JPS6295289A - Thermal transfer recording film - Google Patents

Abstract

PURPOSE:To prevent a sticking phenomenon at the time of transfer and to attain not only to increase a recording speed but also to enhance the sharpness of a printed character or a printed image, by using a biaxially oriented polyethy lene-2, 6-naphthalenedicarboxylate film having specific Young's modulus, thick ness and density as a base film. CONSTITUTION:A biaxially oriented oolyethylene-2, 6-naphthalenedicarboxylate film, wherein the sum of Young modulus in a longitudinal direction and that in a transverse direction is 1,200kg/mm<2> or more, a thickness is 0.5-8mum and density is 1.345-1.365g/cm<2>, is used as a base film. If the thickness of the base film is less than 0.5mum, stiffness is lowered even if the sum of Young modulus in the longitudinal direction and that in the transverse direction is 1,200kg/mm<2> or more and, therefore, bending and wrinkles are generated at the time of the running of a recording film. If it exceeds 8mum, heat transmission is obstructed and a heating time becomes long and a thermal transfer recording speed is decreased and, when heat transfer is fastened and the input power to a thermal head is increased, a sticking phenonomenon becomes easy to generate.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thermal transfer recording film.
More specifically, the present invention relates to a heat-sensitive transfer recording film that can be printed by melting colorant ink by heating with a heat-sensitive head and transferring it to recording paper, and in particular, it relates to an improved technology that enables high-speed printing.

[Prior Art] Various recording methods are already known, but thermal transfer using a thermal recording device such as a thermal printer has the advantage of excellent operability and maintainability. In this method, the recording paper and the thermal ink layer (thermal transfer colored layer) of the thermal transfer recording film ribbon are avoided, and the film is selectively heated by a pulse signal from a heating head on the opposite side of the ink layer. When doing so, the ink (@colorant) is heated through the film, melts, and is transferred to the recording paper.

Until now, paper such as condenser paper has been used as this thermal transfer recording film.

However, when trying to shorten the input time to the heating head in order to speed up recording, it becomes necessary to speed up heat transfer, which requires either making the thermal transfer recording film thinner or increasing the input power. In either case, the following problems arise.

For example, thin paper such as capacitor paper has low mechanical strength and is particularly susceptible to tearing, so it cannot be made thinner.

A possible solution to this problem would be to use a strong plastic film as the base material, but this also poses the following problems. In other words, when printing, the heating head applies 250 to 300 yen to the thermal transfer recording film.
When heat of around 81° C. or more is applied, a phenomenon occurs in which the base plastic partially fuses to the head, preventing the feeding of the thermal transfer recording film. This phenomenon is called sticking, and not only does it reduce the clarity of the recording, but it also causes operational problems such as poor running of the thermal transfer film.

As a measure to enable the use of plastic films as base materials for dry heat transfer recording films, it has been proposed to provide a heat-resistant protective layer such as a thermosetting resin.

However, even if these methods are used, if the heat-resistant protective layer is made thick enough to be effective in preventing the stick phenomenon in order to speed up recording, the resolution of printing deteriorates, so it is not a sufficient solution.

In addition, when trying to improve heat transfer by thinning the base material to speed up recording, the @ (stiffness) of the thermal transfer film becomes weaker (lower), causing wrinkles and bending of the thermal transfer film. However, tape feeding becomes poor, causing operational trouble.

In this way, when trying to increase the output speed of a computer, there is a lack of suitable thermal transfer recording materials.
This has been pointed out as an unresolved issue.

[Objective of the Invention] The object of the present invention is to provide a thermal transfer recording film that can improve the stick phenomenon during thermal transfer, and can meet issues such as increasing the speed of recording and making the image clearer. That is.

[Structure of the Invention] The present invention provides a heat-sensitive transfer recording film having a heat-sensitive transferable colored layer that melts by heating on one surface of the base film, wherein the base film has a Young's modulus in the longitudinal direction and a Young's modulus in the width direction. The sum is 120ON9/mr4 or more, the thickness is 0.5μm to 8μm, and the density is 1.34
This is a thermal transfer recording film characterized by using a biaxially oriented polyethylene-2,6-naphthalenedicarpoxylate film having a film density of 5 g/ci to 1.365/r,j. Note that the actual FM embodiment is to form a heat-resistant protective film on the surface of the base film.

The present invention will be explained in detail below.

The base film in the present invention needs to have a sum of Young's modulus in the length direction and Young's modulus in the width direction of 1200 Kg/rruA or more.

The reason why a high Young's modulus is required is that as the base film becomes thinner to increase the speed of thermal transfer, its stiffness decreases. This is to avoid operational troubles such as bending or wrinkles while driving.

The sum of Young's modulus in the length direction and width direction of the base film is 1
200Kg/mff1 or more is required, but preferably 1
250 to 9/mrA or more, more preferably 1300K
g/- or more.

The sum of the Young's modulus in the length direction and the width direction is 2200'J
/mtA is not preferable because the film has poor stretchability during film formation and the film is easily torn. Preferably, the sum of the Young's moduli in the length direction and the width direction is 2000 Kg/s or less, more preferably 18
00Kg/mtA or less, particularly preferably 1600Kg
/- or less. The Young's modulus in the width direction is at least 4.
The requirement is 9/7 to 50, preferably 500 Kg/mA or more. - An oriented film that is too axially biased is not preferred.

