JP2581270B2 - Thermal transfer ribbon - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer ribbon excellent in printing performance used for a transfer material for a thermal transfer printer.

[Conventional technology]

As a base film of a ribbon for a thermal transfer printer, a film having a specified surface roughness (Japanese Patent Application Laid-Open No. 62-299389 and Japanese Patent Application Laid-Open No. 62-193889), a material having a specified material and a Young's modulus in the longitudinal direction ( JP-A-62-111719) is known.

[Problems to be solved by the invention]

However, in recent years, as the printing speed has been required to be higher, the temperature of the thermal head at the time of printing has increased, and as a result, the amount of heat received by the thermal transfer printer ribbon has increased. For this reason, the deformation of the film used for the base material of the ribbon becomes large, and the printing becomes unclear at the time of printing, or wrinkles are generated on the ribbon, and in an extreme case, printing becomes impossible at all. A trouble occurred and this improvement was necessary.

It is an object of the present invention to improve such a problem and to provide a thermal transfer ribbon excellent in printability.

[Means for solving the problem]

The present invention relates to a thermal transfer ribbon in which a biaxially oriented polyester film is used as a base material layer and a thermal transfer ink layer is provided on one surface of the base material layer, and measures a transverse temperature dimensional change curve of the biaxially oriented polyester film. When there is a point at which the slope of the curve changes from negative to positive, the temperature at that point is 200 ° C. or more, and the dimensional change rate with respect to the original length of the film at the point is −5 to + 5%. The present invention provides a ribbon for thermal transfer, which is characterized in that there is a feature.

In the present invention, the polyester is a condensation polymer containing an ester group obtained from a dicarboxylic acid component and a diol component by a condensation method. Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, and sebacic acid.The diol component includes ethylene glycol, diethylene glycol, butanediol, and the like.
Hexanediol, neopentyl glycol, p-xylene glycol, 1,4-cyclohexanedimethanol,
Examples thereof include polyalkylene glycols having an average molecular weight of 150 to 20,000.

Further, the polyester used in the present invention has a particle size of 0.1.
It is preferable to contain 0.1 to 1.0% by weight of an inorganic or organic lubricant such as silicon dioxide, calcium carbonate, kaolin, fluororesin particles, or silicone particles of 3 to 3 μm. By adding these inorganic or organic lubricants, a biaxially oriented polyester film having an average surface roughness of 0.03 to 0.3 μm can be obtained. The average surface roughness of the film is 0.
If it is smaller than 03 μm, sufficient slip properties cannot be obtained, and it becomes difficult to wind up. On the other hand, when the average surface roughness is larger than 0.3 μm, when printing with a thermal transfer printer, heat conduction is deteriorated and the printing becomes unclear. If the particle size of the inorganic or organic lubricant to be added is smaller than 0.3 μm, a sufficiently large surface roughness cannot be obtained, and if it is larger than 3 μm, the film tends to be broken in the stretching step.

Further, the polyester used in the present invention may contain a stabilizer, a colorant, an antioxidant, other additives, and the like, if necessary.

In the present invention, the lateral temperature dimensional change curve of the film (hereinafter also referred to as “TMA curve”) refers to a film in which both ends in the lateral direction of the film are gripped and a specific constant load is applied.
A curve in which a film is heated at a constant rate of temperature increase, and the temperature is plotted on the horizontal axis, and the dimensional change rate of the film relative to the original length is plotted on the vertical axis.

The biaxially oriented polyester film used in the present invention has a point at which the gradient of the curve changes from negative to positive (hereinafter referred to as "minimum point") when a temperature dimensional change curve in the transverse direction of the film is measured. The temperature at the minimum point (hereinafter, also simply referred to as “minimum point temperature”) is 200 ° C. or more, and the dimensional change rate with respect to the original length of the film at the minimum point (hereinafter, also simply referred to as “dimensional change rate at the minimum point”) ) Is -5 to +5
%. Minimum point temperature below 200 ° C or 2
When the dimensional change rate of the minimum point is lower than −5% even at 00 ° C. or higher,
Since the shrinkage of the film at the time of printing increases and wrinkles occur on the film, printing cannot be performed. On the other hand, if the dimensional change rate of the minimum point is larger than + 5%, the film is stretched by the heat applied when the ink layer or the back surface treatment layer is applied to the base film. Spots are likely to occur.

The thickness of the biaxially oriented polyester film used in the present invention is preferably 2 to 10 μm, and the F-5 value in the longitudinal direction is 11 to 10 μm.
15 kg / mm ² is preferred. If the thickness exceeds 10 μm, it takes time for heat transfer, which is not suitable for high-speed printing. Conversely, if the thickness is less than 2 μm, the strength is low and the workability is poor, which is not preferable. When the F-5 value is less than 11 kg / mm ² , the ribbon is stretched during running of the ribbon, so that printing becomes unclear or wrinkles are easily generated. When F-5 value exceeding 15 kg / mm ^2,
Since the minimum point of the TMA curve is out of the appropriate range, wrinkles occur during printing.

