JP2733974B2 - Thermal transfer material for printer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer material for a printer, and more particularly to a heat-sensitive transfer material excellent in dimensional stability, durability and slitting properties used for a thermal printer.

[Problems to be solved by conventional technology and invention]

As a base of a thermal transfer material for a printer, a polyester film is suitable because it has excellent properties such as high crystallinity, high melting point, heat resistance, chemical resistance, strength, and elastic modulus. In the thermal transfer method, the base film is made thinner, and a film having high strength and excellent heat resistance dimensional stability is required.

Further, as the base film is made thinner, the slitting property is deteriorated when a heat transfer layer is applied to the base film to produce a transfer material and then slit.

[Means for solving the problem]

The present inventor has conducted intensive studies in view of the above problems,
It has been found that a heat-sensitive transfer material excellent in slitting property, dimensional stability and durability can be obtained by using a polyester film having certain specific properties, and the present invention has been achieved.

That is, the gist of the present invention is that the thickness is 1 to 15 μ,
F ₅ value 12~15kg / mm ^2, refractive index longitudinal, 1.650～ laterally both
1.675, transfer ink on one surface of a biaxially oriented polyester film having a surface centerline average roughness of 0.02 to 1μ and an intrinsic viscosity of 0.30 to 0.57 measured in a mixed solution of phenol / tetrachloroethane = 50/50. It is in a thermal transfer material for printers provided with a layer.

 Hereinafter, the present invention will be described in detail.

The polyester referred to in the present invention is an aromatic dicarboxylic acid such as terephthalic acid isophthalic acid, and naphthalene-2,6-dicarboxylic acid, or an ester thereof and a diol such as ethylene glycol, diethylene glycol, tetramethylene glycol, and neopentyl glycol. It is a crystalline aromatic polyester that can be obtained by polycondensation. The polyester used in the present invention is obtained by directly polycondensing an aromatic dicarboxylic acid and a glycol, and is also subjected to a transesterification reaction between an aromatic dicarboxylic acid dialkyl ester and a glycol, followed by polycondensation, or a diglycol of an aromatic dicarboxylic acid. It can also be obtained by a method such as polycondensation of an ester.

Representative of such polymers are polyethylene terephthalate, polyethylene-2,6-naphthalate,
Examples include polytetramethylene terephthalate and polytetramethylene-2,6-naphthalate.For example, polyethylene terephthalate, and polyethylene-2,6-naphthalate are terephthalic acid or naphthalene-2,6-dicarboxylic acid and ethylene glycol combined. Not only polyesters, but also copolymer polyesters in which 80 mol% or more of the repeating units are composed of ethylene terephthalate or ethylene-2,6-naphthalate units and 20 mol% or less of the repeating units are other components, or other polyesters It is a mixed polyester obtained by adding and mixing a polymer.

The polyester film used in the present invention has at least one surface having a center line average roughness (Ra) in the range of 0.02 to 1 µ, preferably 0.04 to 0.8 µ. If Ra is less than 0.02μ, the slipperiness will worsen, the film will wrinkle,
It is not preferable because troubles during processing and sticking of the thermal head portion occur. If Ra exceeds 0.8 μ, the printing lacks sharpness, lowers the sensitivity and causes wear of the thermal head, which is a practical problem.

One of the methods for obtaining a film having such a surface roughness is to act a phosphorus compound or the like on a metal compound dissolved in the reaction system during the production of polyethylene naphthalate, for example, a metal compound dissolved in the system after the transesterification reaction. There is a method of depositing fine particles by so-called deposition particle method. However, since this method has a limit in the amount of precipitated particles, another so-called additive particle method is preferably used. In other words, the additive particle method is a method in which inert fine particles are blended into the polyester in any of the steps from the polyester production step to the extrusion step before film formation. Examples of the inert particles include kaolin, talc, magnesium carbonate, and the like. , Calcium carbonate, barium carbonate, calcium sulfate,
One or more metal compounds selected from barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, aluminum oxide, silicon oxide, titanium oxide, lithium fluoride, and terephthalates such as Ca, Ba, Zn, and Mn Alternatively, carbon black and the like can be cited, but are not limited thereto.

