JP2011255523A - Resin composition for thermal transfer image-receiving sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for thermal transfer image-receiving sheets which can provide the thermal transfer image-receiving sheets excellent in dyeing capacity and light resistance, and to provide a thermal transfer image-receiving sheet which has a dye receiving layer that includes the resin composition.SOLUTION: The resin composition for thermal transfer image-receiving sheets contains a resin (A) which contains a polyester segment obtained by polycondensing an alcohol component that includes an alkyleneoxide adduct of 2,2-bis(4-hydroxyphenyl) propane in an amount of 50 mol% or above with a carboxylic acid component, and a compound (B) which includes a 2,2-bis(4-hydroxyphenyl) propane segment and has a melting point of lower than 30°C.

Description

  The present invention relates to a resin composition for a thermal transfer image receiving sheet, a thermal transfer image receiving sheet having a dye receiving layer containing the resin composition, and a method for producing the resin composition for a 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. Therefore, a thermal transfer image receiving sheet for exhibiting these performances has been developed.

In Patent Document 1, for the purpose of improving film physical properties and transfer density, an image receiving layer for receiving an image of a dye transferred from a thermal transfer dye donating material when heated on a support and forming an image is provided. In the thermal transfer image-receiving material provided at least in one layer, the image-receiving layer is made of a composition in which a dye-accepting substance is dispersed in a water-soluble binder, and the uppermost layer of the image-receiving surface constituting layer of the image-receiving material has a silicone compound and [organic / [Inorganic] A thermal transfer image-receiving material containing a co-dispersion of a plasticizer having a value of 1.5 or more is disclosed.
Patent Document 2 also contains an alcohol component containing 50 mol% or more of an alkylene oxide adduct of bisphenol A and an alicyclic carboxylic acid of more than 50 mol% for the purpose of improving dyeability and releasability. Disclosed is a composition for a receiving layer of a thermal transfer image-receiving sheet, which comprises a resin containing a polyester obtained by condensation polymerization of a carboxylic acid component and a polyether-modified silicone having an oxyethylene group and / or an oxypropylene group. Yes.

Japanese Patent Laid-Open No. 3-101993 JP 2009-262337 A

Printing is performed by coloring the ink sheet to the thermal transfer image-receiving sheet by heating from the thermal head, so that high dye dyeability is required to express the target color. Is done. In addition, there has been a problem that the printed material is faded due to a change with time. Therefore, there is a demand for a thermal transfer image-receiving sheet that has high dyeing property and excellent light fastness that suppresses fading of printed matter. From the viewpoint of achieving both the dyeability and the light resistance, the thermal transfer image receiving sheets described in Patent Documents 1 and 2 still have room for improvement.
The present invention relates to a resin composition for a thermal transfer image-receiving sheet that can provide a thermal transfer image-receiving sheet having excellent dyeability and light resistance, a thermal transfer image-receiving sheet having a dye-receiving layer containing the resin composition, and the resin for a thermal transfer image-receiving sheet It is an object to provide a method for producing a composition.

The present inventors have considered that the factor affecting the dyeing property and light fastness is the state of the dye-receiving layer when heated by a thermal head. As a result, it has been found that dyeing property and light resistance are improved by using a resin composition containing a resin containing a specific polyester resin portion and a compound having a specific structure for the dye-receiving layer.
That is, the present invention provides the following [1] to [3].
[1] Resin (A) containing a polyester portion obtained by condensation polymerization of an alcohol component containing 50 mol% or more of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane and a carboxylic acid component, And a resin composition for a thermal transfer image-receiving sheet, comprising a compound (B) containing a 2,2-bis (4-hydroxyphenyl) propane moiety and having a melting point of less than 30 ° C.
[2] A thermal transfer image receiving sheet having a dye-receiving layer containing the resin composition for a thermal transfer image receiving sheet according to [1].
[3] The resin (A) or the polyester resin (a1) serving as a precursor of the resin (A) and the compound (B) are mixed, water is added, and the compound (B) is included in the resin (A). The manufacturing method of the resin composition for thermal transfer image receiving sheets as described in said [1] including the process of obtaining the aqueous dispersion performed.

  The resin composition for a thermal transfer image receiving sheet of the present invention can provide a thermal transfer image receiving sheet excellent in dyeability and light resistance. Moreover, the thermal transfer image-receiving sheet having a dye-receiving layer containing the resin composition can achieve both excellent dyeability and light resistance.

[Resin composition for thermal transfer image-receiving sheet]
The resin composition for a thermal transfer image-receiving sheet of the present invention is a polyester obtained by condensation polymerization of an alcohol component containing 50 mol% or more of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane and a carboxylic acid component. Resin (A) containing the resin part (A1) (hereinafter simply referred to as “resin part (A1)” or “polyester resin segment (A1)” or simply “segment (A1)”) (hereinafter simply referred to as “resin”) (A) ") and a compound (B) containing a 2,2-bis (4-hydroxyphenyl) propane moiety and having a melting point of less than 30 ° C.

The reason why the thermal transfer image-receiving sheet having the resin composition for a thermal transfer image-receiving sheet of the present invention in the dye-receiving layer is excellent in dyeing property and light resistance is not clear, but is considered as follows.
The raw material monomer of the segment (A1) in the resin (A) contained in the resin composition for a thermal transfer image-receiving sheet of the present invention is an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane as an alcohol component. Including. Since this compound has two aromatic rings derived from 2,2-bis (4-hydroxyphenyl) propane in the molecule, that is, a structure similar to a dye, it has a high affinity with the dye and dyes the thermal transfer image-receiving sheet. It is thought that it contributes to the improvement of wearability.
By the way, the dye staying on the sheet surface is easily decomposed by light. In addition to the resin (A), the present invention contains a compound (B) containing a 2,2-bis (4-hydroxyphenyl) propane moiety and having a melting point of less than 30 ° C. Since this compound has the same structural portion as the resin (A), it has a high affinity with the resin (A) and increases the molecular mobility of the resin, whereby the dye penetrates into the inside of the dye receiving layer, and thermal transfer image receiving It is considered that the dyeing property and light resistance of the sheet are remarkably improved.

<Resin (A)>
The resin (A) contained in the resin composition for a thermal transfer image-receiving sheet of the present invention comprises an alcohol component containing 50 mol% or more of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane and a carboxylic acid component. The polyester resin part (A1) obtained by polycondensation is contained.
The resin (A) may be a polyester resin consisting only of the polyester resin portion (segment) (A1), but is added to the polyester resin segment (A1) from the viewpoint of dyeing property and light resistance of the thermal transfer image-receiving sheet. It is preferably a resin containing a polymer resin segment (A2) (hereinafter also simply referred to as “segment (A2)”), a graft having the segment (A1) as the main chain and the segment (A2) as the side chain More preferably, it is a polymer. When the resin (A) is a graft polymer, the segment (A2) is hardly compatible with the main chain segment (A1) made of the polyester resin having the above structure, so that a fine phase separation structure is formed. It is considered that the permeability of the dye is increased, and the dyeing property and light resistance of the thermal transfer image receiving sheet are greatly improved.
When the resin (A) is a graft polymer having the segment (A1) as the main chain and the segment (A2) as the side chain, the weight ratio of the segment (A1) and the segment (A2) constituting the graft polymer [segment (A1) / segment (A2)] is preferably 55/45 to 95/5, more preferably 65/35 to 95/5, and more preferably 75/25 from the viewpoint of improving the dyeing property of the thermal transfer image-receiving sheet. To 95/5, more preferably 85/15 to 95/5. With more segments (A1) than segments (A2), the dyeing property derived from the molecular structure of segments (A1) can be sufficiently exhibited while forming a fine phase separation structure. Conceivable.

