JPH07329436A - Thermal transfer receiving sheet - Google Patents

Abstract

PURPOSE:To provide a thermal transfer receiving sheet forming a printing image free from wrinkles and usable in various dye thermal transfer printers even in a printing system wherein the driving speed of a receiving sheet is different from that of an ink ribbon. CONSTITUTION:In a thermal transfer receiving sheet consisting of a sheet like support and the receiving layer based on a dyeing polymer on one surface of the sheet like support, the receiving layer contains silica with a mean particle size of 1.5-9.0mum and a specific surface area of 30-250m<2>/g in an amt. of 5-15 pts.wt. per 100 pts.wt. of the dyeing polymer and the coefficient of friction based on J. TAPPI No. 30 of the surface of the receiving layer and an ink ribbon is 0.25-0.50.

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) which forms a dyed image by transferring a sublimable dye by heat. More specifically, the present invention relates to a receiving sheet which does not cause ribbon wrinkles in a printed image when used in combination with an ink ribbon, particularly in a printing method in which the driving speed of the receiving sheet and the ink ribbon during printing are different. .

[0002]

2. Description of the Related Art A thermal transfer type color hard copy, particularly a dye thermal transfer printer capable of printing a clear full-color image has been attracting attention. Dye thermal transfer printers are based on an ink ribbon that has a sublimable dye layer printed on a base film, a sheet-like support (hereinafter simply referred to as a substrate), and a resin that is easily dyed with a sublimable dye as a main component. The surface of the receptive sheet provided with the receptive layer is superposed, and the heat supplied from the thermal head transfers the dye at the required position of the sublimation dye layer onto the receptive layer in the required concentration to form an image. is there.

A PET film having a thickness of 4.5 to 6.0 μm is usually used as the base film of the ink ribbon, but since the maximum heating temperature of the thermal head reaches about 300 ° C., the ink ribbon shrinks due to heat and wrinkles. Occurs.
Since wrinkles formed on the ink ribbon are transferred to the receiving sheet as they are, there is a problem that wrinkles appear in the printed image. In order to prevent this problem, conventionally, about 30% of the blank portion not used for image formation exists on the receiving sheet. That is, heat is applied to the margin of the receiving sheet to such an extent that the dye of the ink ribbon is not transferred, and wrinkles that occur on the ink ribbon are brought out of the image forming range to prevent wrinkles from forming in the printed image. However, when the area of the margin portion of the receiving sheet is large, a slightly larger receiving sheet is required to obtain a print of a predetermined size, which is one of the causes that hinder the downsizing of the printer.
Further, in recent years, a printing method that reduces the consumption of the ink ribbon has attracted attention due to environmental problems and economical efficiency. For example,
This is a printing method in which the ink ribbon consumption during printing is set to 1 / n times (n> 1) the drive speed of the receiving sheet to reduce the consumption of the ink ribbon to 1 / n of the printing area. In this case, the amount of heat applied to the ink ribbon having the same area is larger than that in the conventional printing method in which the driving speed of the ink ribbon and that of the receiving sheet are the same. Therefore, there is a problem in that wrinkles formed on the ink ribbon cannot be brought out of the image forming range by simply heating the margin portion, and a large amount of wrinkles are formed in the printed image.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a receiving sheet for use in various dye thermal transfer printers, and when used in combination with an ink ribbon, the printing speed is the same when the receiving sheet and the ink ribbon are driven. method,
Another object of the present invention is to provide a receiving sheet in which ribbon wrinkles do not enter the printed image in a printing system in which the driving speed of the receiving sheet and the ink ribbon are different.

[0005]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted diligent research in order to achieve the above-mentioned object in view of the present situation, and as a result, at least the base material and the surface of the base material, which is formed on the surface of the base material, receives the dye. In a configuration having a receiving layer for forming a printed image by increasing the friction coefficient of the receiving layer surface,
The inventors have found the possibility of preventing wrinkles on the ribbon from entering the printed image, and have completed the present invention.