The shape of the inert compound may be spherical, massive or flat, and its hardness, specific gravity, color,
There is no particular limitation on the like. The average particle size of the inert compound is usually 0.1 to 10 μm in equivalent sphere diameter, preferably
It is selected from the range of 0.3 to 3μ. The compounding amount of the film is selected from the range of 0.01 to 5% by weight, preferably 0.05 to 3% by weight, and more preferably 0.05 to 2% by weight. In addition, various resins and lubricants may be applied for the same purpose, or a known method such as composite of a roughened film, promotion of crystallization of a film after melt extrusion, a sand mat method, a chemical treatment method, and a coating mat. Can be applied as appropriate.

Polyester film used in the present invention, which has been biaxially oriented, vertical F ₅ value of the film 12~15kg
/ mm ^2, preferably in the range of 12~14kg / mm ^2. F ₅ value of 12
If it is less than kg / mm ^2, it is easy to stretch and it is difficult to recover elasticity. On the other hand, if it exceeds 15 kg / mm ² , the shrinkage becomes too high, which is inappropriate.

The refractive index of the polyester film used in the present invention is in the range of 1.650 to 1.675, preferably 1.655 to 1.670, in both the longitudinal and transverse directions of the film. When the refractive index is less than 1.650, the film is stretched by the printing pressure, and when it exceeds 1.675, the film is easily torn by the printing pressure, which is inappropriate.

The thickness of the polyester film used in the present invention is 1 to 15 μ, preferably 2 to 10 μ. If the thickness of the film is more than 15 μm, heat transfer takes a long time, which is not suitable for high-speed recording. Conversely, if the thickness is less than 1 μm, the strength is low and the workability is poor, which is not preferable.

Further, the polyester film used in the present invention must satisfy the above various physical properties and have an intrinsic viscosity of the film in the range of 0.30 to 0.57. Preferably it is 0.45-0.57, More preferably, it is 0.50-0.55. The intrinsic viscosity of the film is 0.
If it is less than 30, breakage at the time of film formation is increased and productivity is lowered, and the cost is increased.
On the other hand, if the intrinsic viscosity of the film exceeds 0.57, it is inappropriate because the film has poor slitting properties after being used as a transfer material.

Further, the polyester film used in the present invention has a heat shrinkage rate of 3 hours at 150 ° C. for 15 minutes in both the longitudinal and transverse directions of the film.
% Is preferable. More preferably, it is at most 2%. When the heat shrinkage is more than 3%, it is not preferable because shrinkage is caused in the process of processing into a transfer material for a printer, thereby causing unevenness in thickness and reduction in yield.

Further, the film used in the present invention has a plane orientation degree ΔP of 0.
Preferably it is in the range of 145 to 0.168. More preferably, it is in the range of 0.150 to 0.165. When the degree of plane orientation ΔP is less than 0.145, the strength of the film is too low, which is inappropriate. on the other hand,
If the film exceeds 0.168, the film is likely to tear, which is not preferable.

Next, the method for producing a transfer material of the present invention will be specifically described, but is not limited to the following production examples.

First, a polyester chip adjusted to have an intrinsic viscosity of 0.57 or less in a film is dried, melted, extruded into a sheet from a slit-shaped die, and preferably cooled and solidified by a casting drum while being adhered by an electrostatic adhesion method. A non-stretched sheet is formed, and the sheet is vertically stretched in multiple stages at a high magnification in a high-magnification direction, that is, heated to 80 ° C. to 130 ° C. in two or more sections, and the peripheral speed difference between the rolls. After stretching so that the total magnification becomes 3 to 7 times, 90
The film is transversely stretched at a temperature of up to 120 ° C. and 3.0 to 4.5 times and then heat-treated at a temperature of 200 ° C. or higher, preferably 230 ° C. or higher, to obtain a biaxially oriented polyester film. Further, if necessary, within the scope of the present invention, after the above-mentioned transverse stretching, a stretching temperature of 95 to 120 ° C., a re-longitudinal stretching of a stretching ratio of 1.03 or more to 2.5 times or more, and heat-treating. To obtain a biaxially oriented polyester film.