  Further, from the viewpoint of releasability and storage stability of the thermal transfer image receiving sheet, the softening point of the resin (A) is preferably 80 to 165 ° C. From the same viewpoint, the acid value of the resin (A) is preferably 5 to 40 mgKOH / g, more preferably 5 to 35 mgKOH / g, and still more preferably 10 to 35 mgKOH / g.

(Polyester resin part (segment) (A1))
The polyester resin part (segment) (A1) constituting the resin (A) contained in the resin composition for a thermal transfer image receiving sheet of the present invention is an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane. It is a resin portion obtained by condensation polymerization of an alcohol component and a carboxylic acid component containing 50 mol% or more.

Specifically, the alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane is preferably a compound represented by the following general formula (I).

In the general formula (I), R ¹ O and R ² O are both oxyalkylene groups, preferably each independently an oxyalkylene group having 1 to 4 carbon atoms, more preferably an oxyethylene group or an oxypropylene group. It is.
x and y correspond to the added mole number of alkylene oxide, and are positive numbers. Furthermore, from the viewpoint of reactivity with the carboxylic acid component, the average value of the sum of x and y is preferably 2-7, more preferably 2-5, and still more preferably 2-3.
Further, x R ¹ O or y R ² O may be the same or different, but the dyeing property of the thermal transfer image-receiving sheet and the intermediate layer and the dye-receiving layer in the thermal transfer image-receiving sheet From the viewpoint of adhesion, it is preferably the same and more preferably an oxypropylene group. The alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane may be used alone or in combination of two or more.

  From the viewpoint of releasability and dyeing property of the thermal transfer image-receiving sheet, the content of the oxypropylene group is preferably 50 to 100 mol%, more preferably 60 to 100 mol%, still more preferably in the oxyalkylene group. It is 70-100 mol%, More preferably, it is substantially 100 mol%. The other oxyalkylene group is preferably an oxyethylene group or an oxytrimethylene group from the viewpoint of dyeability of the thermal transfer image-receiving sheet, and more preferably an oxyethylene group from the viewpoint of dyeability of the thermal transfer image-receiving sheet.

  The alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane is contained in the alcohol component in an amount of 50 mol% or more, preferably 70 mol%, from the viewpoint of releasability and dyeing property of the thermal transfer image-receiving sheet. More preferably, it is 80 mol% or more, and still more preferably 100 mol%. In the present invention, the alkylene oxide adduct means the whole structure in which an oxyalkylene group is added to 2,2-bis (4-hydroxyphenyl) propane.

The alcohol component which is a raw material monomer of the segment (A1) can contain other alcohol components in addition to the alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane.
Specifically, examples of the alcohol component of the raw material monomer derived from the structural unit of the resin portion (A1) (hereinafter also simply referred to as “raw material monomer of the resin portion (A1)”) include, for example, ethylene glycol, propylene glycol (1 , 2-propanediol), glycerin, pentaerythritol, trimethylolpropane, hydrogenated bisphenol A, sorbitol, or their alkylene (2 to 4 carbon) oxide adduct (average number of added moles 1 to 16). . You may use the said alcohol component individually or in combination of 2 or more types.
Further, when the resin (A) is a graft polymer having the resin part (segment) (A1) as a main chain and the segment (A2) as a side chain, an alcohol having a non-aromatic carbon-carbon unsaturated bond For example, an alcohol component containing an unsaturated aliphatic alcohol can be used. The portion of the carbon-carbon unsaturated bond in the unsaturated aliphatic alcohol can be a bonding portion with the segment (A2) in the graft polymer, in which case the unsaturated bond becomes a saturated bond. Examples of the alcohol having a non-aromatic carbon-carbon unsaturated bond include unsaturated aliphatic alcohols such as allyl alcohol.

Since the resin portion (A1) is a polyester resin, a carboxylic acid component is used as a raw material monomer in addition to the alcohol component.
Examples of the carboxylic acid component that is a raw material monomer of the resin portion (A1) include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid; succinic acid having adipic acid, succinic acid, an alkyl group, and / or an alkenyl group. Aliphatic dicarboxylic acids such as cycloaliphatic dicarboxylic acids, cycloaliphatic dicarboxylic acids, decalin dicarboxylic acids and the like; trivalent or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid, and anhydrides of these acids and their Alkyl (C1-C3) ester etc. are mentioned. From the viewpoint of dyeability of the thermal transfer image-receiving sheet, aromatic dicarboxylic acids and alicyclic dicarboxylic acids are preferable, and cyclohexanedicarboxylic acid and isophthalic acid are more preferable. Among these, aromatic dicarboxylic acids are preferable, and isophthalic acid is more preferable. The said carboxylic acid component may be individual or 2 or more types may be contained.
Further, when the resin (A) is a graft polymer having the resin part (segment) (A1) as a main chain and the segment (A2) as a side chain, a carboxyl having a non-aromatic carbon-carbon unsaturated bond It is preferred to include an acid, such as an unsaturated aliphatic carboxylic acid and / or an unsaturated alicyclic carboxylic acid. The carbon-carbon unsaturated bond portion is preferably a bond portion with the segment (A2) in the resin (A). In this case, the unsaturated bond is a saturated bond.

  Examples of carboxylic acids having non-aromatic carbon-carbon unsaturated bonds (unsaturated aliphatic carboxylic acids and unsaturated alicyclic carboxylic acids) include unsaturated fats such as fumaric acid, maleic acid, acrylic acid, and methacrylic acid. Group carboxylic acids; unsaturated alicyclic carboxylic acids such as tetrahydrophthalic acid. From the viewpoint of reactivity, fumaric acid, maleic acid and tetrahydrophthalic acid are preferable, and fumaric acid is more preferable.

  In the carboxylic acid component, the content of the carboxylic acid having a non-aromatic carbon-carbon unsaturated bond is preferably 5 to 30 mol%, more preferably 7 to 25 mol%, still more preferably 8 to 15 mol%. It is.

  In the case where the resin (A) is a graft polymer having the resin part (segment) (A1) as the main chain and the segment (A2) as the side chain, among the raw material monomers derived from the structural unit of the segment (A1) The raw material monomer having a non-aromatic carbon-carbon unsaturated bond may include at least one selected from unsaturated aliphatic carboxylic acid, unsaturated alicyclic carboxylic acid, and unsaturated aliphatic alcohol, From the viewpoint of reactivity, it is preferable to include an unsaturated aliphatic carboxylic acid and / or an unsaturated alicyclic carboxylic acid, and more preferably only an unsaturated aliphatic carboxylic acid and / or an unsaturated alicyclic carboxylic acid. preferable.

