the ribbon and the adhesiveness between the image receiving layer and the substrate, the image receiving layer formulation to which a release agent is added has a problem that transfer failure of the laminate protective layer occurs.

JP-A-10-337968 (pages 1 to 3) JP-A-10-337969 (pages 1 and 2) JP-A-3-39293 (page 2) JP-A-4-219286 (page 2) Japanese Patent Laid-Open No. 6-8661 (page 2)

  The present invention improves the above-mentioned disadvantages of the prior art, has good releasability from the dye thermal transfer sheet at the time of printing, provides a clear and excellent light-resistant printed image, and is excellent in transferability of the laminate protective layer. It is intended to provide a thermal transfer receiving sheet.

The present invention includes the following inventions.
(1) In a thermal transfer receiving sheet in which an image receiving layer is formed on at least one surface of a sheet-like support, a sheet-like support, and the sheet-like support, the image receiving layer includes the following (A) to ( A thermal transfer receiving sheet comprising a polyurethane resin synthesized from a polymerization component containing C) and a release agent.
(A) Polyisocyanate comprising 90% by mass or more of alicyclic polyisocyanate and / or aliphatic polyisocyanate.
(B) A polyol comprising 50% by mass or more of an aromatic diol.
(C) Low molecular weight polyamine compound (2) The blending ratio of (A) and (B) during the synthesis of the polyurethane resin is such that the isocyanate group possessed by (A) and the hydroxyl group possessed by (B) The thermal transfer receiving sheet according to (1), which has a molar ratio of 100: 40 to 100: 90.
(3) The polyurethane resin is further synthesized from a polymerization component containing the following (D), and the carboxyl group content is 0.3 to 6% by mass with respect to 100% by mass of the polyurethane resin. The thermal transfer receiving sheet according to (1) or (2).
(D) A diol having a carboxyalkyl group as a side chain.
(4) The thermal transfer receiving sheet according to (1) to (3), wherein the release agent is at least one selected from waxes and fluorine compounds.
(5) The thermal transfer receiving sheet according to (4), wherein the fluorine compound is a nonionic compound.
(6) The thermal transfer receiving sheet according to (5), wherein the fluorine compound is perfluoroalkylethylene oxide.
(7) The thermal transfer receiving sheet according to (2) to (6), wherein fluorine atoms present on the surface of the image receiving layer are 0.5 to 5.0 atomic% by X-ray photoelectron spectroscopy.
(8) The thermal transfer receiving sheet according to (4), wherein the wax is at least one selected from carnauba wax, paraffin wax, carboxyl group-containing paraffin wax, and carboxyl group-containing polyethylene wax.
(9) An intermediate layer is provided between the sheet-like support and the image receiving layer, and the intermediate layer contains a resin having a glass transition temperature of 40 to 90 ° C. as a main component (1) to ( 8) Thermal transfer receiving sheet.

  According to the present invention, a high-density image excellent in sharpness and light resistance can be obtained, and a thermal transfer receiving sheet excellent in transferability of the laminate protective layer can be obtained. Further, since the thermal transfer receiving sheet of the present invention has good releasability from the dye thermal transfer sheet at the time of printing, it is possible to reduce printer paper discharge defects at the time of printing.

In a thermal transfer receiving sheet having a sheet-like support and an image receiving layer formed on at least one surface of the sheet-like support, the image receiving layer is synthesized from a polymerization component containing polyisocyanate, polyol and low molecular weight polyamine. And a polyurethane resin and a release agent.
The present invention is described in detail below.

(Sheet support)
As the sheet-like support used in the present invention, papers and synthetic resin sheets mainly composed of cellulose pulp are used. Examples of paper include high-quality paper (acidic paper, neutral paper), medium-quality paper, coated paper, art paper, glassine paper, and resin-laminated paper.
Examples of the sheet mainly composed of a synthetic resin include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polyamide, polyvinyl chloride, polystyrene, polycarbonate, and polyvinyl chloride.
Examples of the porous stretched sheets include, for example, synthetic paper, porous polyester sheet and the like mainly composed of a thermoplastic resin such as polyolefin and polyester. These materials may be used alone, or may be a laminate sheet obtained by laminating and adhering porous stretched sheets, porous stretched sheets and other sheets and / or papers.

The sheet-like support may have a structure in which a first base layer on which a receiving layer is formed, an adhesive layer, a release agent layer, and a second base layer are sequentially laminated. Of course, a support having a structure of (also referred to as a seal type) can be used.
The smoothness on the receiving layer surface side of the sheet-like support is preferably 50 seconds or more. If it is less than 50 seconds, the smoothness of the obtained receiving sheet may be insufficient, and the image uniformity may be impaired. The smoothness is an index of the smoothness of the sheet surface. It is obtained by measuring the flow rate of air flowing between the reference surface and the test piece surface under a certain condition, and is defined in J. TAPPI paper pulp test method No. 5 (Oken type smoothness).

  Among the above supports, papers mainly composed of cellulose pulp are preferable. The texture of the receiving sheet obtained is close to that of photographic paper, which is advantageous in terms of cost. When using papers mainly composed of cellulose pulp as the sheet-like support, it is preferable to provide an intermediate layer containing hollow particles on the sheet-like support. Although the material and manufacturing method of the hollow particles used in the intermediate layer are not particularly limited, specifically, as the material for forming the walls of the hollow particles, acrylonitrile, vinylidene chloride, styrene acrylate ester or the like alone Examples thereof include polymers, copolymers thereof, and homopolymer mixtures thereof. Examples of a method for producing these hollow particles include a method of encapsulating butane gas in resin particles and heating and foaming, an emulsion polymerization method, and the like.

(Receptive layer)
The present invention relates to a thermal transfer receiving sheet in which an image receiving layer is formed on at least one surface of a sheet-like support, wherein the image receiving layer contains a polyurethane resin having a specific composition in the molecule. Is.

(Polyurethane resin)
In the present invention, the method for synthesizing the polyurethane resin to be used is not particularly limited. Generally, after synthesizing a urethane prepolymer obtained from polyisocyanate and polyol as raw materials, a low molecular weight polyamine compound is used, Obtained by chain extension of urethane prepolymer.

(Urethane prepolymer)
The urethane prepolymer used as an intermediate raw material for the polyurethane resin is synthesized by polycondensation of polyisocyanate and polyol. In this invention, it is preferable to synthesize | combine in ratio of polyisocyanate and polyol in the range of 100: 40-100: 90 in the molar ratio of the isocyanate group: hydroxyl group of a raw material, More preferably, it is 100: 55-100: 85 It is preferable to synthesize in the range, even more preferably in the range of 100: 60 to 100: 70. When the ratio of the polyol to the polyisocyanate is less than 40, the synthesized polyurethane resin has an excessive crystal region, the dyeability is lowered, and the color density of the printed matter printed by thermal transfer is lowered. On the other hand, if it exceeds 90, the amorphous region of the synthesized polyurethane resin becomes excessive, the heat resistance of the resulting receiving layer is lowered, and troubles such as fusion with the dye ribbon and peeling of the receiving layer are likely to occur during printing. . In addition, the prints that have been heat-transfer printed have bleeding over time, which impairs the storage stability of the prints.

