JPH1024665A - Thermal transfer ribbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer ribbon excellent in printability, capable of obtaining clear print without generating wrinkles at the time of print. SOLUTION: In 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, a gradient of a temperature dimensional change curve in a width direction of the biaxially oriented polyester film. Is 160 to 200
There is a point A where the temperature changes from positive to negative between 0 ° C., and the dimensional change rate with respect to the original length of the film at the point A is 0.5.
２．５2.5%, and the slope of the curve is 200
There is a point B at which the temperature changes from negative to positive between ２３０230 ° C., and the dimensional change rate with respect to the original length of the film at the point B is in the range of −0.5 to −2%. Thermal transfer ribbon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A biaxially oriented polyester film is used as a base of a transfer material for a thermal transfer printer because of its excellent properties such as high crystallinity, high melting point, heat resistance, strength, elastic modulus and chemical resistance. ing. For the transfer material, the base film is required to be as thin as possible in the thermal transfer system, so that it is required to have high strength and to minimize deformation due to heat.

[0003]

In recent years, as the printing speed has been required to be increased, the energy applied by the thermal head during printing has been increased, and as a result, the amount of heat received by the thermal transfer printer ribbon has been increased. I have. 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, and wrinkles are generated on the ribbon. There was a need for improvement in this regard.

An object of the present invention is to provide a thermal transfer ribbon excellent in printability, which can solve such a problem.

[0005]

In order to solve the above-mentioned problems, a ribbon for thermal transfer according to the present invention comprises a biaxially oriented polyester film as a base layer, and a heat transfer ink layer provided on one surface of the base layer. In the thermal transfer ribbon, there is a point A where the gradient of the temperature dimensional change curve in the width direction of the biaxially oriented polyester film changes from positive to negative between 160 and 200 ° C., and the film origin at the point A is changed. A dimensional change rate with respect to the length is in the range of 0.5 to 2.5%, and further, there is a point B where the slope of the curve changes from negative to positive between 200 and 230 ° C., and at this point B The dimensional change rate with respect to the original length of the film is in the range of -0.5 to -2%.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a polyester is a condensation polymer containing an ester group obtained by a condensation method from a dicarboxylic acid component and a diol component. Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, and sebacic acid. Examples of the diol component include ethylene glycol, diethylene glycol, butanediol, and hexane. Diol, neopentyl glycol, p-xylene glycol, 1,4-cyclohexanedimethanol, average molecular weight 150 to 20,000
Can be used.

The polyester used in the present invention may contain an inorganic or organic lubricant such as colloidal silica, agglomerated silica, alumina, calcium carbonate, kaolin, fluororesin particles, silicone particles, and the like. More than one species may be added. The average particle diameter of the particles mainly added is preferably 0.1 to 5 μm, more preferably 0.3 to 3 μm.
μm is preferred. Those having different average particle sizes may be added. When the particle size of the inorganic or organic lubricant to be added is 0.1 μm or more, sufficient lubricity can be obtained, so that the ribbon can be easily wound. If it is larger than 5 μm,
Breakage is likely to occur in the film stretching step, and the productivity is reduced.

[0008] The polyester used in the present invention may contain a stabilizer, a colorant, an antioxidant, and other additives as necessary.

In the present invention, a temperature dimensional change curve in the film width direction (hereinafter also referred to as a "TMA curve") is defined as a film having a constant rise while holding both ends in the width direction of the film and applying a specific constant load. A curve in which a film is heated at a temperature rate, and the temperature is plotted on the horizontal axis, and the dimensional change rate with respect to the original length of the film is plotted on the vertical axis.

In the biaxially oriented polyester film used in the present invention, when a dimensional change curve in the width direction of the film is measured, a point A at which the slope of the curve changes from positive to negative.
(Hereinafter referred to as “maximum point”), and the temperature at the maximum point A (hereinafter, also simply referred to as “maximum point temperature”) is 160 ° C.
２００200 ° C., and the dimensional change with respect to the original length of the film at the maximum point A (hereinafter simply referred to as “dimensional change rate at the maximum point”).
) Is 0.5 to 2.5%. In addition to it,
When a dimensional change curve in the width direction of the film is measured, the curve has a point B (hereinafter, referred to as a "minimum point") where the gradient of the curve changes from negative to positive, and the temperature at the minimal point B (hereinafter, "point"). The temperature at the minimum point B is 200 ° C. to 230 ° C., and the dimensional change of the film at the minimum point B with respect to the original length of the film (hereinafter, also simply referred to as the “dimensional change rate of the minimum point”) is −0.5 to -2%.

If the temperature at the maximum point A is lower or higher than 160 ° C. to 200 ° C., or the dimensional change rate at the maximum point A is lower than 0.5% even at 160 ° C. to 200 ° C., the film shrinks during printing. And the film becomes wrinkled, so that printing cannot be performed. Further, when the dimensional change rate of the maximum point A is larger than 2.5%, the film elongation due to the heat applied when applying the back surface treatment layer or the ink layer to the base film becomes large, so that the film sags at the time of coating. , Coating streaks and coating unevenness are likely to occur. Further, if the temperature of the minimum point B is lower or higher than 200 ° C. to 230 ° C., or if the dimensional change rate of the minimum point B is lower than −2% even at 200 ° C. to 230 ° C., the film shrinks greatly during printing. Since the film is wrinkled, printing cannot be performed. Further, when the dimensional change rate of the minimum point B is larger than -0.5%, the elongation of the film due to the heat applied when applying the back surface treatment layer or the ink layer to the base film becomes large. Slack, coating streaks and coating unevenness are likely to occur.

