JPH0247095A - Transfer material for printer - Google Patents

Abstract

PURPOSE:To improve slit properties, dimensional stability, durability by providing a transfer ink layer on one side face of a biaxially oriented polyester film having specific thickness, longitudinal F5 value, refractive index, central line mean roughness critical viscosity on its surface. CONSTITUTION:A transfer ink layer is provided on one side face of a biaxially oriented polyester film having 1-15 of mum of thickness, 12-15kg/mm<2> of longitudinal F5 value, 1.650-1.675 of both longitudinal and lateral refractive indices, 0.02-1mum of central line mean roughness of its surface, and 0.30-0.57 of critical viscosity. Polyester chip having high molecular weight is so dried and melted that the critical viscosity of the film becomes 0.57 or less, extruded in a sheet state from a slitlike die, solidified by cooling by a casting drum to form an unoriented sheet. The sheet is heated to 80-130 deg.C in two or a plurality of zones, so oriented that the total magnification becomes 3 to 7 times by the peripheral speed difference between the rolls, then laterally oriented 3.0-4.5 times at 90-120 deg.C, and then heat treated at 200 deg.C or higher to obtain a film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transfer material for printers, and more particularly to a thermal transfer material that is used in thermal printers and has excellent dimensional stability, durability, and slitting performance.

[Problems to be solved by conventional technology and invention]

Polyester films are suitable as a base for thermal transfer materials for printers because they have excellent properties such as high crystallinity, high melting point, heat resistance, chemical resistance, strength, and elastic modulus. In this heat-sensitive transfer method, the base film is becoming thinner, and a film that is not only high in strength but also has excellent heat-resistant dimensional stability is required.

Furthermore, as the base film becomes thinner, the slitting performance deteriorates when slitting is performed after a transfer material is manufactured by applying a heat-sensitive transfer layer to the base film.

[Means for solving problems]

As a result of intensive studies in view of the above-mentioned problems, the present inventor discovered that by using a polyester film having certain specific physical properties, a thermal transfer material with excellent slitting properties, dimensional stability, and durability can be obtained. invention has been achieved.

That is, the gist of the present invention is that the thickness is /~15μ, the F5 value in the longitudinal direction is 72~/ta kg/ma2, and the refractive index is /, A! ; 0~/, A7 &, a transfer ink layer on one side of a biaxially oriented polyester film whose surface has a center line average roughness of 0.02~/μ and an intrinsic viscosity of 0.30~0.57. A thermal transfer material for a flinter is provided.

The present invention will be explained in detail below.

The polyester referred to in the present invention is a polymer formed by polymerizing an aromatic dicarboxylic acid such as terephthalic acid isophthalic acid and naphthalene-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 condensation. The polyester used in the present invention can be obtained by direct polycondensation of aromatic dicarboxylic acid and glycol, or can be obtained by polycondensation after transesterification of aromatic dicarboxylic acid dialkyl ester and glycol, or by polycondensation of aromatic dicarboxylic acid dialkyl ester and glycol. It can also be obtained by methods such as polycondensation of esters.

Typical such polymers include polyethylene terephthalate, polyethylene-core 6-naphthalate,
Examples include polytetramethylene terephthalate and polytetramethylene-26-naphthalate, such as polyethylene terephthalate and polyethylene-2,2-naphthalate.
Naphthalate is terephthalic acid or naphthalene, A
- Not only polyesters in which dicarboxylic acid and ethylene glycol are bonded, but also polyesters in which 0 mol% or more of the repeating units consist of ethylene terephthalate or ethylene-2,2-naphthalate units, and 2θ mol% or less of the repeating units are other components. These are polymerized polyesters or mixed polyesters obtained by adding and mixing other polymers to these polyesters.

The polyester film used in the present invention has a center line average roughness (Ra) of 0.0 ~/μ at least on one side.
, preferably in the range of 0.0 Hiro to O1 gμ. If Ra is less than 0.02μ, slipperiness deteriorates, wrinkles may appear in the film, trouble during processing, and even sticking of the thermal head portion may occur, which is undesirable.

If it exceeds Rah'-00gμ, the print will lack clarity,
This poses a practical problem as it causes a decrease in sensitivity and wear of the thermal head.

