JP2011136433A - Resin composition for thermal transfer image-receiving sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for a thermal transfer image-receiving sheet which provides the thermal transfer image-receiving sheet exhibiting excellent dyeing properties, mold releasability and light resistance, and a thermal transfer image-receiving sheet with a dye receiving layer containing the resin composition, and a production method for the resin composition for the thermal transfer image-receiving sheet. <P>SOLUTION: [1] The resin composition for the thermal transfer image-receiving sheet contains a graft polymer (A) containing a main chain segment (A1) formed of a polyester resin obtained by polycondensing an alcohol component containing an alkyleneoxide adduct of 2,2-bis (4-hydroxyphenyl) propane in an amount of 50 mol% or larger with a carboxylic acid component, and a side chain segment (A2) formed of an addition polymer-based resin, and a resin (B) having a glass transition temperature lower by an amount of 10 to 80°C than the glass transition temperature of the graft polymer (A). [2] The thermal transfer image-receiving sheet has, on a substrate, the dye receiving layer containing the resin composition for the thermal transfer image-receiving sheet. [3] The production method for the resin composition for the thermal transfer image-receiving sheet is provided. <P>COPYRIGHT: (C)2011,JPO&INPIT

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 density and image defects, the support has at least one receiving layer containing a polymer latex and at least one heat insulating layer containing a hollow polymer on the support. A thermal transfer image-receiving sheet is disclosed in which the polymer latex contained in the layer is composed of two or more dyeable polymers having different glass transition temperatures.
In Patent Document 2, for the purpose of improving color density and image stability, thermal sublimation printing comprising a dye receiving layer comprising a graft polymer comprising an unsaturated copolyester as a trunk and a vinyl copolymer as a branch, and a support. Dye-receiving materials for use are disclosed.
In Patent Document 3, for the purpose of improving dyeing sensitivity, image durability and storage stability, the main chain is a polyester having an unsaturated bond, and the side chain is a polymer of a radical polymerizable unsaturated monomer. A polyester resin mainly comprising a graft product having a tan δ peak temperature of 40 ° C. or higher, a glass transition temperature of 15 ° C. or higher, and a molecular weight of 0.15 to 1.5 in terms of reduced viscosity, and the polyester system A sublimation transfer image receiver having a dyed layer mainly composed of a dyeable resin containing a resin is disclosed.
Patent Document 4 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.

JP 2007-229987 A JP-A-4-318989 Japanese Patent Laid-Open No. 10-60063 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. For this reason, there is a problem that fusion occurs between the ink sheet and the thermal transfer image receiving sheet during coloring. 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 excellent in dyeing property of high dyes, releasability that suppresses fusion with an ink sheet, and light resistance that suppresses fading of printed matter. From the viewpoint of achieving both the dyeing property, the release property and the light resistance, there is still room for improvement in the thermal transfer image receiving sheets described in Patent Documents 1 to 4.
The present invention is capable of providing a thermal transfer image-receiving sheet excellent in dyeability, releasability and light resistance, a thermal transfer image-receiving sheet resin composition, a thermal transfer image-receiving sheet having a dye-receiving layer containing the resin composition, and the above-mentioned It is an object of the present invention to provide a method for producing a resin composition for a thermal transfer image receiving sheet.

The present inventors have considered that the factors affecting the dyeing property, the release property and the light resistance are in the state of the dye-receiving layer when heated by a thermal head. As a result, a graft polymer containing a main chain segment made of a specific polyester resin and a side chain segment made of an addition polymerization resin, and a resin composition containing a resin having a glass transition temperature lower than the graft polymer within a certain range are dyed. It has been found that by using it in the receiving layer, the dyeing property, release property and light resistance are improved.
That is, the present invention provides the following [1] to [3].
[1] Main chain segment (A1) 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 And a side chain segment (A2) composed of an addition polymerization resin, and a glass transition temperature of 50 ° C. or higher and a graft polymer (A) having a glass transition temperature lower by 10 to 80 ° C. than the graft polymer (A) ( A resin composition for a thermal transfer image-receiving sheet, comprising B).
[2] A thermal transfer image-receiving sheet having a dye-receiving layer containing the resin composition for a thermal transfer image-receiving sheet of [1] above on a substrate.
[3] The method for producing a resin composition for a thermal transfer image receiving sheet according to the above [1], comprising the following steps (1) to (3).
Step (1): A non-aromatic carbon-carbon non-aromatic compound is obtained by polycondensing an alcohol component containing 50 mol% or more of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane with a carboxylic acid component. Step of preparing a polyester resin (a1) having a saturated bond and mixing the polyester resin (a1) with an aqueous medium to obtain an aqueous dispersion of the polyester resin (a1) Step (2): In Step (1) Step of adding an addition polymerizable monomer (a2) to the obtained aqueous dispersion and polymerizing to obtain an aqueous dispersion of graft polymer (A) Step (3): Graft polymer obtained in step (2) ( A step of mixing an aqueous dispersion of resin (B) with an aqueous dispersion of A) to obtain an aqueous dispersion of a resin composition for a thermal transfer image-receiving sheet.