From the viewpoint of releasability and storage stability of the thermal transfer image-receiving sheet, the acid value of the resin portion (A1) is preferably 5 to 40 mgKOH / g, more preferably 5 to 35 mgKOH / g, and still more preferably 5 to 30 mgKOH / g. More preferably, it is 10-20 mgKOH / g.
Further, from the viewpoint of film forming properties when used in the dye-receiving layer, the number average molecular weight of the resin portion (A1) is preferably 1,000 to 10,000, more preferably 2,000 to 8,000. .

(Side chain segment (A2) made of addition polymerization resin)
When the resin (A) is a graft polymer, the segment (A2) constituting the graft polymer that is the resin (A) is derived from the addition polymerizable monomer (a2) (hereinafter also referred to as “monomer (a2)”). It is a segment made of an addition polymerization resin composed of structural units. The segment (A2) is a side chain in the graft polymer.
Examples of the addition polymerizable monomer (a2) used in the present invention include styrene, methylstyrene, α-methylstyrene, β-methylstyrene, t-butylstyrene, chlorostyrene, chloromethylstyrene, methoxystyrene, styrenesulfonic acid or the like. Styrenes such as salts; (meth) acrylic acid esters such as alkyl (meth) acrylate (C1-18), benzyl (meth) acrylate, dimethylaminoethyl (meth) acrylate; polyethylene, propylene, butadiene, etc. Olefins such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as vinyl methyl ether; vinylidene halides such as vinylidene chloride; N-vinyl compounds such as N-vinyl pyrrolidone; Is mentioned.
Among these, styrenes and (meth) acrylic acid esters are preferable, among which addition polymerizable monomers having an aromatic group are more preferable, and styrene, methylstyrene, benzyl methacrylate and benzyl acrylate are more preferable. Among these, styrene is preferable from the viewpoint of the raw material price of the monomer, the releasability of the thermal transfer image-receiving sheet, and the storage stability.
In the segment (A2), the content of the structural unit derived from the addition polymerizable monomer having an aromatic group is from the viewpoint of releasability of the thermal transfer image-receiving sheet, releasability at high temperature and high humidity, and dyeing property. Preferably it is 70 weight% or more, More preferably, it is 85 weight% or more, More preferably, it is 90 weight% or more, More preferably, it is substantially 100 weight%.

  The weight ratio of the total amount of unsaturated aliphatic carboxylic acid, unsaturated alicyclic carboxylic acid and unsaturated aliphatic alcohol among the raw material monomers of segment (A2) and segment (A1) [segment (A2) / segment (A1 The total of the above-mentioned components having unsaturated groups] is preferably from 1/1 to 15/1, more preferably from 1/1 to 10/1, from the viewpoint of dyeability and releasability of the thermal transfer image-receiving sheet. More preferably, it is 2/1 to 5/1.

<Compound (B)>
The compound (B) contained in the resin composition for a thermal transfer image-receiving sheet of the present invention contains a 2,2-bis (4-hydroxyphenyl) propane moiety and has a melting point of less than 30 ° C. Compound (B) is an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane from the viewpoint of increasing the affinity with the resin (A) and improving the dyeability and light resistance of the thermal transfer image-receiving sheet. It is preferable to have a portion.
A preferable structure of the alkylene oxide adduct portion of 2,2-bis (4-hydroxyphenyl) propane is represented by the above general formula (I), and in the above general formula (I), R ¹ O and R ² O are both oxyalkylene groups, preferably each independently an oxyalkylene group having 1 to 4 carbon atoms, more preferably an oxyethylene group or an oxypropylene group. x and y correspond to the added mole number of alkylene oxide, and are positive numbers. Furthermore, from the viewpoint of reactivity with the carboxylic acid component, the average value of the sum of x and y is preferably 2 to 7, more preferably 2 to 5, and still more preferably 2 to 3.

The compound (B) is preferably a diester of a 2,2-bis (4-hydroxyphenyl) propane moiety or an alkylene oxide adduct moiety of 2,2-bis (4-hydroxyphenyl) propane and a carboxylic acid.
Examples of the carboxylic acid include aliphatic monocarboxylic acids and aromatic monocarboxylic acids, and aliphatic monocarboxylic acids are preferable. Specific examples of the aliphatic monocarboxylic acid include butanoic acid, hexanoic acid, octanoic acid, decanoic acid, dodecanoic acid, octadecanoic acid, octadecenoic acid, and docosanoic acid, and dodecanoic acid is used from the viewpoint of plastic effect and dyeing property. preferable.
The compound (B) is preferably a diester of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane and an aliphatic monocarboxylic acid, and 2,2-bis (4-hydroxyphenyl) propane A diester of ethylene oxide adduct and lauric acid is more preferable.
The compound (B) has a melting point of less than 30 ° C. from the viewpoint of plasticizing the resin and improving the dyeability and light resistance of the thermal transfer image-receiving sheet. The melting point is obtained by measuring under the following conditions using a differential scanning calorimeter (trade name: DSC210, manufactured by Seiko Denshi Kogyo Co., Ltd. (measuring condition: heated up to 150 ° C., and 10 ° C./min from that temperature). The temperature of the endothermic peak observed by lowering the temperature at -100 ° C. and raising the temperature at 10 ° C./min is taken as the melting point). Moreover, it is preferable that the viscosity at 30 degreeC of a compound (B) is 1-500 mPa * s. The viscosity can be measured with a B-type viscometer.

  In the resin composition for a thermal transfer image-receiving sheet of the present invention, the weight ratio of the resin (A) to the compound (B) [resin (A) / compound (B)] is preferably from the viewpoint of dyeing property and light resistance. 100/5 to 100/40, more preferably 100/5 to 100/30, still more preferably 100/5 to 100/20, and more preferably 100/5 to 100/10 from the viewpoint of dyeing properties. From the viewpoint of light resistance, it is more preferably 100/10 to 100/20.

[Method for producing resin composition for thermal transfer image-receiving sheet]
The resin composition for a thermal transfer image-receiving sheet of the present invention may be obtained by containing the resin (A) and the compound (B) by any method, but the resin (A) or the precursor of the resin (A) is 2, Polyester resin (a1) obtained by condensation polymerization of an alcohol component containing 50 mol% or more of an alkylene oxide adduct of 2-bis (4-hydroxyphenyl) propane and a carboxylic acid component (hereinafter also referred to as resin (a1)) And a compound (B) are mixed, water is added, and it is preferable to obtain by the manufacturing method including the process of obtaining the aqueous dispersion in which the compound (B) was included in resin (A).
When the resin (A) is a graft polymer, an alcohol component containing 50 mol% or more of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane and a carboxylic acid component are subjected to polycondensation. A polyester resin (a1) having an aromatic carbon-carbon unsaturated bond is prepared, the polyester resin (a1) and the compound (B) are mixed, water is added, and the compound (B1) is added to the resin (a1). ) In an aqueous dispersion in which the addition polymerizable monomer (a2) is subjected to addition polymerization to obtain an aqueous dispersion in which the compound (B) is included in the resin (A). Is preferred.
Especially, it is preferable to obtain by the method which has the following process (1)-(3).
Step (1): Step of mixing polyester resin (a1) and compound (B) to obtain a resin mixture Step (2): Mixing the resin mixture obtained in step (1) with an aqueous medium to obtain a resin mixture Step (3): Addition-polymerizable monomer (a2) is added to the aqueous dispersion obtained in Step (2) to polymerize, and the compound (B) is a resin (a graft polymer). A step of obtaining an aqueous dispersion of the resin composition encapsulated in A)

(Polyester resin (a1))
Resin (a1) is a polyester resin obtained by condensation polymerization of an alcohol component containing 50 mol% or more of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane and a carboxylic acid component. When a1) becomes the main chain segment (A1) of the graft polymer, it preferably has a non-aromatic carbon-carbon unsaturated bond. The “non-aromatic carbon-carbon unsaturated bond” is preferably derived from one or more selected from the above-mentioned unsaturated aliphatic carboxylic acid, unsaturated alicyclic carboxylic acid and unsaturated aliphatic alcohol. To do.

