JP2001121828A - Thermal transfer receiving sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer receiving sheet which is free from blocking in the heat treating process of a dye receiving layer and shows high radation reproducibility even in a low-energy image printing region and also superb light resistance in a recorded image. SOLUTION: In the thermal transfer receiving sheet composed of a sheetlike support and a dye receiving layer formed at least on one of the faces of the support, the dye receiving layer contains a polyester resin as a dye receiving resin generated by a polycondensation reaction between a dicarboxylic acid component having a content of 40 mol% or more alicyclic dicarboxylic acid compound and a diol component having a content of 15 mol% or more diol component with a bisphenol A skeleton. In addition, the sheet is characterized in that it contains at least one kind selected from among phosphate compounds as a preservability improver.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer receiving sheet. More specifically, the present invention relates to a heat transfer receiving sheet which does not cause blocking in a heat treatment step of a dye receiving layer, has good gradation reproducibility even in a low energy printing area, and has excellent light resistance of a recorded image.

[0002]

2. Description of the Related Art In a dye thermal transfer printer, a dye receiving layer (hereinafter also simply referred to as a receiving layer) containing a thermoplastic resin having a dye-dyeing property of a thermal transfer receiving sheet (hereinafter simply referred to as a receiving sheet) is added to a dye ink sheet. ) Is superimposed, and heat is supplied from a thermal head or the like to transfer the dye onto the receptor layer to form an image, and high-quality image recording is obtained. Is advancing.

[0003] However, dye images obtained by the dye thermal transfer system generally undergo fading during storage, particularly by light. This is presumably because the dye or thermoplastic resin used is affected by ultraviolet rays (290 to 400 nm) contained in sunlight or the like and deteriorates. When a commonly used polyester resin, polyurethane resin, polycarbonate resin or the like is used as the thermoplastic resin, the image is particularly fading. Further, even in hydrocarbon polymers such as polyolefins, not only photodecomposition of the dye itself but also residual impurities and free radicals may act as photosensitizers, and it is considered that photodegradation proceeds. .

[0004] In order to improve the storage stability,
Various methods have been proposed for blending auxiliary agents such as an ultraviolet absorber, a quencher, a light stabilizer, an antioxidant, and a plasticizer. However, even if the storability of the image is improved by, for example, an auxiliary agent, on the other hand, blocking occurs in the heat treatment step of the receiving layer, or a sufficiently low print density cannot be obtained in a low energy region when the image is printed. So-called "cover"
There was also a problem that the phenomenon described above occurs. Further, a method has been proposed in which the overlaminating layer is transferred after image recording to suppress fading, but the printing time becomes longer and the running cost of printing also increases.

[0005]

The present invention is suitable for a thermal printer, especially for a dye thermal transfer printer, and has good gradation reproducibility at the time of printing without causing blocking in the heat treatment of the receiving layer in the production process, and has a high image quality. To provide a receiving sheet having excellent light resistance.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a specific thermoplastic polyester resin is used as a dye-dyeable resin for a receptor layer and a phosphate ester compound is added as a preservability improver. Thereby, it is found that there is no blocking in the heat treatment step of the receiving layer, a sufficiently low printing density can be obtained in a low energy region when printing an image, there is no so-called "fog", and the light resistance of the image is extremely improved. To complete the invention.

The thermal transfer sheet of the present invention is characterized in that, in a thermal transfer receiving sheet having a sheet-like support and a dye-receiving layer on at least one surface of the support, the dye-receiving layer contains 40 mol% of an alicyclic dicarboxylic acid compound. A polyester resin formed by a polycondensation reaction of the dicarboxylic acid component containing the above and a diol component containing 15 mol% or more of a diol compound having a bisphenol A skeleton as a dye-accepting resin; A thermal transfer receiving sheet comprising at least one selected from compounds.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the dye-dyeing polyester resin includes a dicarboxylic acid component containing an alicyclic dicarboxylic acid compound in an amount of 40 mol% or more and a diol compound having a bisphenol A skeleton in an amount of 15 mol% or more. A polyester resin produced by a polycondensation reaction with a diol component is used. Examples of the alicyclic dicarboxylic acid compound include cyclohexanedicarboxylic acids [Chemical Formula 1], decahydronaphthalenedicarboxylic acids [Chemical Formula 2], and ester compounds and acid halides thereof, but the present invention is not limited to these specific examples. It is not something to be done.
The content of the alicyclic dicarboxylic acid compound is required to be 40 mol% or more in the dicarboxylic acid component, and preferably 50 mol% or more.

