JPH07237365A - Thermal transfer receiver - Google Patents

Abstract

(57) [Summary] [Structure] A thermal transfer image receptor comprising a base material and a coating layer comprising a water-dispersible polymer, a corrodal silica having a shape connected and / or branched in the form of beads and a water-soluble polymer on at least one surface of the substrate. A thermal transfer image receptor characterized in that the coating layer has a smoothness of 100 seconds or more and an oil absorption of 1 ml / m ² or more. [Effect] To provide a thermal transfer image receptor having good ink absorption and excellent printing quality such as sharpness and surface gloss.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer image receptor suitable for a thermal transfer recording system. More specifically, the present invention relates to a thermal transfer image receptor suitable for a thermal transfer recording system that requires high gradation.

[0002]

2. Description of the Related Art In recent years, due to the widespread use of OA, there has been a demand for a printer excellent in printing quality such as color recording and high resolution recording. A thermal transfer printer has been put into practical use as one of the printers that meet these requirements. In particular, recently, in the melt-type thermal transfer method, a printing method has been developed in which the molten ink is partially transferred by the energy provided from the conventional method of completely transferring the melted ink and a high gradation of silver salt tone is obtained (reference: Literature NIP International Conference Oct6-II-
a1 1993.10.).

Conventionally, plain paper or printing paper has been used as an image receiver used in the thermal transfer recording system.

[0004]

However, in the thermal transfer system which requires a high gradation, it is necessary to transfer the ink amount corresponding to the applied energy to the image receiving body, which may result in poor ink transfer properties or excessive ink transfer. Ink transfer (overtransfer)
Has a problem that the sharpness of the transferred image is impaired and the reproducibility of the image is poor, which is a problem with conventional plain paper and printing paper.

Further, with the demand for high-speed recording and high resolution of printers, defects such as missing of recorded images, lack of sharpness and surface gloss have come to the fore. That is, in the case of plain paper,
There are drawbacks such that white spots are generated and the hot-melt ink to be transferred permeates in the direction of the paper fiber, the edges of the transferred image are blurred, and the density unevenness and sharpness are poor, and a sufficiently high transfer density cannot be obtained. On the other hand, since the printing paper does not have absorbency in the coating layer coated to ensure smoothness, there is no risk that the hot-melt ink will permeate into the base paper side. When recording a full-color transfer image with a second color or 3
However, there are drawbacks such that the hot-melt ink of a color is difficult to transfer and the transferred image is inferior in surface gloss. Therefore, improvement of the ink donor sheet and improvement of the apparatus have been proposed, but at present, satisfactory results have not been obtained.

The present invention is intended to provide a full-color thermal transfer image receptor, which is capable of remedying the above drawbacks and which provides an image having good dot reproducibility and transferability of ink even in high-speed recording and having excellent sharpness and gradation. .

[0007]

In order to achieve this object, a thermal transfer image receptor of the present invention comprises a water-dispersible polymer on at least one side of a substrate and a water-soluble colloidal silica in the form of beads connected and / or branched. In a thermal transfer image receptor provided with a polymer coating layer, the coating layer has a smoothness of 1
The essence is a thermal transfer image receptor characterized by having an oil absorption of 1 ml / m ² or more for 00 seconds or more.

As the substrate in the present invention, paper (fine paper), coated paper, Japanese paper, non-woven fabric or plastic film can be used, and among them, plastic film is preferable.

The plastic film in the present invention includes polyolefins such as polyethylene and polypropylene, polyesters, polycarbonates, polyvinyl chlorides, polyamides, polyesteramides, polyethers,
Polyimide, polyamide-imide, polystyrene, poly-
P-phenylene sulfide, polyether ester, poly (meth) acrylic acid ester and the like are preferable. Furthermore, these copolymers, blends, and further crosslinked products can be used. Among them, polyester, preferably polyethylene terephthalate, polyethylene 2,6-naphthalate, polyethylene α, β-bis (2-chlorophenoxy) ethane 4,4′-dicarboxylate, polybutylene terephthalate are preferable, and among these, mechanical properties, Polyethylene terephthalate and polyethylene 2,6-naphthalate are preferable in consideration of quality such as workability and economy.