  According to the present invention, a thermal transfer image-receiving sheet resin composition capable of providing a thermal transfer image-receiving sheet excellent in dyeability, releasability and light resistance, and a thermal transfer image-receiving sheet having a dye-receiving layer containing the resin composition, And the manufacturing method of the said resin composition for thermal transfer image receiving sheets can be provided.

[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. It contains a main chain segment (A1) made of resin “hereinafter simply referred to as segment (A1)” and a side chain segment (A2) made of addition polymerization resin “hereinafter also simply referred to as segment (A2)”, and has a glass transition. Graft polymer (A) having a temperature of 50 ° C. or higher “hereinafter also simply referred to as graft polymer (A)” and resin (B) having a glass transition temperature lower by 10 to 80 ° C. than the graft polymer (A) “hereinafter simply resin (Also referred to as (B) ”.
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, release property and light resistance is not clear, but is considered as follows.
First, it is considered that the dye has a low glass transition temperature and easily penetrates into the resin (B) having a high molecular mobility, thereby improving the dyeing property and light resistance of the thermal transfer image-receiving sheet. Furthermore, the raw material monomer of the segment (A1) in the graft polymer (A) in the resin composition for a thermal transfer image-receiving sheet contains an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane as an alcohol component. Since this compound has two aromatic rings in the molecule, that is, a structure similar to a dye, it has a high affinity with the dye, improves the dyeing property and light resistance of the thermal transfer image-receiving sheet, and has a rigid structure. Therefore, it is considered that the resin becomes hard and contributes to the improvement of the releasability of the thermal transfer image receiving sheet.
In addition, the segment (A2) in the graft polymer (A) is not compatible with both the main chain segment (A1) and the resin (B) made of the polyester resin having the above structure, and thus forms a fine phase separation structure. The permeability of the dye from the interface is increased, and a portion having a poor affinity with the ink sheet is oriented on the surface of the dye receiving layer. Thereby, it is considered that the dyeing property, light resistance and releasability of the thermal transfer image receiving sheet are greatly improved.

The weight ratio [graft polymer (A) / resin (B)] of the graft polymer (A) and the resin (B) in the resin composition for a thermal transfer image-receiving sheet is the dyeing property, light resistance and releasability of the thermal transfer image-receiving sheet. In view of the above, preferably 50/50 to 95/5, more preferably 65/35 to 95/5, more preferably 67/33 to 90/10, more preferably 67/33 to 85/15, still more preferably. 67/33 to 75/25.
From the viewpoint of dyeing property, light resistance and releasability of the thermal transfer image-receiving sheet, the graft polymer (A) and the resin (B) may be contained in a total of 80% by weight or more in the resin composition for the thermal transfer image-receiving sheet. Preferably, it is more preferably 90% by weight or more, and even more preferably accounts for 100% by weight.

(Graft polymer (A))
The graft polymer (A) comprises a main chain segment (A1) composed of a polyester resin containing an alcohol component containing 50 mol% or more of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane and an addition polymerization resin. And a glass transition temperature of 50 ° C. or higher.
The weight ratio [segment (A1) / segment (A2)] of the segment (A1) and the segment (A2) constituting the graft polymer contained in the resin for the thermal transfer image-receiving sheet of the present invention improves the dyeing property of the thermal transfer image-receiving sheet. From this viewpoint, it is preferably 55/45 to 95/5, more preferably 65/35 to 95/5, more preferably 75/25 to 95/5, and still 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, the glass transition temperature of the graft polymer (A) is 50 ° C. or higher, preferably 50 to 100 ° C., more preferably 50 to 80 ° C., and still more preferably 60 to 60 ° C., from the viewpoint of releasability of the thermal transfer image-receiving sheet. 80 ° C. The acid value of the graft polymer (A) is preferably 1 to 35 mgKOH / g, more preferably 5 to 35 mgKOH / g, and still more preferably 10 to 35 mgKOH / g.

(Main chain segment (A1) made of polyester resin)
The segment (A1) constituting the graft polymer contained in the resin for thermal transfer image-receiving sheets of the present invention is composed of an alcohol component containing 50 mol% or more of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane and a carboxyl group. This is a segment made of a polyester resin obtained by condensation polymerization with an acid component. The segment (A1) is a main chain in the graft polymer contained in the thermal transfer image-receiving sheet resin of the present invention.

  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, and more preferably an oxyethylene group or an oxyethylene group. Propylene 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.
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 preferable that they are the same.

As the alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane, from the above viewpoint, specifically, R ¹ O and R ² O are preferably the same, and are oxypropylene groups. Is more preferable. The alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane may be used alone or in combination of two or more.