The resin (a1) is obtained using an alcohol component containing 50 mol% or more of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane as a raw material component.
Here, the alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane is the same as the segment (A1), and the preferred structure and the preferred content are also the same.

As an alcohol component which is a raw material component of the resin (a1), an alcohol component other than this can be used together with an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane. The resin (a1) preferably has a non-aromatic carbon-carbon unsaturated bond, and an alcohol having a non-aromatic carbon-carbon unsaturated bond can be used. Examples of the alcohol having a non-aromatic carbon-carbon unsaturated bond include unsaturated aliphatic alcohols such as allyl alcohol.
Other alcohols are the same as those in the segment (A1). You may use alcohol individually or in combination of 2 or more types.

The resin (a1) preferably has a non-aromatic carbon-carbon unsaturated bond, and a carboxylic acid component having a non-aromatic carbon-carbon unsaturated bond is used as a carboxylic acid component as a raw material component of the polyester. It can be preferably used.
The carboxylic acid having a non-aromatic carbon-carbon unsaturated bond is the same as in the case of the segment (A1), the preferred structure and the preferred content are the same, and fumaric acid is more preferred.
In the carboxylic acid component, the content of the carboxylic acid having a non-aromatic carbon-carbon unsaturated bond is preferably 5 to 30 mol%, more preferably 7 to 25 mol%, still more preferably 8 to 15 mol%. It is.
Other carboxylic acids are the same as in the case of the resin part (A1), and the preferred structure and preferred content are also the same. Cyclohexanedicarboxylic acid and isophthalic acid are preferred, and isophthalic acid is more preferred. You may use these individually by 1 type or in combination of 2 or more types.

The polyester resin (a1) is produced, for example, by subjecting the alcohol component and the carboxylic acid component to condensation polymerization at a temperature of 180 to 250 ° C. in an inert gas atmosphere, if necessary, using an esterification catalyst. be able to.
From the viewpoint of releasability of the thermal transfer image-receiving sheet, the 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 dioxide. From the viewpoint of the reaction efficiency of the esterification reaction in the synthesis of the polyester, a tin catalyst is preferable. As the tin catalyst, dibutyltin oxide, tin dioctylate, salts thereof and the like are preferably used.
In the present invention, since a carboxylic acid having a non-aromatic carbon-carbon unsaturated bond is used, it is preferable to use a radical polymerization inhibitor. As the radical polymerization inhibitor, 4-t-butylcatechol and the like are preferable.

From the viewpoint of releasability and storage stability of the thermal transfer image-receiving sheet, the softening point of the resin (a1) is preferably 80 to 165 ° C, and the glass transition temperature is preferably 50 to 85 ° C. From the viewpoint of releasability and storage stability of the thermal transfer image-receiving sheet, the acid value of the resin (a1) is preferably 5 to 40 mgKOH / g, more preferably 5 to 35 mgKOH / g, still more preferably 5 to 30 mgKOH / g, More preferably, it is 10-20 mgKOH / g.
The glass transition temperature, softening point, and acid value can all be obtained by appropriately adjusting the type of monomer used, the blending ratio, the temperature of condensation polymerization, and the reaction time.
Moreover, from the viewpoint of film forming properties when used in the dye-receiving layer, the number average molecular weight of the resin (a1) is preferably 1,000 to 10,000, more preferably 2,000 to 8,000.

In the present invention, the resin (a1) may be modified within the above range so as not to substantially impair the characteristics. Examples of the modified resin (a1) include grafting with phenol, urethane, epoxy or the like by the method described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like. And blocked polyester.
In the present invention, the content of the polyester portion in the resin (a1) is preferably 50 to 100% by weight, more preferably 60 to 100% by weight, and still more preferably, from the viewpoint of dyeability and releasability of the thermal transfer image receiving sheet. Is substantially 100% by weight.

(Addition polymerizable monomer (a2))
The addition polymerizable monomer (a2) used in the present invention is as described above, and the addition polymerizable monomer having an aromatic group is preferably 55% by weight or more, more preferably 70% by weight or more, more preferably 85% by weight. %, More preferably 90% by weight or more, and still more preferably substantially 100% by weight. The addition polymerizable monomer having an aromatic group is preferably styrene, benzyl methacrylate or benzyl acrylate. Among these, styrene is preferable from the viewpoint of the raw material price of the monomer, the releasability of the thermal transfer image-receiving sheet, and the storage stability.

[Production of resin composition for thermal transfer image-receiving sheet]
The resin composition for a thermal transfer image receiving sheet of the present invention is preferably obtained by a method including the following steps (1) to (3).
Step (1): Step of mixing polyester resin (a1) and compound (B) to obtain a resin mixture Step (2): Mixing the resin mixture obtained in step (1) with an aqueous medium to obtain a resin mixture Step (3): Addition-polymerizable monomer (a2) is added to the aqueous dispersion obtained in step (2) for polymerization, and compound (B) is encapsulated in resin (A). Of obtaining an aqueous dispersion of a resin composition for a thermal transfer image receiving sheet

<Step (1)>
Step (1) is a step of mixing the polyester resin (a1) and the compound (B) to obtain a resin mixture.

As a method of mixing the polyester resin (a1) and the compound (B), it is preferable to dissolve the polyester resin (a1) in a ketone solvent and mix it with the compound (B).
More specifically, for example, a reactor equipped with a stirrer, a reflux condenser, a thermometer, a dropping funnel and a nitrogen gas introduction pipe is prepared, and a polyester resin (a1), a compound (B), and a ketone solvent are mixed. Thus, the resin mixture is obtained as a solution.

  Examples of the ketone solvent include acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, methyl isobutyl ketone, and methyl isopropyl ketone. From the viewpoint of the solubility of the polyester resin (a1) and the ease of distilling off the solvent, methyl ethyl ketone is preferred.

<Step (2)>
Step (2) is a step of mixing the resin mixture obtained in step (1) with an aqueous medium to obtain an aqueous dispersion of the resin mixture.
The aqueous medium in which the resin mixture is dispersed is a water-based medium, that is, a medium having a water content of 50% by weight or more. From the viewpoint of environmental safety, the content of water in the aqueous medium is preferably 80% by weight or more, more preferably 90% by weight or more, and still more preferably substantially 100% by weight. Examples of components other than water include organic solvents that dissolve in water, such as alcohol solvents such as methanol, ethanol, isopropanol, and butanol; ketone solvents such as acetone and methyl ethyl ketone; and ether solvents such as tetrahydrofuran.

