JP5221202B2 - Resin dispersion for dye receiving layer - Google Patents

Description

  The present invention relates to a thermal transfer image receiving sheet, a method for producing the same, and a resin dispersion for a receiving layer of the thermal transfer image receiving sheet.

There has been proposed a method of forming a color image on a thermal transfer image-receiving sheet that can be dyed with a sublimation dye, using a sublimation dye as a recording agent and a thermal transfer sheet carried on a substrate. In this method, a thermal head of a printer is used as a heating means, and a dye is transferred to an image receiving sheet by heating to obtain a color image. The image formed in this way is very clear because it uses a dye, and is excellent in transparency. Therefore, it is excellent in reproducibility of intermediate colors and gradation, and a high-quality image can be expected.
As the dye-receiving layer of the thermal transfer image-receiving sheet, polyester is sometimes used from the viewpoint of excellent dyeing properties. As such a thermal transfer image-receiving sheet using polyester, for example, a dye-receiving layer is a dicarboxylic acid containing a diol component containing 60 to 70 mol% of bisphenol A alkylene glycol adduct and 50 mol% or more of terephthalic acid. A polyester polymer obtained from the components, a dye thermal transfer image receiving sheet containing a cross-linked product thereof as a main component (Patent Document 1), a sublimable dye thermal transfer image receiving layer containing a polyester resin as a main component, Sublimable dye thermal transfer which is a copolycondensation product of a diol component containing ethylene glycol, neopentyl glycol and 40-60 mol% bisphenol A-alkylene oxide adduct and a dicarboxylic acid component containing terephthalic acid and isophthalic acid Image receiving sheet (Patent Document 2), dyeing Thermal transfer image-receiving sheet formed from a mixture of an aqueous dispersion of a polyester resin that is insoluble or hardly soluble in a solvent and an aqueous dispersion of a thermoplastic resin other than the polyester resin, or an aqueous dispersion of a mixture of both resins (Patent) Document 3) and the like are disclosed. Also, a paper surface treatment for applying a composition using a polyester containing polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane as an alcohol component to a print medium for electrophotographic toner. It is disclosed that it is used as an agent (Patent Document 4, Example 1).

Japanese Patent No. 2933338 JP-A-3-124492 JP-A-6-24156 JP-A-5-295100

  In the techniques of Patent Documents 1 to 3, none of the dyeing property of the dye to the image receiving sheet at the time of thermal transfer or the releasability associated with the thermal fusion between the image receiving sheet and the transfer sheet is obtained. There is a problem that the image performance of the transferred image is not sufficient. In particular, if the image density is increased, the amount of attached dye increases, but the releasability of the image receiving sheet decreases, the surface state of the image area becomes non-uniform and irregular reflection occurs, so that a high image density cannot be obtained. There was a problem. The technique of Patent Document 4 is intended to print electrophotographic toner, and when used for printing by thermal transfer, the same problems and problems as described above occur. In contrast to the electrophotographic toner printing process, the toner that is the recording agent is electrically and mechanically transferred to the medium, and then the toner transferred by a heat roller or the like is heated and fixed to the medium. This is because thermal transfer is a system in which a sublimation dye, which is a recording agent, is transferred to a medium and fixed simultaneously under heating, so that the mechanism and required characteristics for releasability are different.

  The present invention is a thermal transfer image-receiving sheet that is excellent in dyeing property at the time of thermal transfer, has excellent releasability from a transfer sheet, and provides excellent transfer image performance, a method for producing the image-receiving sheet, and the image-receiving sheet A resin dispersion for forming a dye receiving layer is provided.

The present invention
(1) A resin dispersion in which a polyester is dispersed in an aqueous medium, and a resin dispersion for a dye-receiving layer containing a release agent, wherein the polyester has the formula (1):

(In the formula, RO represents an oxyalkylene group, R represents an ethylene group or a propylene group, x and y represent the number of added moles of alkylene oxide, each is a positive number, and the average of the sum of x and y) The value is 2-7.)
An alkylene oxide addition product of 2,2-bis (4-hydroxyphenyl) propane represented by the formula: and (b) an alkylene oxide addition of 2,2-bis (4-hydroxyphenyl) propane. Using an alcohol component in which the content ratio of ethylene oxide adduct and propylene oxide adduct (ethylene oxide adduct / propylene oxide adduct) is 50/50 to 0/100 in molar ratio in the alkylene oxide adduct of the product Obtained resin dispersion for dye-receiving layer,

(2) (1) A step of preparing a resin dispersion by dispersing polyester in an aqueous medium, and (2) a resin dispersion and a release agent obtained in step (1) on at least one surface of the substrate. A process for forming a dye-receiving layer using a thermal transfer image-receiving sheet, wherein the polyester is (a) 2,2-bis (4-hydroxyphenyl) represented by the above formula (1) A content ratio of ethylene oxide adduct and propylene oxide adduct in the alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane containing 80 mol% or more of propane alkylene oxide adduct Thermal transfer image receiving sheet obtained from an alcohol component having an ethylene oxide adduct / propylene oxide adduct in a molar ratio of 50/50 to 0/100 The method of production and,