The polyester used in the present invention is a well-known one, specifically, for example, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, bis-α, β (2-chlorophenoxy) ethane-4,4'-dicarboxylic acid. Polycondensation of at least one bifunctional carboxylic acid such as acid, adipic acid and sebacic acid with at least one glycol such as ethylene glycol, triethylene glycol, tetramethylene glycol, hexamethylene glycol and decamethylene glycol The polyester obtained can be mentioned. Further, the polyester may be blended or copolymerized with another type of polymer within a range that does not impair the object of the present invention, and includes an antioxidant, a heat stabilizer, a lubricant, a pigment, an ultraviolet absorber and the like. It may be. The intrinsic viscosity of the polyester (measured in 25 ° C. orthochlorophenol) is 0.4 to 2.0, preferably 0.5 to 1.
Those in the range of 0 are usually used.

The polyester film used in the present invention may be whitened by containing white inorganic particles in the polyester.

The white inorganic particles are known inorganic particles which are almost uncolored, and examples thereof include calcium carbonate, amorphous zeolite particles, anatase type titanium dioxide, calcium phosphate, barium sulfate, silica, kaolin, talc and clay. Can be mentioned. In addition to such fine particles, it is also possible to use fine particles precipitated by the reaction of a catalyst residue and a phosphorus compound in a polyester polymerization reaction system.The polyester film used in the present invention contains fine air bubbles inside the film, It is also possible to use those that are whitened by scattering light with bubbles. The formation of these fine bubbles is caused by the formation of a film base material, for example, polyester,
Incompatible polymers, such as poly-3-methylbutene-1, poly-4-methylpentene-1, polypropylene, polyvinyl-t-butane, 1,4-trans-poly-2,3-
It is formed by finely dispersing dimethyl butadiene, cellulose triacetate, cellulose tripropionate, polychlorotrifluoroethylene, or the like, or by adding the above-mentioned whitening fine particles and stretching them uniaxially or biaxially. During the stretching, voids (air bubbles) are formed around the incompatible polymer particles and the white fine particles, and these exhibit white light scattering effect. Further, since it has fine bubbles, it has a low specific gravity, has cushioning properties, and has good adhesion to the thermal recording head, so that a clear image can be obtained.

When such a bubble-containing polyester film is used, it is desirable that the apparent specific gravity of the bubble-containing polyester film is 0.4 or more and 1.3 or less, preferably 0.6 or more and 1.2 or less. When the apparent specific gravity is lower than the above range, mechanical properties and thermal dimensional stability are poor, which is not preferable.

When the polyester film is a film which has been subjected to surface treatment by a known method, that is, corona discharge treatment (in air, nitrogen, carbon dioxide, etc.) or easy adhesion treatment, adhesion to the receptor layer, It is more preferably used because it has improved water resistance and solvent resistance. For the easy-adhesion treatment, various known methods can be used, and various easy-adhesives such as acrylic, urethane, and polyester adhesives are applied in the film process, or the above-mentioned film is uniaxially or biaxially stretched. Those coated with such various types of easy-adhesives can be preferably used.

The substrate film may be a transparent film or a colored film.

The thickness of the base material is not particularly limited, but is usually 10 μm or more and 500 μm or less, preferably 20 μm or more and 300 μm or less, more preferably 30 μm or more and 250.
It is desirable that the thickness is less than μm.

The water-dispersible polymer referred to in the present invention may be an aqueous dispersion of various polymers. Specific examples thereof include acrylic polymers, ester polymers, urethane polymers, olefin polymers and vinylidene chloride polymers. Aqueous dispersions of polymers, epoxy polymers, amide polymers, and their modified products and copolymers can be used. Among these, use of acrylic polymers and urethane polymers is preferable, and acrylic polymers are particularly preferable in terms of mechanical stability of the coating film and coating strength.

The above-mentioned polymer used in the present invention is preferably dispersed in water and has a particle shape. If it does not have a particle shape, that is, a water-soluble polymer has poor water resistance. The particles are preferably those dispersed with primary particles, but they are not necessarily dispersed with primary particles.
It may contain secondary agglomerated particles.