  In the alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane, the content of the propylene oxide adduct is 2,2-bis from the viewpoint of dyeability and releasability of the thermal transfer image-receiving sheet. In the alkylene oxide adduct of (4-hydroxyphenyl) propane, preferably 50 to 100 mol%, more preferably 60 to 100 mol%, more preferably 70 to 100 mol%, still more preferably substantially 100 mol%. is there. The other oxyalkylene group is preferably an oxyethylene group or an oxytrimethylene group from the viewpoint of dyeing property of the dye on the thermal transfer image-receiving sheet, and more preferably an oxyethylene group from the viewpoint of dyeing property 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 from the viewpoint of dyeability and releasability of the thermal transfer image-receiving sheet, preferably 70 More than mol%, more preferably more than 80 mol%, still more preferably substantially 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, the raw material monomer derived from the structural unit of the segment (A1) “hereinafter also simply referred to as the raw material monomer of the segment (A1)” is an alcohol having a non-aromatic carbon-carbon unsaturated bond, Alcohol components including unsaturated aliphatic alcohols can be used. In the resin composition for a thermal transfer sheet, the carbon-carbon unsaturated bond portion in the unsaturated aliphatic alcohol can become a bond portion with the segment (A2). In this case, the unsaturated bond is saturated. It becomes a bond. As alcohol (unsaturated aliphatic alcohol) which has a non-aromatic carbon-carbon unsaturated bond, unsaturated aliphatic alcohols, such as allyl alcohol, etc. are mentioned.
Examples of other alcohols include ethylene glycol, propylene glycol (1,2-propanediol), glycerin, pentaerythritol, trimethylolpropane, hydrogenated bisphenol A, sorbitol, or alkylene (2 to 4 carbon atoms) oxide thereof. Examples include adducts (average added mole number of 1 to 16). You may use these individually by 1 type or in combination of 2 or more types.

Since the segment (A1) is a polyester resin, a carboxylic acid component is used as a raw material monomer in addition to the alcohol component.
The carboxylic acid component which is a raw material monomer of the segment (A1) includes a carboxylic acid having a non-aromatic carbon-carbon unsaturated bond, that is, an unsaturated aliphatic carboxylic acid and / or an unsaturated alicyclic carboxylic acid. It is preferable. The carbon-carbon unsaturated bond portion is preferably a bond portion with the segment (A2) in the resin for thermal transfer sheets of the present invention. 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.
Examples of other carboxylic acids include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid; aliphatic dicarboxylic acids such as adipic acid, succinic acid, succinic acid having an alkyl group and / or alkenyl group; cyclohexanedicarboxylic acid Alicyclic dicarboxylic acids such as acids and decalin dicarboxylic acids; Trivalent or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid, anhydrides of these acids, and alkyl (1 to 3 carbon atoms) esters thereof Is mentioned. From the viewpoint of the dyeability of the thermal transfer image-receiving sheet, preferably an aromatic dicarboxylic acid, an alicyclic dicarboxylic acid, more preferably an aromatic dicarboxylic acid, more preferably isophthalic acid, cyclohexanedicarboxylic acid, and still more preferably isophthalic acid. You may use these individually by 1 type or in combination of 2 or more types.
Among the raw material monomers derived from the structural unit of segment (A1), as the raw material monomer having a non-aromatic carbon-carbon unsaturated bond, unsaturated aliphatic carboxylic acid, unsaturated alicyclic carboxylic acid, One or more selected from unsaturated aliphatic alcohols may be included, but from the viewpoint of reactivity, it is preferable to include an unsaturated aliphatic carboxylic acid and / or an unsaturated alicyclic carboxylic acid. More preferably, it is only an acid and / or an unsaturated alicyclic carboxylic acid.

  The segment (A1) has a molar ratio (hydroxyl group / carboxy group) between the hydroxyl group of the alcohol component and the carboxy group of the carboxylic acid component from the viewpoint of dyeability and releasability of the thermal transfer image-receiving sheet. 100/120, more preferably 100/100 to 100/110, more preferably 100/102 to 100/107, and still more preferably 100/102 to 100/104.

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

In the present invention, the segment (A1) may be modified within the range so as not to substantially impair the characteristics. Examples of the modified segment (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 segments made of blocked polyester resin.
In the present invention, the content of the polyester portion in the segment (A1) is preferably 50 to 100% by weight, more preferably 60 to 100% by weight, and more preferably 60 to 100% by weight, from the viewpoint of dyeability and releasability of the thermal transfer image-receiving sheet. Preferably, it is substantially 100% by weight.

(Side chain segment (A2) made of addition polymerization resin)
The segment (A2) constituting the graft polymer contained in the thermal transfer image-receiving sheet resin of the present invention is an addition polymerization system composed of structural units derived from the addition polymerizable monomer (a2) (hereinafter also referred to as monomer (a2)). A segment made of resin. The segment (A2) is a side chain in the graft polymer contained in the thermal transfer image-receiving sheet resin of the present invention.
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, and among them, an addition polymerizable monomer having an aromatic group is more preferable, and styrene, methylstyrene, benzyl methacrylate, and benzyl acrylate are more preferable. Among these, styrene is particularly 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.
The content of the structural unit derived from the addition-polymerizable monomer having an aromatic group is preferably 55% by weight or more in the segment (A2) from the viewpoint of releasability of the thermal transfer image-receiving sheet and storage stability of the resin. Preferably it is 70 weight% or more, More preferably, it is 80 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.