(3) A thermal transfer image-receiving sheet having a dye-receiving layer formed on at least one surface of a substrate, wherein the dye-receiving layer is formed from a resin dispersion in which polyester is dispersed in an aqueous medium and a release agent. The polyester contains (a) 80 mol% or more of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane represented by the above formula (1), and (b) the 2,2 -The content ratio of ethylene oxide adduct to propylene oxide adduct (ethylene oxide adduct / propylene oxide adduct) in the alkylene oxide adduct of bis (4-hydroxyphenyl) propane is 50/50 to 0/100 in molar ratio. A thermal transfer image-receiving sheet obtained from an alcohol component,
About.

  ADVANTAGE OF THE INVENTION According to this invention, while being excellent in the dyeing | staining property of the dye at the time of thermal transfer, it is excellent also in releasability with a transfer sheet, and the thermal transfer image receiving sheet from which the outstanding image performance is obtained can be provided.

[Resin dispersion for dye-receiving layer]
The resin dispersion for a dye-receiving layer of the present invention (hereinafter sometimes referred to as “resin dispersion of the present invention”) is a resin dispersion in which polyester is dispersed in an aqueous medium, and a resin dispersion containing a release agent. The polyester contains (a) 80 mol% or more of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane represented by the formula (1), and (b) the above The content ratio of ethylene oxide adduct and propylene oxide adduct (ethylene oxide adduct / propylene oxide adduct) in the alkylene oxide adduct of the alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane is molar. It is obtained by using an alcohol component having a ratio of 50/50 to 0/100.

Polyester In the present invention, polyester is obtained using the following alcohol component as a raw material monomer. That is,
(A) containing 80 mol% or more of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane represented by the formula (1), and (b) the 2,2-bis (4- The content ratio of ethylene oxide adduct and propylene oxide adduct (ethylene oxide adduct / propylene oxide adduct) in the alkylene oxide adduct of hydroxyphenyl) propane is 50/50 to 0/100 in molar ratio.

  As a raw material monomer for forming polyester, an alcohol component containing 80 mol% or more of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane represented by the above formula (1) is used. In the general formula (1), R represents an ethylene group or a propylene group. x and y represent the number of moles of alkylene oxide added and each is a positive number. Each R may be the same or different. The average value of the sum of x and y is 2-7 from a reactive viewpoint with carboxylic acid, Preferably it is 2-5, More preferably, it is 2-4.

As the alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane represented by the above formula (1), specifically, polyoxypropylene-2,2-bis ( 4-hydroxyphenyl) propane, polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane and the like.
The alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane represented by the above formula (1) has a content ratio of ethylene oxide adduct and propylene oxide adduct (ethylene oxide adduct / propylene oxide addition). Product) in a molar ratio of 50/50 to 0/100. If the said content ratio is in the said range, it is preferable from being excellent in mold release property. From the above viewpoint, the content ratio is preferably 40/60 to 0/100, and more preferably 30/70 to 0/100.

  The alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane represented by the above formula (1) is included in the raw alcohol component from the viewpoint of releasability of the thermal transfer image-receiving sheet and dyeing property. The content is 80 mol% or more, preferably 90 mol% or more, and more preferably 100 mol%.

  In the present invention, a known alcohol component other than this is used together with an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane represented by the above formula (1) as an alcohol component which is a raw material component. be able to. For example, ethylene glycol, propylene glycol, glycerin, pentaerythritol, trimethylolpropane, hydrogenated bisphenol A, sorbitol, or an alkylene (2 to 4 carbon) oxide (average number of added moles 1 to 16) adduct thereof may be mentioned. It is done. This alcohol component may be used individually by 1 type, and may be used in combination of 2 or more type.

  Specific examples of the carboxylic acid component as a raw material component include dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, fumaric acid, maleic acid, adipic acid, and succinic acid, and carbons such as dodecenyl succinic acid and octenyl succinic acid. Succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms; a trivalent or higher polyvalent carboxylic acid such as trimellitic acid and pyromellitic acid, anhydrides of those acids, and their Alkyl (C1-C3) ester etc. are mentioned. The said carboxylic acid component may be used individually by 1 type, and may be used in combination of 2 or more type.