The acrylic polymer suitable for the present invention is at least 40 mol% or more of an acrylic monomer and / or a methacrylic monomer and an ester-forming monomer thereof, an acrylic monomer having various functional groups, for example,
Acrylic acid, methacrylic acid, alkyl acrylate, alkyl methacrylate (methyl group as the alkyl group,
Ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, lauryl group, stearyl group, cyclohexyl group,
(Phenyl group, benzyl group, etc.), and hydroxy-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylamide, methacrylamide, N-methylacrylamide, N- Methylmethacrylamide, N-
Amido group-containing monomers such as methylol acrylamide, N-methylol methacrylamide, N, N-dimethylol acrylamide, N-methoxymethyl methacrylamide, N-phenyl acrylamide, N, N-diethylaminoethyl methacrylate, N, N-diethylaminoethyl It is composed of amino group-containing monomers such as acrylate, epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, and salts of acrylic acid and methacrylic acid (sodium salt, potassium salt, ammonium salt, etc.). It can also be used together. Examples of various monomers include monomers containing epoxy group-containing monomers such as allyl glycidyl ether, sulfonic acid groups such as styrenesulfonic acid, vinylsulfonic acid and their salts (sodium salt, potassium salt, ammonium salt, etc.) or salts thereof. , Monomers containing a carboxyl group such as crotonic acid, itaconic acid, maleic acid, fumaric acid, and salts thereof or salts thereof, maleic anhydride, monomers containing an acid anhydride such as itaconic anhydride, vinyl isocyanate, allyl isocyanate , Styrene, vinyl methyl ether, vinyl ethyl ether, vinyl trisalkoxysilane,
Examples thereof include alkyl maleic acid monoester, alkyl fumaric acid monoester, acrylonitrile, methacrylonitrile, alkyl itaconic acid monoester, vinyl chloride, vinyl acetate and vinylidene chloride. The above-mentioned monomers are copolymerized by using one kind or two or more kinds.

The colloidal silica mixed with the above-mentioned water-dispersible polymer is preferably the following silica because it causes ink absorption. That is, those having a long chain structure in which spherical colloidal silica is connected in a beaded shape (a shape in which a plurality of spherical colloidal silica are connected in a chain).
When the branched silica and / or the bent silica that is connected are used, a silica having a waviness structure on the surface can be obtained, which is preferable from the viewpoint of ink absorbability. The colloidal silica is obtained by connecting primary particles of spherical silica with intervening divalent or higher valent metal ions to connect the particles with each other, and at least 3 or more, preferably 5 or more, and more preferably 7 or more are connected. The term also means a thing in which particles connected in a beaded shape are branched and / or bent. Further, it may be a composite or mixed particle of colloidal silica and other inorganic particles, such as alumina, ceria, titania, etc., or may be one in which these particles are intervened and linked. 2 as the metal ion to be interposed
Valent or higher valent metal ions are preferred, such as Ca ²⁺ , Z
^Examples thereof include n ²⁺ , Mg ²⁺ , Ba ²⁺ , Al ³⁺ and Ti ⁴⁺ . Particularly when Ca ²⁺ is used, it is suitable for producing colloidal silica that is connected and branched in a beaded shape. The primary particles of colloidal silica are 5 nm to 100 nm, preferably 7 nm to 50 nm, more preferably 8 nm to 30 n.
When it is m, it is preferable in terms of ink absorbency. Further, the waviness structure is developed when the silica particles are connected and branched in a beaded shape, and the larger the number of primary particles of the connected silica is, the more preferable, but usually 3 or more and less than 100, preferably 5 Greater than or equal to 50 and more preferably 7
It is desirable that the number is not less than 30 and less than 30. When the number is 2 or less, the waviness is insufficiently expressed, and when the number is 100 or more, the silica particles connected and / or branched in a beaded shape tend to be thickened and the water dispersibility tends to deteriorate. The content of the silica particles connected and / or branched in a beaded shape in the coating layer is 3
-80 parts by weight, preferably 10-70 parts by weight, more preferably 20-60 parts by weight. If the content is less than 3 parts by weight, no waviness is exhibited and the ink absorbency tends to be delayed. If the content exceeds 80 parts by weight, defects such as a decrease in coating film strength are likely to occur.

