JPH11180050A - Thermal-transfer receiving sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal-transfer receiving sheet by which a clear recorded image can be obtained, and also, wherein a printing curl is small, and in addition, there is no trouble in a paper discharging. SOLUTION: For this thermal-transfer receiving sheet having a sheet-like supporting body and a receiving layer which is formed on one surface of the sheet-like supporting body, and contains a dye-dyeing resin as the major component, the sheet-like supporting body is a drawn film of which the major component is polyethylenenaphthalate. The thickness of the polyethylenenaphthalate drawn film is preferable to be 20-300 μm. When the thickness is less than 20 μm, the mechanical strength becomes insufficient, and the hardness and the repulsion for deformation, of the receiving sheet becomes insufficient, and there may be a case wherein a curl which arises at the time of printing cannot be sufficiently prevented from arising. Also, when the thickness exceeds 300 μm, the thickness of the obtained receiving sheet becomes too large.

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 (hereinafter simply referred to as a receiving sheet).
More specifically, when the present invention is used in a thermal printer, especially a dye thermal transfer printer, a clear recorded image can be obtained, and the print curl (curl after printing) is small, and furthermore, there is no problem of paper ejection trouble. It is about a sheet.

[0002]

2. Description of the Related Art In recent years, the development of a color hard copy of a thermal transfer system, in particular, a sublimation type thermal transfer printer has been developed.
In a sublimation type thermal transfer printer, an ink sheet containing a sublimable dye layer of three colors (yellow, magenta, cyan) or four colors (yellow, magenta, cyan, black) is used.
By sequentially heating with a thermal head and controlling the transfer amount of each color dye, it is possible to transfer and form a full-color image excellent in density gradation. Such a thermal transfer printer is used for printing images taken by a television image or a video camera on, for example, a postcard-type receiving sheet or a sticker-type receiving sheet. It is also rapidly spreading at home. The receiving sheet used in such a thermal transfer printer is required to be capable of receiving a high-quality recorded image and to be capable of printing without any trouble.

[0003] Generally, a receiving sheet is made of a thermoplastic resin such as polyolefin because it has low thermal conductivity, uniform thickness, flexibility, and uniform and high-density printed images as compared with paper and the like. In general, a biaxially stretched film mainly composed of a resin is used as a substrate, and an image receiving layer mainly composed of a thermoplastic resin is provided on the substrate. However, when thermally transferred to a receiving sheet using a stretched film of polyolefin or the like as a base material, high heat is applied by a thermal head at the time of printing, so that the receiving sheet is thermally deformed, and the curl generated causes a paper ejection error.

[0004] In order to solve such problems, there is an attempt to prevent print curl by laminating and bonding substrates having different heat shrinkage rates. In other words, balance the heat shrinkage by combining and laminating a substrate with a small heat shrinkage ratio on the print surface side where high heat is applied and a base material with a relatively large heat shrinkage ratio on the non-print surface side where heat is low. This is to prevent print curl. However, forming a sheet-like support by laminating and bonding several layers of different base materials in this way complicates the processing step, increases the production cost, and is not always a method with good reproducibility. . Especially in the dye thermal transfer type full color printer,
The demand for improved image quality is strict, and the thermal energy to be added is also increased with the increase in the dot density of thermal heads.Therefore, there is a demand for the development of a receiving sheet with excellent thermal stability, but this has not yet been sufficiently achieved. That is the fact.

[0005] In addition to the above-described print curl, there is a print curl that causes a paper discharge trouble. Most of the receiving sheets are sheet-fed sheets.However, in order for the receiving sheets to be fed, printed, and discharged without trouble, the coefficient of friction between the receiving sheets, the coefficient of friction between the receiving sheets and the conveying rolls, The thickness, stiffness, dimensional stability, curl and the like of the sheet become problems. Among them, the curl of the receiving sheet is a major cause of paper feed and paper discharge problems. If the blank sheet curl of the receiving sheet is large, the sheet is caught by a pickup roller for feeding paper or a roll or guide inside the printer, and misfeeding or jamming occurs. Further, even when the blank curl is flat, misfeed may occur.