In the present invention, succinic acid having an alkyl group and / or alkenyl group is preferably used from the viewpoint of dyeing property of the dye onto the thermal transfer image-receiving sheet, and alkyl having 1 to 22 carbon atoms such as dodecenyl succinic acid and octenyl succinic acid. It is more preferable to use a succinic acid substituted with a group or an alkenyl group having 2 to 22 carbon atoms, and a linear, branched or cyclic group having 8 to 22 carbon atoms, more preferably 10 to 20 carbon atoms. Or an alkyl group having 8 to 22 carbon atoms, more preferably a linear, branched or cyclic alkenyl group having 10 to 20 carbon atoms.
Specifically, in the succinic acid having an alkyl group and / or an alkenyl group, examples of the alkyl group include various octyl groups, various decyl groups, various dodecyl groups, various tetradecyl groups, various hexadecyl groups, various octadecyl groups, various icosyl groups. Examples include groups.

Examples of the alkenyl group include various octenyl groups, various decenyl groups, various dodecenyl groups, various tetradecenyl groups, various hexadecenyl groups, various octadecenyl groups, and various icocenyl groups.
The succinic acid having an alkyl group and / or an alkenyl group is preferably contained in the carboxylic acid component in an amount of 5 to 50 mol%, thereby improving the dyeing property of the dye on the thermal transfer image-receiving sheet. This is presumed that the interaction between the polyesters weakens due to the presence of the alkyl group and / or alkenyl group in the side chain of the succinic acid, so that the dye soaks into the polyester, from the viewpoint of the permeability of the dye, The succinic acid is more preferably contained in the carboxylic acid component in an amount of 10 to 40 mol%, further preferably 20 to 40 mol%.

The polyester can be produced, for example, by subjecting the alcohol component and the carboxylic acid component to polycondensation at a temperature of 180 to 250 ° C. using an esterification catalyst as necessary in an inert gas atmosphere. From the viewpoint of releasability of the thermal transfer image-receiving sheet of the present invention, the raw material polyester preferably has a sharp molecular weight distribution, and is preferably subjected to condensation polymerization using an esterification catalyst. Examples of the esterification catalyst include metal compounds such as tin catalyst, titanium catalyst, antimony trioxide, zinc acetate, and germanium oxide.
From the viewpoint of releasability of the thermal transfer image-receiving sheet and dyeing property, the softening point of the polyester is preferably 80 to 165 ° C, and the glass transition point is preferably 50 to 85 ° C. The acid value is preferably from 1 to 35 mgKOH / g, more preferably from 5 to 35 mgKOH / g, from the viewpoint of dispersibility of the resin containing polyester in an aqueous medium, that is, emulsifying properties. The glass transition point, softening point, and acid value can all be obtained by appropriately adjusting the type and blending ratio of the monomers used, the temperature of the condensation polymerization, and the reaction time.
Further, from the viewpoint of film formability when obtaining a thermal transfer image-receiving sheet, the number average molecular weight of the polyester is preferably 1,000 to 10,000, and more preferably 2,000 to 8,000.

  In the present invention, the polyester includes a polyester modified to such an extent that the characteristics are not substantially impaired within the above range. Examples of the modified polyester include grafting and blocking with phenol, urethane, epoxy and the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like. And a composite resin having two or more kinds of resin units including a polyester unit.

  In the present invention, the polyester can be used together with other resins than the polyester. As resins other than polyester, known resins used as the receiving layer of thermal transfer image-receiving sheets, for example, polyolefin resins such as polypropylene, halogenated polymers such as polyvinyl chloride and polyvinylidene chloride, polyvinyl acetate, polyacrylic esters, Examples include vinyl polymers such as polyvinyl acetal, polystyrene resins, polyamide resins, copolymer resins of olefins such as ethylene and propylene and other vinyl monomers, cellulose resins such as ionomers and cellulose diacetates, and polycarbonates. Polyvinyl chloride and polycarbonate are preferable from the viewpoints of releasability of the thermal transfer image-receiving sheet and dyeing property.

Resin dispersion in which polyester is dispersed In the present invention, polyester is used as a resin particle in a resin dispersion obtained by dispersing a resin containing the polyester in an aqueous medium, together with a release agent. It is preferably contained in the resin dispersion. The content of the polyester in the resin containing the polyester is preferably 70% by weight or more, more preferably 80% by weight or more, and still more preferably 100% by weight from the viewpoint of dyeing properties.
The aqueous medium in which the polyester is dispersed is one containing water as a main component, that is, water containing 50% or more. From the environmental viewpoint, the content of water in the aqueous medium is preferably 80% by weight or more, more preferably 90% by weight or more, and further preferably 100% by weight. Examples of components other than water include organic solvents that dissolve in water, such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran.

The resin particles in the resin dispersion in which the polyester is dispersed have a volume median particle size (D50) of preferably 1 μm or less, and 20 nm to 1 μm, from the viewpoint of film-forming properties when obtaining a thermal transfer image-receiving sheet. More preferably, it is 50-800 nm more preferably. Here, “volume median particle size (D50)” means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle size. The measuring method is as described later.
The polyester or a resin containing the polyester is preferably contained in an amount of 80 to 100% by weight, more preferably 85 to 100% in the solid content of the resin dispersion from the viewpoint of dyeability of the dye on the thermal transfer image-receiving sheet. It is contained by weight%, more preferably 90-100% by weight.