The average particle size ratio of water-dispersible polymer / colloidal silica is 2/1 to 1000/1, preferably 5/1.
It is particularly preferable that it is from 500/1, more preferably from 10/1 to 200/1 from the viewpoint of ink absorbency. In the case of the above-mentioned colloidal silica linked in a beaded shape, the length in the minor axis direction of the linked particles observed with an electron microscope is taken as the particle diameter, and the average value of 100 measurement lengths is taken as the average particle diameter.

The water-soluble polymer referred to in the present invention means a polymer which is soluble in water at room temperature, and examples thereof include starches such as oxidized starch, etherified starch, esterified starch, dextrin, carboxymethyl cellulose and hydroxyethyl cellulose. Cellulose derivatives such as casein, gelatin,
Polyvinyl alcohol and its derivatives, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid or its esters, salts and their copolymers, vinyl polymers such as polyhydroxyethyl, methacrylate and their copolymers, and various polymers thereof. A functional group-modified polymer such as a combined carboxyl group can be preferably used, but the present invention is not limited thereto.

In the present invention, in order to further improve the recording characteristics of the coating layer, inorganic and / or organic particles may be dispersed in the coating layer. Examples of the inorganic particles include silica, clay, talc, diatomaceous earth, calcium carbonate, barium sulfate, aluminum silicate, synthetic zeolite, alumina, zinc oxide, mica and the like. As the organic particles, for example,
Plastic pigments such as polymethylmethacrylate, polystyrene, copolymers thereof, polyvinyl chloride, polyethylene, polypropylene, polyvinylidene chloride, and polycarbonate can be preferably used, but not limited thereto.

In the present invention, the thickness of the coating layer is not particularly limited, but is usually 1 to 50 μm, preferably 3 to 40 μm, more preferably 5 to 30 μm. If the thickness is too thin, the ability to absorb ink or the like will be insufficient, and if it is too thick, the strength of the coating film will tend to be insufficient.

In the present invention, when used as a thermal transfer image receptor, it is preferable to impart an antistatic function from the viewpoint of adhesion of dust due to static electricity and running property. In order to impart antistatic properties, it is desirable to provide a receptive layer on one surface of the substrate and an antistatic layer on the other surface, or to add an antistatic agent to the receptive layer.

The antistatic layer in the present invention is a coating layer made of an antistatic agent, a resin layer containing an antistatic agent, a vapor deposition layer made of a metal or a metal oxide, etc. Examples include certain surfactants, conductive polymers, conductive carbon fine particles, metal or metal oxide fine particles, and the like. As for the antistatic property, the surface resistance value of the receiving layer is 5 × 10 ¹³
It is preferably Ω / □ or less. More preferably 5 ×
It is 10 ¹² Ω / □ or less. The surface resistance value of the antistatic layer on the side opposite to the receiving layer is preferably 10 ⁵ to 10 ¹³ Ω / □.

In the present invention, inorganic / and / or organic particles may be dispersed in order to enhance the recording characteristics of the receiving layer. Examples of the inorganic particles include silica, clay,
Talc, diatomaceous earth, calcium carbonate, barium sulfate,
Aluminum silicate, synthetic zeolite, alumina, zinc oxide,
Examples include mica. Examples of organic particles include polymethylmethacrylate, polystyrene, copolymers thereof, polyvinyl chloride, polyethylene, polypropylene,
Plastic pigments such as polyvinylidene chloride and polycarbonate can be preferably used, but not limited thereto.

In the receptive layer of the thermal transfer image receptor of the present invention, known additives such as defoaming agents, coating improvers, thickeners, antistatic agents, and antioxidants are used within the range not impairing the characteristics of the present invention. , An anti-UV agent, a dye, etc. may be contained.

The method of applying the coating layer is not particularly limited,
Gravure coat method, reverse coat method, kiss coat method,
Known methods such as a die coating method and a bar coating method can be applied. At this time, by applying a known surface treatment such as corona discharge treatment or primer treatment in air or other atmosphere on the film as needed before coating, not only the coating property is improved but also the coating is performed. The layer can be more firmly formed on the film surface. The coating agent concentration and the coating film drying conditions are not particularly limited, but it is desirable that the coating film drying conditions be performed within a range that does not adversely affect various characteristics of the substrate.

The thermal transfer image receptor thus obtained is very excellent in absorbing ink and the like, has good ink transfer property and sharpness, and has excellent coating film strength, and thus can be suitably used as a thermal transfer image receptor.