[0006]

SUMMARY OF THE INVENTION The present invention, when used in a thermal printer for thermal transfer, accepts an image forming dye such as a sublimation dye transferred by heat, has a small print curl, and has a paper discharge trouble after printing. The object of the present invention is to provide a receiving sheet which has no image and has a clear recorded image.

[0007]

Means for Solving the Problems As a result of diligent studies on the sheet-like support, the present inventors have found that the use of a stretched film containing polyethylene naphthalate as a main component results in extremely small print curl, and the discharge after printing. The present invention was found to be a receiving sheet capable of obtaining a clear recorded image without any paper trouble, and completed the present invention.

That is, the thermal transfer receiving sheet of the present invention has a sheet-like support and a receiving layer formed on one surface of the sheet-like support and containing a dye-dyeable resin as a main component. Wherein the sheet-like support is a stretched film mainly composed of polyethylene naphthalate.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a stretched film having polyethylene naphthalate as a main component and uniaxially or biaxially stretched is used as a sheet-like support. The heat shrinkage of the stretched polyethylene naphthalate film is not particularly limited, but after heating at 150 ° C. for 30 minutes, 0.7% or less in the machine direction (MD, machine flow direction) and the transverse direction (MD). (CD or machine width direction) is preferably 0.1 or less, more preferably 0.5% or less in the vertical direction and 0.05 or less in the horizontal direction. Further, the glass transition temperature is preferably 100 ° C or higher, more preferably 110 to 120 ° C.

[0010] The stretched polyethylene naphthalate film may contain a stabilizer, a plasticizer, a filler, a pigment, a foaming agent, and other auxiliary materials, if necessary, in addition to the polyethylene naphthalate, if necessary. Good. Among them, inorganic pigments are preferably used for improving the opacity and writability of the film, for example, clay, gypsum, calcium carbonate, calcined clay, diatomaceous earth, talc, titanium oxide, barium sulfate, aluminum sulfate, silica, and others And used alone or as a mixture.
Furthermore, it is also possible to improve cushioning properties, heat insulation properties, and the like by forming a film having a foamed structure.

The thickness of the stretched polyethylene naphthalate film is preferably from 20 to 300 μm. 20 μm thick
If less than, the mechanical strength becomes insufficient, the hardness of the receiving sheet, and the repulsive force against deformation becomes insufficient,
In some cases, curling that occurs during printing cannot be sufficiently prevented. On the other hand, if the thickness exceeds 300 μm, the thickness of the obtained receiving sheet becomes excessive. In other words, the capacity of the receiving sheet is limited in a printer having a predetermined capacity. Therefore, an increase in the thickness naturally causes a decrease in the number of receiving sheets of the printer, or increases the capacity of the printer, making it difficult to make the printer compact. This is because

The receiving layer provided on the surface of the sheet-like support is not particularly limited, and is a layer mainly composed of a dye-dyeable resin dyed by a dye transferred from an ink ribbon. Examples of such dyeable resins include polyester resins, vinyl chloride-vinyl acetate copolymer resins, polycarbonate resins, acrylic resins, cellulose derivatives such as acetate butyrate resins, and other dye-stainable dyes. There are resins and the like. The thickness of the receiving layer is preferably 1 to 12 μm, more preferably 2 to 7 μm.
m. If the receiving layer is too thin, there are disadvantages such as a decrease in image density and sensitivity, or a decrease in gloss of the printed surface. On the other hand, if the thickness is too large, the effect is saturated and not only is uneconomical, but also the print density may decrease.

The receiving layer may have a resin cross-linking agent, a slipping agent, an anti-fusing agent, and the like, for the purpose of preventing fusion with the ink ribbon due to heating of the thermal head during printing. . If necessary, other additives such as an antioxidant, a pigment, and an ultraviolet absorber may be appropriately added. For example, as a cross-linking agent, an isocyanate-based compound and an epoxy-based compound, as an anti-fusion agent, an acrylic silicone-based resin, and as an ultraviolet absorber, a benzotriazole-based, benzophenone-based, phenyl salicylate-based, and cyanoacrylate-based compound are used. Used. These additives may be mixed with the main component of the receiving layer and applied, or may be applied as a separate coating layer on the receiving layer.