Next, a method for producing the biaxially oriented polyester film used in the present invention will be described. However, the present invention is not limited to the manufacturing method described below.

First, the polyester is melted and molded into a film by a slit die. This film has a surface temperature of 20 ~
It is wound around a casting drum at 70 ° C and solidified by cooling to form an unstretched film. The unstretched film is stretched in multiple stages at a high magnification, that is, heated to 80 to 130 ° C. in two or more sections, and a total magnification of 4 is obtained by a difference in peripheral speed between rolls.
After stretching to ７7 times, the film is stretched in the transverse direction at 90 to 120 ° C. at 3 to 4 times. Next, after a heat treatment at 210 to 240 ° C. for 5 to 20 seconds, a re-heat treatment is performed at a temperature lower by 10 to 20 ° C. while shrinking by 3 to 10% in a transverse direction to obtain a biaxially oriented polyester film.

In the present invention, the thermal transfer ink layer is not particularly limited, and a known one can be used. That is, a binder component, a coloring component, and the like are used as main components, and a softener, a plasticizer, a dispersant, and the like are added in appropriate amounts as needed. Specific examples of the main component include, as binder components, known waxes such as carnauba wax and paraffin wax and various low-melting polymer materials, and as a coloring agent, mainly carbon black, and other various dyes Alternatively, an organic or inorganic pigment is used. Further, the thermal transfer ink layer may contain a sublimable dye.

As a method of providing the thermal transfer ink layer on one side of the base material layer, a known method, for example, hot melt coating, gravure with a solvent added, reverse, a solution coating method such as a slit die method and the like can be used. . In order to prevent sticking of the thermal head portion, it is preferable to provide a fusion preventing layer such as a silicone resin, a melamine resin, a fluororesin, a silicone oil, or a mineral oil on the side where the thermal transfer ink layer is not provided. Further, it is desirable to provide the anti-fusion layer after unstretching or after longitudinal stretching. This makes it possible to reduce the heat history when processing into a transfer ribbon, and to easily maintain the temperature dimensional change characteristics of the biaxially oriented polyester film within the range of the present invention.

The method for measuring and evaluating the characteristic value specified in the present invention will be described below.

(1) Temperature dimension change curve Measured using TMA (thermal mechanical analyzer) manufactured by PERKIN ELMER. However, the heating rate is 10 ° C /
And the load was 200 g / mm ² .

(2) F-5 value The sample was set on a Tensilon-type tensile tester according to ASTM-D-882 so as to have a test width of 10 mm and a test length of 100 mm, under the conditions of a pulling speed of 200 mm / min, a temperature of 20 ° C, and a humidity of 65% RH. The corresponding strength of the 5% elongation of the film is measured.

(3) Printability Black solid was printed by a bar code printer (BC-8) manufactured by Oaks Co., Ltd., and printability was evaluated according to the following criteria.

：: Clear printing Δ: Pitch shift occurs in printing.

×: Wrinkles appear on the ribbon and printing is disturbed.

XX: Wrinkles are formed on the film during hot melt coating, and the transfer ink cannot be applied uniformly.

〔Example〕

Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited to the following examples.

Example 1 Polyethylene terephthalate containing 0.2% by weight of silicon dioxide having an intrinsic viscosity of 0.61 and a particle size of 1.0 μm, measured by melting o-chlorophenol at 35 ° C., was extruded with an extruder and T
It was melt-extruded into a sheet shape by a die, and was adhered to a water-cooled drum to be cooled and solidified to obtain an amorphous sheet having a thickness of 30 to 120 μm. Multi-stage longitudinal stretching equipment, ie the first stage is 2.2 ° C at 125 ° C
Three-stage longitudinal stretching was carried out at 1.1 times at 125 ° C in the second stage and 2.3 times at 115 ° C in the third stage, a total of 5.6 times.

On one side of this longitudinally stretched film, after coating with a gravure coater so that the coating thickness after drying is 0.5 μm as a fusion-preventing layer, the coating thickness after drying is 110 ° C., 3.8 times in a tenter oven. In the transverse direction. Next, after performing a tension heat treatment at a fixed length at 225 ° C., 6% in a lateral direction at 210 ° C.
Re-heat treatment was performed while shrinking to obtain a biaxially oriented polyester film having a thickness of 5 μm (excluding the coating film).