[0031]

[Measurement Method of Physical Properties] First, the measurement method of various characteristics in the present invention will be described.

(1) Smoothness Oken type air permeability smoothness tester (model KB1 manufactured by Asahi Seiko Co., Ltd.)
It was measured in 5). The average value of n = 5 is shown.

(2) Printability Printing was performed with a bar code printer (MKII BC-8 manufactured by Autonics) using a commercially available wax ink ribbon.

(3) Clearness of Transfer Surface The surface of the printed surface printed by the above method was visually judged, and the presence or absence of transfer omission (portion where ink was not transferred) and the surface gloss were judged according to the following criteria.

⊚: No transfer bleeding is observed and the surface glossiness is excellent. ◯: No transfer bleeding, but the surface gloss is slightly lowered. Δ: 1-5 transfer bleeds / 10 cm ² which can be visually determined.
Existence, and surface gloss is considerably reduced. X: There are innumerable transfer gaps and surface gloss is poor.

(4) Gradation property Color Point 2 (high-definition printer manufactured by Seiko Denshi Kogyo Co., Ltd.) is used to attach 8 gradations software (PALMIX)
A printing test was conducted at. The thermal transfer ink ribbon is dedicated CH737 (4 colors, Seiko Eye Supply Co., Ltd.)
Manufactured) was used.

◯: 5 gradations or more can be reproduced Δ: 3 gradations or more can be reproduced ×: No gradation

(5) Oil absorption amount The initial weight of a sample of 10 × 10 cm ² was W ₀ , a sufficient amount of oleic acid was permeated into the surface of the receiving layer, and the weight after completely wiping off excess oleic acid was W. Then, the oil absorption Q (ml / m ² ) is calculated by the following formula.

Q = [(W−W ₀ ) /0.866] × 100 where 0.866 is the specific gravity of oleic acid.

(6) Water resistance of coating layer: Water was applied to a cotton swab and the coating layer was slightly rubbed for evaluation.

⊚: Good (does not dissolve up to 10 times) ◯: Good (dissolves after rubbing 5 to 10 times) ×: Poor (dissolves after less than 5 times)

(7) Adhesion of coating layer The adhesion of the substrate / coating layer is determined by cross-cutting (1
00 / cm ² ) and put 4 on the cross-cut surface
"Cellotape" (T-24 manufactured by Nichiban Co., Ltd.) was attached at 5 °, and a hand roller was used to apply a load of about 45 kg to 10
The cellophane tape was forcedly peeled in the direction of 180 ° by reciprocating back and forth, and the degree of peeling of the coating layer was observed and evaluated.

⊚: Very good (no peeling) ○: Good (peeling area less than 5%) Δ: Slightly inferior (peeling area 5% or more and less than 20%) ×: Poor (peeling area 20% or more)

(8) Specific gravity The film was cut into 100 × 100 mm squares, and a dial gauge (No. 2109-10, manufactured by Mitoyo Seisakusho) was used to measure a diameter of 10 m.
The thickness of a minimum of 10 points is measured with the one to which the m measuring element (No. 7002) is attached, and the average value d (μm) of the thickness is calculated. In addition, this film is weighed with a direct balance and the weight w (g) is read to the unit of 10 ⁻⁴ g. This time,
The specific gravity was calculated by the following formula.

Specific gravity = (w / d) × 100

[0046]

EXAMPLES Next, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

Example 1 Polyethylene terephthalate homopolymer chips produced by a conventional method (intrinsic viscosity: 0.62, melting point: 25)
9 ° C) and 188 μm by a conventional method, specific gravity 1.4
A transparent biaxially stretched polyester film of 0 was obtained. Corona discharge treatment was performed on the polyester film thus obtained. Next, an acrylic polymer emulsion having an average particle diameter of 0.2 μm (methyl methacrylate /
50 parts by weight of ethyl acrylate / acrylic acid = 60/35/5% by weight copolymer) (solid content) and 50 parts by weight of branched beaded colloidal silica (Nissan Chemical's "Snowtex" UP average particle diameter 0.015 μm). (Solid content) was diluted with water to 30% by weight, and 100% by weight of a 10% aqueous solution of polyvinyl alcohol (B-17S manufactured by Denki Kagaku Kogyo Co., Ltd.) was added at a solid content ratio of the above polyester. The film was applied on one side of the film by a metalling bar method so that the dry film thickness was 20 g / m ² , to obtain a thermal transfer image receptor of the present invention. The characteristics of the thermal transfer image receptor thus obtained are as shown in Table 1 and were extremely fast in ink absorption, and were excellent in sharpness, bleeding and water resistance.