  The resin dispersion is prepared by dissolving the polyester or a resin containing the same in a ketone solvent, adding a neutralizing agent to ionize the carboxyl group of the polyester or the resin containing the ion, and then adding water, It can be obtained by a method in which the solvent is distilled off and the phase is changed to an aqueous system. Specifically, for example, a reactor equipped with a stirrer, a reflux condenser, a thermometer, a dropping funnel, a nitrogen gas introduction tube is prepared, and a polyester dissolved in a ketone solvent or a resin containing the neutralizer, etc. Is added to ionize the carboxyl group (unnecessary if already ionized), and then water is added, and then the ketone solvent is distilled off and the phase is changed to an aqueous system. The dissolution in the ketone solvent and the addition of the neutralizing agent are usually carried out at a temperature not higher than the boiling point of the ketone solvent, and examples of the water used here include deionized water.

  Examples of the ketone solvent used here include acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, methyl isobutyl ketone, and methyl isopropyl ketone. From the viewpoint of the solubility of the resin and the ease of evaporation of the solvent. Preferably, methyl ethyl ketone is used.

  Examples of the neutralizing agent include aqueous alkaline solutions such as aqueous ammonia and sodium hydroxide, allylamine, isopropylamine, diisopropylamine, ethylamine, diethylamine, triethylamine, 2-ethylhexylamine, 3-ethoxypropylamine, diisobutylamine, and 3-diethylamino. Propylamine, tri-n-octylamine, t-butylamine, sec-butylamine, propylamine, methylaminopropylamine, dimethylaminopropylamine, n-propanolamine, butanolamine, 2-amino-4-pentanol, 2- Amino-3-hexanol, 5-amino-4-octanol, 3-amino-3-methyl-2-butanol, monoethanolamine, N, N-dimethylethanolamine, isopropanol Amine, neopentanolamine, diglycolamine, ethylenediamine, 1,3-diaminopropane, 1,2-diaminopropane, 1,6-diaminohexane, 1,9-diaminononane, 1,12-diaminododecane, dimer Fatty acid diamine, 2,2,4, -trimethylhexamethylenediamine, 2,4,4, -trimethylhexamethylenediamine, hexamethylenediamine, N-aminoethylpiperazine, N-aminopropylpiperazine, N-aminopropyldipiperidi Examples thereof include amines such as propane and piperazine. These neutralizing agents may be used in an amount that can neutralize at least the acid value of the resin containing polyester.

From the viewpoints of storage stability, storage stability of the thermal transfer image-receiving sheet obtained using the resin dispersion of the present invention, and releasability, the resin dispersion has a glass transition point of 40 to 80 ° C. It is preferable that it is 50-75 degreeC. Moreover, it is preferable that a softening point is 80-250 degreeC, More preferably, it is 120-220 degreeC. The number average molecular weight is the same as the molecular weight of the polyester.
From the viewpoint of productivity, the solid concentration in the resin dispersion is preferably 20 to 40% by weight, more preferably 25 to 40% by weight, and further preferably 30 to 40% by weight. Further, the pH of the resin dispersion at 25 ° C. is preferably 5 to 10, more preferably 6 to 9, and still more preferably 7 to 8 from the viewpoint of storage stability of the resin dispersion.

Release agent The resin dispersion of the present invention contains a release agent together with the polyester. As the release agent, for example, a water-dispersible or water-soluble modified silicone oil and / or a colloidal solution of silica fine particles (for example, colloidal silica) is preferably used. From the viewpoint of dispersibility in the thermal transfer image-receiving sheet, the average particle size in the colloidal solution of the silica fine particles is preferably 100 nm or less, and more preferably 20 nm or less colloidal silica. The resin dispersion liquid of the present invention can contain a release agent such as polyethylene and polypropylene in addition to the above release agent. These release agents are used in an amount of 0.1 to 20 parts by weight with respect to 100 parts by weight of the resin containing the polyester in the resin dispersion of the present invention, from the viewpoint of releasability of the thermal transfer image-receiving sheet and dyeability. It is preferable to contain, More preferably, it can contain 0.5-10 weight part.

Resin dispersion for dye-receiving layer The resin dispersion of the present invention contains a resin dispersion in which the polyester is dispersed, and the release agent.
In addition, the resin dispersion of the present invention includes pigments such as titanium oxide, zinc oxide, kaolin clay, calcium carbonate, and finely divided silica from the viewpoint of improving the whiteness of the dye-receiving layer and increasing the sharpness of the transferred image. Fillers can be included. From the viewpoint of the whiteness of the thermal transfer image-receiving sheet, these pigments and fillers are added in an amount of 0.1 to 20 parts by weight, preferably 0.1 to 100 parts by weight of the resin containing polyester in the resin dispersion of the present invention. -10 parts by weight.
The resin dispersion of the present invention may further contain additives such as a film forming agent such as butyl carbitol acetate and diethyl carbitol, a crosslinking agent, a curing agent, and a catalyst, if necessary.