That is, the thermal transfer receiving sheet according to the present invention comprises a sheet-like support and a receiving layer containing a dye-dyeable polymer as a main component formed on one surface of the sheet-like support. In the above, the receptive layer contains silica having an average particle size of 1.5 to 9.0 μm and a specific surface area of 30 to 250 m ² / g, and the content is the dye-dyeable polymer 100 described above.
5 to 15 parts by weight with respect to parts by weight, and the J.I. TAPPI No. The friction coefficient based on 30 is in the range of 0.25 to 0.50.

The base material used in the present invention includes paper base materials such as coated paper, art paper, and fine paper, laminated paper in which a resin such as polyethylene is laminated on the front and back of the paper base material, polyethylene terephthalate, nylon, polystyrene and the like. Examples thereof include a polyolefin (for example, polypropylene) film, or a biaxially stretched multi-layered film containing a polyolefin resin and an inorganic pigment as main components and having a void structure. Furthermore, it is also possible to use a laminated structure in which these are laminated.

The thickness of the substrate is preferably 20 to 300 μm. When the thickness is 20 μm or less, the mechanical strength becomes insufficient, and the hardness of the receiving sheet obtained from it is
In addition, the repulsive force against deformation is insufficient, and curling of the receiving sheet that occurs during printing cannot be prevented sufficiently. On the other hand, when it exceeds 300 μm, the thickness of the receiving sheet obtained becomes excessively large. In a printer having a predetermined volume, there is a limit to the volume of the receiving sheet that can be accommodated, and an increase in the thickness causes a decrease in the number of receiving sheets that can be accommodated, or increases the volume of the printer, making it difficult to make the printer compact.

In the receiving sheet of the present invention, the receiving layer provided on the surface of the base material contains as a main component a dye-dyeing resin dyed with a sublimable dye transferred from the ink ribbon. The performance required of the dyeable resin needs to have a high affinity with the sublimable dye of the ink ribbon in order to obtain a high density printed image. Examples of such dyeable resin include polyester resin, polycarbonate resin, vinyl chloride copolymer, cellulose derivative and the like.

Generally, the thickness of the receiving layer is preferably 3 to 10 μm. If the thickness of the receiving layer is too thin, the surface of the base material cannot be completely covered, which may lead to deterioration of image quality such as blank areas and fusion. Further, if the thickness of the receiving layer is too thick, not only is the effect saturated and uneconomical, but also the strength of the receiving layer is reduced, and the distance between the receiving layer and the base material is increased, and the heat insulating effect of the base material is sufficiently exhibited. The image density is reduced.

The present inventors maintain a high dyeing density and
As a method of obtaining a receiving sheet in which ribbon wrinkles do not appear in the printed image-an average particle size in the receiving layer is 1.5 to 9.0.
It contains 5 to 15 parts by weight of silica having a specific surface area of 30 to 250 m ² / g and a content of 5 to 15 parts by weight based on 100 parts by weight of the dye-dyeable polymer. It has been found that the friction coefficient based on TAPPI No30 should be increased. A release agent such as silicone is added to the receiving layer in order to prevent block transfer (hereinafter simply referred to as fusion) with the binder of the ink ribbon, or an overcoat containing a releasing agent is provided on the receiving layer. It is usual to provide a coat layer.

The present invention has found that the release agent causes the reduction of the friction coefficient on the surface of the receiving layer, and that when the friction coefficient is low, ribbon wrinkles are easily formed in the printed image. However, since the release agent cannot be completely removed to prevent fusion, it is necessary to add silica having an average particle size of 1.5 to 9 μm and a specific surface area of 30 to 250 m ² / g to the receptive layer. While preventing adhesion, the coefficient of friction between the receiving layer surface and the ink ribbon was increased so that wrinkles formed on the ribbon did not enter the printed image.

Although various pigments can be added to the receptor layer, it is important that the refractive index of the pigment is substantially equal to that of the dye-dyeable resin which is the main component of the receptor layer. This is because when the resin and the pigment have different refractive indices, the receiving layer does not become transparent and the pigment is visible. The silica selected as a pigment by the present invention has a refractive index in the range of 1.45 to 1.55, and since the refractive index of all resins is close to that, the receiving layer containing silica becomes transparent. The average particle size of silica is 1.5-9.0μ.
It is preferably m, but more preferably 2.0 to 9.
It is 0 μm. Since the thickness of the receiving layer is 3 to 10 μm, if the average particle size of silica is too large, the silica protrudes from the receiving layer, and the portion is not dyed, which causes printing defects such as white spots. If the average particle size is too small, the effect of adding the pigment will not be exhibited and the coefficient of friction will not increase.

