JPH02206591A - Transfer medium for printer - Google Patents

Abstract

PURPOSE:To improve dimensional stability, durability, thickness uniformity, and the like by a method wherein a transfer medium for printer is formed by providing a transfer ink layer on one surface of a biaxially oriented polyester film having specific characteristics, such as coefficient of heat contraction and tensile strength. CONSTITUTION:A polyester containing fine particles of kaoline or the like and additives such as a stabilizer is extruded, cooled, and solidified to form an unoriented polyester film. This amorphous film is longitudinally oriented by a magnification ranging 4.0-9.0 and, thereafter, laterally oriented by a magnification of 3.2 or more to form a biaxially oriented film. A transfer ink layer is provided on one surface of the biaxially oriented film to form a transfer medium for printer. The obtained transfer medium for printer is superior in dimensional stability, durability, thickness uniformity, running properties, and printing characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transfer material for printers. More specifically, the present invention relates to an ink transfer material that is used in typewriters and thermal printers and has excellent dimensional stability, durability, thickness unevenness, runnability, and printing characteristics.

[Prior art and problems to be solved by the invention] As a base material for transfer materials for printers, polyester film has excellent properties such as high crystallinity, high melting point, heat resistance, chemical resistance, strength, and elastic modulus. It is used because it has

Dot impact type transfer materials for typewriters and printers must be durable enough to withstand the tension and printing pressure applied to the transfer ribbon and can be used repeatedly, and thermal transfer type transfer materials are Since an extremely thin base film is used, not only high strength but also high dimensional stability is required.

However, with a transfer material that uses a normal biaxially oriented polyester film as a base film, the film tends to stretch during transfer and the remaining printed area tends to undergo plastic distortion, making it unsatisfactory for use with transfer ribbons that require high tension and printing pressure. It was nothing.

On the other hand, a film with high strength is desired as a base film, but if, for example, a normal reinforced polyester film with a high F value in the longitudinal direction is used, longitudinal tearing is likely to occur during transfer, and For thermal transfer, there are drawbacks such as excessive thermal shrinkage, making it unsuitable for use in transfer.

[Means to solve the problem]

In view of the above-mentioned problems, the present inventors conducted extensive studies and found that a transfer material in which a transfer ink layer is provided on one side of a polyester film that satisfies certain physical properties has excellent properties and has arrived at the present invention. It is something.

That is, the gist of the present invention resides in a transfer material for a printer, which is formed by providing a transfer ink layer on one side of a biaxially stretched polyester film that satisfies the following formulas [1] to [3] at the same time.

≦3゜　≦2.35-0.1　・　F.

... ■ Indicates the heat shrinkage rate (%) of the film after treatment, and F5 is the strength at 5% elongation in the longitudinal direction of the film (kg/ll1m")
(1li15' indicates the strength at 5% elongation in the transverse direction of the film (kg/mm"), nMD indicates the refractive index of the film in the longitudinal direction, and n indicates the average refractive index of the film). Detailed description of the invention.

The polyester referred to in the present invention refers to aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalene-2,6-dicarboxylic acid or their esters, and ethylene glycol, diethylene glycol, tetramethylene glycol, neopentyl glycol, etc. It is a polymer that can be obtained by polycondensation with glycol. Such polyesters can be obtained by direct polycondensation of aromatic dicarboxylic acids and glycols, or by polycondensation after transesterification of aromatic dicarboxylic acid dialkyl esters and glycols, or by polycondensation of aromatic dicarboxylic acid dialkyl esters and glycols. It can be obtained by a method of polycondensing glycol esters.

Typical examples of such polymers include polyethylene terephthalate and polyethylene-2,6 naphthalene dicarpoxylate.

The polyester of the present invention may be a homopolymer,
In addition, within a range that does not deteriorate its properties, for example, 15 mol% or less of the dicarboxylic acid component is 15 mol% of the dicarboxylic acid component other than the aromatic dicarboxylic acid as the main component or the diol component.
A copolymerized polyester having the following diol components other than the main component diol may be used.

Furthermore, it may be a polymer blend of the polyester and another polymer. Other polymers that can be blended include polyamides, polyolefins, polycarbonates,
Examples include other types of polyester. Furthermore, fine particles may be added to impart slipperiness to the polyester film. Such fine particles include kaolin, clay, calcium carbonate, silicon oxide, calcium terephthalate,
Inert external particles such as aluminum oxide, spherical silica, titanium oxide, etc., high melting point organic compounds that are insoluble during melt film formation of polyester resin, metal compounds such as alkali metal compounds and alkaline earth metal compounds used during crosslinked polymer and polyester synthesis. The catalyst is appropriately selected from internal particles formed inside the polymer during polyester production by the catalyst. Naturally, each particle may be used alone or in combination.

The amount of fine particles contained in the film is usually in the range of 0.01 to 5% by weight, preferably 0.05 to 3% by weight, and the average particle size of the particles is usually in the range of 0.1 to 10 μm, preferably 0.
．． It is in the range of 3 to 3 μm.

In addition, the polyester in the present invention may include, if necessary,
It may also contain additives such as stabilizers, colorants, antioxidants, and antifoaming agents.