  The resin dispersion of the present invention preferably does not contain a surfactant from the viewpoint that the resulting polyester has self-dispersibility and improves the hydrophobicity of the thermal transfer image-receiving sheet.

[Thermal transfer image-receiving sheet]
The thermal transfer image-receiving sheet of the present invention comprises a dye-receiving layer formed on at least one surface of a substrate, and the dye-receiving layer is formed from a resin dispersion in which polyester is dispersed in an aqueous medium and a release agent, The polyester contains (a) 80 mol% or more of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane represented by the above formula (1), and (b) the 2,2- The content ratio of ethylene oxide adduct and propylene oxide adduct (ethylene oxide adduct / propylene oxide adduct) in the alkylene oxide adduct of bis (4-hydroxyphenyl) propane is 50/50 to 0/100 in molar ratio. It is obtained from a certain alcohol component.

Dye-receiving layer The thermal transfer image-receiving sheet of the present invention is a reverse roll using, for example, a gravure printing method, a screen printing method, or a gravure plate on at least one surface of a substrate as the coating liquid of the resin dispersion of the present invention. It is obtained by applying and drying by a coating method or the like to form a dye receiving layer.
The thickness of the dye-receiving layer formed as described above is generally 1 to 50 μm, and preferably 3 to 15 μm from the viewpoint of image quality and productivity. Further, the solid content after drying is preferably 3 to 15 g per 1 m ² of the receiving layer.
A release layer containing a release agent can be formed on the dye-receiving layer from the viewpoint of further improving the release property from the thermal transfer sheet during transfer. As a preferable release layer, it is preferable to use reactive silicones such as hydroxy-modified, amino-modified, carboxy-modified, and mercapto-modified, and this reactive silicone may be cross-linked using a cross-linking agent as necessary. .

Thermal transfer image-receiving sheet The thermal transfer image-receiving sheet of the present invention is formed by forming the dye-receiving layer on at least one surface of a substrate. Examples of the substrate include synthetic paper (polyolefin-based, polystyrene-based, etc.). , Fine paper, art paper, coated paper, cast coated paper, wallpaper, backing paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin internal paper, paperboard, etc., cellulose fiber paper, polyolefin, polyvinyl chloride Films or sheets of various resins such as polyethylene terephthalate, polystyrene, polymethacrylate, polycarbonate, etc. can be used, and white opaque films or foamed foam sheets formed by adding white pigments and fillers to these resins Etc. can also be used. Moreover, the laminated body which combined the said base material can also be used.
As for the thickness of these base materials, about 10-300 micrometers is common, for example. From the viewpoint of improving the adhesion to the dye-receiving layer, it is preferable to subject the surface of the substrate to primer treatment or corona discharge treatment.

The transfer sheet used when performing thermal transfer using the thermal transfer image-receiving sheet of the present invention as described above is usually a paper or polyester film provided with a dye layer containing a sublimation dye, and a conventionally known transfer Any sheet can be used.
Examples of sublimable dyes that can be suitably used for the thermal transfer image-receiving sheet of the present invention include pyridoneazo series, dicyanostyryl series, quinophthalone series, merocyanine series for yellow dyes; benzeneazo series, pyrazolone azomethine series, isothiazole series for magenta dyes, Pyrazolotriazole series: As cyan dyes, anthraquinone series, cyanomethylene series, indophenol series, and indonaphthol series are listed.
As the means for applying thermal energy at the time of thermal transfer, any conventionally known means for applying can be used. For example, by controlling the recording time with a recording device such as a thermal printer, it is about 5 to 100 mJ / mm ² . This can be done by applying thermal energy.

[Method for producing thermal transfer image-receiving sheet]
The method for producing a thermal transfer image-receiving sheet of the present invention is obtained in step (1) on (1) a step of preparing a resin dispersion by dispersing polyester in an aqueous medium, and (2) on at least one surface of a substrate. A process for forming a dye-receiving layer using a resin dispersion and a release agent, wherein the polyester is (a) 2, 2 represented by the formula (1) An ethylene oxide adduct containing at least 80 mol% of an alkylene oxide adduct of bis (4-hydroxyphenyl) propane and (b) the alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane And alcohol content of propylene oxide adduct (ethylene oxide adduct / propylene oxide adduct) in a molar ratio of 50/50 to 0/100 It is obtained from the minute.

  Details of the polyester in step (1), the aqueous medium, the resin dispersion, and the release agent in step (2) are as described above. The thermal transfer image-receiving sheet of the present invention is obtained by forming a dye-receiving layer on at least one surface of the base material using the resin dispersion obtained in the step (1) and a release agent. The details of the substrate and the dye receiving layer are also as described above.

