JP2000052666A - Dye thermal transfer image receiving sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image receiving sheet having excellent printing image quality and feedability (curling axis) by cutting a laminate adhered base material using paper as a core material along stripes. SOLUTION: In the dye thermal transfer image receiving sheet comprising a sheet-like support using paper as a core material obtained by laminating plastic films on front and rear surfaces of the core material and a layer containing dye dyeable resin formed on one surface of the support as a main component; thermal shrinkage factor of the film in a lateral direction of the side formed with the layer containing the dye dyable resin as the main component is 1/3 to 5/6 of that of a lateral direction of the plastic film disposed at its opposite side, and cut along stripes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dye thermal transfer image receiving sheet (hereinafter simply referred to as an image receiving sheet). More specifically, the print quality is good,
The present invention relates to an image receiving sheet which has a small white paper curl and a small print curl and has no running trouble in a printer.

[0002]

2. Description of the Related Art A high-quality color hard copy printing system based on a dye thermal transfer system includes a printer, a dye ink sheet, and an image receiving sheet. The printer has a thermal head that can control the amount of heat generated according to the electric signal, and forms a hard copy with gradation by moving and fixing the dye according to the amount of heat from the ink sheet to the image receiving sheet. . In such a printer of the dye thermal transfer system, the ink sheet is usually supplied in a roll state, but the image receiving sheet is generally supplied in sheet form.

In recent years, there has been a demand for a printing system with higher speed and higher sensitivity, and it has become an important technical problem how to efficiently use the amount of heat generated by a thermal head to form an image. Therefore, in order to reduce heat loss, the sheet-like support of the image receiving sheet (hereinafter, simply referred to as a base material) contains a thermoplastic polymer having smoothness, good cushioning properties, good adhesion, and high heat insulation properties as a main component. Is used. However, when a plastic film alone is used as the base material of the image receiving sheet, there has been a problem that the film is deformed by the heat of the thermal head at the time of printing and curl occurs. The curled image receiving sheet has the drawbacks that it significantly impairs the commercial value and causes running trouble in the printer.

[0004] In order to solve this problem, a method of preventing deformation of an image receiving sheet due to heat by using a substrate in which a plurality of films are laminated and bonded (Japanese Patent No. 2627739) has been adopted. However, in reality, curling during printing cannot be sufficiently prevented by simply laminating and laminating a plurality of films. Therefore, a method in which films having different heat shrinkage rates are stuck on the front and back surfaces of the core material to prevent curling (Japanese Patent No. 2525).
No. 88614, Japanese Patent No. 2085901, Japanese Patent No. 267
4866, JP-A-6-115268, and Patent 20
No. 85901). Typically,
A biaxially stretched film is often used as the plastic film constituting the base material of the image receiving sheet. Since a stretched film has a residual stress at the time of stretching, when heat or a mechanical load is applied, a force for shrinking occurs to reduce the residual stress. In general, the heat shrinkage of a biaxially stretched film is smaller in the transverse direction (direction perpendicular to the film flow direction) than in the longitudinal direction (film flow direction). This is because the residual stress in the horizontal direction of the film can be relaxed by an operation such as tension when heat setting after stretching the film to a predetermined magnification, whereas there is no method of relaxing the residual stress in the vertical direction. That's why. Therefore, a substrate obtained by laminating and laminating a plurality of films as in the present invention has a large heat shrinkage in the vertical direction, and is a layer having a dye-dyeing resin as a main component (hereinafter, simply referred to as a dyeing layer). In general, curling about the axis in the lateral direction of the film is caused by drying during coating. When the image receiving sheet is carried into the printer, the curl axis of the image receiving sheet is preferably parallel to the thermal head of the printer. For this reason, when cutting the image receiving sheet, vertical trimming (cutting method in which the long side of the image receiving sheet is the flow direction of the film constituting the base material) is performed.

[0005]

However, in the case of a base material composed of a single film or a base material obtained by laminating and laminating a plurality of films, there is no problem in vertical graining. In the case of the laminated base material used, it was found that the image quality of the print was deteriorated by vertical perforation. Since the orientation of the fibers in the paper is in the flow direction, the direction perpendicular to the flow direction is good for contact with the thermal head. Therefore, a horizontal image (cutting in the direction opposite to the vertical image) provides a more uniform image. As described above, in the case of horizontal graining, the curl axis of the image receiving sheet may be in an undesired direction, which may hinder running performance. Therefore, an image receiving sheet having both good print quality and good running performance has been awaited. Was. The present invention provides an image receiving sheet which is excellent in both print image quality and runnability (curl axis) by cutting a laminated bonding substrate using paper as a core material into a horizontal cut.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies on an image receiving sheet composed of a base material obtained by laminating and laminating a plurality of films using paper as a core material. In order to obtain an image-receiving sheet with good print quality, the heat shrinkage in the lateral direction of the plastic film located on the side where the dyeing layer is formed is reduced by the lateral heat shrinkage of the plastic film located on the opposite surface. 1 / shrinkage
It has been found that it is sufficient to set it to 3 or more and 5/6 or less and to make the cutting direction of the image receiving sheet horizontal.