(Method for producing graft polymer (A))
As a method for producing the graft polymer (A), 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 to form a non-aromatic compound. A polyester resin (a1) having a carbon-carbon unsaturated bond (hereinafter also referred to as resin (a1)), and addition polymerization of the addition polymerizable monomer (a2) in the presence of the polyester resin (a1) The method is preferred.

-Polyester resin (a1)-
Resin (a1) is a non-aromatic carbon 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 polyester resin having a carbon unsaturated bond, which is preferable for constituting the main chain segment (A1) made of the polyester resin. The “non-aromatic carbon-carbon unsaturated bond” is derived from one or more selected from the above-mentioned unsaturated aliphatic carboxylic acid, unsaturated alicyclic carboxylic acid and unsaturated aliphatic alcohol. It is.

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 in the case of 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) 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 by 1 type or in combination of 2 or more types.

The resin (a1) has a non-aromatic carbon-carbon unsaturated bond, and a carboxylic acid 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.
The other carboxylic acid is the same as in the case of the segment (A1), and the same structure and preferable content are the same. Cyclohexanedicarboxylic acid and isophthalic acid are preferable, and isophthalic acid is more preferable. 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, t-butylcatechol is 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 5 to 40 mgKOH / g, preferably 5 to 35 mgKOH / g, 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.

(Resin (B))
The resin (B) is a resin having a glass transition temperature lower by 10 to 80 ° C. than the graft polymer (A) from the viewpoint of dyeability and releasability of the thermal transfer image receiving sheet.
From the same viewpoint, the difference in glass transition temperature between the resin (B) and the graft polymer (A) is 10 to 80 ° C., preferably 20 to 55 ° C., more preferably 30 to 45 ° C., and still more preferably 30 to 30 ° C. 40 ° C.
The resin (B) is not limited to the type of resin as long as the glass transition temperature is different from that of the graft polymer (A) as described above. For example, polyester, vinyl chloride polymer, vinyl chloride vinyl acetate copolymer, chloride A vinyl acrylic copolymer and a polyurethane are mentioned.
From the viewpoint of dyeability, releasability and light resistance of the thermal transfer image-receiving sheet, a resin having the same structure as the vinyl chloride acrylic copolymer or the graft polymer (A), that is, 2,2-bis (4-hydroxyphenyl) ) A resin comprising a segment comprising a polyester resin containing an alcohol component containing 50 mol% or more of an propane alkylene oxide adduct and a segment comprising an addition polymerization resin is preferred, and a vinyl chloride acrylic copolymer is more preferred.
Examples of commercially available vinyl chloride acrylic copolymers include “ViniBran (registered trademark) 278”, “Vinibrand (registered trademark) 271” (manufactured by Nissin Chemical Industry Co., Ltd.), and the like.
These resins can be used by dissolving in an organic solvent, but are preferably used as an aqueous dispersion from the viewpoint of environmental properties.

  The glass transition temperature of the resin (B) is preferably 60 ° C. or less, more preferably 45 ° C. or less, more preferably −20 to 45 ° C., from the viewpoints of dyeability, releasability and light resistance of the thermal transfer image receiving sheet. More preferably, it is 0-45 degreeC, More preferably, it is 25-45 degreeC.

[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 is obtained by mixing the graft polymer (A) obtained by the method of polymerizing the addition polymerizable monomer (a2) and the resin (B) in the presence of the resin (a1). Obtainable. There is no limitation on the polymerization method of the graft polymer (A), a method in which the resin (a1) and the monomer (a2) are directly mixed and polymerized, and the resin (a1) and the monomer (a2) are dissolved in an organic solvent for polymerization. And the like. Moreover, there is no restriction | limiting in the method of mixing graft polymer (A) and resin (B), the method of mixing the aqueous dispersion of resin (B) with the aqueous dispersion of graft polymer (A), the reverse method, etc. Can be mentioned.
The resin composition for a thermal transfer image receiving sheet of the present invention is preferably obtained by a method having the following steps (1) to (3).
Step (1): Step of mixing the polyester resin (a1) with an aqueous medium to obtain an aqueous dispersion of the polyester resin (a1) Step (2): Adding to the aqueous dispersion obtained in Step (1) A step of adding a polymerizable monomer (a2) and polymerizing to obtain an aqueous dispersion of the graft polymer (A) Step (3): The aqueous dispersion of the graft polymer (A) obtained in the step (2) is added to the resin ( Step of mixing the aqueous dispersion of B) to obtain an aqueous dispersion of the resin composition for a thermal transfer image receiving sheet

(Process (1))
Step (1) is a step of mixing the polyester resin (a1) with an aqueous medium to obtain an aqueous dispersion of the polyester resin (a1).
The aqueous medium in which the polyester resin (a1) 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 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 polyester resin (a1) in the aqueous medium, the polyester resin (a1) is dissolved in a ketone solvent, a neutralizing agent described later is added to ionize the carboxyl group of the polyester resin (a1), and then A method of phase change to an aqueous system by adding water, preferably a method of adding a water and then distilling off the ketone solvent to phase-change to an aqueous system.
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 neutralizer or the like is added to the polyester resin (a1) dissolved in the ketone solvent. To ionize the carboxyl group (not necessary if already ionized), and then add water to invert the phase to an aqueous system. Preferably, after adding water, the ketone solvent is distilled off to convert to an aqueous system. I agree.
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 equal to or lower than the boiling point of the ketone solvent. Examples of the water used include deionized water.
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.