Hereinafter, the present invention will be described more specifically with reference to examples and the like. In the following examples and the like, each property value was measured and evaluated by the following method.
[Acid value of resin]
Measured according to JIS K0070. However, as a measurement solvent, a mixed solvent of ethanol and ether was a mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[Polyester and resin particles and solid softening point and glass transition point]
(1) Using a flow tester (Shimadzu Corporation, “CFT-500D”), a 1 g sample was heated at a heating rate of 6 ° C./min, a load of 1.96 MPa was applied by a plunger, a diameter of 1 mm, a length Extrude from a 1 mm nozzle. Plot the flow tester drop by the flow tester against the temperature, and let the softening point be the temperature at which half the sample flowed out.
(2) Glass transition point Using a differential scanning calorimeter (Perkin Elmer, Pyris6DSC), the temperature was raised to 200 ° C., and the sample cooled to 0 ° C. at a temperature lowering rate of 10 ° C./min from that temperature was heated to 10 ° C. The temperature is increased at a rate of 1 min / min, and the temperature is defined as the intersection of a base line extension below the maximum peak temperature of endotherm and a tangent line indicating the maximum slope from the peak rising portion to the peak apex.

[Number average molecular weight of resin]
The molecular weight distribution is measured by gel permeation chromatography and the number average molecular weight is calculated by the following method.
(1) Preparation of sample solution The resin is dissolved in tetrahydrofuran (THF) so that the concentration is 0.5 g / 100 ml. Subsequently, this solution is filtered using a fluororesin filter having a pore size of 2 μm [manufactured by Sumitomo Electric Industries, Ltd., “FP-200”] to remove insoluble components to obtain a sample solution.
(2) Molecular weight distribution measurement Using the following apparatus, THF is flowed at a flow rate of 1 ml per minute, and the column is stabilized in a constant temperature bath at 40 ° C. 100 μl of the sample solution is injected therein and measurement is performed. The molecular weight of the sample is calculated based on a calibration curve prepared in advance. In this calibration curve, several types of monodisperse polystyrene (2.63 × 10 ³ , 2.06 × 10 ⁴ , 1.02 × 10 ⁵ manufactured by Tosoh Corporation), 2.10 × manufactured by GL Sciences Inc. 10 ³ , 7.00 × 10 ³ , 5.04 × 10 ⁴ ) are used as standard samples.
Measuring device: CO-8010 (manufactured by Tosoh Corporation)
Analysis column: GMHLX + G3000HXL (manufactured by Tosoh Corporation)

[Particle size of resin particles containing polyester]
Laser diffraction-type particle size measuring instrument (HORIBA Ltd., "LA-920") using a distilled water was added to the measuring cell, at concentrations absorbance is within a proper range, measuring the volume median particle size (D ₅₀₎ To do.

[Solid content concentration of resin dispersion in which polyester is dispersed]
Using an infrared moisture meter (Ketto Science Laboratory Co., Ltd .: FD-230), 5 g of the dispersion was wet at a drying temperature of 150 ° C. and a measurement mode 96 (monitoring time 2.5 minutes / variation width 0.05%) Measure the moisture content of the base. The solid content concentration was calculated according to the following formula.
Solid content concentration (%) = 100-M
M: wet base moisture (%) = [(W−W ₀ ) / W] × 100
W: Sample weight before measurement (initial sample weight)
W ₀ : Sample weight after measurement (absolute dry weight)

[Softening point and glass transition point of resin dispersion with polyester dispersed]
After the resin dispersion in which the polyester is dispersed is freeze-dried at −10 ° C. for 9 hours using a freeze dryer (FDU-2100, manufactured by Tokyo Rika Kikai Co., Ltd.), the same as the measurement of the softening point and glass transition point of the polyester described above. Measured.

Production Example 1 (Production of polyester a)
1,050 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 355 g of fumaric acid, 1 g of hydroquinone and 1.4 g of dibutyltin oxide were introduced into a nitrogen introduction tube, dehydration tube, stirrer and thermoelectric The mixture was placed in a four-necked flask equipped with a pair and allowed to react at 210 ° C. for 5 hours under a nitrogen atmosphere and normal pressure. Polyester a was obtained by reacting at 210 ° C. under reduced pressure until the softening point measured according to ASTM D36-86 reached 100 ° C. The obtained polyester a had a softening point of 100 ° C., a glass transition point of 59 ° C., an acid value of 21 mgKOH / g, and a number average molecular weight of 4280.

Production Example 2 (Production of polyester b)
1,040 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 10 g of polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, terephthalic acid 199 g and 4 g of dibutyltin oxide were put into a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple, and reacted at 230 ° C. for 5 hours under a nitrogen atmosphere, and further reacted under reduced pressure. . The temperature was cooled to 210 ° C., 209 g of fumaric acid and 1 g of hydroquinone were added and reacted for 5 hours, and further reacted under reduced pressure until the softening point measured according to ASTM D36-86 reached 110 ° C. to obtain polyester b. . Polyester b obtained had a softening point of 108 ° C., a glass transition point of 69 ° C., an acid value of 22 mgKOH / g, and a number average molecular weight of 4110.