As a method of dispersing the resin mixture in the aqueous medium, a neutralizing agent described later is added to the solution of the resin mixture to ionize the carboxyl group of the polyester resin (a1), and then water is added to invert the phase to an aqueous system. A method, preferably a method in which water is added and then the ketone solvent is distilled off and the phase is changed to an aqueous system.
More specifically, for example, the solution of the resin mixture is put into a reactor equipped with a stirrer, a reflux condenser, a thermometer, a dropping funnel and a nitrogen gas introduction pipe, and a neutralizing agent is added as necessary. Water is added for phase inversion, preferably water is added, and then the ketone solvent is distilled off to phase in the aqueous system.
The dissolving operation of the polyester resin (a1) in the ketone solvent and the subsequent addition of the neutralizing agent are usually performed at a temperature not higher than the boiling point of the ketone solvent. Examples of the water used include deionized water.

  Examples of the neutralizing agent include aqueous alkaline solutions such as aqueous ammonia and sodium hydroxide, allylamine, isopropylamine, diisopropylamine, ethylamine, diethylamine, triethylamine, 2-ethylhexylamine, tri-n-octylamine, t-butylamine, sec- Butylamine, propylamine, methylaminopropylamine, dimethylaminopropylamine, n-propanolamine, butanolamine, 5-amino-4-octanol, monoethanolamine, N, N-dimethylethanolamine, isopropanolamine, neopentanolamine And amines such as diglycolamine, ethylenediamine, and piperazine. The amount of the neutralizing agent used may be an amount that can neutralize at least the acid value of the polyester resin (a1).

<Step (3)>
In step (3), an addition polymerizable monomer (a2) is added to the aqueous dispersion obtained in step (2) for polymerization, and the resin for thermal transfer image-receiving sheet in which compound (B) is encapsulated in resin (A) This is a step of obtaining an aqueous dispersion of the composition (hereinafter also referred to as an aqueous dispersion (A)).
First, the addition polymerizable monomer (a2) is added to an aqueous dispersion of a resin mixture containing the polyester resin (a1). The addition amount is a weight ratio of the polyester resin (a1) and the addition polymerizable monomer (a2) [polyester resin (a1) / addition polymerizable monomer (a2)], preferably 55/45 to 95/5, more preferably 65/35 to 95/5, more preferably 75/25 to 95/5, still more preferably 85/15 to 95/5.
Moreover, you may add water etc. further from the point of the efficiency of stirring.

Next, the addition polymerizable monomer (a2) is polymerized in the presence of the polyester resin (a1).
In the polymerization, a known radical polymerization initiator, a crosslinking agent and the like are added as necessary. As the radical polymerization initiator, a water-soluble radical polymerization initiator is preferably used, and a persulfate is more preferably used.
The polymerization reaction is advanced by heating a mixed solution containing the polyester resin (a1) and the addition polymerizable monomer (a2). The polymerization temperature depends on the type of polymerization initiator used, but for example, when sodium persulfate is used, it is preferably 60 to 100 ° C., more preferably 70 to 90, from the viewpoint of efficiently performing the polymerization reaction. ° C.

The glass transition temperature of the graft polymer (A) in the aqueous dispersion (A) obtained as described above is from the viewpoint of the storage stability of the dispersion, the storage stability of the thermal transfer image-receiving sheet, and the dyeing property. The temperature is preferably 40 to 80 ° C, more preferably 50 to 80 ° C, and still more preferably 60 to 80 ° C. The softening point of the graft polymer (A) is preferably 80 to 250 ° C, more preferably 120 to 220 ° C.
The solid content concentration of the aqueous dispersion (A) is preferably 20 to 40% by weight, more preferably 25 to 40% by weight, and still more preferably 30 to 40% by weight, from the viewpoint of the dispersibility and productivity of the resin particles. It is. The pH of the aqueous dispersion (A) at 25 ° C. is preferably 5 to 10, more preferably 6 to 9, and still more preferably 7 to 9 from the viewpoint of storage stability of the aqueous dispersion (A). is there.

  The volume median particle size (D50) of the resin particles in the aqueous dispersion (A) is preferably 20 to 1000 nm, more preferably 50 to 800 nm, and still more preferably, from the viewpoint of film forming properties when obtaining a thermal transfer image-receiving sheet. Is 80-500 nm. 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 in the examples.

[Thermal transfer image-receiving sheet]
The thermal transfer image receiving sheet of the present invention has a dye receiving layer containing the resin composition for a thermal transfer image receiving sheet on a substrate.

(Base material)
Examples of the base material include synthetic paper (polyolefin, polystyrene, 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 Various resin films or sheets such as internal paper, paperboard, cellulose fiber paper, polyolefin, polyvinyl chloride, polyethylene terephthalate, polystyrene, polymethacrylate, polycarbonate, etc. can be used. A white opaque film formed by adding an agent or a foamed foam sheet 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 that the surface of the substrate is subjected to primer treatment or corona discharge treatment.

(Dye-receiving layer)
The dye receiving layer in the thermal transfer image receiving sheet of the present invention contains the resin composition for a thermal transfer image receiving sheet of the present invention.
The dye-receiving layer is manufactured using a coating liquid form obtained by dissolving a resin in an organic solvent, or a coating liquid form containing a resin dispersion liquid obtained by dispersing each resin in an organic solvent or water. From the viewpoint of environmental safety and the like, the latter is preferable, and it is more preferable to manufacture by the method including the following steps (4) and (5).
Step (4): A step of preparing a dye-receiving layer coating solution containing an aqueous dispersion of the resin composition for a thermal transfer image-receiving sheet obtained in Step (3).
Step (5): A step of providing a dye receiving layer using the dye receiving layer coating solution obtained in step (4).

<Process (4)>
Step (4) is a step of preparing a dye-receiving layer coating solution containing an aqueous dispersion of the thermal transfer image-receiving sheet resin composition obtained in step (3).
The dye-receiving layer coating solution preferably contains a release agent from the viewpoint of further improving the release property of the thermal transfer image-receiving sheet during thermal transfer. As the release agent, for example, a dispersible or water-soluble modified silicone oil can be appropriately used. These release agents can be contained in the dye-receiving layer coating solution in an amount of 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the resin composition. As a commercially available release agent, “KF-615A” (trade name) manufactured by Shin-Etsu Chemical Co., Ltd. can be preferably used.
In order to uniformly disperse or dissolve the release agent, it is preferable to use a stirrer such as a ball mill, and the dispersion or dissolution temperature is preferably 20 to 40 ° C.