As the pigment which may be used in combination with the receiving layer, silica is preferably used, and has an average particle diameter of 1 to 12 μm.
Silica having a specific surface area of 30 to 250 g / m ² is more preferably used. The content of the silica pigment is about 5 to 20% by weight based on the dye-dyeing resin. When the average particle diameter of silica protrudes from the receiving layer, the portion is not dyed and tends to cause print defects such as white spots.
By using the silica for the receiving layer of the support of the present invention, fusion with the ink ribbon is prevented, the friction with the receiving layer is appropriately adjusted, and the wrinkles generated on the ribbon are of course not included in the printed image. However, paper ejection after printing is extremely good, and an excellent recorded image can be obtained.

The surface roughness Ra value of the receiving layer is related to the adhesion between the ink sheet and the receiving sheet. Generally, by adjusting the Ra value of the surface of the receiving layer to 1.5 μm or less,
A print faithful to desired image information and having good density uniformity can be obtained. When Ra exceeds 1.5 μm, the adhesion between the ink sheet and the receiving sheet tends to decrease, and the image uniformity tends to decrease. The Ra value of the receiving layer is preferably 1.0 μm or less, more preferably 0.01 to 1.0.
0 μm. If the thickness is 0.01 μm or less, slippage between the receiving sheets may be insufficient, and the receiving sheet may run over during printing with a printer. Note that the surface roughness Ra in the present invention means a center line average roughness, and is JIS B 0
601.

The sheet-like support of the present invention may have a sheet-like core layer on the back surface (the side opposite to the receiving layer) of the stretched polyethylene naphthalate film. As the sheet-like core material layer, paper containing cellulose pulp as a main component, or pigment coated paper such as coated paper, art paper, cast coated paper, laminated paper having a thermoplastic resin layer provided on at least one side, or polyester And a film (or sheet) mainly composed of a synthetic resin such as polyamide, polyolefin, polystyrene, polycarbonate, polyvinyl alcohol, polyvinyl chloride, or the like. Among these, when a paper containing cellulose pulp as a main component, a pigment-coated paper, or the like is used, an appropriate cushioning property or heat insulating property is obtained, so that the effects of the present invention are more remarkable and cost reduction is achieved. It is also advantageous.

For laminating the stretched polyethylene naphthalate film and the sheet-like core layer, a known technique such as wet lamination, extrusion lamination, dry lamination or wax lamination is used. Preferably, a dry lamination method is used, and a polyether-based or polyester-based adhesive can be used as the adhesive. Further, the coating amount of the adhesive is 1.0
The range is preferably from 5 to 50.0 g / m ² . The sticking of the sheet-like core material layer and the stretched polyethylene naphthalate film is performed before or after the receiving layer is provided on the surface of the stretched polyethylene naphthalate film, and is appropriately selected.

A thermoplastic resin coating layer may be provided on the back surface (the surface on which polyethylene naphthalate is not laminated) of the sheet core layer. As a specific example of the thermoplastic resin,
Α-olefin homopolymers such as ethylene and propylene, or copolymers of two or more α-olefins, or copolymers of α-olefins as main components with other monomers copolymerizable therewith, and mixtures thereof And the like, but are not limited to these. Further, a pigment, a stabilizer, an antioxidant, an antistatic agent, a plasticizer, a dispersant, a lubricant, a fluorescent agent, and the like may be added to the resin. The thermoplastic resin coating layer is coated by a known method such as extrusion coating or solvent coating, and the coating amount is 0.1 to 50.0 g /
Desirably, it is in the range of m ² .

Further, it is a preferred embodiment of the present invention to provide a backside film layer on the backside of the sheet-like core material layer for the purpose of curling improvement and waterproofing. For example, a film (or sheet) mainly composed of a synthetic resin such as polyester, polyamide, polyolefin, polystyrene, polycarbonate, polyvinyl alcohol, and polyvinyl chloride, or a stretched polyethylene naphthalate film can be appropriately selected and used. . Examples of the method for attaching the sheet-like core material layer and the back side film layer include wet lamination, extrusion lamination,
A known technique such as dry lamination or wax lamination is used. Preferably, a dry lamination method is used, and a polyether-based or polyester-based adhesive can be used as the adhesive. Further, the coating amount of the adhesive is preferably in the range of 1.0 to 50.0 g / m ² . In addition, the lamination order of the polyethylene naphthalate stretched film and the sheet-like core material layer, or the sheet-like core material layer and the back side film is not particularly limited.