(Polyisocyanate)
The polyisocyanate combines with a low molecular weight polyamine compound to form a hard block in the polyurethane resin. The hard block forms a crystalline region by electrical or chemical bonding with the hard block of another molecular chain. This crystal region imparts heat resistance to the urethane resin.
Polyisocyanates are mainly classified into alicyclic, aliphatic, and aromatic types. Among these, when aromatic polyisocyanates are used as raw materials for polyurethane resins, the light resistance of images is significantly reduced. The reason why the aromatic polyisocyanate reduces the light resistance of the image is not clear, but the hard block in which the aromatic rings of the polyisocyanate are regularly arranged prevents the dye molecules from penetrating into the image receiving layer, This is presumably because the dye tends to be unevenly distributed in the surface layer portion of the image receiving layer which is easily affected by ultraviolet rays.

  The present invention is characterized by containing 90% by mass or more of alicyclic polyisocyanate and / or aliphatic polyisocyanate in 100% by mass of polyisocyanate used for the synthesis of urethane prepolymer, more preferably 95% by mass. As described above, it is more preferably 98% by mass or more. When the content of the alicyclic polyisocyanate and / or the aliphatic polyisocyanate is less than 90% by mass, the light resistance of the printed matter thermally transferred to the obtained thermal transfer receiving sheet is remarkably lowered. Moreover, it is preferable to adjust content of aliphatic polyisocyanate to the range of 20 mass% or less of the polyisocyanate used for the synthesis | combination of a urethane prepolymer. When the content of the aliphatic polyisocyanate exceeds 20% by mass, the heat resistance of the obtained polyurethane resin is lowered, and the peelability between the ink ribbon and the receiving sheet is lowered, or the bleeding of the printed matter is deteriorated. It becomes easy.

Examples of the aliphatic polyisocyanate that can be used in the present invention include hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, and hexamethylene triisocyanate. Among these, hexamethylene diisocyanate is preferably used.
Examples of the alicyclic polyisocyanate that can be used in the present invention include isophorone diisocyanate, dicyclohexylmethane diisocyanate, cyclohexane diisocyanate, and triisocyanate cyclohexane. Among these, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and cyclohexane diisocyanate are preferably used. The aliphatic polyisocyanate and alicyclic polyisocyanate that can be used in the present invention are not limited to the above examples, and can be used alone or in combination of two or more.

  In addition to the aliphatic polyisocyanate and the alicyclic polyisocyanate, an aromatic polyisocyanate can be used within a range that does not impair the effects of the present invention. Examples of aromatic polyisocyanates include aromatics such as phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, and polyisocyanates such as xylylene diisocyanate, tetramethylxylylene diisocyanate, and triisocyanate methylbenzene. Group polyisocyanate etc. are mentioned, These can be used independently and can also use 2 or more types together.

(Polyol)
The polyol that forms a urethane prepolymer together with the polyisocyanate forms a soft block in the polyurethane resin. The soft block contributes to the dyeing property of the image receiving layer. The polyurethane resin used in the present invention is characterized by containing 50% by mass or more of an aromatic polyol with respect to 100% by mass of all polyol components as a polyol component, preferably 60% by mass or more, more preferably 70% by mass or more. Further, it is preferable to contain 80% by mass or more. When the aromatic polyol is less than 50% by mass, the dyeing property of the obtained image receiving layer is lowered, and a highly sensitive thermal transfer receiving sheet cannot be obtained, or the heat resistance of the image receiving layer is lowered, and the dye ribbon Problems such as fusing and peeling of the receiving layer occur.

  Examples of aromatic polyols that can be used in the present invention include aromatic polyester polyols such as polyethylene terephthalate diol, polyethylene isophthalate diol, polyhexamethylene isophthalate adipate diol, polyethylene oxide adducts and ethylene oxide adducts of aromatic polyesters. These may be used alone or in combination of two or more.

  Also, it is possible to use a polyol other than the aromatic polyol in combination as long as the effects of the present invention are not hindered. Examples of polyols other than aromatic polyols include polyethylene adipate diol, polybutylene adipate diol, polyethylene butylene adipate diol, polyethylene succinate diol, polybutylene succinate diol, polyethylene sebacate diol, polybutylene sebacate diol, and poly-ε. -Polyester polyols such as caprolactone diol, poly (3-methyl-1,5-pentylene adipate) diol, polytetramethylene carbonate diol, polyhexamethylene carbonate diol, poly (1,4-cyclohexanedimethylene carbonate) diol, poly (Hexamethylene-1,4-cyclohexanedimethylene) polycarbonate polyol such as carbonate diol, polyethylene glycol , Polypropylene glycol, polyether polyol such as polytetramethylene glycol, and acrylic polyols and the like, which can be used alone or may be used in combination of two or more.

Examples of the low molecular weight polyol include ethylene glycol, propylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, pentaerythritol, sorbitol, and the like. It can be used or two or more types can be used in combination.

(Polyamine compound)
The polyurethane resin used in the present invention is obtained by synthesizing the urethane prepolymer and then chain-extending the urethane prepolymer with a low molecular weight polyamine compound. The low molecular weight polyamine compound forms a hard block in the polyurethane resin together with the polyisocyanate. As described above, it is preferable that the low molecular weight polyamine compound is non-aromatic because the light resistance of the dye thermally transferred to the receiving layer is reduced when a large amount of aromatic component is contained in the crystalline region.

  Examples of the low molecular weight polyamine compound that can be used in the present invention include hydrazine, ethylenediamine, propylenediamine, hexamethylenediamine, bisaminomethylcyclohexane, di (aminocyclohexyl) methane, piperazine, 2-methylpiperazine, isophoronediamine, diethylenetriamine, and imino. Examples thereof include low molecular weight polyamines such as bispropylamine and triethylenetetramine, and these can be used alone or in combination of two or more.

The method for synthesizing the urethane resin of the present invention is not particularly limited, and is synthesized using various known methods, reaction catalysts, and reaction inhibitors.
The urethane resin of the present invention may be a solvent-soluble type or a water-dispersed type such as a self-emulsifying type or a forced emulsifying type using a dispersing agent. In recent years, it is preferable to use a water-dispersed type in consideration of the environment, and among the water-dispersed types, a self-emulsifying type is preferable because a film-forming property during coating can be obtained and a uniform image-receiving layer can be obtained.

  The method of self-emulsification or forced emulsification of the urethane resin is not particularly limited, and various known methods can be used. By adding a diol having a carboxyl alkyl side chain as a raw material to the urethane resin, A method of introducing a carboxyl group to make it hydrophilic is preferable. The content ratio of the carboxyl group derived from the diol having the carboxyl alkyl as a side chain is preferably 0.3 to 6% by mass, more preferably 0.5 to 5% by mass, more preferably 100% by mass of the polyurethane resin. Preferably it is 2.5-4 mass%. When the content ratio of the carboxyl group is less than 0.3% by mass, the urethane resin becomes unstable in the coating liquid, and smear occurs in the coating and drying process, which may lower the print image quality. Further, when the content ratio of the carboxyl group exceeds 6% by mass, the water resistance of the obtained receiving layer is inferior, and when the printed matter is stored in a high-temperature and high-humidity environment, bleeding of the printed matter occurs or the storage stability is lowered. There is.