The specific surface area of silica is 30 to 250 m.
A range of ² / g is preferred. Silica having a relatively small specific surface area is known as a precipitating type and is a soft silica. On the contrary, silica having a large specific surface area is known as gel type silica and is hard silica. Since the printing of the receiving sheet is performed while contacting the thermal head, the receiving layer needs to reduce the contact resistance with the thermal head and efficiently transfer the heat transfer from the thermal head. Therefore, it is necessary to use silica that is as soft as possible and has a good cushioning property. Since the surface area and the average particle diameter are in a proportional relationship, if the specific surface area of the silica of the present invention is less than 30 m ² / g, the friction coefficient of the receiving layer will not increase, and if the specific surface area is more than 250 m ² / g, white spots, etc. May cause defective printing.

There is an appropriate value for the amount of silica added. If the amount of addition is too large, the glossiness of the receiving layer is lowered, and image defects such as white spots are likely to occur. Further, the friction coefficient becomes too high depending on the type of release agent used in combination, which causes a problem that a large number of sheets are simultaneously fed when the receiving sheet is fed. On the other hand, if the amount added is too small, the friction coefficient will be low and the occurrence of ribbon wrinkles cannot be sufficiently prevented. The amount of silica added is preferably 5 to 15 parts by weight (solid content) with respect to 100 parts by weight (solid content) of the dye-dyeing resin which is the main component of the receiving layer, and the friction coefficient between the ink ribbon and the receiving layer is 0. .25
A range of up to 0.50 is preferred.

In the receiving layer of the present invention, a resin cross-linking agent, a slipping agent, a release agent, a pigment, etc. may be added, if necessary, for the purpose of preventing fusion with the ink ribbon due to heating of the thermal head during printing. It is preferable to add it. If necessary, other additives such as colored pigments, fluorescent dyes, colored dyes, ultraviolet absorbers, antioxidants, and ceramic fine particles may be added.

In the receiving sheet of the present invention, on the surface of the base material opposite to the surface on which the receiving layer is provided, a back surface layer for antistatic and controlling the friction coefficient of the receiving sheet, and between the receiving layer and the base material are provided. In order to prevent static electricity, another layer such as a layer coated with a conductive agent may be provided. The receiving layer and other coating layers of the receiving sheet of the present invention can be produced by coating and drying with a coater such as a bar coater, a gravure coater, a comma coater, a blade coater, an air knife coater and a gate roll coater.

[0018]

EXAMPLES The present invention will be described in more detail below with reference to examples. In addition, "part" in an Example shows a "solid content weight part." Example 1 Polyethylene terephthalate (PET) having a thickness of 50 μm
A multilayer structure film (trademark: YUPO FPG50, FPG6) having a thickness of 50 μm and 60 μm, which is obtained by biaxially stretching a polyolefin containing an inorganic pigment as a main component on both sides of the film.
No. 0, made by Oji Yuka Synthetic Paper) was laminated by a dry lamination method using a polyester adhesive. Paint-1 as a receptive layer on the side of the 50 μm multilayer structure film with a solid content of 5 g /
A receiving sheet was prepared by coating with a die coating method at a ratio of m ² and drying. Paint-1 Saturated polyester resin (trademark: Byron 200, manufactured by Toyobo) 100 parts Silicone oil (trademark: KF101, manufactured by Shin-Etsu Chemical) 5 parts Isocyanate (trademark: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) 5 parts Silica (trademark: C212, Mizusawa Chemical Industry Co., Ltd.) 8 parts of the mixture was made into a 15% solution of a mixed solvent of toluene: methyl ethyl ketone = 5: 1. The physical properties of silica added to the receiving layer are shown below. Average particle size 2.2 μm; specific surface area 170 m ² / g