(Composition of coating agent) Acrylic ester 14.0% by weight Amino-modified silicone 5.9% by weight Isocyanate 0.1% by weight Water 80.0% by weight About the obtained biaxially oriented polyester film, the F-5 value in the longitudinal direction and the temperature in the transverse direction The dimensional change curve was measured, and the temperature at the minimum point and the dimensional change rate at the minimum point were determined. FIG. 1 is a lateral temperature dimensional change curve of the biaxially oriented polyester film of this example, and point A is a minimum point.

Next, a transfer ink having the following composition was applied to a coating having a thickness of 3.5 μm.
Was applied to the surface opposite to the anti-fusing layer using a hot melt coater to obtain a transfer ribbon.

(Composition of Transfer Ink) Carnauba wax 60.6% by weight Microcrystalline wax 18.2% by weight Vinyl acetate / ethylene copolymer 0.1% by weight Carbon black 21.1% by weight Printability of the produced thermal transfer ribbon was evaluated.
Table 1 shows the evaluation results.

Example 2 Polyethylene terephthalate containing 0.2% by weight of silicon dioxide having an intrinsic viscosity of 0.61 and a particle size of 1.0 μm measured by melting o-chlorophenol at 35 ° C. was extruded with an extruder and T
It was melt-extruded into a sheet shape by a die, and was adhered to a water-cooled drum to be cooled and solidified to obtain an amorphous sheet having a thickness of 30 to 120 μm. Multi-stage longitudinal stretching equipment, ie the first stage is 125 ° C, 2.1
After performing three-stage longitudinal stretching at a temperature of 125 ° C. in the second stage and 2.6 times at 115 ° C. in the third stage, and a total of 6.0 times, a transverse stretching of 110 ° C. and 3.8 times in a tenter oven was performed. Next, after performing tension heat treatment at 230 ° C. with a fixed length,
% Heat shrinkage to obtain a biaxially oriented polyester film having a thickness of 5 μm. One side of this film was coated with a coating composition having the following composition as a fusion preventing layer using a gravure coater so that the coating film thickness after drying was 0.2 μm.
Drying was performed at 0 ° C.

(Composition of coating agent) Acrylic ester 14.0% by weight Amino-modified silicone 5.9% by weight Isocyanate 0.1% by weight Toluene 80.0% by weight Next, a transfer ink was applied in the same manner as in Example 1 to prepare a thermal transfer ribbon and evaluated. did. Table 1 shows the evaluation results.

Comparative Example 1 After stretching longitudinally at 2.75 times at 90 ° C., stretching transversely at 100 ° C. and 3.4 times, stretching longitudinally again at 130 ° C. and 2.0 times, and then performing a tensile heat treatment at 220 ° C. A ribbon for thermal transfer was produced and evaluated in the same manner. Table 1 shows the evaluation results.

Comparative Example 2 After performing longitudinal stretching, transverse stretching, and tension heat treatment in the same manner as in Example 1, a transfer ribbon was prepared and evaluated without performing reheat treatment. Table 1 shows the evaluation results.

Comparative Example 3 After performing longitudinal stretching, transverse stretching, and tension heat treatment in the same manner as in Example 1, the heat treatment was performed again while shrinking 12% in the horizontal direction at 215 ° C., and a thermal transfer ribbon was produced and evaluated. Table 1 shows the evaluation results.

[Effect of the Invention] The thermal transfer ribbon of the present invention can obtain clear printing without wrinkles during printing.

[Brief description of the drawings]

FIG. 1 shows a temperature dimensional change curve in a lateral direction of the biaxially oriented polyester film obtained in Example 1. In the drawing, a point A is a point (minimum point) where the slope of the curve changes from negative to positive, a point B indicates a temperature at the minimum point, and a point C indicates a dimensional change rate with respect to the original length of the film at the minimum point. .

Continuation of the front page (56) References JP-A-62-95289 (JP, A) JP-A-2-43022 (JP, A) JP-A-1-186380 (JP, A) JP-A-63-237989 (JP) JP-A-63-170018 (JP, A) JP-A-1-193327 (JP, A) JP-A-63-182331 (JP, A) JP-A-63-178143 (JP, A)

Claims (2)

(57) [Claims] In a thermal transfer ribbon having a biaxially oriented polyester film as a base material layer and a heat transfer ink layer provided on one surface of the base material layer, a lateral temperature dimensional change curve of the biaxially oriented polyester film is obtained. When measured, there is a point where the slope of the curve changes from negative to positive, the temperature at the point is 200 ° C. or more, and the dimensional change rate of the original length of the film at the point is −5 to + 5%. A ribbon for thermal transfer, characterized in that: 2. The biaxially oriented polyester film has a thickness of 2 to 10 μm and an F-5 value in the longitudinal direction of 11 to 15 kg / m 2.
^2. The thermal transfer ribbon according to claim 1, wherein the thermal transfer ribbon is m2.