The lower limit value of the glass transition temperature of the urethane resin used in the present invention is preferably −30 ° C., more preferably −10 ° C., and still more preferably 0 ° C. When the glass transition temperature of the urethane resin is less than −30 ° C., fusion between the image receiving layer and the ink ribbon is likely to occur. The upper limit of the glass transition temperature of the urethane resin used in the present invention is preferably 60 ° C, more preferably 50 ° C, and still more preferably 40 ° C. When the glass transition temperature of the urethane resin exceeds 60 ° C., the dyeing property of the image receiving layer is inferior, and a sufficient print density cannot be obtained, which is not preferable.
In the present invention, the glass transition temperature is measured according to ISO-11359-2.
(Measurement example of glass transition temperature of resin)
Measuring instrument: Dynamic viscoelasticity measuring device DMS6100 type (manufactured by Seiko Instruments Inc.)
Drive frequency: 10Hz
Measurement mode: Tensile mode Distance between chucks: 20 mm
Temperature increase rate: 5 ° C / min
From the measurement results of the viscoelasticity / temperature characteristics of the resin, a viscoelasticity / temperature graph was created, and the glass transition temperature was determined as the peak value of tan δ.

(Release agent)
The image receiving layer of the present invention is characterized by containing a release agent.
The release agent used in the image receiving layer of the present invention is preferably a wax or a fluorine compound.

(Wax)
Examples of waxes include carnauba wax, paraffin wax, carboxyl group-containing paraffin wax, microcrystalline wax, polyethylene wax, carboxyl group-containing polyethylene wax, candelilla wax, rice wax, montan wax, fatty acid amide wax, and fatty acid metal salt. Can be mentioned.
Since waxes have almost no polarity and low surface tension, they have a property of being difficult to adhere to other substances, so-called releasability. In the step of applying and drying the image-receiving layer paint containing wax, the hydrophobic wax moves to the surface of the coating layer as the moisture on the surface of the coating layer evaporates. For this reason, high releasability can be imparted to the surface of the image receiving layer.
Among the waxes, it is preferable that the image receiving layer contains at least one selected from carnauba wax, paraffin wax, carboxyl group-containing paraffin wax, and carboxyl group-containing polyethylene wax. Paraffin wax, carboxyl group-containing paraffin wax, carboxyl It is particularly preferable that the image-receiving layer contains at least one selected from group-containing polyethylene wax and carnauba wax.

Carnauba wax is a kind of natural plant wax, and its main component is a fatty acid ester. Since it has a high content of fatty acid ester and a low content of low molecular weight hydrocarbons, it is characterized by high hardness despite being a natural plant wax.
By adding carnauba wax to the image receiving layer, it is possible to improve the releasability of the ink ribbon during thermal transfer printer printing, further increase the surface strength of the image receiving layer, and form a receiving layer surface that is not easily damaged.
Moreover, the fatty acid ester which is the main component of carnauba wax has a fatty acid part mainly of n-hexacosanoic acid (carbon number 26) and an ester part mainly of a myricyl group (carbon number 30). n-Hexacosanoic acid is a linear saturated fatty acid, and carnauba wax has a low melt viscosity compared to waxes containing fatty acids having a branched structure or fatty acids having a cyclic structure as components.
In the step of applying and drying the image-receiving layer coating material containing wax, the wax has a property of being melted and softened by the heat of the dryer and transferred to the surface of the image-receiving layer.
In particular, carnauba wax tends to migrate to the surface of the image receiving layer because of its low melt viscosity and is uniformly distributed. Therefore, carnauba wax has a high effect of improving the releasability of the image receiving layer.

Carnauba wax is a natural plant-based wax, and since the raw material is palm leaf secretions, the components may vary depending on seasonal factors and the melting point may vary. For example, when the content of low molecular weight hydrocarbons is large in addition to the fatty acid ester as the main component, the resulting carnauba wax has a low melting point.
The carnauba wax used in the present invention preferably has a melting point of 80 to 90 ° C. By using a carnauba wax having a specific melting point, it is possible to obtain an image receiving sheet having a stable quality even when a wax obtained from a naturally derived raw material is used. When the melting point of the carnauba wax to be used is less than 80 ° C., the hardness is insufficient and the surface gloss of the resulting image receiving sheet may be lowered or the scratch resistance may be inferior. When the melting point of the carnauba wax used exceeds 90 ° C, the melt viscosity is not sufficiently lowered, and the releasability of the receiving layer surface is difficult to be uniform, so that the ink ribbon is fused to the image receiving layer. May be a problem.
In the present invention, the carnauba wax contained in the image receiving layer is preferably 1 to 30% by mass based on the solid content of the image receiving layer. If the amount of carnauba wax contained in the image receiving layer is less than 1% by mass, the image receptive layer may have insufficient releasability and print running performance may be poor. When the carnauba wax contained in the image receiving layer exceeds 30% by mass, the transferability of the laminate protective layer may be insufficient.

In the present invention, it is preferable that at least one selected from paraffin wax, carboxyl group-containing paraffin wax, and carboxyl group-containing polyethylene wax and carnauba wax are contained in the image receiving layer.
Paraffin wax is a wax derived from petroleum, and the main component is a linear hydrocarbon. Paraffin wax has a low melt viscosity, and easily moves to the surface of the image receiving layer when the image receiving layer is formed by coating and drying.
Furthermore, paraffin wax is characterized by good compatibility with carnauba wax.
As described above, in the process of applying and drying the image-receiving layer coating, carnauba wax is melted by the heat of the dryer, becomes a low-viscosity liquid, moves to the surface of the image-receiving layer, and is uniformly distributed. And exhibits good releasability. However, in order for the carnauba wax to melt, it is necessary to maintain the temperature of the image receiving layer at the time of drying at a temperature equal to or higher than the melting point of the carnauba wax.
When the heat resistance temperature of the sheet-like support is low, or when hollow particles having a low heat resistance temperature are used for the undercoat layer, the drying temperature cannot be raised to a temperature at which carnauba wax is sufficiently melted, and as a result In some cases, the carnauba wax is insufficiently melted, unevenly distributed on the surface of the image receiving layer, and good releasability may not be obtained.
In such a case, the carnauba wax is added to the image receiving layer together with the carnauba wax by adding a paraffin wax that can be co-melted and made into a low-viscosity liquid at a temperature lower than the melting point of the carnauba wax. It can be uniformly distributed on the surface of the image receiving layer.

The paraffin wax used in the present invention preferably has a melting point of 50 to 70 ° C. When the melting point of the paraffin wax is less than 50 ° C., the hardness of the paraffin wax is insufficient and the surface of the obtained receiving paper may be easily damaged. When the melting point of the paraffin wax exceeds 70 ° C., the melt viscosity becomes high, and the effect of accelerating the melt softening of the carnauba wax is insufficient, and it may not be possible to impart uniform releasability to the surface of the image receiving layer.
The ratio of carnauba wax to paraffin wax contained in the image receiving layer is preferably 5: 1 to 1: 1 in terms of solid content. When the ratio of carnauba wax is more than 5: 1, the melt viscosity is high, so that a high drying temperature is required in order to sufficiently melt and soften the wax in the application / drying process of the image receiving layer coating, and the sheet form When the heat resistance temperature of the support or the undercoat layer material is low, thermal deformation or the like may occur. When the ratio of carnauba wax is less than 1: 1, the releasability is insufficient and the image receiving layer and the ink ribbon may be fused.
In addition, melting | fusing point of wax was measured based on JIS-K7121, for example, it measured with the temperature increase rate of 10 degree-C / min using the measurement differential scanning calorimeter (DSC-210C by Seiko Instruments Inc.). The maximum endothermic peak is obtained as the melting point.