Moreover, it is preferable that the coating liquid for dye receiving layers contains a film forming agent. Examples of the film forming agent include butyl carbitol acetate, diethyl carbitol, gelatin and the like. From the viewpoint of the strength and releasability of the dye receiving layer, gelatin is preferred.
From the viewpoint of uniformly dissolving the film-forming agent, it is preferable to previously dissolve the film-forming agent in water. The aqueous dispersion of the resin composition for a thermal transfer image-receiving sheet and the aqueous solution of the film-forming agent are mixed and stirred. It is preferable to do. A ball mill etc. are mentioned as an agitator used suitably. In order to uniformly mix the film-forming agent in a dissolved state, the stirring temperature is preferably 30 to 60 ° C, more preferably 40 to 50 ° C.
The dye receiving layer coating solution further contains pigments and fillers such as titanium oxide, zinc oxide, kaolin clay, and calcium carbonate from the viewpoint of improving the whiteness of the dye receiving layer and increasing the sharpness of the transferred image. can do. From the viewpoint of whiteness of the thermal transfer image-receiving sheet of the present invention, these pigments and fillers may be contained in an amount of 0.1 to 20 parts by weight with respect to 100 parts by weight of the resin composition in the dye-receiving layer coating solution. it can. The dye-receiving layer coating solution may further contain other additives such as a catalyst and a curing agent, if necessary.
Moreover, the coating liquid for dye receiving layers can contain other resins other than the resin composition for thermal transfer image receiving sheets of the present invention within a range not impairing the effects of the present invention. Specific examples of the other resin include vinyl chloride polymer, vinyl chloride vinyl acetate copolymer, vinyl chloride acrylic copolymer, polyurethane, and the like, dyeing property and light resistance of thermal transfer image-receiving sheet, and resin dispersion From the viewpoint of dispersibility of the liquid, a vinyl chloride acrylic copolymer is preferred.
These other resins can also be contained in the dye-receiving layer coating solution by dissolving them in an organic solvent together with the resin composition for a thermal transfer image-receiving sheet of the present invention in the process of producing the resin. Alternatively, the resin dispersion may be added to the aqueous dispersion of the resin composition for a thermal transfer image-receiving sheet and mixed to be contained in the dye-receiving layer coating liquid.

<Step (5)>
Step (5) is a step of providing a dye-receiving layer using the dye-receiving layer coating solution obtained in step (4).
The dye-receiving layer of the thermal transfer image-receiving sheet of the present invention is obtained by forming a coating liquid on one surface of a substrate and drying it. For example, a gravure printing method, a screen printing method, or a gravure plate is used. It is preferably applied by a reverse roll coating method or the like. In addition, when an intermediate layer is provided between the substrate and the dye-receiving layer as described later, the intermediate layer coating solution and the dye-receiving layer coating solution are applied in layers and dried on one surface of the substrate. An intermediate layer and a dye-receiving layer can also be provided.
The thickness of the dye receiving layer to be formed is generally 1 to 50 μm, and preferably 3 to 15 μm from the viewpoint of image quality and productivity. The solid content after drying is preferably 3 to 15 g per 1 m ^{2 of} the dye receiving layer.

(Middle layer)
The thermal transfer image-receiving sheet of the present invention preferably has an intermediate layer between the substrate and the dye-receiving layer, and the intermediate layer more preferably contains a water-soluble polymer and hollow particles.
<Water-soluble polymer>
The water-soluble polymer is used as a binder for fixing the hollow particles, and examples thereof include gelatin, polyvinyl alcohol, polyvinyl pyrrolidone and the like. Among these, the gelation temperature of the aqueous solution near room temperature of 10 to 30 ° C. From the viewpoint of thermal properties of having gelatin, gelatin is preferable. The viscosity (60 degreeC) measured by JISK6503-2001 from the viewpoint of the mold release property and film forming property of a thermal transfer image receiving sheet, Preferably it is 2.5-6.0 mPa * s, More preferably, it is 3. 0 to 5.5 mPa · s.
The content of the water-soluble polymer in the intermediate layer is preferably 1 to 75% by weight, more preferably 1 to 50% by weight of the entire intermediate layer.
The water-soluble polymer contained in the intermediate layer is preferably crosslinked with a crosslinking agent such as aldehydes, epoxies, vinyl sulfones, triazines, and carbodiimides.

<Hollow particles>
The hollow particles contained in the intermediate layer are not particularly limited as long as they are polymer particles having pores at least partially. For example, 1) Non-foamed hollow particles in which the water present inside the particle partition walls formed of resin evaporates outside the particles after coating and drying, and the inside of the particles becomes hollow. 2) Low boiling point such as butane and pentane 3) Hollow polymer particles in which the low-boiling liquid inside the particles expands to become hollow by heating the particles coated with the resin, 3) Hollow polymer particles obtained by heating and foaming the above 2) in advance, 4) Resin particles And hollow particles formed by neutralizing at least a part of the acidic groups contained in the polymer forming the. In the present invention, those obtained by the above method 1) or 3) can be preferably used from the viewpoint of the dyeing property of the thermal transfer image-receiving sheet and the adhesion between the intermediate layer and the dye-receiving layer in the thermal transfer image-receiving sheet.

  The material constituting the hollow particles is not particularly limited, and various known materials used in the methods 1) to 3), such as polyacrylic acid, polyacrylic acid ester, styrene-acrylic copolymer, Acrylic resins such as a mixture thereof, polystyrene, polyvinylidene chloride, polyacrylonitrile, vinylidene chloride-acrylonitrile copolymer, and the like can be used. In the present invention, a styrene-acrylic copolymer, a vinylidene chloride-acrylonitrile copolymer, and the like are preferable from the viewpoint of the dyeing property of the thermal transfer image-receiving sheet and the adhesion between the intermediate layer and the dye-receiving layer in the thermal transfer image-receiving sheet. Used.

The shape of the hollow particles is not particularly limited and may be any shape other than spherical as well as spherical, but in the present invention, from the viewpoint of adhesion between the intermediate layer and the dye-receiving layer in the thermal transfer image-receiving sheet, It is preferably substantially spherical.
The volume-median particle size (D50) of the hollow particles is preferably 0.1 to 5 μm, more preferably 0.3 to 3 μm, from the viewpoint of adhesion between the intermediate layer and the dye-receiving layer in the thermal transfer image-receiving sheet. More preferably, it is 0.3-1 micrometer. This value can be measured with a field emission scanning electron microscope (manufactured by Hitachi, Ltd., trade name: S-4800 type).

In the present invention, the hollow particles are preferably used as a dispersion in an aqueous medium. Examples of commercially available hollow particles that can be preferably used include “Nipol MH8101” manufactured by Nippon Zeon Co., Ltd. and “SX8782” manufactured by JSR Corporation. (D) "etc. (all are trade names).
The intermediate layer has a weight ratio (hollow particles / water-soluble polymer) of the hollow particles to the water-soluble polymer from the viewpoint of dyeing property and adhesion between the intermediate layer and the dye-receiving layer in the thermal transfer image-receiving sheet. The ratio is preferably 30/70 to 90/10, more preferably 40/60 to 80/20, and still more preferably 50/50 to 80/20.

The intermediate layer may contain pigments and fillers such as titanium oxide, zinc oxide, kaolin clay, calcium carbonate, fine powder silica from the viewpoint of improving the whiteness of the intermediate layer and increasing the clarity of the transferred image. it can. These pigments and fillers are preferably 0.1 to 20 parts by weight, more preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the water-soluble polymer in the intermediate layer from the viewpoint of the whiteness of the thermal transfer image-receiving sheet. 10 parts by weight can be contained.
If necessary, the intermediate layer may further contain additives such as a film-forming aid such as glycol ethers, a mold release agent, a curing agent, and a catalyst.