[0009]

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(In the formula, R represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkylene group.)

[0011]

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(Wherein R ₁ and R ₂ represent a hydrogen atom or an alkyl or alkylene group having 1 to 4 carbon atoms)

Other dicarboxylic acid components include aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecadionic acid, dimer acid, terephthalic acid, isophthalic acid, orthophthalic acid, and 2,6-naphthalenedicarboxylic acid. Aromatic dicarboxylic acids such as acids can be used in combination. The carboxylic acid component may contain a small amount of a polyfunctional carboxylic acid, for example, using aromatic carboxylic acids such as trimetic acid and pyrometic acid, and aliphatic polycarboxylic acids such as butanetetracarboxylic acid. Can be.

Examples of the diol compound having a bisphenol A skeleton include bisphenol A, ethylene oxide and propylene oxide adducts of bisphenol A, and ethylene oxide and propylene oxide adducts are preferred. These contents need to be 15 mol% or more in the diol component, and preferably 30 mol% or more.

As other diol compounds, general aliphatic glycols, aromatic glycols, alicyclic glycols and the like can be used. For example, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-
Butanediol, 1,5-pentanediol, 1,6-
It can be selected from hexanediol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanedimethanol neopentyl glycol, and the above-mentioned diol compounds having a bisphenol A skeleton.

Although not particularly limited, the number average molecular weight of the polyester resin of the present invention is from 3,000 to 100,
About 000, more preferably 5,000 to 5
It is 0000. The glass transition temperature (Tg) of these polyester resins is preferably about 45 to 120 ° C., and more preferably the glass transition temperature (Tg) is 50 to 90 ° C.
° C.

In the present invention, by using such a polyester resin in combination with a phosphoric acid ester as a storability improving agent, there is no blocking during printing or storage, a high recording density, and excellent image quality can be obtained. In the present invention, examples of the phosphate compound used in the receptor layer as the preservability improver include tributyl phosphate, tri-2-ethylhexyl phosphate, triphenyl phosphate, tricresyl phosphate, and the like. Among them, triphenyl phosphate is excellent in the effect of improving image persistence and is preferably used.

In the receiving layer, it is of course possible to use a commonly used thermoplastic resin as described below as long as the effects of the present invention are not impaired. For example, polyvinyl acetal such as polyvinyl formal, polyvinyl butyral, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polystyrene, styrene-acrylonitrile copolymer, polyethylene, ethylene-vinyl acetate copolymer,
Polypropylene, polymethyl methacrylate, MMA-
Various resins such as styrene copolymer, polyamide, ethyl cellulose, cellulose acetate, propyl cellulose, cellulose acetate / butyrate, cellulose nitrate, polycarbonate, phenoxy, and polyurethane can be used alone or in combination.

Further, a crosslinking agent can be blended in the receiving layer. In this case, it is preferable that the receiving layer component contains a component that causes a crosslinking reaction via a crosslinking agent. Further, a fusion preventing agent such as silicone oil can be blended in the receiving layer.
In addition, a fluorescent dye, a quencher, an antioxidant, and the like can be appropriately added. The coating amount of the receiving layer is 0.1 to
A range of 20.0 g / m ² is preferred.

In the receiving layer, known hindered amine light stabilizers and ultraviolet absorbers can be added to such an extent that the properties of the receiving sheet are not impaired. The hindered amine light stabilizer (HALS) is, for example, a compound having a 2,2,6,6-tetramethylpiperidine skeleton as shown in the following [Chemical Formula 3], and any compound having this skeleton may be used. There is no particular limitation.

[0021]

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Specifically, Sanol TS-770,
LS-2626, LS-765 (manufactured by Sankyo), TIN
UVIN 144, 622, 111FD, 123, 29
2, Chimasorb 944 (all manufactured by Ciba Specialty Chemicals), Mark LA-57, LA-8
7, LA-82, LA-63, LA68LD, LA-6
2, LA-67 (from Asahi Denka), Cyasorb U
V-3346 (made by ACC), Sumisorb TM-
061, 577 (all manufactured by Sumitomo Chemical Co., Ltd.) and the like. Of course, the hindered amine light stabilizer is not limited to these, and two or more hindered amine light stabilizers can be used in combination.

