JPH07246782A - Thermal transfer image receiving material - Google Patents

Abstract

PURPOSE:To provide a thermal transfer image receiving material good in ink absorbability at the time of high speed recording and forming an image good in sharpness and surface gloss by coating at least the single surface of a base material with a recording layer based on colloidal silica connected and/or branched in a rosary shape and a water-soluble polymer. CONSTITUTION:At least the single surface of a base material is coated with a recording layer based on colloidal silica connected and/or branched in a rosary shape and a water-soluble polymer. The pH of colloidal silica is made acidic and, as the water-soluble polymer, polyvinyl alcohol with a saponification value of 70mol% or more and a polymerization degree of 1000-3000 is used and, as the base material, a polyester film, especially, a white polyester film with apparent specific gravity of 0.5-1.3 is used. By this constitution, a thermal transfer image receiving material having good thermal transfer printing properties, good in ink absorbability and excellent in sharpness and surface gloss is obtained.

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.

[0002]

2. Description of the Related Art In recent years, with the spread of OA, color recording,
A printer excellent in print quality such as high resolution recording is required. A thermal transfer printer has been put into practical use as one of printers that meet these requirements. Conventionally, plain paper, printing paper, etc. have been used as an image receiver used in the thermal transfer recording system.

[0003]

However, with the demand for high-speed recording and high resolution of printers, defects such as missing of recorded images and lack of sharpness and surface gloss have come to the fore. That is, in the case of plain paper, the occurrence of white spots and the heat-melt ink that is 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. There is. 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 a full-color transfer image is recorded by using a full-color transfer image, the second and third colors of the hot-melt ink are difficult to transfer, and the transferred image has inferior 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 has improved these drawbacks and provides a thermal transfer image receptor capable of obtaining an image having good ink absorbability and good sharpness and surface gloss even at high speed recording.

[0005]

A thermal transfer image receptor of the present invention for this purpose comprises, as a main component, at least one surface of a base material, a colloidal silica having a bead-shaped connection and / or branching shape and a water-soluble polymer. The recording layer is coated with the recording layer.

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.

Materials for the plastic film include polyester, polyolefin, polyamide, polyesteramide, polyether, polyimide, polyamideimide, polystyrene, polycarbonate, poly-ρ-phenylene sulfide, polyetherester, polyvinyl chloride, poly (meth). Acrylic acid esters are preferred. Moreover, these copolymers, blends, and further crosslinked products can be used.

Further, among the above plastic films, polyester such as polyethylene terephthalate,
Polyethylene 2,6-naphthalate, polyethylene α,
β-bis (2-chlorophenoxy) ethane 4,4′-dicarboxylate, polybutylene terephthalate, etc., among them, mechanical properties, workability and other qualities,
Considering economical efficiency and the like, polyethylene terephthalate is preferable. The polyester in the present invention is a well-known one, for example, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, bis-α, β.
At least one bifunctional carboxylic acid such as (2-chlorophenoxy) ethane 4,4′-dicarboxylic acid, adipic acid, and sebacic acid, and ethylene glycol, triethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol. Polyester obtained by polycondensing at least one kind of glycol such as Further, the polyester may be blended with or copolymerized with various polymers within a range not impairing the object of the present invention, and may include 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 ortho-chlorophenol at 25 ° C.) is usually preferably 0.4 to 2.0, more preferably 0.5 to 1.0.

As the polyester film used in the present invention, it is possible to use a film in which fine bubbles are contained in the film, and the bubbles are whitened by scattering light. The formation of these fine air bubbles results in the formation of incompatible polymers, such as poly-3-methylbutene-1, poly-4-methylpentene-1, polypropylene, polyvinyl-t-butane, in the film matrix, for example polyester.
It is formed by finely dispersing 1,4-trans-poly-2,3-dimethylbutadiene, cellulose triacetate, cellulose tripropionate, polychlorotrifluoroethylene, etc., and stretching it uniaxially or biaxially. During stretching, voids (air bubbles) are formed around the incompatible polymer particles, and these exhibit white light scattering effect. In addition, since it has fine bubbles, it has a low specific gravity, has cushioning properties, and has good adhesion to the thermal transfer image receptor 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 0.5 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.

Further, in the present invention, it is also possible to use a combination of fine particles such as calcium carbonate, amorphous zeolite particles, anatase type titanium dioxide, calcium phosphate, silica, kaolin, talc and clay in polyester. In addition to such fine particles, fine particles precipitated by the reaction of the catalyst residue and the phosphorus compound in the polyester polymerization reaction system may be used in combination.