  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, neopen Examples include amines such as tanolamine, 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).

(Process (2))
In the step (2), the addition polymerizable monomer (a2) is added to the aqueous dispersion obtained in the step (1) and polymerized to obtain an aqueous dispersion of the graft polymer (A) (hereinafter referred to as an aqueous dispersion (A). It is a process of obtaining also.
First, the addition polymerizable monomer (a2) is added to the aqueous dispersion of 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.
Further, from the viewpoint of stirring efficiency, water or the like may be further added.

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 preferably 40 from the viewpoints of storage stability, dyeability of the thermal transfer image-receiving sheet and light resistance. It is -80 degreeC, More preferably, it is 50-80 degreeC, More preferably, it is 60-80 degreeC. 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, the “volume median particle size (D50)” means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% calculated from the smaller particle size. The measuring method is as described in the examples.

(Process (3))
In step (3), the aqueous dispersion (A) obtained in step (2) is mixed with an aqueous dispersion of resin (B) (hereinafter also referred to as aqueous dispersion (B)), and the resin for thermal transfer image-receiving sheet. This is a step of obtaining an aqueous dispersion of the composition.
The aqueous dispersion (A) obtained in the step (2) contains the graft polymer (A), and the aqueous dispersion (B) containing the resin (B) is mixed with the aqueous dispersion (B). It is preferable to obtain an aqueous dispersion of the resin composition for a thermal transfer image receiving sheet. From the viewpoint of obtaining a uniform aqueous dispersion of the resin composition, the solid content concentration when mixing both is preferably 10 to 50% by weight, more preferably 20 to 40 for the aqueous dispersion (A). The aqueous dispersion (B) is preferably 10 to 50% by weight, more preferably 20 to 40% by weight, still more preferably 25 to 35% by weight. . The solid content concentration is preferably adjusted by diluting with deionized water or the like.
In addition, although there is no restriction | limiting in the manufacturing method of the aqueous dispersion liquid (B) containing resin (B), it can obtain by the following methods. For example, emulsion polymerization, suspension polymerization, etc., a method of obtaining the aqueous dispersion (B) by polymerizing the raw material monomer of the resin (B) in an aqueous medium, and dispersing the resin solution obtained by solution polymerization in the aqueous medium Then, if necessary, the solvent is removed to obtain an aqueous dispersion (B), and the resin (B) obtained by bulk polymerization or polycondensation is dispersed in an aqueous medium as it is or after being dissolved in a solvent. In addition, there may be mentioned a method of obtaining the aqueous dispersion (B) by removing the solvent as necessary.
The pH of the aqueous dispersion of the resin composition for a thermal transfer image receiving sheet obtained in the step (3) is preferably adjusted to 7 to 10, more preferably 8 to 9. The pH is preferably adjusted with an aqueous ammonia solution or the like.
The mixing method of the aqueous dispersions (A) and (B) in the step (3) is not particularly limited as long as the aqueous dispersions are sufficiently mixed with each other. If the amount of each aqueous dispersion is small, they can be sufficiently mixed by putting both in a glass container and shaking.

[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 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. The latter is preferable from the viewpoint of environmental safety and the like, and it is more preferable to manufacture by performing the following steps (4) to (5).
Step (4): 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): Obtained in Step (4) A step of providing a dye-receiving layer using the dye-receiving layer coating solution

(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, based on 100 parts by weight of the resin. As a commercially available release agent, KF-615A 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 temperature for dispersing or dissolving 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 the 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 a stirrer 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 clarity of the transferred image. Can be contained. 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 of the present invention may further contain other additives such as a catalyst and a curing agent, if necessary.
Further, the dye-receiving layer coating solution may contain a resin other than the resin composition for a thermal transfer image-receiving sheet of the present invention as long as the effects of the present invention are not impaired. Specific examples of the other resin include vinyl chloride polymer, vinyl chloride vinyl acetate copolymer, vinyl chloride acrylic copolymer, polyurethane, etc., from the viewpoint of dyeing property and light resistance of the thermal transfer image-receiving sheet, A vinyl chloride acrylic copolymer is preferred.
These other resins can be contained in the dye-receiving layer coating solution by being dissolved 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, or as a resin dispersion. The dye-receiving layer coating solution may be added to and mixed with the aqueous dispersion of the resin composition for a thermal transfer image-receiving sheet.