Example 2 Polyethylene 2,6-naphthalate homopolymer chip produced by a conventional method (intrinsic viscosity [η] = 0.7)
After being sufficiently vacuum dried, it is supplied to an extruder, melt-extruded at 295 ° C., filtered through a 10 μm-cut metal sintered filter, and then extruded into a sheet from a T-shaped die, which is then placed on a cooling drum having a surface temperature of 50 ° C. It was wrapped and cooled and solidified. In order to improve the adhesion between the sheet and the surface of the cooling drum during this period, a wire electrode was arranged on the sheet side and a DC voltage of 6000 V was applied. The thus-obtained unstretched polyethylene 2,6-naphthalate film was stretched 4.5 times in the longitudinal direction by a roll group heated to 120 ° C. and cooled to 25 ° C. to obtain a uniaxially stretched film.

Further, the stretched film was introduced into a tenter, stretched 4.3 times in the width direction in an atmosphere kept at 125 ° C., heat-set at 225 ° C., and biaxial with a thickness of 75 μm and a specific gravity of 1.35. A stretched film was obtained. The film thus obtained was subjected to corona discharge treatment, and a thermal transfer image receptor was obtained on the treated surface in the same manner as in Example 1.

The characteristics of this thermal transfer image receptor are shown in Table 1.
As is clear from Table 1, the characteristics were excellent in dot reproducibility and ink transferability, and were excellent in sharpness and gradation, and were excellent as a thermal transfer image receptor.

Furthermore, since a biaxially stretched polyethylene 2,6-naphthalate film was used as the substrate, it was found that the flatness of the printed portion was not deteriorated due to heat absorption and the heat resistance was excellent. .

Example 3 Polyethylene terephthalate chips and molecular weight 40
The master chip to which polyethylene glycol of 00 was added at the time of polymerization of polyethylene terephthalate was vacuum dried at 180 ° C., and then mixed so as to be 89% by weight of polyethylene terephthalate, 1% by weight of polyethylene glycol, and 10% by weight of polymethylpentene, and then mixed at 270 to 270. 300
Feed to extruder B heated to ° C. Further, after drying polyethylene terephthalate containing 10% by weight of calcium carbonate having an average particle diameter of 1.0 μm as described above,
Supply to extruder A. Polymers extruded from extruders A and B are laminated so as to have a three-layer structure of A / B / A, and T
Molded into a sheet from a die. Further, the unstretched film obtained by cooling and solidifying this film with a cooling drum having a surface temperature of 25 ° C. was guided to a roll group heated to 85 to 95 ° C., stretched 3.4 times in the longitudinal direction, and cooled by a roll group of 25 ° C. Subsequently, the longitudinally stretched film was guided to a tenter while holding both ends with clips, and stretched 3.6 times in the direction perpendicular to the longitudinal direction in an atmosphere heated to 130 ° C. After that, heat setting was carried out at 230 ° C. in a tenter, and after uniform slow cooling, it was cooled to room temperature and wound up to obtain a white film having a thickness of 188 μm and a specific gravity of 1.0. The laminated constitution of the film is 9/170/9.
was μm. On the polyester film obtained by the above method, 10 parts by weight of silica particles (“Fineseal” 3.5 μm manufactured by Tokuyama Soda Co., Ltd.) and styrene particles (Mitsui Toatsu Co., Ltd.) were added to the coating material of Example 1. A thermal transfer image receptor of the present invention was obtained in the same manner except that 10 parts by weight of "Muticle" (manufactured by "Muticle") was added. The coated surface of the PET film was one that had been subjected to corona discharge treatment in air. The characteristics of this thermal transfer image receptor are shown in Table 1. As is clear from Table 1, the characteristics are such that the absorption speed of ink or the like is extremely high, and the characteristics are excellent in sharpness, bleeding, and water resistance.
The coating film strength was also sufficient, and it showed excellent properties as a thermal transfer image receptor.