In the case where the polyester film is subjected to surface treatment by a known method, that is, corona discharge treatment (in air, nitrogen, carbon dioxide gas, etc.) or easy adhesion treatment, the 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 adhesives such as acrylic, urethane, and polyester adhesives are applied in the film manufacturing process, or the above-mentioned film is uniaxially or biaxially stretched. Those coated with such various adhesives can be preferably used.

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

The thickness of this substrate is not particularly limited, but is usually preferably 10 μm or more and 500 μm or less, more preferably 20 μm or more and 300 μm or less, and more preferably 30.
It is desirable that the thickness is at least μm and at most 250 μm.

The colloidal silica used in the present invention is
It has a beaded and / or branched shape, and specific examples thereof include those having a long chain structure in which spherical colloidal silica is connected in a bead shape, and those in which the connected colloidal silica is branched. You can The colloidal silica is obtained by binding primary particles of spherical silica with a metal ion having a valence of 2 or more intervening between the particles, preferably at least 3 or more, more preferably 5 or more.
More than 7 pieces, more preferably 7 pieces or more,
Further, a particle in which beads connected in a bead shape are branched is also included.

In addition, colloidal silica and other inorganic particles,
For example, it may be a composite or mixed particle of alumina, ceria, titania, etc., or may be one in which these particles are interposed and linked. The intervening metal ion is preferably a divalent or higher valent metal ion, for example, Ca ²⁺ , Zn ²⁺ , M
g ²⁺ , Ba ²⁺ , Al ³⁺ , Ti ⁴⁺ and the like. Especially Ca ²⁺
In such a case, it is suitable for producing a colloidal silica which is connected and / or branched in a beaded shape.

The primary particle size of colloidal silica is 5
To 100 nm is preferable, and 7 to 50 n is more preferable.
m, more preferably 8 to 30 nm is preferable in terms of increasing the ink absorbency of the recording layer.

Further, the ink absorbency of the recording layer is increased when the colloidal silica particles are connected and / or branched in a beaded shape. The larger the number of primary particles of the connected colloidal silica, the more preferable. 100 is preferable, 5 to 50 is more preferable, and 7 is more preferable.
Selected from the range of up to 30. When the number is less than 3, the ink absorbency is insufficiently expressed, and when the number is more than 100, the colloidal silica particles tend to thicken and the water dispersibility deteriorates, which is not preferable.

The pH of the colloidal silica in the present invention is preferably acidic, preferably 2 to 6, and more preferably 2 to 4. When it exceeds this range, the viscosity of the coating solution tends to increase when mixed with a water-soluble polymer, and the workability is deteriorated, which is not preferable.

The water-soluble polymer in the present invention refers to a polymer that is soluble in water at room temperature, and examples thereof include starches such as oxidized starch, etherified starch and dextrin, and cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose. Casein, gelatin, polyvinyl alcohol and derivatives thereof, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid or esters thereof, salts and copolymers thereof, polyethers such as polyethylene glycol and polypropylene glycol or esters thereof, ethers and copolymers thereof. Examples thereof include polymers, vinyl polymers such as polyhydroxyethyl methacrylate and copolymers thereof, and functional group-modified polymers such as carboxyl groups of these various polymers.

The water-soluble polymer preferably used in the present invention is polyvinyl alcohol and its derivatives, and the degree of saponification of vinyl acetate units is usually 70 mol% or more, preferably 80 mol% or more.

The degree of polymerization of polyvinyl alcohol is usually 1000 to 3000, preferably 1500 to 2500.
Those in the range of are used.

The colloidal silica and the water-soluble polymer have a weight ratio of colloidal silica / water-soluble polymer of 1/1 to 10 /.
1 is preferable, further preferably 2/1 to 8/1, and more preferably 3/1 to 5/1. When the colloidal silica / water-soluble polymer is less than 1/1, the water resistance of the recording layer formed is poor, and when it exceeds 10/1, the strength of the recording layer formed is lowered, and the coating property is further deteriorated. However, it is difficult to form a uniform layer, which is not preferable.

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

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

The coating thickness of the recording layer is not particularly limited,
1 to 50 μm is preferable, and more preferably 3 to 30 μm
Is. When it is thinner than this range, the ink absorbency is poor, and when it is thicker than this range, the strength of the recording layer is lowered and the workability is deteriorated, which is not preferable.