The carboxyl group-containing paraffin wax is one in which a carboxyl group is introduced by a method of adding an acid to the paraffin wax or oxidizing the air. Similarly, the carboxyl group-containing polyethylene wax is one in which a carboxyl group is introduced by a method of adding an acid to the polyethylene wax or oxidizing it with air.
The carboxyl group-containing paraffin wax and the carboxyl group-containing polyethylene wax both have good compatibility with carnauba wax, have low melt viscosity, and are added together with carnauba wax to the image-receiving layer coating process. This contributes to uneven distribution of carnauba wax on the surface of the image receiving layer, and can impart uniform releasability to the image receiving layer.
In a normal color thermal transfer printer, there is a step of transferring a laminate protective layer after the yellow, magenta and cyan printing steps. When the adhesiveness of the laminate protective layer of the image receiving layer is insufficient, the laminate protective layer is not transferred, and the durability of the obtained image is significantly impaired. When carboxyl group-containing paraffin wax or carboxyl group-containing polyethylene wax is used for the image receiving layer, an effect of improving laminate transferability can be obtained. This is presumably because the adhesion is improved by the carboxyl group.
In the carboxyl group-containing paraffin wax and the carboxyl group-containing polyethylene wax of the present invention, the acid value indicating the content of carboxy groups is preferably 5 to 150 mgKOH / g. When the acid value is less than 5 mgKOH / g, the adhesiveness to the polyurethane resin is insufficient and the release agent may be detached from the surface of the image receiving layer. When the acid value exceeds 150 mgKOH / g, the releasability is insufficient and the image receiving layer and the ink ribbon may be fused.
The ratio of the carnauba wax to the carboxyl group-containing paraffin wax and the ratio of the carnauba wax to the carboxyl group-containing polyethylene wax are preferably 5: 1 to 1: 1 in terms of solid content. When the ratio of carnauba wax is more than 5: 1, a high drying temperature is required to melt and soften the wax in the application / drying process of the image-receiving layer coating, and to make it unevenly distributed on the surface of the image-receiving layer. In some cases, the sheet-like support or the undercoat layer material is exposed to a temperature higher than the heat-resistant temperature to cause thermal deformation and the like, and the smoothness of the thermal transfer receiving sheet is deteriorated to deteriorate the image quality. In addition, defective laminate transfer may occur and the durability of the image may be impaired. When the ratio of carnauba wax is less than 1: 1, the releasability is insufficient and the image receiving layer and the ink ribbon may be fused.
(Fluorine compound)
In the present invention, examples of the fluorine compound contained as a release agent in the image receiving layer include perfluoroalkyl ethylene oxide, perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, and perfluoroalkyl phosphate. Among these, a nonionic fluorine compound is preferable, and as the nonionic fluorine compound, a perfluoroalkylethylene oxide compound is particularly preferable.
The perfluoroalkylethylene oxide compound has a perfluoroalkyl group in the molecule. A perfluoroalkyl group is one in which all hydrogen atoms in the alkyl group are substituted with fluorine, and has a very low surface energy and excellent releasability. The perfluoroalkylethylene oxide compound has ethylene oxide as a hydrophilic group in the molecule, and has good dispersion stability in an aqueous coating solution. The alkyl group of the perfluoroalkyl group may be linear or branched, and the carbon number is preferably 4-20. When the carbon number is less than 3, the releasability may be insufficient, and when it exceeds 20, the dispersibility in the aqueous coating liquid may become unstable.

What determines the releasability of the resulting receiving sheet is not the amount of fluorine compound added to the image receiving layer, but the amount of fluorine groups present on the surface of the image receiving layer.
The abundance of fluorine groups on the surface of the image receiving layer is a value measured by X-ray photoelectron spectroscopy, and is expressed as atomic% as a ratio of the number of fluorine atoms to the total number of atoms on the surface of the image receiving layer.
X-ray photoelectron spectroscopy is an analytical method in which a sample is irradiated with X-rays in an ultrahigh vacuum and the photoelectron energy emitted is measured. The kinetic energy of the photoelectrons emitted when the X-rays are applied becomes a value determined by the kind of atoms. X-rays penetrate from the sample surface to several μm, but the depth at which photoelectrons can escape is up to several hundred mm, and only the photoelectrons on the very surface are detected.
Measurement of surface fluorine atoms by X-ray photoelectron spectroscopy is performed in a high vacuum (1 × 10 ⁶ Pa or more) using Mg—Kα rays as X-rays. Examples of atoms present on the surface of the image receiving layer include oxygen atoms, nitrogen atoms, carbon atoms, and fluorine atoms. From the peak intensities of O _1S electrons, N _1S electrons, C _1S electrons, and F _1S electrons, the number of fluorine atoms The ratio Atom% of the total number of atoms is calculated.
In the present invention, the number of fluorine atoms present on the surface of the image receiving layer is preferably 0.5 to 5.0 atomic%. If it is less than 0.5 Atomic%, the releasability of the receiving sheet is insufficient, and printing running troubles may occur. If it exceeds 5.0 Atomic%, the transferability of the laminate protective layer is insufficient and the laminate protective layer cannot sufficiently cover the image, and the durability of the image may be impaired.

When the image-receiving layer coating solution to which the perfluoroalkylethylene oxide compound is added is applied to the sheet-like support and dried, the drying temperature is preferably 60 to 120 ° C, more preferably 70 to 100 ° C. If the temperature is lower than 60 ° C, the perfluoroalkylethylene oxide compound may not move to the interface of the image receiving layer, and the releasability of the resulting receiving sheet may not be sufficient. If the temperature exceeds 120 ° C, the sheet-like support shrinks. The receiving sheet obtained may have insufficient surface smoothness.
The amount of perfluoroalkylethylene oxide added to the image receiving layer is preferably 0.05 to 1% by mass based on the total solid content of the image receiving layer. If it is less than 0.05 mass%, the releasability of the resulting receiving sheet may not be sufficient. If it exceeds 1% by mass, the image quality of the receiving sheet that may cause uneven coating may be insufficient when the image receiving layer is applied.
Examples of the fluorine compound used in the present invention include Megafac F-114, F-410, F-493, F-494 (manufactured by DIC), S-111n, S-113, S-121 (AGC Seimi Chemical Co., Ltd.). Examples of nonionic fluorine compounds include Megafac F-444, F-445 (manufactured by DIC), Surflon S-131, S-132 (manufactured by AGC Seimi Chemical Co., Ltd.), and the like. .