The thickness of the biaxially oriented polyester film used in the present invention is preferably in the range of 1 to 10 μm, more preferably 1.5 to 7 μm, and the F-5 value in the longitudinal direction is 98 MPa or more is preferable. Thickness 1
If it exceeds 0 μm, it takes a long time for heat transfer, which is not suitable for high-speed printing. Conversely, if the thickness is less than 1 μm, the strength is low and the workability is poor, which is not preferable. F-5 value is 98M
When it is less than Pa, the ribbon is stretched during running of the ribbon, so that printing becomes unclear or wrinkles are easily generated.

The average surface roughness of the film is preferably 0.03 to 0.3 μm, more preferably 0.05 to 0.
2 μm. If the average surface roughness is smaller than 0.03 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, the thermal conductivity is deteriorated and the printing becomes unclear.

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 formed into a film shape by a die having a slit-shaped discharge port. This film,
The film is wound around a casting drum having a surface temperature of 20 ° C. to 70 ° C., cooled and solidified to obtain an unstretched film. The unstretched film is heated to 80 ° C. to 130 ° C. and stretched in one or more stages in the longitudinal direction so that the total magnification becomes 4 to 7 times depending on the peripheral speed difference between the rolls. 3
Stretch in the width direction up to 6 times. Then from 210 ° C to 24
After heat treatment at 0 ° C. for 1 to 20 seconds, re-heat treatment is performed at 0 ° C. to 150 ° C. lower than the heat treatment temperature while shrinking by 0 to 10% in the width direction to obtain a biaxially oriented polyester film.

In the present invention, the thermal transfer ink layer is not particularly limited, and comprises a binder component, a coloring component, and the like as main components, and if necessary, an appropriate amount of a softener, a plasticizer, a dispersant, and the like. Is done. Specific examples of the main component include, as a binder component, carnauba wax, waxes such as paraffin wax and various low-melting polymer materials are used, and as a coloring agent, mainly carbon black, other various dyes, or Organic and inorganic pigments are used. Further, the thermal transfer ink layer may include a sublimable dye.

As a method for providing the thermal transfer ink layer on one surface of the substrate layer, for example, a hot melt coating, a solution coating method such as a gravure, reverse, slit die method or the like with a solvent added can be used. In order to prevent sticking of the thermal head, it is preferable to provide a fusion preventing layer of a silicone resin, a melamine resin, a fluororesin, a silicone oil, a mineral oil or the like 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 values specified in the present invention will be described below. (1) Temperature dimension change curve Measured using a TMA (thermal mechanical analyzer) manufactured by PERKIN ELMER. However, the heating rate was 10 ° C./min, the length of the measurement sample was 14 mm, the width was 5 mm, and the tension was 50 mN.

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

(3) Printability Black solid was printed by a fax machine FAX-1350M manufactured by Brother Industries, Ltd., and printability was evaluated according to the following criteria. : Clear printing (no wrinkles on the ribbon) △: Clear printing but wrinkles on the ribbon ×: Wrinkles on the ribbon and disturbed printing XX: On the film during hot melt coating Each sample was wrinkled and the transfer ink could not be applied uniformly. Each sample was tested 5 times under the same conditions, and when all of the above criteria were ○, the samples were passed.

(4) Average surface roughness Based on JIS-B0601, using a stylus type surface roughness meter 3E-3F manufactured by Kosaka Laboratory Co., Ltd. under the conditions of a measurement length of 2.5 mm and a cutoff value of 0.25 mm. Was used to measure the average surface roughness Ra.

(5) Intrinsic viscosity Measured at 25 ° C. using an o-chlorophenol solvent.

[0022]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to the examples. Example 1 Polyethylene terephthalate containing 0.3% by weight of silicon dioxide having an average particle diameter of 1 μm and having an intrinsic viscosity of 0.61 is melt-extruded into a sheet shape by an extruder and a T-die, and is closely adhered to a water-cooled drum and cooled. Solidification yielded an amorphous sheet. This unstretched film is stretched 6.1 times in the longitudinal direction at 125 ° C. by a roll stretching method, and further guided to a stenter.
The film was stretched 3.7 times in the width direction at 0 ° C. Next, it is led to the heat treatment zone as it is, heat-set at 225 ° C. for 3 seconds, and further relaxed at 200 ° C. in the width direction by 2%.
After being guided to an intermediate cooling chamber at 0 ° C., where the intermediate cooling is performed, relaxation of 2% of the original length is given in the width direction, and the biaxial shaft having a thickness of 4.5 μm is gradually cooled and wound up. An oriented polyester film was obtained.