In the present invention, the runnability of the thermal transfer image receptor,
An antistatic agent may be applied to the surface opposite to the recording layer or a coating material containing inorganic or organic fine particles may be applied in order to improve the double running property.

The coating method of the recording 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, if the coating property is only improved by applying a known surface treatment such as a corona discharge treatment in air or other atmosphere or a primer treatment on the substrate as needed before coating. Therefore, the recording layer can be more firmly formed on the substrate. 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 extremely excellent in absorbing ink and the like, has good ink transfer property and sharpness, and has excellent coating film strength, and can be suitably used as a thermal transfer image receptor.

[0030]

[Characteristic Evaluation Method] First, various characteristic evaluation methods in the present invention will be described.

(1) Printability A commercially available wax-based ink ribbon was used for printing with a bar code printer (MKII BC-8 manufactured by Autonics).

(2) Clearness of Transfer Surface The surface of the printed surface printed by the method of (1) 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.

⊚: Transfer blemishes are not observed and surface glossiness is excellent. ◯: No transfer blemishes, but surface gloss is slightly reduced. Δ: 1-5 transfer blemishes / 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.

(2) Water resistance of recording layer: Water was applied to a cotton swab and the recording layer was lightly rubbed for evaluation.

⊚: Very good (no loss of recording area even after rubbing 50 times) ○: Good (loss of recording area after rubbing 30 times or more but less than 50 times) △: Slightly inferior (10 times or more but less than 30 times) Then, the recording part falls off. ×: Bad (falls off less than 10 times)

(3) Adhesion of recording layer The adhesion of the substrate / recording layer is determined by cross-cutting (1
00 pieces / cm ² ) and put 4 on the cross-cut surface.
"Cellotape" (CT-24 manufactured by Nichiban Co., Ltd.) is attached at 5 °, and is reciprocated 10 times with a load of about 45 kg using a hand roller to forcibly peel off "Cellotape" in the 180 ° direction and peel off the recording layer. The degree 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)

(4) 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 obtain a diameter of 10 m.
The thickness of at least 10 points was measured using the one to which the stylus of m (No. 7002) was attached, and the average value of the thickness d (μm)
To calculate. In addition, this film is weighed with a direct balance,
The weight w (g) was read to the unit of 10 ⁻⁴ g and determined by the following formula.

Specific gravity = (w / d) × 100

(5) pH pH meter (manufactured by HORIBA, pH METE
It was measured using R F-14).

[0041]

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.), a biaxially stretched polyester film having a thickness of 100 μm and a specific gravity of 1.4 was obtained by a conventional method. Corona discharge treatment was performed on the polyester film thus obtained. Next, a coating composition having the following coating composition was used as a recording layer on the surface treated with corona discharge, and the coating was dried by a gravure coater so that the thickness after drying was 10 μm, 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 the ink absorption rate was extremely fast, and the sharpness, bleeding and water resistance were excellent.

[Coating composition] Polyvinyl alcohol (PVA-H-24 manufactured by Denki Kagaku Co., Ltd., saponification degree: 95.5)
%, Degree of polymerization 2400) and acidic beaded colloidal silica (“Snowtex” OUP pH manufactured by Nissan Chemical Industries, Ltd.)
2.9) is dissolved in water so that the solid content ratio becomes 1/5,
A paint having a solid content of 15% was used.

Example 2 In Example 1, polyvinyl alcohol (Kuraray Co., Ltd.)
PVA-CM318 manufactured by PVA-CM318 A thermal transfer image receptor of the present invention was obtained in the same manner except that a saponification degree of 88.0% and a polymerization degree of 1800) were used. The characteristics of the thermal transfer image receptor thus obtained are as shown in Table 1, and the ink absorption rate was extremely fast, and the sharpness, bleeding and water resistance were excellent.

Example 3 A thermal transfer image receptor of the present invention was obtained in the same manner as in Example 1 except that polyvinyl alcohol (PVA-W-24 manufactured by Denki Kagaku KK, saponification degree: 78.0%, polymerization degree: 2400) was used. It was The characteristics of the thermal transfer image receptor thus obtained are as shown in Table 1, which shows that the ink absorption rate is extremely high.
The sharpness, bleeding and water resistance were also excellent.