(Process (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 formed as described above 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 more preferably has an intermediate layer containing 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 ° C.) measured by JIS K6503-2001 is preferably 2.5 to 6.0 mPa · s from the viewpoint of releasability and film-forming property of the thermal transfer image-receiving sheet. More preferably, it is -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 viewpoints of dyeability and light resistance of the thermal transfer image-receiving sheet and 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, and the like. Acrylic resins such as a mixture of these, polystyrene, polyvinylidene chloride, polyacrylonitrile, vinylidene chloride-acrylonitrile copolymer, etc. can be used, but in the present invention, the dyeing property and light resistance of the thermal transfer image-receiving sheet, and From the viewpoint of adhesion between the intermediate layer and the dye-receiving layer in the thermal transfer image-receiving sheet, a styrene-acrylic copolymer, a vinylidene chloride-acrylonitrile copolymer, or the like is preferably 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.
Further, 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 having a solid concentration of preferably 10 to 40% by weight, more preferably 15 to 35% by weight are used.
In addition, the hollow particles preferably have an insoluble content of methyl ethyl ketone (MEK) of 70% by weight or less from the viewpoint of dyeability and light resistance of the thermal transfer image-receiving sheet and adhesion between the intermediate layer and the dye-receiving layer in the thermal transfer image-receiving sheet. More preferably, it is 10-70 weight%, More preferably, it is 30-70 weight%. In the present invention, “MEK insoluble matter” is defined as the weight ratio of the insoluble hollow particle component of hollow particles when 2,000 parts by weight of hollow particles are dissolved with respect to 95 parts by weight of MEK at 25 ° C. It is what is done.
The MEK insoluble content of the hollow particles can be adjusted, for example, by controlling the degree of crosslinking of the resin constituting the hollow particles.

In the present invention, the hollow particles are preferably used as a dispersion in an aqueous medium, and as commercially available hollow particles that can be preferably used, for example, “Ropeke HP-1055” manufactured by Rohm and Haas Japan Co., Ltd. Examples thereof include “Nipol MH8101” manufactured by Nippon Zeon Co., Ltd., “SX8782 (D)” manufactured by JSR Corporation, and the like.
In the intermediate layer, the weight ratio of the hollow particles to the water-soluble polymer (hollow particles / water-soluble polymer) is determined from the viewpoint of dyeing property and adhesion between the intermediate layer and the dye-receiving layer in the thermal transfer image-receiving sheet. , Preferably 30/70 to 90/10, more preferably 40/60 to 80/20, 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 the thermal transfer using the thermal transfer image receiving sheet of the present invention as described above is usually 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 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 pyridone azo series, dicyanostyryl series, quinophthalone series, merocyanine series for yellow dyes; benzeneazo series, pyrazolone azomethine series, isothiazole for magenta dyes. Examples of cyan dyes include anthraquinone, cyanomethylene, indophenol, and indonaphthol.

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 apparatus such as a thermal printer, thermal energy of about 5 to 100 mJ / mm ^{2 is obtained.} It can be done by giving.

  Hereinafter, the present invention will be described more specifically with reference to examples and the like. In the following examples and the like, each physical property was measured by the following method.

[Acid value of resin]
Measured according to JIS K0070. However, as the measurement solvent, 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, “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 (Perkin Elmer, Pyris 6DSC), 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 temperature rising rate of 10 ° C./min. The temperature at the intersection of the base line extension below the maximum peak temperature of endotherm 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 binder resin was dissolved in chloroform 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., “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 molecular weight of the sample was calculated based on a calibration curve prepared in advance. In this calibration curve, 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), GL A monodispersed polystyrene manufactured by Science Co., Ltd .; 2.10 × 10 ³ , 7.00 × 10 ³ , 5.04 × 10 ⁴ (weight average molecular weight)) is used as a standard sample.
Measuring device: CO-8010 (manufactured by Tosoh Corporation)
Analysis column: GMHLX + G3000HXL (manufactured by Tosoh Corporation)

[Volume Median Particle Size (D50) of Resin Particles]
Using a laser diffraction particle size analyzer ("LA-920", manufactured by Horiba, Ltd.), distilled water is added to the measurement cell, and the volume-median particle size (D50) is such that the absorbance is in the proper range. Was measured.

[Solid concentration of resin dispersion]
Using an infrared moisture meter (manufactured by KETO Scientific Laboratory Co., Ltd .: FD-230), 5 g of the dispersion was subjected to a drying temperature of 150 ° C. and a measurement mode 96 (monitoring time 2.5 minutes / variation width 0.05%). Then, the moisture (% by weight) of the wet base was measured, and the solid content concentration was calculated according to the following formula.
Solid content concentration (% by weight) = 100-M
M: wet base moisture (% by weight) = [(W−W0) / W] × 100
W: Sample weight before measurement (initial sample weight)
W0: Sample weight after measurement (absolute dry weight)

[PH of resin dispersion]
It measured at 25 degreeC with the pH meter "HM-20P" by Toa DK Corporation.