Example 2 A receiving sheet was prepared in the same manner as in Example 1 except that the receiving layer was formed by using the following paint 2. Paint-2 Saturated polyester resin (trademark: Byron 200, manufactured by Toyobo) 100 parts Silicone oil (trademark: KF101, manufactured by Shin-Etsu Chemical) 5 parts Isocyanate (trademark: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) 5 parts Silica (trademark: P527, Mizusawa Chemical Industry Co., Ltd.) 8 parts of the mixture was made into a 15% solution of a mixed solvent of toluene: methyl ethyl ketone = 5: 1. The physical properties of silica added to the receiving layer are shown below. Average particle size 2.1 μm; specific surface area 55 m ² / g

Example 3 A receiving sheet was produced in the same manner as in Example 1 except that the receiving layer was formed by using the following paint 3. Paint-3 Saturated polyester resin (trademark: Byron 200, manufactured by Toyobo) 100 parts Silicone oil (trademark: KF101, manufactured by Shin-Etsu Chemical) 5 parts Isocyanate (trademark: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) 5 parts Silica (trademark: P527, Mizusawa Chemical Industry Co., Ltd.) 12 parts of the mixture was made into a 15% solution of a mixed solvent of toluene: methyl ethyl ketone = 5: 1. The physical properties of silica added to the receiving layer are shown below. Average particle size 2.1 μm; specific surface area 55 m ² / g

Comparative Example-1 A receiving sheet was produced in the same manner as in Example 1 except that the receiving layer was formed by using the following paint 4. Paint-4 Saturated polyester resin (trademark: Byron 200, manufactured by Toyobo) 100 parts Silicone oil (trademark: KF101, manufactured by Shin-Etsu Chemical) 5 parts Isocyanate (trademark: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) 5 parts A mixture of toluene: methyl ethyl ketone = 5: 1 as a 15% solution of a mixed solvent.

Comparative Example-2 A receiving sheet was prepared in the same manner as in Example 1 except that the coating layer 5 was used to form the receiving layer. Paint-5 Saturated polyester resin (trademark: Byron 200, manufactured by Toyobo) 100 parts Silicone oil (trademark: KF101, manufactured by Shin-Etsu Chemical) 5 parts Isocyanate (trademark: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) 5 parts Silica (trademark: C212, 20 parts of a mixture was made into a 15% solution of a mixed solvent of toluene: methyl ethyl ketone = 5: 1.

Comparative Example-3 A receiving sheet was prepared in the same manner as in Example 1 except that the receiving layer was formed by using the following paint 6. Paint-6 Saturated polyester resin (trademark: Byron 200, manufactured by Toyobo) 100 parts Silicone oil (trademark: KF101, manufactured by Shin-Etsu Chemical) 5 parts Isocyanate (trademark: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) 5 parts Silica (trademark: P527, 20 parts of a mixture was made into a 15% solution of a mixed solvent of toluene: methyl ethyl ketone = 5: 1.

Comparative Example-4 A receiving sheet was produced in the same manner as in Example 1 except that the receiving layer was formed by using the following paint 7. Paint-7 Saturated polyester resin (trademark: Byron 200, manufactured by Toyobo) 100 parts Silicone oil (trademark: KF101, manufactured by Shin-Etsu Chemical) 5 parts Isocyanate (trademark: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) 5 parts Silica (trademark: C212, Mizusawa Chemical Co., Ltd.) 1 part of the mixture was used as a 15% solution of a mixed solvent of toluene: methyl ethyl ketone = 5: 1.

Comparative Example 5 A receiving sheet was produced in the same manner as in Example 1 except that the receiving layer was formed by using the following paint 8. Paint-8 Saturated polyester resin (trademark: Byron 200, manufactured by Toyobo) 100 parts Silicone oil (trademark: KF101, manufactured by Shin-Etsu Chemical) 5 parts Isocyanate (trademark: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) 5 parts Silica (trademark: P527, Mizusawa Chemical Co., Ltd.) 1 part of the mixture was used as a 15% solution of a mixed solvent of toluene: methyl ethyl ketone = 5: 1.