Production Example 3 (Production of polyester c)
17,500 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 16,250 g of polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, 11,454 g of terephthalic acid, 1,608 g of dodecenyl succinic anhydride, 4,800 g of trimellitic anhydride and 15 g of dibutyltin oxide were placed in a four-necked flask equipped with a nitrogen introducing tube, a dehydrating tube, a stirrer and a thermocouple, The mixture was stirred at 220 ° C. in a nitrogen atmosphere and reacted until the softening point measured according to ASTM D36-86 reached 120 ° C. to obtain polyester c. The obtained polyester c had a softening point of 125 ° C., a glass transition point of 65 ° C., an acid value of 19 mgKOH / g, and a number average molecular weight of 3580.

Production Example 4 (Production of polyester d)
3920 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 1560 g of polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, dodecenyl succinic anhydride 1672 g, 1354 g of terephthalic acid, and 25 g of tin octylate are placed in a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple, and are reacted at 230 ° C. under normal pressure for 5 hours under a nitrogen atmosphere. It reacted with. Trimellitic anhydride (304 g) was added and reacted until the softening point measured according to ASTM D36-86 reached 120 ° C. to obtain polyester d. The obtained polyester d had a softening point of 115 ° C., a glass transition point of 57 ° C., an acid value of 15 mg KOH / g, and a number average molecular weight of 4200.

Production Example 5 (Production of polyester e)
525 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 1,950 g of polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, terephthalic acid 1,552 g, glycerin 138 g and tin octylate 21 g were put into a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, stirred at 220 ° C. in a nitrogen atmosphere, and measured according to ASTM D36-86. Reaction was performed until the softening point reached 120 ° C. to obtain polyester e. The obtained polyester e had a softening point of 121 ° C., a glass transition point of 73 ° C., an acid value of 21 mgKOH / g, and a number average molecular weight of 3870.

Production Example 6 (Production of polyester f)
Equipped with 6,500 g of polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, 2,656 g of terephthalic acid and 46 g of dibutyltin oxide, equipped with nitrogen introduction tube, dehydration tube, stirrer and thermocouple The reaction mixture was placed in a four-necked flask and allowed to react at 230 ° C. under normal pressure for 5 hours under a nitrogen atmosphere, and further reacted under reduced pressure. 384 g of trimellitic anhydride was added and reacted until the softening point measured according to ASTM D36-86 reached 100 ° C. to obtain polyester f. Polyester f obtained had a softening point of 101 ° C., a glass transition point of 62 ° C., an acid value of 21 mgKOH / g, and a number average molecular weight of 2660.

The compositions and properties of the polyesters a to f obtained in Production Examples 1 to 6 are shown in Table 1 below.

Production Example 7 (Production of resin dispersion A)
300 g of polyester a was placed in a four-necked flask equipped with a nitrogen inlet tube, a reflux condenser, a stirrer, and a thermocouple, and dissolved in 540 g of methyl ethyl ketone at 40 ° C. Next, 7.64 g of 25% aqueous ammonia was added, 720 g of deionized water was added with stirring, and then methyl ethyl ketone was distilled off at 50 ° C. under reduced pressure to obtain Resin Dispersion A. The resin particles in the obtained resin dispersion A had a volume median particle size of 360 nm, a solid content of 33% by weight, and a pH of 7.0.

Production Examples 8 to 12 (Production of resin dispersions B to F)
Resin dispersions B to F were obtained in the same manner as in Production Example 7 except that the amounts of each component were as shown in Table 2.

The composition and properties of each of the resin dispersions A to F obtained in Production Examples 7 to 12 are summarized in Table 2 below. The value for each component indicates the blending amount (g).

Examples 1 to 4 and Comparative Examples 1 and 2 (Production of Resin Dispersion for Dye Receiving Layer and Thermal Transfer Image Receiving Sheet)
Each of the resin dispersions of the present invention obtained by mixing the resin dispersions and additives described in Table 3 on cast coated paper (thickness 210 μm) was dried with a wire bar as a coating liquid and then 5.0 g / After coating at 25 ° C. so as to be m ² , it was dried at 60 ° C. to obtain a thermal transfer image receiving sheet. A monochrome gradation pattern (18 gradations) was printed on this thermal transfer image-receiving sheet using a sublimation printer (SELPHY ES-1 manufactured by Canon Inc.). The monochrome gradation pattern is a 0.6 cm square solid image in which the L value is changed from 0 to 255 in 15 increments. The evaluation items were printing sensitivity, maximum density, and thermal fusion with the ink ribbon at the time of printing, and were measured and evaluated as follows. The results are shown in Table 3. In addition, each number shown in Table 3 shows the compounding quantity of each component, and all represent gram (g).