(Crosslinking agent)
It is also possible to add a crosslinking agent to the image receiving layer of the present invention to increase the heat resistance of the polyurethane resin and further enhance the effect of preventing fusion with the ink ribbon.
As a crosslinking agent, the crosslinking agent which has a carbodiimide group, an isocyanate group, an oxazoline group, an epoxy group as a crosslinking group, and a titanium chelate type crosslinking agent are mentioned. Among these, a crosslinking agent having a carbodiimide group is preferable because the crosslinking reaction is fast and the effect of improving the heat resistance of the image receiving layer after the crosslinking reaction is high.
In the present invention, a crosslinking agent further having a hydrophilic group is preferably used.
Examples of hydrophilic groups include polyalkylene glycol groups such as polyethylene glycol groups and polypropylene glycol groups, carboxyl groups, sulfone groups, and phosphate ester groups. Among these, a crosslinking agent having a polyalkylene glycol group is particularly preferable from the viewpoint of good physical properties of the paint obtained by addition.

(Other auxiliaries)
An antifoaming agent, a thickener, a surfactant, a wetting agent, and the like can be added to the coating for the image receiving layer of the present invention in order to improve workability and coating suitability.
The coating amount of the image-receiving layer is preferably 0.5-4 g / ^{m 2,} more preferably from 0.5 to 3 g / ^{m 2.} If it is less than 0.5 g / m ² , the light resistance of the image may be inferior. If it exceeds 4 g / m ² , blurring of the image may occur.

(Middle layer)
In the present invention, an intermediate layer can be provided between the image receiving layer and the sheet-like support. By including a resin having a glass transition temperature higher than that of the resin used in the image receiving layer in the intermediate layer, the dye transferred from the ink ribbon to the image receiving layer penetrates into the sheet-like support. Image blurring can be prevented.
The resin contained in the intermediate layer preferably has a glass transition temperature of 40 to 90 ° C, and more preferably a glass transition temperature of 55 to 90 ° C.
If the glass transition temperature of the resin contained in the intermediate layer is less than 40 ° C., it may not be possible to prevent bleeding of the image. If the glass transition temperature exceeds 90 ° C., the film formability of the intermediate layer paint will be insufficient, so a uniform intermediate In some cases, the layer is not formed, and the effect of preventing bleeding of the image is lowered.

Examples of the resin forming the intermediate layer include vinyl chloride resin, urethane resin, polyester resin, polycarbonate resin, polyvinyl acetal resin, polyvinyl butyral resin, polystyrene resin, polyacrylate resin, acrylic resin, and cellulose resin. Examples thereof include thermoplastic resins such as resins and polyamide resins, and these thermoplastic resins may be used alone or in combination of two or more.
0.5-10 g / m < ² > is preferable and the coating amount of the intermediate | middle layer of this invention has more preferable 1.0-6 g / m < ² >. If the coating amount of the intermediate layer is less than 0.5 g / m ² , the effect of preventing image bleeding may be insufficient. When the coating amount of the intermediate layer exceeds 10 g / m ² , the effect obtained for an increase in cost is small.

(Undercoat layer)
An undercoat layer containing hollow particles can be provided between the support and the intermediate layer. Since the undercoat layer containing hollow particles can impart heat insulation and cushioning properties, it can improve image clarity and image uniformity. The material and manufacturing method of the hollow particles used in the undercoat layer are not particularly limited, and specific examples of the material for forming the walls of the hollow particles include acrylonitrile, vinylidene chloride, styrene acrylate polymer, and the like. . As a method for producing these hollow particles, a method of heating and foaming microcapsules in which butane gas is sealed in resin particles, an emulsion polymerization method, and the like can be mentioned.
The coating amount of the undercoat layer is, 1 to 30 g / ^{m 2} is preferred. If the coating amount of the undercoat layer is less than 1 g / m ² , sufficient heat insulating properties and cushioning properties cannot be expected, and if it exceeds 30 g / m ² , the effect obtained for an increase in cost is small.
The particle size of the hollow particles is preferably 0.1 to 10 μm. When the particle size of the hollow particles is less than 0.1 μm, the walls of the hollow particles become thin and the heat resistance is insufficient, and is easily broken in the coating and drying process. On the other hand, when the thickness exceeds 10 μm, surface irregularities of the obtained receiving sheet are increased and image uniformity may be deteriorated.
The volume hollow ratio of the hollow particles is preferably 50 to 90%. When the volumetric hollow ratio of the hollow particles is less than 50%, the effect of imparting heat insulating properties and cushioning properties may be insufficient. If it exceeds 90%, the walls of the hollow particles become thin and the durability may be lowered.

(Back layer)
A back layer can be appropriately provided on the surface (back surface) on which the receiving layer is not provided.
The purpose of the back layer is to improve runnability, prevent static electricity, prevent scratching of the receiving layer due to friction between the receiving sheets, and prevent dye transfer to the back surface when the receiving sheets are stacked. The back layer contains a resin, a pigment, an antistatic agent and the like according to the purpose.

(Calendar processing)
The receiving sheet may be calendered. By the calendering process, the unevenness of the surface of the obtained receiving sheet can be reduced and a uniform image can be obtained. The calendar process may be performed at any stage. As the calendar apparatus used for the calendar process, a calendar apparatus generally used in the paper industry such as a super calendar, a soft calendar, a gloss calendar, and a clearance calendar can be appropriately used.

Various auxiliary agents such as wetting agents, dispersants, thickeners, antifoaming agents, colorants, antistatic agents, preservatives and the like used in the production of general coated papers are appropriately added to each coating layer. The
The coating layer such as the image receiving layer of the receiving sheet of the present invention is a known coating material such as a bar coater, gravure coater, comma coater, blade coater, air knife coater, gate roll coater, die coater, curtain coater, and slide bead coater. Using a coater, a predetermined coating solution can be applied and dried.

  Hereinafter, the present invention will be described in more detail with reference to examples. Unless otherwise specified, “parts” and “%” in the examples all represent “parts by mass” and “% by mass”, and are solid amounts except for those relating to solvents. Tg represents the glass transition temperature.

[Polyurethane resin synthesis examples UP1 to UP5]
After the urethane prepolymer obtained from polyisocyanate and polyol was synthesized by the following method, the urethane prepolymer was chain-extended using low molecular weight polyamine compounds to synthesize polyurethane resins UP1 to UP5.
To a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen blowing tube, the polyol components shown in Table 1 and 2,2-dimethylolbutanoic acid were added in the amounts shown in Table 1, and further dibutyl 0.001 g of tin dilaurate and 120 g of methyl ethyl ketone were added and mixed uniformly. Next, the amount of the isocyanate component shown in Table 1 was added to this and the amount shown in Table 1 was added, and the mixture was reacted at 80 ° C. for 5 hours to obtain a methyl ethyl ketone solution of a prepolymer.
The resulting prepolymer solution of methyl ethyl ketone was cooled to 30 ° C., neutralized by adding triethylamine in the amount shown in Table 1, and then 403 g of water was gradually added to emulsify and disperse. To this emulsified dispersion, a 20% by mass aqueous solution of ethylenediamine was added in the amount shown in Table 1 (in terms of solid content) and stirred for 2 hours. The solvent was removed while the temperature was raised to 50 ° C. over 2 hours under reduced pressure to obtain a polyurethane resin emulsion having a nonvolatile content of about 39% by mass. In the present invention, the nonvolatile content of the polyurethane resin emulsion means the residual weight ratio after the aqueous dispersion is dried at 105 ° C. for 3 hours.