One method for obtaining a film with such surface roughness is to apply a phosphorus compound or the like to a metal compound dissolved in the reaction system during the production of polyethylene naphthalate, for example, a metal compound dissolved in the yarn after the transesterification reaction. There is a so-called precipitated particle method, in which fine particles are precipitated.

However, since this method has a limit on 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 polyester either in the polyester manufacturing process or in the extrusion process before film formation.These inert fine particles include, for example, kaolin, Merck, magnesium carbonate, etc. , calcium carbonate, barium carbonate, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, aluminum oxide, silicon oxide, titanium oxide, lithium fluoride, etc., and Ca, Ba, Zn, Mn.
Examples include, but are not limited to, seven or more metal compounds selected from terephthalates such as, carbon blanks, etc.

The shape of this inert compound may be spherical, blocky or flat, and there are no particular limitations on its hardness, specific gravity, color, etc.

Further, the average particle size of the inert compound is usually selected from the range of O1/~10μ, preferably 0.3~3μ in terms of equivalent spherical diameter. In addition, the blending amount for the film is 307~
5% by weight, preferably 0.05-3% by weight, more preferably 0.05% by weight. selected from the range of OS-cowt%. Also,
Various resins and lubricants may be applied for the same purpose, or known methods such as composite of roughened film, promotion of crystallization of film after melt extrusion, sand mat method, chemical treatment method, coating cloak, etc. may be used as appropriate. It can also be applied.

The polyester film used in the present invention is biaxially oriented, and the F5 value in the longitudinal direction of the film is 72-/
! kg/mm", preferably l/'l
kg/mx2. F5 value is /2kg/rA-
If it is less than /kg/, the shrinkage rate will be too high and it is unsuitable.

Further, the refractive index of the polyester film used in the present invention is /, Ota 0 ~ /, A? in both the longitudinal and lateral directions of the film.
Evening, preferably/A S! It is in the range of r~/, A70. If the refractive index is less than 0, the film will stretch due to the printing pressure, and if it exceeds the refractive index, the film will easily tear due to the printing pressure, which is inappropriate.

Moreover, the thickness of the polyester film used in the present invention is /
-1μ, preferably 2-10μ. If the film thickness is thicker than /μ, heat transfer takes time and it is not suitable for high-speed recording.On the other hand, if it is thinner than /μ, the strength is low and the processability is undesirable.

Further, the polyester film used in the present invention satisfies the above-mentioned various physical properties and has an intrinsic viscosity of 0.3θ to 0.3θ.
Must be in the range 57.

Preferably 0. lI left ~ 0.37, more preferably 0.
50~θ, 5pm. The intrinsic viscosity of the film is 0.30
If it is less than that, there will be many breaks during film formation, resulting in a decrease in productivity and, as a result, an increase in cost. On the other hand, the intrinsic viscosity of the film is 0. ! If it exceeds '7', it is unsuitable because the slitting properties of the film after being used as a transfer material are poor.

Further, it is preferable that the polyester film used in the present invention has a heat shrinkage rate of 3% or less at /0°C for /5 minutes in both the longitudinal and transverse directions of the film. More preferably, it is 2% or less. If the thermal shrinkage rate is greater than 3%, it is not preferable because shrinkage occurs during the process of processing into a transfer material for a printer, resulting in worsening of thickness unevenness and a decrease in yield.

Further, the film used in the present invention has a degree of plane orientation ΔP of 0.
/! ! r~0. /6g is preferable. More preferably 0. The range is / &0-o, /Ari. Planar orientation degree ΔP is 0. / & If it is less than 3, the strength of the film is too low and is inappropriate. - direction, o,
/ A g is undesirable because it tends to tear the film.

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

First, polyester tinog whose intrinsic viscosity in the film is adjusted to be 0.57 or less is dried, melted, extruded into a sheet using a slit-like die, and preferably adhered using an electrostatic adhesion method to a casting drum. The sheet is cooled and solidified to form an unstretched sheet, and the sheet is subjected to high-temperature longitudinal stretching at a high magnification in the longitudinal direction in multiple stages, that is, heated to 30°C to 30°C in multiple sections of 1 or more. After stretching so that the total magnification is 3 to 7 times depending on the difference in circumferential speed between 90~/ko0℃1, ? , 0-F, and 5 times, and then heat-treated at 200° C. or higher, preferably 230° C. or higher, to obtain a biaxially oriented polyester film.