Evaluation method [printing sensitivity ( evaluation of dyeing property)]
The transfer color density at the low density print (9th gradation (L = 120)) was measured with a Gretag densitometer (manufactured by G RETAG-MACBETH). Higher transfer color density means better dyeing properties.
[Maximum concentration (evaluation of dyeing property and releasability from transfer sheet)]
The transfer color density at high density printing (18th gradation (L = 0)) was measured with a Gretag densitometer (manufactured by GRETAG-MACBETH). Higher image density means better dyeing properties. As the density increases, the amount of attached dye increases. However, when the releasability is poor, the surface state of the image area becomes non-uniform and irregular reflection occurs, so that a high image density cannot be obtained.

[Heat fusion (Evaluation of releasability from transfer sheet)]
From the peeling sound of the ink ribbon and the dye-receiving sheet at the time of gradation pattern printing, the heat fusion property was judged according to the following criteria.
A: No abnormal noise at the time of peeling and no problem due to thermal fusion between the thermal transfer receiving sheet and the ink ribbon B: Although some abnormal noise is heard at the time of peeling, there is no problem due to thermal fusion C: Heat Fusing and difficult to peel

  The resin dispersion of the present invention is excellent in dyeing properties of the resulting thermal transfer image-receiving sheet and also excellent in releasability, and thus can be suitably used for a thermal transfer image-receiving sheet having excellent image performance. .

Claims (8)

A resin dispersion in which a polyester is dispersed in an aqueous medium, and a resin dispersion for a dye-receiving layer containing a release agent, the polyester comprising (a) the formula (1)

(In the formula, RO represents an oxyalkylene group, R represents an ethylene group or a propylene group, x and y represent the number of added moles of alkylene oxide, each is a positive number, and the average of the sum of x and y) The value is 2-7.)
An alkylene oxide addition product of 2,2-bis (4-hydroxyphenyl) propane represented by the formula: and (b) an alkylene oxide addition of 2,2-bis (4-hydroxyphenyl) propane. Using an alcohol component in which the content ratio of ethylene oxide adduct and propylene oxide adduct (ethylene oxide adduct / propylene oxide adduct) is 50/50 to 0/100 in molar ratio in the alkylene oxide adduct of the product Obtained resin dispersion for dye-receiving layer.   The resin dispersion for a dye receiving layer according to claim 1, wherein the average value of the sum of x and y in the alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane represented by the formula (1) is less than 4. liquid.   The resin dispersion for a dye receiving layer according to claim 1 or 2, wherein the polyester is obtained by using a carboxylic acid component containing 5 to 50 mol% of succinic acid having an alkyl group and / or an alkenyl group.   The resin dispersion for a dye-receiving layer according to any one of claims 1 to 3, wherein the acid value of the polyester is 5 to 35 mgKOH / g.   The resin dispersion for a dye receiving layer according to any one of claims 1 to 4, wherein the volume median particle size of the resin particles in the resin dispersion in which the polyester is dispersed is 1 µm or less.   The resin dispersion for a dye-receiving layer according to any one of claims 1 to 5, wherein a solid content concentration in the resin dispersion in which the polyester is dispersed is 20 to 45% by weight. (1) A step of preparing a resin dispersion by dispersing polyester in an aqueous medium, and (2) using the resin dispersion and the release agent obtained in step (1) on at least one surface of the substrate. A process for forming a dye-receiving layer, wherein the polyester comprises (a) formula (1)

(In the formula, RO represents an oxyalkylene group, R represents an ethylene group or a propylene group, x and y represent the number of added moles of alkylene oxide, each is a positive number, and the average of the sum of x and y) The value is 2-7.)
An alkylene oxide addition product of 2,2-bis (4-hydroxyphenyl) propane represented by the formula: and (b) alkylene oxide addition of the 2,2-bis (4-hydroxyphenyl) propane Of an ethylene oxide adduct and a propylene oxide adduct in the product (ethylene oxide adduct / propylene oxide adduct) obtained from an alcohol component having a molar ratio of 50/50 to 0/100, Method. A thermal transfer image-receiving sheet having a dye-receiving layer formed on at least one surface of a substrate, wherein the dye-receiving layer is formed from a resin dispersion in which polyester is dispersed in an aqueous medium and a release agent, Polyester is (a) Formula (1)

(In the formula, RO represents an oxyalkylene group, R represents an ethylene group or a propylene group, x and y represent the number of added moles of alkylene oxide, each is a positive number, and the average of the sum of x and y) The value is 2-7.)
An alkylene oxide addition product of 2,2-bis (4-hydroxyphenyl) propane represented by the formula: and (b) alkylene oxide addition of the 2,2-bis (4-hydroxyphenyl) propane A thermal transfer image-receiving sheet obtained from an alcohol component having a molar ratio of ethylene oxide adduct / propylene oxide adduct (ethylene oxide adduct / propylene oxide adduct) of 50/50 to 0/100.