  Polyisocyanate, polyol, low molecular weight polyamine compound used for the synthesis of polyurethane resins UP1 to UP5, and types of diol having carboxylalkyl as a side chain, alicyclic polyisocyanate, aliphatic polyisocyanate and aromatic polyisocyanate in polyisocyanate component Table 2 shows the content ratio (mass ratio) of the isocyanate, the ratio of polyisocyanate and polyol in the prepolymer (isocyanate group: molar ratio of hydroxyl groups), and the content ratio of carboxyl groups to the polyurethane resin obtained by synthesis. there were.

<Example 1>
(Formation of sheet-like support and undercoat layer)
As the sheet-like support, art paper having a thickness of 150 μm (trade name: OK Kanto N, manufactured by Oji Paper Co., Ltd., basis weight 174.4 g / m ² ) was used. On one side, an undercoat layer coating solution having the following composition was applied and dried so that the solid content coating amount was 10 g / m ² to form an undercoat layer.
(Preparation of undercoat layer coating solution)
An undercoat layer coating solution was prepared by stirring materials having the following composition.
45 parts of pre-expanded hollow particles made of a copolymer mainly composed of acrylonitrile and methacrylonitrile (average particle diameter: 3.2 μm, volume hollow ratio: 85%)
10 parts of polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray)
45 parts of vinyl chloride / vinyl acetate copolymer resin dispersion (trade name: VINYBRAN 603, manufactured by Nissin Chemical Co., Ltd.,
(Vinyl chloride / vinyl acetate = 70/30, Tg 64 ° C.)
200 parts of water (formation of intermediate layer)
On the undercoat layer, an intermediate layer coating solution having the following composition was applied such that the solid content coating amount was 2 g / m ² to form an intermediate layer.
(Preparation of intermediate layer coating solution)
45 parts of vinyl chloride / vinyl acetate copolymer resin dispersion (trade name: VINYBRAN 603, manufactured by Nissin Chemical Co., Ltd.,
(Vinyl chloride / vinyl acetate = 70/30, Tg 64 ° C.)
5 parts of carbodiimide-based crosslinking agent (trade name: Carbodilite V-02, manufactured by Nisshinbo)
(Vinyl chloride / vinyl acetate = 70/30, Tg 64 ° C.)
200 parts of water (formation of image receiving layer)
Further, an image receiving layer coating liquid R-1 having the following composition was applied on the intermediate layer so that the solid content coating amount was 3 g / m ² , and the following image receiving layer drying conditions D-1 Was dried to form an image receiving layer, and a thermal transfer receiving sheet was obtained.
The fluorine atom number ratio (Atomic%) on the surface of the image receiving layer was measured with a photoelectron spectrometer (ESCALAB-250: manufactured by VG Scientific).
(Preparation of image-receiving layer coating solution R-1)
Urethane resin UP1 in the above synthesis example 94.5 parts Carbodiimide-based crosslinking agent 5 parts (trade name: Carbodilite V-02, manufactured by Nisshinbo Co., Ltd.)
Perfluoroethylene oxide adduct 0.5 parts (trade name: F-444, manufactured by DIC)
300 parts of water (image receiving layer drying condition D-1)
Time from applying the image-receiving layer coating to entering the dryer 6 seconds Temperature in the dryer 100 ° C
Dryer wind speed 1.8m / sec Drying time 60sec

<Example 2>
A receiving sheet was obtained in the same manner as in Example 1 except that the receiving layer coating solution R-2 was used instead of the receiving layer coating solution R-1 in the preparation of the receiving layer coating solution of Example 1.
(Preparation of receiving layer coating solution R-2)
Urethane resin UP1 in the above synthesis example 94.5 parts Carbodiimide-based crosslinking agent 5 parts (trade name: Carbodilite V-02, manufactured by Nisshinbo Co., Ltd.)
0.5 part of perfluoroalkyl group-containing carboxylic acid (trade name: F-410, manufactured by DIC)
300 parts of water

<Example 3>
A receiving sheet was obtained in the same manner as in Example 1 except that the following image receiving layer drying condition D-2 was used instead of the image receiving layer drying condition D-1.
A receiving sheet was obtained.
(Image-receiving layer drying condition D-2)
Time from application of the image-receiving layer coating to entering the dryer 4 seconds Temperature in the dryer 120 ° C
Air velocity of dryer 2.5m / sec Drying time 40sec

<Example 4>
A receiving sheet was obtained in the same manner as in Example 1 except that the following image receiving layer drying condition D-3 was used instead of the image receiving layer drying condition D-1 in Example 1.
A receiving sheet was obtained.
(Image receiving layer drying condition D-3)
Time from application of the image-receiving layer coating to entering the dryer 12 seconds Temperature in the dryer 60 ° C
Dryer wind speed 0.9m / sec Drying time 120sec

<Example 5>
A receiving sheet was obtained in the same manner as in Example 1 except that the following receiving layer coating solution R-2 was used instead of the receiving layer coating solution R-1 in the preparation of the receiving layer coating solution of Example 1. .
(Preparation of receiving layer coating solution R-2)
Urethane resin UP1 of the above synthesis example 75 parts Carbodiimide type crosslinking agent 5 parts (trade name: Carbodilite V-02, Nisshinbo Co., Ltd.)
Carnauba wax 20 parts (trade name: Torasor CN, manufactured by Chukyo Yushi Co., Ltd.)
300 parts of water

<Example 6>
In the preparation of the receiving layer coating liquid C1 of Example 1, a receiving sheet was obtained in the same manner as in Example 1 except that the following receiving layer coating liquid R-3 was used instead of the receiving layer coating liquid R-1. It was.
(Preparation of receiving layer coating solution R-3)
Urethane resin UP1 of the above synthesis example 75 parts Carbodiimide type crosslinking agent 5 parts (trade name: Carbodilite V-02, Nisshinbo Co., Ltd.)
Paraffin wax (trade name: SPW-116H, manufactured by Arakawa Chemical) 20 parts 300 parts water

<Example 7>
In the preparation of the receiving layer coating liquid C1 of Example 1, a receiving sheet was obtained in the same manner as in Example 1 except that the following receiving layer coating liquid R-4 was used instead of the receiving layer coating liquid R-1. It was.
(Preparation of receiving layer coating solution R-4)
Urethane resin UP1 of the above synthesis example 75 parts Carbodiimide type crosslinking agent 5 parts (trade name: Carbodilite V-02, Nisshinbo Co., Ltd.)
20 parts of microcrystalline wax (trade name: Hi-Mic-1045, manufactured by Nippon Seiki)
300 parts of water

<Example 8>
In the preparation of the receiving layer coating liquid C1 of Example 1, a receiving sheet was obtained in the same manner as in Example 1 except that the following receiving layer coating liquid R-5 was used instead of the receiving layer coating liquid R-1. It was.
(Preparation of receiving layer coating solution R-5)
Urethane resin UP1 of the above synthesis example 75 parts Carbodiimide type crosslinking agent 5 parts (trade name: Carbodilite V-02, Nisshinbo Co., Ltd.)
Carnauba wax 15 parts (trade name: Torasor CN, manufactured by Chukyo Yushi Co., Ltd.)
Paraffin wax (trade name: SPW-116H, Arakawa Chemical) 5 parts Water 300 parts