With respect to the obtained biaxially oriented polyester film, the F-5 value in the longitudinal direction and the temperature dimensional change curve in the horizontal direction were measured, and the temperature and the dimensional change rate at the maximum point A and the temperature and the size at the minimum point B were measured. The rate of change was determined. FIG. 1 shows the temperature dimensional change rate in the width direction of the biaxially oriented polyester film of Example 1, where point A is the point where the slope of the curve changes from positive to negative (maximum point), and point C is the maximum. The temperature at the point is shown, and the point E shows the dimensional change rate with respect to the original length of the film at the maximum point. Point B is a point where the slope of the curve changes from negative to positive (minimum point), point D indicates the temperature at the minimum point, and point F indicates the dimensional change rate of the film at the minimum point with respect to the original length of the film.

Next, a coating having the following composition as a heat-resistant and lubricious layer was dried on one side of this film to a coating thickness of 0.1 μm.
Was coated with a gravure coater. (Composition of coating agent) Acrylate: 14.0% by weight Amino-modified silicone: 5.9% by weight Isocyanate: 0.1% by weight Water: 80.0% by weight

Subsequently, a transfer ink having the following composition was applied to the surface opposite to the heat-resistant / easy-slip layer with a hot melt coater so that the thickness of the coating film became 3.5 μm, thereby producing a thermal 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 Regarding the produced thermal transfer ribbon The printability was evaluated. Table 1 shows the evaluation results.

Example 2 Polyethylene terephthalate having an intrinsic viscosity of 0.61 and containing 0.3% by weight of silicon dioxide having an average particle diameter of 1 μm was melt-extruded into a sheet by an extruder and a T-die, and brought into close contact with a water-cooled drum. After cooling and solidification, an amorphous sheet was obtained. This unstretched film is stretched 4.65 times in the longitudinal direction at 125 ° C. by a roll stretching method, and further guided to a stenter.
The film was stretched 4 times in the width direction at 0 ° C. Next, the mixture was directly guided to a heat treatment zone, and heat treatment was performed at 115 ° C. while relaxing 0.39% in the width direction. Subsequently, the film was stretched 1.025 times in the longitudinal direction again at 110 ° C., and led to a stenter.
C. for 1.5 seconds under tension and heat, relaxed in the 6% width direction, slowly cooled and wound up to obtain a biaxially oriented polyester film having a thickness of 4.5 .mu.m. Next, Example 1 was applied to the obtained biaxially oriented polyester film.
In the same manner as described above, a heat-resistant / easy-to-slide layer and a transfer ink layer were applied to prepare a thermal transfer ribbon. The printability of the produced thermal transfer ribbon was evaluated. Table 1 shows the evaluation results.

Comparative Example 1 An amorphous sheet obtained in the same manner as in Example 1 was heated at 125 ° C.
After stretching 6.1 times longitudinally at 110 ° C., stretched 3.7 times in the width direction at 110 ° C., and heat-fixed at 225 ° C. for 1.5 seconds, 225 ° C.
Then, a thermal transfer ribbon was prepared and evaluated in the same manner as in Example 1, except that the thermal transfer ribbon was relaxed by 2% at 210 ° C. and then by 2%. Table 1 shows the evaluation results.

Comparative Example 2 An amorphous sheet was obtained in the same manner as in Example 1 and subjected to longitudinal stretching and transverse stretching.
After relaxing at 2.9% at 200 ° C. and then at 2.9% at 200 ° C., a thermal transfer ribbon was produced and evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.

Comparative Example 3 An amorphous sheet was obtained in the same manner as in Example 1 and subjected to longitudinal stretching and transverse stretching.
After relaxing at 2.5 ° C. by 2.5% and then at 200 ° C. by 1.5%, a thermal transfer ribbon was prepared and evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.

[0030]

[Table 1]

[0031]

According to the ribbon for thermal transfer of the present invention, clear printing can be obtained without wrinkles during printing.

[Brief description of the drawings]

FIG. 1 is a temperature dimensional change curve in the width direction of a biaxially oriented polyester film obtained in Example 1.

[Explanation of symbols]

 A Point where the gradient changes from positive to negative (maximum point) B Point where the gradient changes from negative to positive (minimum point)

Claims (2)

[Claims] 1. A thermal transfer ribbon in which a biaxially oriented polyester film is used as a base material layer and a heat transfer ink layer is provided on one surface of the base material layer, the temperature dimensional change curve of the biaxially oriented polyester film in the width direction is obtained. Gradient 160-200
There is a point A where the temperature changes from positive to negative between 0 ° C., and the dimensional change rate with respect to the original length of the film at the point A is 0.5.
２．５2.5%, and the slope of the curve is 200
There is a point B at which the temperature changes from negative to positive between ２３０230 ° C., and the dimensional change rate with respect to the original length of the film at the point B is in the range of −0.5 to −2%. Thermal transfer ribbon. 2. The biaxially oriented polyester film has a thickness in the range of 1 to 10 μm, and has a vertical and horizontal F
The thermal transfer ribbon according to claim 1, wherein each of the -5 values is 98 MPa or more.