If necessary, within the scope of the present invention, the above-mentioned transverse stretching may be followed by longitudinal stretching at a stretching temperature of 95 to 0°C and a stretching ratio of 7.03 or more to 2.5 times or less for heat treatment. Furthermore, after the transverse stretching, a biaxially oriented polyester film can be obtained by performing heat treatment.

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

The transfer ink of the present invention is not particularly limited,
Well-known ones can be used.

Specifically, the main components are a binder component, a coloring component, etc., and if necessary, a softener, a flexibilizer, a melting point regulator, a smoothing agent, a dispersant, etc. may be mixed as additive components.

As specific examples of the above-mentioned main components, well-known waxes such as paraffin wax, carnauba wax, and ester wax are useful as binder components, and various low-melting point polymers are useful, and as colorant components, carbon black and various Organic and inorganic pigments or dyes are useful. In addition, sublimable inks are also included.

As a method for providing the transfer ink layer on one side of the film of the present invention, well-known methods such as hot melt coating and solution coating methods such as gravure, reverse, and slit die methods with the addition of a solvent can be used. can.

In addition, 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-fusion layer on the side of the film where the transfer ink layer is not provided.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to the following examples unless it exceeds the gist thereof. The methods for evaluating the characteristics of the film and thermal transfer material are shown below.

■ A sample film with an F5 value of 1/2 inches wide and a chuck distance of
) at 20°C and 63% RH in the evening Oma/min.
Divide the load at 5% elongation by the initial cross-sectional area,
Expressed in kg/mg2.

■ Intrinsic viscosity [η] Add 200 m9 of the sample to a mixed solution of phenol/tetrachloroethane = s o / s o: lomi,
Measurement was performed at 30°C after heating and dissolving at approximately 10°C/hour.

(2) Birefringence Using a polarizing microscope equipped with a Berek compensator, retardation was measured at room temperature and humidity by directing NaD rays perpendicularly to the film surface, and the birefringence was calculated by dividing by the thickness.

■ Heat shrinkage rate Measured after being left in an open, stress-free state at 150°C for 5 minutes. The original length was taken as llo and the length after measurement was determined using the following formula.

Heat shrinkage rate (%) = (llo 11) / 7o
X/θO■Refractive index The refractive index in two directions, vertical and horizontal, was measured at room temperature and pressure using an Na-D line using an Abbe refractometer.

■ Evaluation of slitting properties After creating a transfer material with a transfer ink layer on a polyester film, it was slit to a predetermined width of 1,000 m, and there was no breakage at the time of slitting, no bulging on the end surface, and no winding properties after slitting. (○ if there were no problems,
×, those that clearly did not become a product and caused a decrease in yield.
The middle point is shown as △.

■ Surface roughness Measured according to JISB-OAO/.

Example Polyethylene terephthalate having an intrinsic viscosity of 0657 and containing 0.3% by weight of calcium carbonate was melt-extruded into a sheet and cooled and solidified on a casting drum to obtain an amorphous unstretched sheet. The obtained unstretched sheet is
First, it was stretched 7.0 times in the machine direction at ior°C, then stretched /, /5 times at 700 °C, then stretched 3.9 times in the transverse direction, and then stretched again in the machine direction /, uO times. 70 at 3°C
Heat fixed for seconds. A transfer ink layer was applied to one side of the thus obtained tμ film, and 6mM! A transfer material was obtained by making widthwise slits.

Comparative Example In the example, the intrinsic viscosity was 0. A transfer material was obtained in the same manner as in the example except that polyethylene terephthalate (&j) was used.

The results obtained above are summarized in Table-/.

table / 〔Effect of the invention〕 The thermal transfer material of the present invention has durability, printability, vinegar Li Invading sex, Its industrial value is high.

Claims (1)

[Claims] (1) Thickness is 1-15μ, vertical F_5 value is 12-1
5kg/mm^2, refractive index 1.650 in both vertical and horizontal directions
~1.675, surface centerline average roughness 0.02~1μ
A thermal transfer material for printers, comprising a biaxially oriented polyester film having an intrinsic viscosity of 0.30 to 0.57, and a transfer ink layer provided on one side of the film.