<Example 9>
In the preparation of the receiving layer coating liquid C1 of Example 1, a receiving sheet was obtained in the same manner as in Example 1 except that the following receiving layer coating liquid R-6 was used instead of the receiving layer coating liquid R-1. It was.
(Preparation of receiving layer coating solution R-6)
Urethane resin UP1 of the above synthesis example 74.5 parts Carbodiimide-based crosslinking agent 5 parts (trade name: Carbodilite V-02, manufactured by Nisshinbo Co., Ltd.)
Carnauba wax 15 parts (trade name: Torasor CN, manufactured by Chukyo Yushi Co., Ltd.)
Paraffin wax (trade name: SPW-116H, manufactured by Arakawa Chemical) 5 parts perfluoroethylene oxide adduct 0.5 parts (trade name: F-444, manufactured by DIC)
300 parts of water

<Example 10>
In Example 9, a synthetic paper (trade name: FPG200, YUPO) having a thickness of 200 μm was used instead of the art paper (trade name: OK Kanto N, manufactured by Oji Paper Co., Ltd., basis weight 174.4 g / m ² ) having a thickness of 150 μm as a support. A receiving sheet was obtained in the same manner as in Example 9 except that the intermediate layer was not formed.

<Example 11>
A receiving sheet was obtained in the same manner as in Example 1 except that the receiving layer coating solution R-7 was used instead of the receiving layer coating solution R-1 in the preparation of the receiving layer coating solution C1 in Example 1. .
(Preparation of receiving layer coating solution R-7)
Urethane resin UP2 of the above synthesis example 74.5 parts Carbodiimide type crosslinking agent 5 parts (trade name: Carbodilite V-02, manufactured by Nisshinbo Co., Ltd.)
Carnauba wax 15 parts (trade name: Torasor CN, manufactured by Chukyo Yushi Co., Ltd.)
Paraffin wax (trade name: SPW-116H, manufactured by Arakawa Chemical) 5 parts perfluoroethylene oxide adduct 0.5 parts (trade name: F-444, manufactured by DIC)
300 parts of water

<Example 12>
A receiving sheet was obtained in the same manner as in Example 1 except that the receiving layer coating solution R-8 was used instead of the receiving layer coating solution R-1 in the preparation of the receiving layer coating solution C1 of Example 1. .
(Preparation of receiving layer coating solution R-8)
Urethane resin UP3 of the above synthesis example 74.5 parts Carbodiimide type crosslinking agent 5 parts (trade name: Carbodilite V-02, Nisshinbo Co., Ltd.)
Carnauba wax 15 parts (trade name: Torasor CN, manufactured by Chukyo Yushi Co., Ltd.)
Paraffin wax (trade name: SPW-116H, manufactured by Arakawa Chemical) 5 parts perfluoroethylene oxide adduct 0.5 parts (trade name: F-444, manufactured by DIC)
300 parts of water

<Example 13>
A receiving sheet was obtained in the same manner as in Example 1 except that the receiving layer coating solution R-9 was used instead of the receiving layer coating solution R-1 in the preparation of the receiving layer coating solution C1 in Example 1. .
(Preparation of receiving layer coating solution R-9)
Urethane resin UP2 of the above synthesis example 72.5 parts Carbodiimide type crosslinking agent 5 parts (trade name: Carbodilite V-02, Nisshinbo Co., Ltd.)
Carnauba wax 17 parts (trade name: Torasor CN, manufactured by Chukyo Yushi Co., Ltd.)
Carboxyl group-containing paraffin wax 5 parts (trade name: P618, manufactured by Chukyo Yushi Co., Ltd., acid value 120 mgKOH / g)
Perfluoroethylene oxide adduct 0.5 parts (trade name: F-444, manufactured by DIC)
300 parts of water

<Example 14>
A receiving sheet was obtained in the same manner as in Example 1 except that the receiving layer coating solution R-10 was used instead of the receiving layer coating solution R-1 in the preparation of the receiving layer coating solution C1 in Example 1. .
(Preparation of receiving layer coating solution R-10)
Urethane resin UP3 of the above synthesis example 72.5 parts Carbodiimide type crosslinking agent 5 parts (trade name: Carbodilite V-02, manufactured by Nisshinbo Co., Ltd.)
Carnauba wax 17 parts (trade name: Torasor CN, manufactured by Chukyo Yushi Co., Ltd.)
Carboxyl group-containing polyethylene wax 5 parts (trade name: L787, acid value 15 mg KOH / g, manufactured by Chukyo Yushi)
Perfluoroethylene oxide adduct 0.5 parts (trade name: F-444, manufactured by DIC)
300 parts of water

<Comparative Example 1>
A receiving sheet was obtained in the same manner as in Example 1 except that the receiving layer coating solution R-9 was used instead of the receiving layer coating solution R-1 in the preparation of the receiving layer coating solution C1 in Example 1. .
(Preparation of receiving layer coating solution R-9)
Urethane resin UP4 of the above synthesis example 74.5 parts Carbodiimide type cross-linking agent 5 parts (trade name: Carbodilite V-02, manufactured by Nisshinbo Co., Ltd.)
Carnauba wax 15 parts (trade name: Torasor CN, manufactured by Chukyo Yushi Co., Ltd.)
Paraffin wax (trade name: SPW-116H, manufactured by Arakawa Chemical) 5 parts perfluoroethylene oxide 0.5 part (trade name: F-444, manufactured by DIC)
300 parts of water

<Comparative example 2>
A receiving sheet was obtained in the same manner as in Example 1 except that the receiving layer coating solution R-10 was used instead of the receiving layer coating solution R-1 in the preparation of the receiving layer coating solution C1 in Example 1. .
(Preparation of receiving layer coating solution R-10)
Urethane resin UP5 of the above synthesis example 74.5 parts Carbodiimide-based crosslinking agent 5 parts (trade name: Carbodilite V-02, manufactured by Nisshinbo Co., Ltd.)
Carnauba wax 15 parts (trade name: Torasor CN, manufactured by Chukyo Yushi Co., Ltd.)
Paraffin wax (trade name: SPW-116H, manufactured by Arakawa Chemical) 5 parts perfluoroethylene oxide 0.5 part (trade name: F-444, manufactured by DIC)
300 parts of water

<Comparative Example 3>
A receiving sheet was obtained in the same manner as in Example 1 except that the receiving layer coating solution R-11 was used instead of the receiving layer coating solution R-1 in the preparation of the receiving layer coating solution C1 in Example 1. .
(Preparation of Receptor Layer Coating Solution R-11)
Urethane resin UP1 in the above synthesis example 94.5 parts Carbodiimide-based crosslinking agent 5 parts (trade name: Carbodilite V-02, manufactured by Nisshinbo Co., Ltd.)
Silicone oil (trade name: SF8427, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5 parts Water 300 parts

<Comparative example 4>
A receiving sheet was obtained in the same manner as in Example 1 except that the receiving layer coating solution R-12 was used instead of the receiving layer coating solution R-1 in the preparation of the receiving layer coating solution C1 in Example 1. .
(Preparation of receiving layer coating solution R-12)
90 parts of urethane resin UP1 of the above synthesis example 5 parts of carbodiimide-based crosslinking agent (trade name: Carbodilite V-02, manufactured by Nisshinbo Co., Ltd.)
Silicone oil (trade name: SF8427, manufactured by Shin-Etsu Chemical Co., Ltd.) 5 parts Water 300 parts