The film of the present invention can be obtained using the polyester detailed above, but 5% in the longitudinal direction of the obtained film
It is necessary to add the elongation strength F and the value of 100°C by three.

Films that do not satisfy the above formula have a dimensional stability difference of more than 2.0 kg/mm2, which is undesirable because they tend to tear vertically or horizontally, especially when used as a dot impact type transfer material.

Furthermore, the strength FS at 5% elongation in the longitudinal direction of the film of the present invention,
It is necessary that the longitudinal refractive index nM11 and the average refractive index -n- satisfy the following condition (2).

If it is less than 0.7%, preferably 0.7% or less, and more preferably lume, it will shrink when processed into a transfer material, which is inappropriate. Further, the value of F is usually in the range of 12.5 to 15.5 kg/am", preferably 13 to 15 kg/lIIm"
More preferably, 13.5 to 14.5 kg/mm”
is within the range of If the F value is less than 12.5 kg/mm, it is difficult to make the film thinner, and the F value is less than 15.5 kg/mm.
A film exceeding kg/mm2 is not preferred because of poor dimensional stability. In addition, the difference between the strength F, / value and F, value at 5% elongation in the transverse direction of the film must be within 2.0 kg/am", preferably 1.5 kg/mm".
within 1.0 kg/mm", more preferably within 1.0 kg/mm".

Films that do not satisfy the formula (2) are undesirable because they have poor productivity and increase costs.

Further, the average refractive index -i- of the film of the present invention is usually 1
, 602 to 1.605. Films with a n of less than 1.602 have poor dimensional stability, and films with an n of more than 1.605 are not practical because they tend to tear during printing.

The film thickness of the present invention is usually 1.0 to 9.0 μm, preferably 1.0 to 6.0 μm, and more preferably 1.0 to 6.0 μm.
The range is 4.0 μm. If the film thickness is less than 1.0 μm, the film strength is low, the film tends to stretch, and cannot be used as a transfer material.

On the other hand, a film exceeding 9.0 μm is not suitable as a transfer material for a printer. Further, the lengthwise direction 5 of the film of the present invention
The thickness unevenness R5 at m is usually less than 5%, preferably 3% or less. When Rs is 5% or more, the running properties of the film deteriorate, and the printing performance when used as a transfer material also deteriorates.

Next, the method for forming a polyester film of the present invention will be explained in more detail.

Fine particles such as kaolin, silica, calcium carbonate, aluminum oxide, stabilizers, colorants, antifoaming agents, organic lubricants,
The polyester chips, optionally containing additives such as polyalkylene glycol, are dried by conventional means, extruded through an extruder, and solidified by cooling on a rotating cooling drum to form an unstretched polyester sheet. At this time, it is preferable to use a conventional electrostatic application cooling method. The substantially amorphous film thus obtained was stretched at a stretching ratio (λt) of 4.
A biaxially oriented film is formed by stretching in the machine direction within a range of 0 to 9.0 and then stretching in the cross direction at a stretching ratio of 3.2 times or more.

When producing the film of the present invention, the stretching in the longitudinal direction is performed by (A) stretching the amorphous film at a stretching ratio of 1.2 to 4.0 times and a birefringence of 1 x 10-3 to 2.5 x 10; (B) Without cooling the film temperature below the glass transition point, the birefringence is 3.0X at a stretching ratio of 1.1 to 3.5 times.
10-" to 8.0 x 10-", (C) After cooling the film temperature to below the glass transition point, (D) After heating the film to above the glass transition point. It is preferable to include a step of longitudinal stretching in one stage or in multiple stages.

Further, the biaxially oriented film after the horizontal stretching may be subjected to longitudinal and/or horizontal stretching again as necessary.

In particular, it is preferable to perform transverse stretching again before heat setting and then heat set. The heat setting temperature at that time is at least 200°C or higher, preferably 210°C or higher.

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

The transfer ink of the present invention is not particularly limited,
Well-known ones can be used. Specifically, it is possible to use a material containing binder components, coloring components, etc. as the main components, and additive components such as softeners, flexibilizers, melting point regulators, smoothing agents, dispersants, etc., as needed. can.

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 polymer chains with low melting points 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.

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

Example C: The present invention will be explained in more detail in Examples below.
The present invention is not limited to the following examples unless it exceeds the gist thereof.

The characteristics of the film and tape were evaluated as follows.

(t) FS value ■ Tensile tester Innasco Model 2001 manufactured by Intesco
Using a mold, cut the film lengthwise into a length of 5 mm in a room controlled at a temperature of 23° C. and a humidity of 50% RH.
0 [Dll, a sample film with a width of 15 mm is
Tensile at a speed of mm/min, the strength at 5% elongation is F,
value.

The length of the sample was calculated by the following formula by heat-treating it in a 100°C atmosphere for 30 minutes in a tension-free state and measuring the length of the sample before and after the heat treatment.

Thermal shrinkage rate (%) - (3) Thickness unevenness R' (%) Measured along the longitudinal direction of the biaxially stretched film using a continuous film thickness measuring device manufactured by Anki Denki Co., Ltd. (using an electronic micrometer). (For a length of 5 m) Calculated from the following formula.