The ultraviolet absorber is, for example, 2- (5-methyl-) as a specific example of a benzotriazole-based ultraviolet absorber.
2-hydroxyphenyl) benzotriazole (TIN
UVIN P: Ciba Specialty Chemicals), 2- [2-hydroxy-3,5-bis (α, α-
Dimethylbenzyl) phenyl] -2H-benzotriazole (TINUVIN 234: manufactured by Ciba Specialty Chemicals), 2- (3,5-di-t-butyl-2)
-Hydroxyphenyl) benzotriazole (TINU
VIN 320: Ciba Specialty Chemicals), 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole (TI
Nuvin 326: Ciba Specialty Chemicals), 2- (3,5-di-t-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole (TIN
UVIN 327: Ciba Specialty Chemicals), 2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole (TINUVIN 32)
8: Ciba Specialty Chemicals), 2-
(2′-hydroxy-5′-t-octylphenyl) benzotriazole (TINUVIN 329: manufactured by Ciba Specialty Chemicals) and the like.

Specific examples of the triazine-based ultraviolet absorber include 2- [4-[(2-hydroxy-3-todecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6.
-Bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- [4-[(2-hydroxy-3-tridecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6- Bis (2,4-dimethylphenyl)-
1,3,5-triazine (TINUVIN 400: manufactured by Ciba Specialty Chemicals), 2- (4,6-
Diphenyl-1,3,5-triazin-2-yl) -5
-[(Hexyl) oxy] -phenol (TINUVI
N 1577: manufactured by Ciba Specialty Chemicals)
As specific examples of the oxalic acid anilide ultraviolet absorber, 2-
Specific examples of benzophenone-based ultraviolet absorbers such as ethoxy-2'-ethyl-oxalic acid bisanilide (TINUVIN 321: manufactured by Ciba Specialty Chemicals) and 2-hydroxy-4-n-octyloxybenzophenone (CHIMASSORB 81: Ciba Specialty) Chemicals Co., Ltd.) and the like, but are not limited to these. These are preferably used in an amount of about 1 to 20% by weight in the receiving layer.
-10% by weight is more preferred.

As the support of the receiving sheet, there can be used known supports such as papers such as high-quality paper, coated paper, art paper, synthetic papers, plastic films, and a laminated base material obtained by appropriately laminating these. As the laminated substrate, the surface layer of the substrate (the side on which the receiving layer is formed) is not particularly limited, but from the viewpoint of uniformity of printed image quality and gradation,
A stretched film mainly composed of polyolefin such as polyethylene and polypropylene, polyester such as polyethylene terephthalate, polyamide, polyvinyl chloride, polystyrene and the like, and a multilayer structure film mainly composed of a thermoplastic resin such as polyolefin are used.

As the core material layer of the laminated base material, a sheet having a small heat shrinkage is preferable, and a paper containing cellulose pulp as a main component, a coated paper, an art paper, a cast coated paper and at least one of a thermoplastic resin and A laminated paper or the like provided with a layer, or a film or sheet of polyester, polyamide, polyolefin, polystyrene, polycarbonate, polyvinyl alcohol, polyvinyl chloride, or the like containing a synthetic resin as a main component is used. A film of the same material as the surface layer of the base material can be appropriately used for the base material back layer (the surface on which the receiving layer is not formed) of the laminated base material.

The method for laminating the laminated substrate is not particularly limited, but known techniques such as wet lamination, extrusion lamination, dry lamination and wax lamination may be used. Used. As the dry laminating adhesive, an adhesive of a polyether type, a polyester type or the like can be used. Further, the laminated base material obtained in the present invention preferably has a thickness of 20 to 300 μm.

In the receiving sheet of the present invention, the running performance is improved, the static electricity is prevented,
A back coating layer is formed for the purpose of preventing damage to the image receiving layer due to rubbing between the receiving sheets, and further preventing transfer of dye from the receiving layer to the back side of the adjacent receiving sheet when the printed receiving sheets are stacked. May be. The back cover layer contains a resin effective as an adhesive, and this resin is also effective for preventing the running of the receiving sheet and preventing the receiving layer surface from being damaged. Such resins include acrylic resins, epoxy resins, polyester resins, phenolic resins, alkyd resins, urethane resins,
Melamine resins and the like, and reaction cured products of these resins can be used.