The present invention provides a sheet-like support comprising paper as a core material, and a plastic film laminated and bonded to the front and back of the core material, and a dye-dyeable resin formed on one surface of the sheet-like support. In a dye thermal transfer image-receiving sheet having a layer composed mainly of, the lateral thermal shrinkage of the plastic film located on the side on which the layer composed mainly of the dye-dyeable resin is formed, the plastic film located on the opposite surface A heat transfer coefficient of 1/3 to 5/6 of the heat shrinkage in the horizontal direction, and the sheet is cut for horizontal graining.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The image receiving sheet of the present invention is formed on a sheet-like support comprising at least paper as a core material, and laminating and laminating plastic films on the front and back of the core material, and on one surface thereof. It consists of a dyed layer. In addition, a back coat layer for improving running properties and an antistatic layer for preventing static electricity may be provided. The base material of the image receiving sheet is smooth,
A plastic film containing a thermoplastic polymer as a main component, which has good cushioning property and adhesiveness and high heat insulating property, is used. Examples of such a film include a film composed of a plurality of layers having uniaxially or biaxially stretched voids obtained by adding an inorganic pigment to polypropylene known as synthetic paper, or a polyethylene terephthalate film which is foamed to reduce the specific gravity. Is used.

However, with a plastic film alone,
Deformation due to heat at the time of printing, curling occurs, there are drawbacks such as hindering runnability and impairing product value, and laminating plastic films, and plastic films via other films and paper etc. The adhered composite base material is used for an image receiving sheet. When considering the image quality of prints, it is best to compose the composite substrate with a plastic film with a uniform surface, but the cost is high, so paper is used for the core material that does not appear on the surface. I have.
The paper fibers are entangled so as to be oriented in the flow direction of the papermaking. For this reason, the size and spacing of the irregularities on the paper surface are perpendicular to the flow direction of papermaking, that is, the width of the paper is smaller, and when the paper is used as the base material of the image receiving sheet, the print quality is better when the paper is cut horizontally. Is improved. The image receiving sheet is often fed so that the long side direction is perpendicular to the thermal head,
In order to stabilize the running property, it is preferable that the direction of the curl is on the short side as the axis. As described above, the heat shrinkage of the plastic film is smaller in the horizontal direction than in the vertical direction, and when the plastic film is cut to the horizontal direction, the plastic film usually curls around the long side of the image receiving sheet. Accordingly, an image-receiving sheet having a substrate obtained by laminating and laminating paper and a plastic film and having the curl axis as a short side was not usually obtained.

The present inventor controls the heat shrinkage of the plastic film constituting the front and back of the base material,
It has been found that an image-receiving sheet can be obtained which is cut sideways and whose curl axis is a short side. That is, by laminating and laminating a plastic film having substantially the same heat shrinkage rate in the vertical direction and the heat shrinkage rate in the horizontal direction on the front and back sides of the paper as the core material, the curl axis is short even when cut in the horizontal direction. I found it to be the direction. When the curl after printing is also taken into consideration, by forming the dyeing layer on the film side having a small heat shrinkage, a curl having the dyeing layer convex is obtained, and the print curl is improved.

The difference in the heat shrinkage in the lateral direction of the plastic film must be one-third or more and five-six or less of the other film. If the heat shrinkage in the vertical and horizontal directions is the same, the heat shrinkage of the dyed layer will govern the curl of the image receiving sheet, and the curl will be concave with the dyed layer deteriorating the runnability. There is a disadvantage that the curl becomes large. If the thermal shrinkage in the horizontal direction is almost equal and there is a difference in the thermal shrinkage in the vertical direction, the curl will be in the horizontal direction of the film, and if the image receiving sheet is cut in the horizontal direction, the curl axis will be the long side. , Which hinders driving performance. When the heat shrinkage in the vertical direction is substantially equal and there is a difference in the heat shrinkage in the horizontal direction, a curl around the short side of the image receiving sheet can be obtained by horizontal cut. In this case, if the difference in heat shrinkage in the horizontal direction of the plastic film is too large,
If the white paper curl is too large and the difference in heat shrinkage is too small, the white paper curl becomes curl with the dyed layer concaved,
Unstable runnability and large print curl. Therefore, the ratio of the heat shrinkage in the horizontal direction of the plastic films used on the front and back sides needs to be 1/3 or more and 5/6 or less. The heat shrinkage of the plastic film can be reduced by heating the film, but in this case, both the longitudinal direction and the lateral direction are simultaneously reduced. Therefore, it is necessary to select a film having the same material and a different manufacturing method or manufacturing machine.

As the paper used as the core material, a fiber sheet mainly composed of wood pulp can be used, and a pigment layer, a resin layer or the like may be formed on one or both sides thereof. For example, known materials such as high quality paper, medium quality paper, coated paper, and art paper can be used, but a smooth surface is preferable because the image quality is excellent. In addition, as a method of laminating the core material and the plastic film, a known method such as an extrusion lamination method and a dry lamination method can be applied.