The intermediate layer is formed on at least one surface of the base material of the thermal transfer image-receiving sheet by dispersing or dissolving a water-soluble polymer and various additives used as necessary in an organic solvent or water, and applying and drying. be able to.
The thickness of the intermediate layer is preferably 10 to 100 μm, more preferably 20 to 50 μm, from the viewpoint of cushioning properties and heat insulating properties. In addition, the solid content after drying is preferably 7 to 70 g / m ² per 1 m ² of the intermediate layer.
The intermediate layer is prepared by, for example, dissolving water-soluble polymer containing gelatin, hollow particles, and additives used as necessary in water on at least one surface of the base material of the thermal transfer image-receiving sheet or dispersing in water. The coating liquid obtained in this manner can be applied and dried by, for example, a gravure printing method, a screen printing method, a reverse roll coating method using a gravure plate, or the like.

[Transfer sheet]
The transfer sheet (ink ribbon) used when performing thermal transfer using the thermal transfer image receiving sheet of the present invention is usually obtained by receiving a dye layer containing a sublimation dye on paper or a polyester film, and receiving the dye. A laminate layer composed of a protective layer or the like to be transferred onto the obtained image is provided, and any conventionally known transfer 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 given means can be used. For example, by controlling the recording time with a recording device such as a thermal printer, a thermal energy of about 5 to 100 mJ / mm ² is obtained. It can be done by giving.

In the production examples, examples and comparative examples described later, each physical property was measured by the following method.
[Acid value of resin]
The measurement solvent was measured according to JIS K0070, except that the mixed solvent of ethanol and ether was changed to a mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[Softening point of resin]
Using a flow tester (manufactured by Shimadzu Corporation, trade name: CFT-500D), a 1 g sample was heated at a heating rate of 6 ° C./min. Extruded from a 1 mm nozzle. The amount of flow tester drop by the flow tester was plotted against the temperature, and the temperature at which half the sample flowed out was taken as the softening point.

[Glass transition temperature of resin]
Using a differential scanning calorimeter (manufactured by Perkin Elmer, trade name: Pyris 6 DSC), the temperature was raised to 200 ° C., and the sample cooled to 0 ° C. at a temperature lowering rate of 10 ° C./min was heated at a rate of 10 ° C. / The temperature was raised in minutes, and the temperature at the intersection of the extended line of the baseline and the tangent indicating the maximum slope from the peak rising portion to the peak apex was defined as the glass transition temperature.

[Number average molecular weight of resin]
The molecular weight distribution was measured by gel permeation chromatography and the number average molecular weight was calculated by the following method.
(1) Preparation of sample solution The resin was dissolved in tetrahydrofuran so that the concentration was 0.5 g / 100 ml. Subsequently, this solution was filtered using a fluororesin filter having a pore size of 2 μm (manufactured by Sumitomo Electric Industries, Ltd., trade name: FP-200) to remove insoluble components to obtain a sample solution.
(2) Molecular weight measurement Tetrahydrofuran was flowed as a dissolution liquid at a flow rate of 1 ml / min, and the column was stabilized in a constant temperature bath at 40 ° C. Measurement was performed by injecting 100 μl of the sample solution. The number average molecular weight of the sample was calculated based on a calibration curve prepared in advance. The calibration curves are several types of monodisperse polystyrene (monodisperse polystyrene manufactured by Tosoh Corporation; 2.63 × 10 ³ , 2.06 × 10 ⁴ , 1.02 × 10 ⁵ (weight average molecular weight), manufactured by GL Sciences Inc. Of monodisperse polystyrene; 2.10 × 10 ³ , 7.00 × 10 ³ , 5.04 × 10 ⁴ (weight average molecular weight)) were used as standard samples.
Measuring device: CO-8010 (trade name, manufactured by Tosoh Corporation)
Analytical column: GMHXL + G3000HXL (both trade names, manufactured by Tosoh Corporation)

[Volume Median Particle Size (D50) of Resin Particles of Aqueous Dispersion]
Using a laser diffraction particle size measuring machine (Horiba, Ltd., trade name: LA-920), add an aqueous dispersion of each resin and distilled water to the measurement cell, and at a concentration where the absorbance is in an appropriate range, Volume median particle size (D50) was measured.

[Solid content concentration of aqueous dispersion]
Using an infrared moisture meter (trade name: FD-230, manufactured by Ketsu Scientific Laboratory Co., Ltd.), 5 g of an aqueous dispersion was measured at a drying temperature of 150 ° C. and a measurement mode 96 (monitoring time 2.5 minutes / variation width 0.05%). ) And the wet base moisture (% by weight) of the aqueous dispersion was measured. The solid content concentration was calculated according to the following formula.
Solid content concentration (% by weight) = 100-M
M: wet base moisture of aqueous dispersion (% by weight) = [(W−W ₀ ) / W] × 100
W: Sample weight before measurement (initial sample weight)
W ₀ : Sample weight after measurement (absolute dry weight)

[PH of aqueous dispersion]
It measured at 25 degreeC with the pH meter (The product name: HM-20P by Toa DKK Corporation).

Production Example 1
(Production of polyester resin a)
The raw material monomer and dioctylic acid tin (II) salt of the polyester resin excluding fumaric acid shown in Table 1 were put into a 5 L four-necked flask equipped with a thermometer, a stirrer, a flow-down condenser and a nitrogen inlet tube, The reaction was carried out in a mantle heater under a nitrogen atmosphere at 235 ° C. for 5 hours, and further under reduced pressure (8.3 kPa) for 1 hour. Next, after adding fumaric acid and 4-t-butylcatechol at 210 ° C. and reacting for 5 hours, the softening point measured according to ASTM D36-86 under reduced pressure (20 kPa) reaches the temperature shown in Table 1. By reacting, polyester a was obtained.
Table 1 shows the physical properties and the like of the obtained polyester resin a.

Production Examples 2-9
(Production of aqueous dispersions (i) to (viii) containing polyester resin (a1))
The polyester resin (a1) and the compound (B) are placed in a four-necked flask having an internal volume of 10 L equipped with a nitrogen introduction tube, a reflux condenser, a stirrer, and a thermocouple in the types and blending amounts shown in Table 2, and 25 ° C. In methyl ethyl ketone. Next, 25% aqueous ammonia was added, deionized water was added with stirring, and methyl ethyl ketone was distilled off at 60 ° C. under reduced pressure. After cooling to room temperature, the mixture was filtered through a 200-mesh wire mesh to obtain aqueous dispersions (i) to (viii) containing a polyester resin (a1). In addition, polyoxyethylene bisphenol A lauric acid ester (EXEPARL BP-DL (trade name, manufactured by Kao Corporation)) used as the compound (B) is 2,2-bis (4-hydroxyphenyl) in its structure. It contains a propane moiety, has a melting point of −2 ° C. and a viscosity at 30 ° C. of 350 mPa · s. In Production Examples 7 to 9, a known plasticizer was used instead of the compound (B). In Production Example 8, di-2-ethylhexyl phthalate (Vinizer 80, trade name, manufactured by Kao Corporation) was used.
Each physical property of the obtained aqueous dispersions (i) to (viii) was measured by the following method. The results are shown in Table 2.