Various conductive agents can be added to the back cover layer for antistatic treatment. It is preferable to use a cationic polymer as the conductive agent. As the cationic polymer, generally, polyethyleneimine, an acrylic polymer containing a cationic monomer, a cation-modified acrylamide polymer, a cationic starch and the like can be used. The coating amount of the back coating layer is 0.3
It is preferably in the range of ｇ10.0 g / m ² .

Each of these coating layers can be formed by coating and drying using a coater such as a blade coater, an air knife coater, and a gate roll coater.

The receiving sheet of the present invention may be subjected to adhesive processing on the back surface thereof for use as a seal or poster, or may be provided with a magnetic recording layer on the back surface for use as a magnetic card or IC.
By laminating the chip with a support having a built-in chip, it can be used for various purposes such as an IC card.

[0032]

The present invention will be described in more detail with reference to the following examples, which, of course, are not intended to limit the scope of the present invention. In the examples, “parts” and “%” all indicate “parts by weight” and “% by weight”.

"Production of Polyester Resin" Production Example 1 (Polyester Resin A) The following mixture of a carboxylic acid component and a glycol component
A trace of tetra-n-butyl titanate is added as a catalyst and the reaction is heated in
C., and kept at this temperature for 2 hours.
At a temperature of 260 ° C. under a vacuum condition of
Unreacted glycol components were removed during the polycondensation reaction for a time to prepare a polyester resin A. (Carboxylic acid component)-1,4-cyclohexanedicarboxylic acid 85 mol%-Succinic acid 15 mol% (glycol component)-Bisphenol A ethylene oxide adduct 70 mol%-Neopentyl glycol 10 mol%-Ethylene glycol 20 mol%

Production Example 2 (Polyester Resin B) A polyester resin B was produced in the same manner as in Production Example 1 except that a mixture of the following carboxylic acid component and glycol component was used. (Carboxylic acid component) ・ 1,4-cyclohexanedicarboxylic acid 50 mol% ・ Succinic acid 50 mol% (glycol component) ・ Ethylene oxide adduct of bisphenol A 80 mol% ・ Neopentyl glycol 10 mol% ・ Ethylene glycol 10 mol%

Production Example 3 (Polyester Resin C) Polyester resin C was produced in the same manner as in Production Example 1 except that a mixture of the following carboxylic acid component and glycol component was used.
Was manufactured. (Carboxylic acid component) 55 mol% of 2,6-decahydronaphthalenedicarboxylic acid 45 mol% of succinic acid (glycol component) 25 mol% of bisphenol A 55 mol% of hydrogenated bisphenol A 55 mol% of ethylene glycol 20 mol%

Production Example 4 (Polyester Resin D) Polyester resin D was produced in the same manner as in Production Example 1 except that a mixture of the following carboxylic acid component and glycol component was used.
Was manufactured. (Carboxylic acid component) 40% by mole of terephthalic acid 60% by mole of isophthalic acid (Glycol component) 60% by mole of bisphenol A 10% by mole of neopentyl glycol 30% by mole of ethylene glycol

Example 1 A biaxially stretched polypropylene-based multilayer structure film (trade name: YUPO FPG50, manufactured by Oji Yuka Synthetic Paper) was laminated on both sides of a high-quality paper having a thickness of 100 μm by dry lamination. This was used as a substrate. Further, one of the substrates was coated with the following coating liquid for a receiving layer so that the coating amount of the solid content was 5 g / m ^2, and dried (120 ° C., 1 minute) to form a receiving layer. Created a sheet. "Coating for receiving layer" Polyester resin A (Production Example 1) 100 parts Silicone oil (trademark: KF393, manufactured by Shin-Etsu Silicone) 3 parts Isocyanate (trademark: Takenate D-140N, manufactured by Takeda Pharmaceutical Co., Ltd.) 5 parts Triphenyl phosphate 17 parts Hindered amine light stabilizer (trade name: ADK STAB LA-63, manufactured by Asahi Denka Kogyo KK: molecular weight 2000) 3 parts Toluene 300 parts

Example 2 A receiving sheet was prepared in the same manner as in Example 1 except that the polyester resin A was replaced by the polyester resin B (Production Example 2) in the formulation of the coating for the receiving layer.

Example 3 A receiving sheet was prepared in the same manner as in Example 1 except that the polyester resin A was replaced by the polyester resin C (Production Example 3) in the formulation of the coating for the receiving layer.

Comparative Example 1 A receiving sheet was prepared in the same manner as in Example 1 except that triphenyl phosphate was omitted from the coating material for the receiving layer of Example 1.