(4) nMD The refractive index of the film in the longitudinal direction with respect to the sodium D line was measured at 23° C. using an Atsbe type refractometer manufactured by Atago Optical Co., Ltd.

(5) Average refractive index n, plane orientation degree ΔP Using an Atsube refractometer manufactured by Atago Optical Co., Ltd., the maximum value nγ of the refractive index in the film plane, the refractive index nβ in the direction perpendicular to it,
The refractive index nα in the thickness direction of the film was measured, and the average refractive index and degree of plane orientation were calculated from the following equation. Note that the refractive index was measured using sodium D line at 23 degrees.

n=1/3 (nα+nβ+nγ) (6) Characteristic evaluation as a thermal transfer material One side of the polyester film contained 35 parts by weight of paraffin wax, 30 parts by weight of carnauba wax, 15 parts by weight of low molecular weight polyethylene, and 12 parts by weight of carbon black. A heat-fusible coloring material layer consisting of the following was applied to give a dry coating thickness of 2 μm. Also, on the opposite side of the coloring material layer, a thickness of 0.5μ
A silicone-based heat-resistant protective layer of m was provided. Such film is manufactured by Fuji Xerox facsimile telecopier 245.
The mold was used to run and print, and the runnability and printability were evaluated using the following ranks.

Example 1 Polyethylene terephthalate chip (intrinsic viscosity 0.60
, 0.3% by weight of AftO with an average particle size of 0.02 μm and 0.3% by weight of calcium carbonate with an average particle size of 0.7 μm were added during polymerization) after drying at 180°C for 5 hours.
It was extruded in a sheet form from a T-die at 5°C and cooled and solidified on a rotating drum kept at 45°C to obtain an unstretched amorphous film with a width of 350n+m.

At that time, a known electrostatic adhesion method was used. The obtained amorphous film was first rolled vertically in the first stage at a film temperature of 112°C for 1.
After stretching 6 times, the film was continuously stretched 2.8 times in the machine direction as a second step at a film temperature of 113°C.

The birefringence index of the film after the first stage stretching is 3.0.
X10-'', and the birefringence of the film after the second stage stretching was 3.8X10-''. The film thus obtained was once cooled to 40°C, and then further heated to a film temperature of 94°C. A third stage of longitudinal stretching was performed at a magnification of 1.22 times. The birefringence of the obtained longitudinally stretched film is 0.
．． It was 078.

Next, it was stretched 3.9 times in the transverse direction at 110°C in a tenter, and then tensioned and heat-set at 225°C to a thickness of 5.4μ.
A film of m was obtained.

A fluorine-based polymer was applied as an anti-sticking layer on one side of the obtained film, and a wax transfer ink layer was applied on the other side to obtain a transfer material.

Comparative Example 1 A film with a thickness of 5.4 μm was obtained in the same manner as in the example except that the third stage longitudinal stretching ratio was 1.01 times.

Note that the birefringence index after the third stage longitudinal stretching was 0.052. The obtained film was coated in the same manner as in Example 1 to obtain a transfer material.

Example 2 A longitudinally stretched film obtained by setting the third stage longitudinal stretching temperature to 75°C in Example 1 and increasing the stretching ratio to 1.3.
The film was stretched 3.9 times in the transverse direction at 10°C, and tension heat-set at 225°C to obtain a film with a thickness of 4.8 μm. The obtained film was coated in the same manner as in Example 1 to obtain a transfer material.

Comparative Example 2 The third stage longitudinal stretching temperature was 83°C, and the stretching ratio was 1.
A film with a thickness of 3° and 8 μm was obtained in the same manner as in Example 1, except that the size was increased by 3 times. The obtained film was coated in the same manner as in Example 1 to obtain a transfer material.

Comparative Example 3 A film with a thickness of 3.8 μm was obtained in the same manner as in Example 2 except that the heat setting temperature was 195'C. The obtained film was coated in the same manner as in Example 1,
A transfer material was obtained.

The results obtained above are summarized in Table 1.

〔Effect of the invention〕

The transfer material for printers of the present invention has excellent dimensional stability, durability, thickness unevenness, runnability, and printing characteristics, and has high industrial value.

Claims (1)

[Claims] (1) A transfer material for printers comprising a biaxially oriented polyester film that satisfies the following formulas [1] to [3] and a transfer ink layer provided on one side of the film. S^1^0^0_3_0≦2.35-0.1・F_5・
...[1] F_5≧225・n_M_D{1+[(1.6045-
@n@)/1.6045]×2}-362...[2] |F_5-F_5'|≦2.0...[3] (However, in the above formula, S^1^0^0_3_0 is 100℃
The heat shrinkage rate (%) of the film after treatment for 30 minutes is shown,
F_5 is the strength at 5% elongation in the longitudinal direction of the film (kg/m
m^2), F_5' indicates the strength at 5% elongation in the transverse direction of the film (kg/mm^2), n_M_D indicates the refractive index of the film in the longitudinal direction, and @n@ indicates the average refraction of the film. percentage)