Example 4 In Example 1, the coating composition was polyvinyl alcohol (PVA-K-24E manufactured by Denki Kagaku Co., Ltd., saponification degree: 9).
8.0%, degree of polymerization 2400) and acidic beaded colloidal silica (“Snowtex” OUP p manufactured by Nissan Chemical Industries, Ltd.)
A thermal transfer image receptor of the present invention was obtained in the same manner except that a solvent dissolved in a water-isopropyl alcohol solvent was used so that H2.9) became 1/5 in solid content ratio. The characteristics of the thermal transfer image receptor thus obtained are as shown in Table 1, and the ink absorption rate was extremely fast, and the sharpness, bleeding and water resistance were excellent.

Example 5 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 the extruders A and B were laminated so as to have a three-layer structure of A / B / A, and formed into a sheet from a T die.

Further, an unstretched film obtained by cooling and solidifying this film with a cooling drum having a surface temperature of 25 ° C. is 85 to 95 ° C.
The film was guided to a roll group heated to 1, was stretched 3.4 times in the longitudinal direction, and was cooled by a roll group at 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 at 230 ℃ in the tenter, after uniform cooling, cooled to room temperature and wound,
A white film having a thickness of 100 μm and a specific gravity of 1.0 was obtained. The laminated constitution of the film was 5/90/5 μm. A thermal transfer image receptor of the present invention was similarly obtained by using the coating material of Example 4 on the polyester film obtained by the above method. The characteristics of the thermal transfer image receptor thus obtained are as shown in Table 1, and the ink transfer rate is extremely fast, the sharpness, bleeding and water resistance are excellent, and the coating strength is sufficient. It showed excellent characteristics as an image receptor.

Example 6 In Example 1, polyethylene glycol (molecular weight 3
00) and acidic beaded colloidal silica (Nissan Chemical Co., Ltd.)
A thermal transfer image receptor of the present invention was obtained in the same manner, except that "Snowtex" OUP pH 2.9 manufactured by SNOWTEX Co., Ltd. was used in a solid content ratio of 1/4. The characteristics of the thermal transfer image receptor thus obtained are as shown in Table 1, and the ink absorption rate was extremely fast, and the sharpness, bleeding and water resistance were excellent.

Comparative Example 1 A thermal transfer image receptor was obtained in the same manner as in Example 1 except that the acidic beaded colloidal silica (“Snowtex” OUP pH 2.9 manufactured by Nissan Chemical Industries, Ltd.) was not used. The characteristics of the thermal transfer image receptor are as shown in Table 1, and the water resistance and adhesion of the recording layer were inferior.

Comparative Example 2 In Example 4, acidic beaded colloidal silica (“Snowtex” OUP pH 2.9 manufactured by Nissan Chemical Industries, Ltd.)
A thermal transfer image receptor was obtained in the same manner except that spherical colloidal silica (“Snowtex” 20 pH 9.5 manufactured by Nissan Chemical Industries, Ltd.) was used instead of. The characteristics of the thermal transfer image receptor are as shown in Table 1 and were inferior in printability and inferior in film forming ability.

[0052]

[Table 1]

[0053]

INDUSTRIAL APPLICABILITY According to the present invention, a laminated film having an ink-receptive recording layer provided on at least one surface of a substrate has good thermal transfer printability and ink absorbability by applying and coating a specific recording layer. The obtained thermal transfer image receptor is excellent and has excellent sharpness and surface gloss. Since the thermal transfer image receptor of the present invention thus obtained has excellent properties, it can be applied as other inks or toner receptors such as thermal ink receptor including sublimation type, electrophotographic toner receptor, fabric ink receptor and the like. You can Furthermore, the recording sheet of the present invention can be preferably used in recording sheets for inkjet printers, offset printing, flexographic printing and the like by utilizing its excellent ink absorbency, and since the recording layer is transparent, it is suitable for OHP applications. Can also be applied.

Claims (6)

[Claims] 1. A thermal transfer image receptor characterized in that at least one surface of a substrate is coated with a recording layer containing colloidal silica in the form of beads connected and / or branched and a water-soluble polymer as a main component. . 2. The thermal transfer image receptor according to claim 1, wherein the colloidal silica has an acidic pH. 3. The thermal transfer image receptor according to claim 1, wherein the water-soluble polymer is polyvinyl alcohol. 4. The thermal transfer image receptor according to claim 1, wherein the polyvinyl alcohol has a saponification degree of 70 mol% or more and a polymerization degree of 1000 to 3000. 5. The thermal transfer image receptor according to claim 1, wherein the substrate is a polyester film. 6. The thermal transfer image receptor according to claim 1, wherein the substrate is a white polyester film having an apparent specific gravity of 0.5 or more and 1.3 or less.