Comparative Example 2 A receiving sheet was prepared in the same manner as in Example 1 except that triphenyl phosphate was changed to adipic acid diester (trade name: K3220, manufactured by Kao Corporation) in the coating for the receiving layer in Example 1. did.

Comparative Example 3 In the coating for the receiving layer of Example 1, triphenyl phosphate was replaced with di-2-ethylhexyl phthalate (trade name: DO).
P, manufactured by Tokyo Chemical Industry Co., Ltd.), except that the receiving sheet was prepared in the same manner as in Example 1.

Comparative Example 4 Polyester resin A in the coating for the receiving layer of Example 1
Was changed to polyester resin D (Production Example 4) to prepare a receiving sheet in the same manner as in Example 1.

"Evaluation" The receiving sheets obtained in the above Examples and Comparative Examples were evaluated by the following methods, and the results are shown in Table 1.

[Evaluation of Blocking] The receiving sheet immediately after being dried at 120 ° C. after coating was coated with a high-quality paper of 100 gf / cm ^{2 on} the receiving layer surface of the receiving sheet at a temperature of 50 ° C.
After 48 hours, blocking was evaluated.

[Low-energy printing characteristics] A printing pattern in which the applied energy of a thermal transfer video printer (trade name: XLS-8400, manufactured by Kodak Co.) is adjusted and OD = 0.10 when printed on a receiving sheet attached to the video printer. It was created. This printing pattern was printed on the receiving sheets obtained in the above Examples and Comparative Examples, and the OD
Is measured. In this test, if the OD is less than 0.11, it can be said that the low-energy printing characteristics are good. Similarly, when the OD is 0.11 or more and less than 0.14, it is shown as Δ, and when the OD is 0.14 or more, it is shown as ×.

[Evaluation of Light Fastness] The obtained receiving sheet was adjusted with a thermal transfer video printer (trade name: XLS-8400, manufactured by Kodak Co.) to adjust the applied energy, and OD = 1.0.
The black solid was printed. The printed sheet was treated with a light resistance tester (trade name: Atlas Fade Meter) for 72 hours, the black solid OD after the treatment was measured, and the residual ratio of the image was calculated according to the following equation. If the residual rate in this compulsory test is 60% or more, the light resistance level is practically satisfactory. Image residual ratio (%) = OD after processing / OD before processing × 100

[0048]

[Table 1]

As shown in the examples of Table 1, when a specific polyester resin is used as the resin for the receiving layer and a phosphate compound is used in combination, the blocking, low-energy printing characteristics, light resistance, and the like can all be improved. Understand. On the other hand, in Comparative Example 1 in which the storage stability improving agent was not added to the receiving layer, blocking and low energy printing characteristics were good, but light resistance was poor. In the case of Comparative Examples 2 and 3 in which a normal ester-based plasticizer was added to the receiving layer, the light resistance was improved, but the blocking and low-energy printing characteristics were deteriorated. The polyester resin of Comparative Example 4 did not have an alicyclic dicarboxylic acid unit, and was inferior to Example 1 in image residual rate.

[0050]

According to the present invention, there is provided a receiving sheet which does not block by the heat treatment of the receiving layer in the production process, has good tone reproducibility even in printing in a low energy region, and has excellent light fastness of a recorded image. Is possible, and greatly contributes to the industry.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H111 AA01 AA09 AA16 CA03 CA12 CA30 CA33 4F100 AH08B AK07C AK41B AT00A BA02 BA03 BA07 BA10A BA10B CA05B CC00B DG10A EJ38C GB41 JD14B JN30

Claims (3)

[Claims] 1. A thermal transfer receiving sheet having a sheet-like support and a dye-receiving layer on at least one surface of the support, wherein the dye-receiving layer contains at least 40 mol% of an alicyclic dicarboxylic acid compound. And a polyester resin formed by a polycondensation reaction with a diol component containing at least 15 mol% of a diol compound having a bisphenol A skeleton as a dye-receiving resin, and further selected from phosphate ester compounds as a preservative improver. At least one
A thermal transfer receiving sheet comprising a seed. 2. The thermal transfer receiving sheet according to claim 1, wherein the phosphate compound is triphenyl phosphate. 3. The heat transfer receiving sheet according to claim 1, wherein the phosphoric acid ester compound is contained in the dye receiving layer in an amount of 1 to 30% by weight.