Example 4 Polyethylene 2,6-naphthalate (Intrinsic viscosity [η] =
0.7) 94% by weight, poly-4-methylpentene-1
(TPI-D820 manufactured by Mitsui Petrochemical Co., Ltd.) 5% by weight, polyethylene glycol having a molecular weight of 4000 1% by weight
The raw material that has been pelletized in advance at a ratio of
It was melted at 295 ° C. by a conventional method and introduced into the center of the T-die three-layer die.

On the other hand, 86% by weight of the above-mentioned polyethylene 2,6-naphthalate was added to calcium carbonate (average particle size 0.8 μm).
The raw material added with 14% by weight of m) was supplied to the extruder B, melted at 295 ° C. by a conventional method and laminated on both surface layers of the T-die three-layer die, and the melt sheet was kept at a surface temperature of 25 ° C. On the cooling drum, it was contact-cooled and solidified by the electrostatic charge method. Then, the cast sheet was subjected to a conventional method at 120 ° C. in the longitudinal direction.
It is stretched 3.5 times using a group of rolls heated to
Cooled to ° C. Further, the stretched film was introduced into a tenter, stretched 3.2 times in the width direction in an atmosphere heated to 125 ° C., and heat-set at 225 ° C. to obtain a biaxially stretched film having a thickness of 100 μm and a specific gravity of 1.0. Obtained. The thickness of each film layer was 6 μm on the surface layer and 88 μm on the central layer.

The film thus obtained was subjected to corona discharge treatment, and a thermal transfer image receptor was obtained on the treated surface in the same manner as in Example 3.

The characteristics of this thermal transfer image receptor are shown in Table 1.
As is clear from Table 1, the characteristics were excellent in dot reproducibility and ink transferability, and were excellent in sharpness and gradation, and were excellent as a thermal transfer image receptor.

Furthermore, since a biaxially stretched polyethylene 2,6-naphthalate film was used as the substrate, it was found that the flatness of the printed portion was not deteriorated due to heat absorption and the heat resistance was excellent. .

Comparative Example 1 A thermal transfer image receptor was prepared in the same manner as in Example 1 except that silica particles having an average particle size of 7.0 μm (for example, “Syloid” manufactured by Fuji Devison Co., Ltd.) were used in place of the colloidal silica. However, the smoothness was 55 seconds, the surface of the coating layer was rough, and the sharpness of the printed image and the surface gloss were inferior.

Comparative Example 2 A coating composition comprising the composition of Example 1 excluding the acrylic polymer emulsion and the branched beaded colloidal silica was prepared, and a thermal transfer image receptor was obtained in the same manner as in Example 1 below. As shown in Table 1, this thermal transfer image receptor was inferior in adhesion and water resistance.

[0060]

[Table 1]

[0061]

INDUSTRIAL APPLICABILITY The present invention provides a laminated film having an ink-receptive coating layer provided on at least one surface of a substrate, which has good thermal transfer printability by applying a specific coating layer.
In addition, a thermal transfer image receptor having good ink absorbability and excellent sharpness and surface gloss is obtained.

Since the thermal transfer image receptor of the present invention thus obtained has excellent properties, other inks and toner receptors such as sublimation type thermal ink receptor, electrophotographic toner receptor, fabric ribbon ink receptor and the like. Also, since the coating layer is transparent, it can be applied to OHP applications.

Claims (6)

[Claims] 1. A thermal transfer image receptor comprising a substrate and at least one surface thereof provided with a coating layer comprising a water-dispersible polymer, corrodal silica in the form of beads connected and / or branched, and a water-soluble polymer. Has a smoothness of 100 seconds or more and an oil absorption of 1 ml / m ² or more. 2. The thermal transfer image receptor according to claim 1, wherein the substrate is a polyester film. 3. The thermal transfer image receptor according to claim 1, wherein the substrate is a white polyester film. 4. The thermal transfer image receptor according to claim 3, wherein the substrate is a white polyester film having an apparent specific gravity of 0.4 or more and 1.3 or less. 5. The thermal transfer image receptor according to claim 1, wherein the substrate has a receiving layer on one surface and an antistatic layer on the other surface. 6. The thermal transfer image receptor according to claim 1, wherein the base material is polyethylene 2,6-naphthalate.