Production Examples 1 and 2 (Production of polyester resin (a1) -a and b)
The raw material monomer and dioctylic acid tin (II) salt 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, and placed in a mantle heater. The reaction was carried out at 235 ° C. for 5 hours under a nitrogen atmosphere, and further reacted for 1 hour under reduced pressure (8.3 kPa). 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, polyesters (a1) -a and b were obtained. Table 1 shows the physical properties and the like of the obtained polyester (a1) -a and b.

Production Example 3 (Production of polyester resin (a1) -c)
The raw material monomer and dioctylic acid tin (II) salt 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, and placed in a mantle heater. The reaction was carried out at 210 ° C. for 5 hours under a nitrogen atmosphere, and the reaction was further carried out for 1 hour under reduced pressure (8.3 kPa). 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 (a1) -c was obtained. Table 1 shows the physical properties and the like of the obtained polyester (a1) -c.

Production Example 4 (Production of polyester resin (a1) -d)
The raw material monomer and dioctylic acid tin (II) salt 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, and placed in a mantle heater. The reaction was carried out at 230 ° C. for 9 hours under a nitrogen atmosphere, and the reaction was further carried out for 1 hour under reduced pressure (8.3 kPa). Next, fumaric acid and 4-t-butylcatechol were added at 210 ° C. and reacted for 5 hours, and then reacted for 1 hour under reduced pressure (8.3 kPa) to obtain polyester (a1) -d. Table 1 shows the physical properties and the like of the obtained polyester (a1) -d.

Production Examples 5 to 8 (Production of aqueous dispersions (i) to (iv) of polyester resin (a1): Step (1))
A polyester resin (a1) -ad is added to a four-necked flask with an internal volume of 10 L equipped with a nitrogen inlet tube, a reflux condenser, a stirrer, and a thermocouple, as shown in Table 2, and dissolved in methyl ethyl ketone at 25 ° C. I let you. 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 (iv) of the polyester resin (a1). Table 2 shows the composition, solid content concentration, pH, and volume-median particle size of the dispersed particles of each of the obtained aqueous dispersions (i) to (iv).

Production Examples 9 to 12 (Production of aqueous dispersions (I) to (IV) of graft polymer (A) or resin (B): Step (2))
A polyester dispersion, deionized water, and addition polymerizable monomer (a2) with the composition shown in Table 3 were added to a 2 L four-necked flask equipped with a nitrogen inlet tube, a reflux condenser, a dropping funnel, a stirrer, and a thermocouple. Was charged with styrene 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 (IV) of the graft polymer (A) or the resin (B). Table 3 shows the composition, solid content concentration, pH, and volume-median particle size of the dispersed particles of each of the obtained aqueous dispersions (I) to (IV).
As will be described later, the aqueous dispersions (I) and (II) are mainly used as the aqueous dispersion (A) of the graft polymer (A), and the aqueous dispersions (III) and (IV) are used. Was used as an aqueous dispersion (B) of resin (B). However, only in Comparative Example 5, the aqueous dispersion (I) is used as the aqueous dispersion (B) of the resin (B), and the aqueous dispersion (II) is used as the aqueous dispersion (A) of the graft polymer (A). did.

Examples 1 to 9 and Comparative Examples 1 to 5 (Production of thermal transfer image receiving sheet)
First, the composition and blending amount shown in Table 4-1 or Table 4-2 were mixed at 45 ° C. to prepare an intermediate layer coating solution. This coating solution was applied to synthetic paper YUPO FGS-250 (thickness 250 μm, basis weight 200 g / m ² ) with a wire bar to 20.0 g / m ² after drying, and dried at 25 ° C. for 5 minutes. An intermediate layer coated sheet was obtained.
Next, after diluting each of the aqueous dispersion (A) and the aqueous dispersion (B) shown in Table 4-1 or Table 4-2 with deionized water to a solid content concentration of 30% by weight, Table 4- 1 or the composition shown in Table 4-2 was placed in a screw tube, and the pH was adjusted to 9.0 with a 25% aqueous ammonium solution (manufactured by Wako Pure Chemical Industries, Ltd.) (step (3)).
As the aqueous dispersion (B), in addition to the aqueous dispersions (III) and (IV), a commercially available resin dispersion “VINYBRAN 278” (manufactured by Nissin Chemical Industry Co., Ltd., vinyl chloride acrylic copolymer) Combined, Tg = 39 ° C.), “Vinibran 271” (manufactured by Nissin Chemical Industry Co., Ltd., vinyl chloride acrylic copolymer, Tg = −5 ° C.) was used.
Subsequently, a release agent (“KF-615A” manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred for 1 hour at 25 ° C. with a ball mill. Then, at 45 ° C., a film-forming agent (gelatin aqueous solution having a solid content concentration of 8% by weight (the amount used in Table 4-1 and Table 4-2 indicates the effective amount)) was stirred for 3 hours with a ball mill, Dye-receiving layer coating solutions A1 to N1 were prepared (step (4)).
Each of the obtained dye-receiving layer coating solutions was applied to the above-mentioned intermediate layer coating sheet so as to be 5.0 g / m ² after drying with a wire bar, and dried at 50 ° C. for 2 minutes. A thermal transfer image receiving sheet was obtained (step (5)).
The obtained thermal transfer image-receiving sheet was measured and evaluated for dyeing property, releasability and light resistance by the following methods. The results are shown in Tables 4-1 and 4-2.