The resin used for the dyeing layer of the image receiving sheet is a polyester resin having high dyeing properties, a polycarbonate resin,
A vinyl chloride-vinyl acetate copolymer resin, an acetate butyrate resin, or the like is used. Further, a release agent or a crosslinking agent is added to the image receiving layer in order to prevent fusion with the ink sheet. As the release agent, various reactive silicone oils, surfactants, lubricants such as alkali soaps and the like, and as the crosslinking agent, isocyanates and the like are used.

The dyeing layer, antistatic layer, back coat layer and other coating layers of the image receiving sheet of the present invention are coated using a coater such as a bar coater, a gravure coater, a comma coater, a blade coater or an air knife coater. It can be formed by processing and drying.

[0015]

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".

Example 1 Art paper having a thickness of 100 μm (Oji Paper Co., Ltd., trademark OK)
Kaneto N127.9 g / m ² ) with a 50 μm thick white foamed PET film (Toyobo Co., Ltd., trademark Crisper CR11-50, heat shrinkage: 0.41% in the vertical direction, 0.07% in the horizontal direction) on the front and back sides. A 50 μm thick white foamed PET film (Toray Industries, Inc., trade name 50E63S, heat shrinkage: 0.44% in the vertical direction, 0.21% in the horizontal direction) was laminated with a dry laminator to prepare a substrate. On the foamed PET side where the thermal shrinkage of the side grain is small, paint 1 having the following composition is 5.0 μm thick.
And dried to form a dyed layer. Then 50 ℃
After heating for 5 days, the sheet was cut sideways to prepare an image receiving sheet.

Paint 1 Polyester resin (Toyobo Co., Ltd., Byron 200) 100 parts Silicone oil (Shin-Etsu Chemical Co., Ltd., KF105) 3 parts Isocyanate (Nippon Polyurethane Co., Ltd., Coronate L) 5 parts Toluene 200 parts MEK 200 copies

Example 2 An image receiving sheet was prepared in the same manner as in Example 1. However, the following foamed PET film was used. White foamed PET film having a thickness of 50 μm (trade name: 50E63S, manufactured by Toray Industries, Inc.)
Thermal shrinkage: 0.44% in the vertical direction, 0.20% in the horizontal direction) and a white foamed PET film having a thickness of 50 μm (Toray Industries, Inc., trade name: 50QE02, heat shrinkage: 0.45% in the vertical direction)
%, Horizontal direction 0.25%)

Comparative Example 1 An image receiving sheet was prepared in the same manner as in Example 1. However, it was cut vertically and an image receiving sheet was prepared.

Comparative Example 2 An image receiving sheet was prepared in the same manner as in Example 1. However, the dyeing layer was formed on the side of the foamed PET having a large thermal shrinkage in the horizontal direction to prepare an image receiving sheet.

Comparative Example 3 An image receiving sheet was prepared in the same manner as in Example 1. However, a foamed PET having a large thermal shrinkage ratio at the side was dry-laminated on both sides of the art paper to form an image receiving sheet.

The image receiving sheet prepared by the above method was evaluated for the curl of a blank sheet, the running property, and the image quality of the print by the following methods. The results are summarized in Table 1.

White paper curl The image receiving sheet was placed on a horizontal table with the surface on which the dyeing layer was formed facing up and down, and the curl height and curl axis at four corners were measured. Table 1 shows the maximum curl height and the curl axis in that case.

Runnability, print curl Using a sublimation color video printer (UP1850, manufactured by Sony) at 10 ° C. under an environment of 5 ° C. and 20 to 30% RH.
00 solid black sheets were printed, and double feed, presence or absence of paper jam, and print curl were measured.

Print Quality Using a sublimation color video printer (UP8800, manufactured by Sony), a gray solid was printed under an environment of 20 ° C. and 60% RH, and the degree of white spots was evaluated.

[0026]

[Table 1]

[0027]

According to the present invention, even in a laminated bonding base material using paper as a core material, the white paper curl can be improved by setting the thermal shrinkage of the front and back films to the side and the cutting direction to the side. It was possible to obtain an image-receiving sheet having stable running properties and good print curl and print quality.

Continued on front page F-term (reference) 2H111 AA01 AA27 CA03 CA04 CA05 CA23 CA25 CA30 CA41 CA46 4F100 AK01B AK01C AK01D AK41B AK41C AK41D BA04 BA07 BA10B BA10D BA26 CA13D CC00D DG10A DJ01B DJ01C04J03B JA03B JA03B

Claims (1)

[Claims] 1. A sheet-like support comprising paper as a core material, and a plastic film laminated and bonded on the front and back of the core material, and a dye-dyeable resin formed on one surface of the sheet-like support. In a dye thermal transfer image-receiving sheet having a layer as a component, the heat shrinkage in the horizontal direction of the plastic film located on the side on which the layer having the dye-dyeable resin as the main component is formed is the same as that of the plastic film located on the opposite surface. Direction heat shrinkage 1
Dye thermal transfer image-receiving sheet, characterized in that the sheet has a width of ３ to 5/6 and is cut to be horizontal grained.