The ratio of the number of fluorine atoms (Atomic%) on the surface of the image receiving layer of the image receiving sheet obtained in the above examples and comparative examples was measured using a photoelectron spectrometer (ESCALAB-250: manufactured by VG Scientific). Are shown in Table 3.
(Evaluation)
The following evaluation was performed about the receiving sheet obtained by said each Example and comparative example. The obtained results are shown in Table 3.
(Releasability from dye thermal transfer sheet)
A commercially available thermal transfer video printer (trade name: UP-50, manufactured by Sony Corporation) equipped with a dye thermal transfer sheet (trade name: UP-540, manufactured by Sony Corporation) was used. Ten continuous black images were printed on the receiving sheet. The ribbon peelability of the receiving sheet was evaluated according to the following criteria and shown in Table 1.
The above evaluation is cold (-5 ° C.), room temperature (25 ° C.) was evaluated at 3 environment of hot (4 8 ℃).
A: There is no fusion between the receiving sheet surface and the dye thermal transfer sheet, and 10 sheets are discharged normally continuously, and there is no problem in practical use.
○: Some sound is generated due to peeling between the receiving sheet surface and the dye thermal transfer sheet, but all 10 sheets are discharged, and there is no problem in practical use.
Δ: Sound is generated due to peeling between the receiving sheet surface and the dye thermal transfer sheet, but all 10 sheets are discharged and practical.
X: The surface of the receiving sheet and the dye thermal transfer sheet are fused, and there is a sheet that is not normally discharged, which is not suitable for practical use.

(Laminate protective layer transferability)
On the receiving layer of the obtained receiving sheet, a thermal transfer tester (trade name: TH-PMI2, manufactured by Okura Electric Co., Ltd.) was used to vary the applied energy, and a sublimation thermal transfer ink ribbon (trade name: UP- 540, manufactured by Sony Corporation) was transferred, and the minimum energy at which the laminate protective layer could be transferred was determined.
A: Laminate protective layer transfer minimum energy is 0. It is less than 7 mJ / dot and has excellent laminate protective layer transferability.
○: The minimum transfer energy of the laminate protective layer is less than 1.1 mJ / dot, and there is no problem in practical use.
Δ: Laminate protective layer transfer minimum energy is less than 1.4 mJ / dot, and there is no problem in practical use.
X: The laminate protective layer transfer minimum energy exceeds 1.4 mJ / dot, which is not suitable for practical use.

(Image light resistance)
Using a commercially available thermal transfer video printer (trade name: UP-50, manufactured by Sony Corporation) equipped with a sublimation type thermal transfer ink ribbon (trade name: UP-540, manufactured by Sony Corporation), solid black printing was performed at room temperature. The obtained black solid image print was processed with an Xe fade meter until the accumulated illuminance reached 10,000 kJ / m ² .
The color tone before and after the light resistance test of the image was measured using a color difference meter (Gretag) in accordance with JIS Z 8721. The measured value was recorded in the L *, a *, b * color system based on JIS Z 8729, and the color difference (ΔE *) before and after treatment was calculated by the method based on JIS Z 8730 to evaluate the light resistance. .

A: ΔE * is less than 7, and the image light resistance is excellent.
○: ΔE * is 7 or more and less than 10, and there is no problem in practical use.
Δ: ΔE * is 10 or more and less than 13 and is practical.
X: ΔE * is 13 or more, which is not suitable for practical use.

[Image density]
Using a commercially available thermal transfer video printer (trade name: UP-50, manufactured by Sony Corporation) equipped with a sublimation type thermal transfer ink ribbon (trade name: UP-540, manufactured by Sony Corporation), the blocking property test was performed in a room temperature environment. A black solid image was printed on the received receiving sheet. Using a Macbeth reflection densitometer RD914, the print density of the black solid image was measured. The image clarity of the receiving sheet was evaluated according to the following criteria.
A: Black solid print density is 2.2 or more, and can be used as a high-sensitivity receiving sheet without problems.
○: The black solid print density is 1.7 or more and less than 2.2, and can be used without any problem in practice.
X: The black solid print density is less than 1.7, which is not suitable for practical use.

表３から明らかなように、実施例１〜１４の熱転写受容シートは、印画濃度が高く、画像の鮮明性、画像の耐光性に優れ、更に、印画時の染料熱転写シートとの離型性が良好で、かつラミネート保護層の転写性に優れた熱転写受容シートである。

As is apparent from Table 3, the thermal transfer receiving sheets of Examples 1 to 14 have high printing density, excellent image sharpness and image light fastness, and further, releasability from the dye thermal transfer sheet during printing. It is a thermal transfer receiving sheet that is good and excellent in the transferability of the laminate protective layer.

  According to the present invention, a high-density image excellent in sharpness and light resistance can be obtained, and a thermal transfer receiving sheet excellent in transferability of a laminate protective layer can be provided. In addition, since the thermal transfer receiving sheet of the present invention has good releasability from the dye thermal transfer sheet at the time of printing, it can reduce defective printer paper discharge at the time of printing, and full color of various thermal transfer systems including the sublimation thermal transfer system. It is useful for printers and greatly contributes to the industry.

Claims (9)

In a thermal transfer receiving sheet having a sheet-like support and an image receiving layer formed on at least one surface of the sheet-like support, the image receiving layer is synthesized from polymerization components including the following (A) to (C): A thermal transfer receiving sheet comprising a polyurethane resin and a release agent.
(A) Polyisocyanate comprising 90% by mass or more of alicyclic polyisocyanate and / or aliphatic polyisocyanate.
(B) A polyol comprising 50% by mass or more of an aromatic diol.
(C) Low molecular weight polyamine compound.   The blending ratio of the (A) and the (B) at the time of synthesizing the polyurethane resin is a molar ratio of the isocyanate group possessed by the (A) and the hydroxyl group possessed by the (B), from 100: 40 to 100: The thermal transfer receiving sheet according to claim 1, which is in the range of 90. The polyurethane resin is further synthesized from a polymerization component containing (D) below, and the carboxyl group content is 0.3 to 6% by mass with respect to 100% by mass of the polyurethane resin. Item 3. The thermal transfer receiving sheet according to Item 1 or 2.
(D) A diol having a carboxyalkyl group as a side chain.   The thermal transfer receiving sheet according to any one of claims 1 to 3, wherein the release agent is at least one selected from waxes and fluorine compounds.   The thermal transfer receiving sheet according to claim 4, wherein the fluorine compound is a nonionic compound.   The thermal transfer receiving sheet according to claim 5, wherein the fluorine compound is perfluoroalkylethylene oxide.   The thermal transfer receiving sheet according to any one of claims 4 to 6, wherein fluorine atoms present on the surface of the image receiving layer are 0.5 to 5.0 atomic% by X-ray photoelectron spectroscopy.   The thermal transfer receiving sheet according to claim 4, wherein the wax is at least one selected from carnauba wax, paraffin wax, carboxyl group-containing paraffin wax, and carboxyl group-containing polyethylene wax.   An intermediate layer is provided between the sheet-like support and the image receiving layer, and the intermediate layer contains a resin having a glass transition temperature in the range of 40 to 90 ° C as a main component. 2. The thermal transfer receiving sheet according to item 1.