On the back surface (the surface opposite to the receiving layer) of the receiving sheet of the present invention, the running performance is improved, static electricity is prevented, the receiving layer is prevented from being damaged by rubbing between the receiving sheets, and the printed receiving sheet is overlaid. When placed, a back cover layer may be formed for the purpose of preventing the transfer of the dye from the receiving layer to the back surface of the receiving sheet in contact with the receiving layer. 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. As such a resin, an acrylic resin, an epoxy resin, a polyester resin, a phenol resin, an alkyd resin, a urethane resin, a melamine resin, and the like, and a reaction cured product of these resins can be used.

Various conductive agents can be added to the back cover layer for antistatic treatment. It is desirable 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 1.5 g / m ² . Is less than 0.3 g / m ^2, may not be sufficiently prevented damage of the receptive layer when receiving layer and the back surface is rubbed, and 1.5 g / m ²
Beyond, the effect is saturated and uneconomical.

The receiving layer and other coating layers of the receiving sheet of the present invention can be formed by coating and drying using a coater such as a bar coater, a gravure coater, a blade coater, an air knife coater, and a gate roll coater. it can.

[0023]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. In the following, “%” and “parts” all indicate “% by weight” and “parts by weight”.

Example 1 A biaxially stretched polyethylene naphthalate film having a thickness of 150 μm (trade name: Teonex, Teijin Limited) as a support
Coating 1) was applied on the surface of the sheet-like support so as to have a solid content of 5 g / m ² and dried to form a receptor layer. Further, on the back surface of this support, a coating material-2 having the following composition was applied so that the coating amount of the solid content was 1 g / m ^2, and dried to form a back coating layer, thereby producing a receiving sheet.

Paint-1 Polyester resin (trademark: Byron 200, manufactured by Toyobo) 100 parts Silicone oil (trademark: KF393, manufactured by Shin-Etsu Silicone) 3 parts Isocyanate (trademark: Takenate D-140N, manufactured by Takeda Pharmaceutical) 5 parts Silica (trade name: C212, manufactured by Mizusawa Chemical Industries, average particle size: 2.2 μm, specific surface area: 170 m ² / g) 12 parts Isocyanate (trade name: Coronate L, manufactured by Nippon Polyurethane Industry) 5 parts Toluene 300 parts

Paint-2 Acrylic ester copolymer (trademark: Primal WL-81, manufactured by Rohm and Haas) 100 parts Epoxy resin (trademark: Epocoat DX-225, manufactured by Shell Chemical Company) 5 parts Conductive agent (trademark) : Saftomer ST1000, manufactured by Mitsubishi Yuka Co., Ltd.) 50 parts Denatured ethanol 1420 parts The heat shrinkage of the PEN film of the support was 150 ° C.
After heating conditions for 30 minutes, the ratio was 0.4% in the vertical direction and 0% in the horizontal direction.

Example 2 A pigment-coated paper having a thickness of 80 μm was used as a core material, and a biaxially stretched polyethylene naphthalate film (trade name: Teonex, manufactured by Teijin Limited) having a thickness of 50 μm was coated on the front and back surfaces with a polyester adhesive. And laminated by a dry lamination method to form a sheet-like support. On the surface of this sheet-shaped support, a coating layer of the above-mentioned composition (Example 1) was applied to a solid content of 8 g / m ² and dried to form a receptor layer. Further, on the back surface of this support, coating material-2 of the above-mentioned composition (Example 1) was applied so as to have a solid content of 1 g / m ^2, and dried to form a back coating layer. Was prepared.

Comparative Example 1 Instead of a polyethylene naphthalate film (trade name: Teonex, manufactured by Teijin Limited) having a thickness of 150 μm as a support, a polyolefin was used as a main component, and about 3
Biaxially stretched thickness containing 0% calcium carbonate
A receiving sheet was produced in the same manner as in Example 1 except that a μm multilayer structure film (trade name: Yupo FPG, manufactured by Oji Yuka Synthetic Paper) was used.