Comparative Example 6 A receiving sheet was produced in the same manner as in Example 1 except that the receiving layer was formed by using the following paint 9. Paint-9 Saturated polyester resin (trademark: Byron 200, manufactured by Toyobo) 100 parts Silicone oil (trademark: KF101, manufactured by Shin-Etsu Chemical) 5 parts Isocyanate (trademark: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) 5 parts Silica (trademark: P363, Mizusawa Chemical Industry Co., Ltd.) 8 parts of the mixture was made into a 15% solution of a mixed solvent of toluene: methyl ethyl ketone = 5: 1. The physical properties of silica added to the receiving layer are shown below. Average particle diameter 10.0 μm; specific surface area 280 to 330 m ²
/ G

Comparative Example 7 A receiving sheet was produced in the same manner as in Example 1 except that the receiving layer was formed by using the following paint 10. Paint-10 Saturated polyester resin (trademark: Byron 200, manufactured by Toyobo) 100 parts Silicone oil (trademark: KF101, manufactured by Shin-Etsu Chemical) 5 parts Isocyanate (trademark: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) 5 parts Silica (trademark: P363, Mizusawa Chemical Co., Ltd.) 1 part of the mixture was used as a 15% solution of a mixed solvent of toluene: methyl ethyl ketone = 5: 1.

COMPARATIVE EXAMPLE 8 Except that a receiving layer was formed using the following paint 11,
A receiving sheet was prepared in the same manner as in Example 1. Paint-11 Saturated polyester resin (trademark: Byron 200, manufactured by Toyobo) 100 parts Isocyanate (trademark: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) 5 parts Silica (trademark: C212, manufactured by Mizusawa Chemical Co., Ltd.) 8 parts A mixture of toluene: methyl ethyl ketone = 5: 1 as a 15% solution of a mixed solvent.

The surface of the receiving layer of each of the above-mentioned receiving sheets and a commercially available ink ribbon (JX-7500, manufactured by Sharp) are described in J.
The friction coefficient based on TAPPI No30 was measured. Furthermore, a commercially available sublimation color video printer (trademark: JX-7
500, manufactured by Sharp) was connected to a signal generator (trademark: CB11A1, manufactured by Shibasoku), and a step pattern of 12 gradations was printed. Ribbon wrinkles, print density, and image quality (white spots) were evaluated. The evaluation method for each item is as follows. (1) Ribbon wrinkles: The presence or absence of ribbon wrinkles was visually determined. (2) Print density: Of the 12 gradations, the print density of the 7th and 11th gradations is the Macbeth densitometer (trademark: RD-91).
4, manufactured by Kollmorgen Corp.). (3) Image quality: Observing the degree of white spots in the halftone image portion of the receiving sheet printed with 12 gradations, JIS P8145
According to the foreign matter measurement chart, if no white spots are found, it is “good”, and if 1 to 3 white spots of less than 1.5 mm ² are found, it is “slightly bad”, and white spots of less than 1.5 mm ² are shown. When 4 or more were observed, or when white spots of 1.5 mm ² or more were observed, the evaluation was made in 3 grades, which was regarded as “poor”.

The test results are shown in Table 1.

[Table 1]

[0031]

INDUSTRIAL APPLICABILITY The thermal transfer receiving sheet of the present invention has a ribbon wrinkle printed image even in a printing method in which the driving speed of the receiving sheet and the ink ribbon during printing is the same and in a printing method in which the driving speed of the receiving sheet and the ink ribbon are different. It is characterized by the fact that it does not enter into, and can be used in various dye thermal transfer printers, and is of high practical value.

Claims (1)

[Claims] 1. A thermal transfer receiving sheet comprising a sheet-like support and a receiving layer containing a dye-dyeable polymer as a main component formed on one surface of the sheet-like support, wherein the receiving layer has an average particle diameter. 1.5-9.0 μm, specific surface area 30-250
m ² / g of silica is contained, the content is 5 to 15 parts by weight with respect to 100 parts by weight of the dye-dyeable polymer, and the J.V. TAPPI No. Three
A thermal transfer receiving sheet having a coefficient of friction based on 0 in the range of 0.25 to 0.50.