[Evaluation methods]
(Dyeing property-maximum concentration)
A black (K) gradation pattern was printed on the obtained thermal transfer image-receiving sheet using a commercially available sublimation type printer (manufactured by Altech Co., Ltd., “MEGAPIXEL III”), and a high density print (18th gradation (L = The transfer color density in 0)) was measured with a Gretag densitometer (manufactured by Gretag Macbeth). The higher the maximum concentration, the better the dyeing property.

(Releasability-heat fusion)
A black solid of 5 × 5 cm was printed on the obtained thermal transfer image receiving sheet, and the releasability was evaluated according to the following criteria from the peeling sound between the ink ribbon and the thermal transfer image receiving sheet during continuous black solid printing.
A: There is no noise and can be peeled off.
B: Although there is some abnormal noise, it can be peeled off.
C: It is heat-sealed and peeling is difficult.

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

-Hue change amount: Using an optical densitometer (measured with Gretag), black (K), yellow (Y), magenta (M), cyan (C), green (G), red (R) ), Measuring the optical reflection density of blue (B), and measuring L ^* a ^* b ^* before and after irradiation with a color difference meter (manufactured by Gretag Macbeth) for the step where the optical reflection density before irradiation is around 1.0. Then, the hue change amount was calculated by the following formula, and the light resistance of each black (K) + chromatic print was evaluated. The smaller the hue change amount, the better the light resistance.
The light resistance of black and chromatic colors (for each print) is black (K), yellow (Y), magenta (M), cyan (C), green (G), red (R), blue ( This is the sum of the hue changes of each color of B).
Hue variation _{^{= [(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 )

  It can be seen that the thermal transfer image-receiving sheets obtained in the examples are excellent in all of dyeing property, releasability and light resistance as compared with the thermal transfer image-receiving sheet obtained in the comparative example.

  Since the thermal transfer image receiving sheet of the present invention is excellent in all of dyeing property, releasability and light resistance, it can be suitably used as a thermal transfer image receiving sheet.

Claims (8)

  Main chain segment (A1) 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, and addition polymerization A side chain segment (A2) made of a resin and a glass transition temperature of 50 ° C. or higher, and a resin (B) having a glass transition temperature lower by 10 to 80 ° C. than the graft polymer (A) A resin composition for a thermal transfer image receiving sheet.   The resin composition for a thermal transfer image-receiving sheet according to claim 1, wherein the resin (B) is a vinyl chloride acrylic copolymer.   The thermal transfer image-receiving device according to claim 1 or 2, wherein the side chain segment (A2) comprising the addition polymerization resin contains 55% by weight or more of a structural unit derived from an addition polymerizable monomer having an aromatic group. Resin composition for sheet.   The thermal transfer image-receiving sheet according to any one of claims 1 to 3, wherein a weight ratio of the graft polymer (A) to the resin (B) [graft polymer (A) / resin (B)] is 50/50 to 95/5. Resin composition.   The weight ratio [segment (A1) / segment (A2)] of the main chain segment (A1) made of a polyester resin and the side chain segment (A2) made of an addition polymerization resin is 55/45 to 95/5. The resin composition for thermal transfer image receiving sheets according to any one of 1 to 4.   The raw material monomer from which the structural unit of the main chain segment (A1) composed of a polyester resin is derived contains at least one selected from unsaturated aliphatic carboxylic acids, unsaturated alicyclic carboxylic acids, and unsaturated aliphatic alcohols. Item 6. The resin composition for a thermal transfer image receiving sheet according to any one of Items 1 to 5.   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 1-6 on a base material. The manufacturing method of the resin composition for thermal transfer image receiving sheets in any one of Claims 1-6 which has following process (1)-(3).
Step (1): A non-aromatic carbon-carbon non-aromatic compound is obtained by polycondensing an alcohol component containing 50 mol% or more of an alkylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane with a carboxylic acid component. Step of preparing a polyester resin (a1) having a saturated bond and mixing the polyester resin (a1) with an aqueous medium to obtain an aqueous dispersion of the polyester resin (a1) Step (2): In Step (1) Step of adding an addition polymerizable monomer (a2) to the obtained aqueous dispersion and polymerizing to obtain an aqueous dispersion of graft polymer (A) Step (3): Graft polymer obtained in step (2) ( A step of mixing an aqueous dispersion of resin (B) with an aqueous dispersion of A) to obtain an aqueous dispersion of a resin composition for a thermal transfer image-receiving sheet.