Next, a transfer ink layer is formed on the biaxially oriented polyester film of the present invention obtained as described above. that time,
If necessary, a pretreatment such as a corona discharge treatment or an undercoat may be performed.

The transfer ink of the present invention is not particularly limited, and a known ink can be used. Specifically, a binder component, a coloring component, or the like may be used as a main component, and a softener, a flexible agent, a melting point regulator, a leveling agent, a dispersant, or the like may be mixed as an additive component as needed.

As specific examples of the main component, well-known waxes such as paraffin wax, carnauba wax, and ester wax as binder components, and various polymers having a low melting point are useful. Organic or inorganic pigments or dyes are useful. Inks include sublimable inks.

As a method for providing the transfer ink layer on one side of the film of the present invention, known methods, for example, hot melt coating, gravure with a solvent added, reverse, using a solution coating method such as a slit die method and the like it can.

When the transfer material is used as a thermal transfer material,
In order to prevent sticking of the thermal head portion, it is desirable to provide a known anti-fusing layer on the side of the film where the transfer ink layer is not provided.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to the following Examples as long as the gist is not exceeded. The method for evaluating the characteristics of the film and the thermal transfer material is described below.

F ₅ value 1/2 inch width, sample film with 50 mm length between chucks,
Tensileon (UTN-III) manufactured by Toyo Baldwin Co., Ltd. was pulled at 50 mm / min at 20 ° C. and 65% RH, and the load at 5% elongation was divided by the initial cross-sectional area and expressed in kg / mm ² .

Intrinsic viscosity [η] A sample of 200 mg was phenol / tetrachloroethane = 50 /
Add to 50 ml of a mixed solution of 50 and heat and dissolve at 110 ° C for 1 hour.
Measured at 0 ° C.

Birefringence NaD using a polarizing microscope equipped with a Berek compensator
The line was perpendicularly incident on the film surface, the retardation was measured at room temperature and normal humidity, and the film was divided by the thickness to calculate the birefringence.

Heat shrinkage Measured at 150 ° C. for 5 minutes in an oven without tension. The original length was l ₀ , and the length after measurement was l, which was determined by the following equation.

Thermal shrinkage (%) = (l ₀ −l) / l ₀ × 100 Refractive index The refractive index in the vertical and horizontal directions was measured at room temperature and normal pressure using a Na-D line with an Abbe refractometer.

Evaluation of slitting property After preparing a transfer material by providing a transfer ink layer of a polyester film, slit it to a predetermined width and slit it to 1000 m, cut at the time of slitting, cut off at the end, swelling of the end face, and there is no problem with winding property after slitting ○
Those that clearly reduced the yield without becoming a product ×,
The middle is indicated by Δ.

 Surface roughness Measured according to JIS B-0601.

Example Intrinsic viscosity is 0.57, and calcium carbonate is 0.3% by weight.
The contained polyethylene terephthalate was melt-extruded into a sheet and cooled and solidified on a casting drum to obtain an amorphous unstretched sheet. First, the obtained unstretched sheet is
Stretched 3.0 times longitudinally at 105 ° C, stretched 1.15 times at 100 ° C,
Next, the film was stretched 3.9 times in the transverse direction, further stretched 1.20 times in the machine direction, and heat-set at 232 ° C. for 10 seconds. Apply a transfer ink layer to one side of the 4μ film thus obtained, and
The sheet was slit to a width to obtain a transfer material.

Comparative Example A transfer material was obtained in the same manner as in Example except that polyethylene terephthalate having an intrinsic viscosity of 0.65 was used.

 The results obtained above are summarized in Table 1.

[Effects of the Invention] The heat-sensitive transfer material of the present invention is excellent in durability, printability and slitting property, and its industrial value is high.

Claims (1)

(57) [Claims] 1. A thickness 1~15μ, F ₅ value in the longitudinal direction 12~15kg
/ mm ² , the refractive index is 1.650 to 1.675 in both the vertical and horizontal directions, the center line average roughness of the surface is 0.02 to 1 μm, and the intrinsic viscosity measured in a mixed solution of phenol / tetrachloroethane = 50/50 is 0.30. A heat-sensitive transfer material for printers comprising a biaxially oriented polyester film having a transfer ink layer on one side of 0.57.