Production Examples 10 to 17
(Production of aqueous dispersions (I) to (VIII) of resin composition for thermal transfer image-receiving sheet)
An aqueous dispersion of polyester resin (a1) with the types and blending amounts shown in Table 3 was added to a 2-liter four-necked flask equipped with a nitrogen inlet tube, reflux condenser, dropping funnel, stirrer and thermocouple. Ion water and styrene which is an addition polymerizable monomer (a2) were charged and stirred for 30 minutes. Under a nitrogen stream, sodium persulfate was added and reacted at 80 ° C. for 6 hours. After cooling to room temperature, the mixture was filtered through a 200-mesh wire mesh to obtain aqueous dispersions (I) to (VIII) of the resin composition for a thermal transfer image-receiving sheet. In addition, as for the compounding amount of each material, the weight ratio between the polyester resin segment (A1) and the addition polymerization resin segment (A2) in the resin for thermal transfer image-receiving sheet in the obtained aqueous dispersion is as shown in Table 3. Was decided.
The physical properties of the obtained aqueous dispersions (I) to (VIII) of the obtained resin for thermal transfer image-receiving sheets were measured by the above-described methods. The results are shown in Table 3.

Examples 1-4 and Comparative Examples 1-4
(Manufacture of thermal transfer image receiving sheet)
First, the composition and blending amount shown in Table 4 were mixed at 45 ° C. to prepare an intermediate layer coating solution. This coating solution was applied to synthetic paper (manufactured by YUPO Corporation, trade name: YUPO FGS-250, thickness 250 μm, basis weight 200 g / m ² ) with a wire bar so that it would be 20.0 g / m ² after drying. And it was made to dry at 25 degreeC for 5 minutes, and the intermediate | middle layer coating sheet was obtained.
In the preparation of the intermediate layer, the following styrene acrylic copolymer was used as the hollow particles, and the following gelatin was used as the binder.
Styrene acrylic copolymer (manufactured by Nippon Zeon Co., Ltd., trade name: Nipol MH8101, hollow rate = 50%, solid content = 26% by weight)
Gelatin (made by Nitta Gelatin Co., Ltd., trade name: G0723K, viscosity 4.4 mPa · s)

Next, it mixed at 25 degreeC by the composition and compounding quantity shown in Table 4, and produced coating liquid A1-H1 for dye receptive layers. The aqueous dispersion of the thermal transfer image-receiving sheet resin used for preparing the dye-receiving layer coating liquid was adjusted to a solid content concentration of 30% by weight. For the preparation of the dye receiving layer, the following gelatin was used as a film-forming agent, and the following polyether-modified silicone was used as a mold release agent.
Gelatin (made by Nitta Gelatin Co., Ltd., trade name: G0723K, viscosity 4.4 mPa · s)
Polyether-modified silicone (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-615A)
Each of the dye-receiving layer coating solutions is applied to the intermediate layer-coated sheet by a wire bar so as to be 5.0 g / m ² and dried at 50 ° C. for 2 minutes to obtain a thermal transfer image-receiving sheet. It was.

<Evaluation>
(Dyeing property)
A black (K) gradation pattern was printed on the produced thermal transfer image-receiving sheet using a commercially available sublimation printer (trade name, MEGAPICEL III, manufactured by Altec Co., Ltd.), and high density printing (18th gradation (L = The transfer color density at 0: the highest density)) was measured with a Gretag densitometer (manufactured by GRETAG-MACBETH) to evaluate the dyeing property. The greater the concentration value, the better the dyeing property. The results are shown in Table 4.

(Light resistance)
A light resistance test was conducted using a xenon weather meter under the following conditions, and the light resistance was evaluated by the hue change amount ΔE.
・ Irradiation tester: Suga Test Instruments Co., Ltd., trade name: SX75
Light source: Xenon lamp Filter: Inside = quartz filter, outside = # 320
・ Panel temperature: 50 ℃
-Humidity in the tank: 35-50% RH
・ Irradiation intensity: 50 W / m ² , measured value at 300 to 400 nm • Integrated illuminance: 10,000 kJ / m ² , integrated value at 300 to 400 nm

Hue change amount ΔE: An optical densitometer (manufactured by Gretag Macbeth Co., Ltd.), and black (K), yellow (Y), magenta (M), cyan (C), green (G), and red of the gradation pattern printed matter Measure the optical reflection density of (R) and blue (B), and use the color difference meter (manufactured by Gretag Macbeth) to measure L ^* a ^* b ^* before and after irradiation for steps where the optical reflection density before irradiation is around 1.0. The hue change amount ΔE was calculated by the following formula, and the light resistance of the black (K) + chromatic print was evaluated. The smaller the hue change amount ΔE, the better the light resistance.
The light resistance of black + chromatic prints is black (K), yellow (Y), magenta (M), cyan (C), green (G), red (R), and blue (B). This is the sum of the hue changes of each color.
Hue change amount ΔE = [(a ^* ₁₋ a ^* ₂ ) ² + (b ^* ₁₋ b ^* ₂ ) ² ] ^1/2
(L ^* a ^* b ^* values before irradiation: L ^* ₁ , a ^* ₁ , b ^* ₁ )
(L ^* a ^* b ^* values after irradiation: L ^* ₂ , a ^* ₂ , b ^* ₂ )

  As is clear from Table 4, the thermal transfer image receiving sheets of Examples 1 to 4 have a high maximum density at the time of high density printing and excellent dyeability as compared with the thermal transfer image receiving sheets of Comparative Examples 1 to 4. It can be seen that the hue change due to light is small and the light resistance is excellent.

  The thermal transfer image receiving sheet of the present invention is excellent in dyeability and light resistance, and can be suitably used as a thermal transfer image receiving sheet.

Claims (7)

  A resin (A) containing a polyester part obtained by condensation polymerization of an alcohol component containing 50 mol% or more of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane and a carboxylic acid component; A resin composition for a thermal transfer image-receiving sheet, comprising a compound (B) containing a 2-bis (4-hydroxyphenyl) propane moiety and having a melting point of less than 30 ° C.   The resin composition for a thermal transfer image-receiving sheet according to claim 1, wherein the weight ratio [resin (A) / compound (B)] of the resin (A) to the compound (B) is 100/5 to 100/40.   The resin composition for a thermal transfer image-receiving sheet according to claim 1 or 2, wherein the compound (B) is a diester comprising an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane and an aliphatic monocarboxylic acid. object.   Resin (A) is a main chain segment comprising a polyester resin obtained by condensation polymerization of an alcohol component containing 50 mol% or more of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane and a carboxylic acid component. The resin composition for a thermal transfer image receiving sheet according to any one of claims 1 to 3, comprising a graft polymer composed of (A1) and a side chain segment (A2) comprising an addition polymerization resin.   The resin composition for a thermal transfer image receiving sheet according to claim 4, wherein the segment (A2) contains 70% by weight or more of a structural unit derived from an addition polymerizable monomer having an aromatic group.   The thermal transfer image receiving sheet which has a dye receiving layer containing the resin composition for thermal transfer image receiving sheets in any one of Claims 1-5.   A resin (A) or a polyester resin (a1) serving as a precursor of the resin (A) and the compound (B) are mixed, water is added, and the resin (A) contains the compound (B). The manufacturing method of the resin composition for thermal transfer image receiving sheets in any one of Claims 1-6 including the process of obtaining a dispersion liquid.