Comparative Example 2 Instead of a polyethylene naphthalate film (trade name: Teonex, manufactured by Teijin Limited) having a thickness of 50 μm as a support, a polyolefin was used as a main component, and about 30% of calcium carbonate was contained as an inorganic pigment. Axial stretched thickness 60
A receiving sheet was prepared in the same manner as in Example 2 except that a μm multilayer structure film (trade name: Yupo FPG60, manufactured by Oji Oil Chemicals, Ltd.) was used.

Comparative Example 3 A 50 μm thick polyethylene naphthalate (PEN) film (trade name: Teonex, Teijin Limited) as a support
Instead of polyethylene terephthalate as a core material, and a biaxially stretched 60 μm thick multilayer structure containing about 30% calcium carbonate as a pigment and an inorganic pigment on the front and back surfaces of a polyolefin having a thickness of 60 μm as a main component. A receiving sheet was produced in the same manner as in Example 2 except that a film (trade name: Yupo FPG60, manufactured by Oji Yuka Synthetic Paper) was used.

"Evaluation" The receiving sheet obtained in each of the above Examples and Comparative Examples was measured and evaluated for quality by the following methods. The results obtained are shown in Table 1.

[Sheet Discharge Trouble]
After heating at 0 ° C. for 48 hours, it was cut into A4 size. A sublimation video printer (trademark: JX7)
000, manufactured by Sharp Corporation), and it was checked whether or not there was a paper ejection trouble due to print curl. ○: No transport trouble and suitable for practical use ×: Transport trouble and not suitable for practical use

[Print curl] The size of the print curl is determined by using the twentieth receiving sheet after printing.
It was placed on a desk with the print side up and the curl heights at the four corners were measured. However, in the case of a cylindrical curl, a portion corresponding to the diameter of the cylinder was measured. Less than 11 mm: Both paper-passing properties and appearance are very excellent and particularly preferred. 11 mm or more and less than 16 mm: Both paper-passing properties and appearance are excellent and there is no practical problem. 16 mm or more and less than 26 mm: Although there is no problem in paper passing property, it is not preferable in appearance. 26 mm or more, occurrence of cylindrical curl: a paper discharge trouble occurs, which is not suitable for practical use.

[Clearness of Recorded Image] A yellow, magenta, and cyan ink having a 6 μm-thick polyester film provided with an ink layer containing a sublimable dye together with a binder.
Contact each ink sheet of the color with the receiving sheet,
Using a commercially available thermal transfer video printer (trademark: VY-50, manufactured by Hitachi, Ltd.), the predetermined image is thermally transferred to the receiving sheet by stepwise heating with a thermal head, and a halftone single color and color superimposed image of each color is obtained. Was printed. The image transferred on the receiving sheet was visually observed for color misregistration and image clarity, and evaluated according to the following criteria. A: There is no color misregistration, the image sharpness is extremely excellent, and it is practically excellent. ：: Almost no color shift, good image clarity, suitable for practical use. Δ: There is considerable color shift, poor image clarity, and insufficient for practical use. X: The color shift is remarkable, the image clarity is poor, and it is not suitable for practical use.

[0035]

[Table 1]

As is clear from Table 1, the receiving sheets obtained in Examples 1 and 2 of the present invention have a small print curl, have no paper ejection trouble even when run by a printer, and have a clear recorded image. Met. On the other hand, in Comparative Examples 1 and 2, the print curl was large, a paper discharge trouble occurred, and the recorded image was unclear.

[0037]

According to the present invention, it is possible to practically use a receiving sheet having a sufficiently small print curl, no paper discharge trouble after printing, and a good clearness of a dye thermal transfer image, which contributes to the industry. But it is big.

Claims (2)

[Claims] 1. A thermal transfer receiving sheet having a sheet-like support and a receiving layer formed on one surface of the sheet-like support and containing a dye-dyeable resin as a main component, wherein the sheet-like support is A heat transfer receiving sheet, which is a stretched film containing polyethylene naphthalate as a main component. 2. The thermal transfer receiving sheet according to claim 1, wherein said sheet-like support has a sheet-like core material layer on a surface opposite to a receiving layer of said stretched film.