The thickness of the base film in the present invention is 0.5 μm to 8 μm.
It is μm. When the thickness of the base film is thinner than 0.5 μm, the Young's modulus in the length direction and width direction is 1200 and 5
Even if it is more than F/mtr, the stiffness is lowered, which is not preferable because it causes operational troubles such as bending and wrinkles when running as a thermal transfer recording film. The thickness of the base film is preferably 0.8 μm or more, more preferably 1.0 μm.
m or more. When the thickness of the base film exceeds 8 μm, heat transfer is inhibited, which requires a long heating time and reduces the speed of thermal transfer recording, which is not preferable.

Furthermore, if heat transfer is to be made faster, it is necessary to increase the input power to the heating head, which is undesirable because it tends to cause the so-called stick phenomenon.

In addition, when the base film becomes thicker, it becomes difficult for the heated area by the heating head to match the area of the colored layer heated and melted by heat transfer, resulting in so-called bleeding, which causes the recording to lose its sharpness. @ It is not preferable because the degree decreases. For these reasons, the thickness of the base film may be 8 μm or less, preferably 6 μm or less, and more preferably 4 μm.
The thickness is particularly preferably 3 μm or less.

The density of the biaxially oriented polyethylene-2,6-naphthalenecarboxylate film used as the base film in the present invention is 1.3459/Cn to 1.365g/
It is a CD.

If the density is lower than 1.345 g/crI, the heat shrinkage rate of the base film is too large, and the film shrinks when it comes into contact with a heating head, resulting in an undesirable phenomenon similar to that of a stick. From this point of view, the density is preferably 1.348'j/crd or more, and 1.351L:j/cI! The above is particularly preferable.

The density of the base film is 1,365'J/cd! If the temperature is higher than that, the heat-sensitive transferable colored layer (ink layer) during heat-sensitive transfer.
The peeling strength between the film and the base film becomes too high, and a peeling ring occurs during thermal transfer, resulting in a decrease in image quality. From this point of view, the density is preferably 1.362'J/crA or less, and 1
．． 359! J/c #1 or less is particularly preferred.

The polyethylene-2,6-naphthalene dicarboxylate used in the present invention has naphthalene-2,6-dicarboxylic acid as its main dicarboxylic acid component. Of the dicarboxylic acid components, naphthalene-2,6-dicarboxylic acid preferably accounts for 85 mol% or more. Further, the diol component of this polymer is mainly composed of ethylene glycol. Among the diol components, those in which ethylene glycol accounts for 85% or more are preferred. Any method can be used to produce this polymer. Rumor has it that a dicarboxylic acid and a diol may be directly polymerized, a diester of a dicarboxylic acid and a diol may be transesterified and then polymerized, or a di(hydroxyalkyl) ester of a dicarboxylic acid is subjected to a deglycol reaction. It may also be polymerized. Before completing the polymerization of this polyethylene-2,6-naphthalene dicarboxylate, one or two suitable
A copolymerized or mixed polyester may be obtained by adding more than one third component, but suitable third components include:
Mixtures with divalent ester-forming functional groups, such as aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, fatty acids such as cyclopropanedicarboxylic acid, cyclobutanedicarboxylic acid, hexahydroterephthalic acid, etc. aromatic dicarboxylic acids such as group dicarboxylic acids, phthalic acid, isophthalic acid, natutalene-2, fudicarboxylic acid, diphenyldicarboxylic acid;

Carboxylic acids such as diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, and sodium 3,5-dicarboxybenzenesulfonate. Glycolic acid.

Oxycarboxylic acids such as P-oxybenzoic acid and P-oxyethoxybenzoic acid. Trimethylene glycol, diethylene glycol, tetramethylene glycol, hexamethylene glycol, 2,2-dimethylpropane-1,3
-diol, P-xylylene glycol, 1,4-cyclohexane dimetatool, bisphenol△, bisphenolic sulfone, 1,4-bis(β-hydroxyethyne)benzene, 2,2-bis(P-β-hydroxy Oxy compounds such as (ethoxyphenyl)propane, polyalkylene glycol, P-phenylenebis(dimethylsiloxane), or functional derivatives thereof, and other derivatives from the above-mentioned carboxylic acids, oxycarboxylic acids, oxy compounds, or functional derivatives thereof. and compounds having one ester-forming functional group, such as benzoic acid, benzoylbenzoic acid, benzyloxybenzoic acid, and methoxypolyalkylene glycol. Also, a compound having three or more ester-forming functional groups,
For example, glycerol, pentaerythritol, trimethylolpropane, etc. can also be used as long as the polymer is substantially linear. The polyester may also contain a matting agent such as titanium dioxide, a stabilizer such as phosphoric acid, phosphorous acid and their esters, and inert solid fine particles such as fine silica and china clay.

In the present invention, the inert solid fine particles are preferably silicon dioxide (hydrate, diatomaceous earth).

(including silica sand 9 quartz, etc.): ■Alumina; ■S! Silicates (for example, amorphous or crystalline clay minerals, aluminosilicates (including calcined products and hydrated products), hot asbestos) containing 30% or more of 02%.

Zircon, fly ash, etc.): ■Ma, Zn.

Oxides of Zr and T1; ■ Sulfates of Ca and 3a; ■ l
-i, Na and Ca phosphates (including monohydrogen salts and dihydrogen salts): ■l-i, Na and 1 benzoates: ■Ca
, 3a, Zn, and Mn terefucurate 20M (1,
Ca, Ba, Zn, Cd, Pb.

Titanate of Sr, Mn, Fe, Co and Ni; ■3a
and Pb chromate; 0 carbon (for example, carbon black, graphite, etc.); 0 glass (for example, glass powder, glass peas, etc.); @Ca and MCI carbonate; ■ fluorite; and ■ ZnS. More preferred are anhydrous silicic acid, hydrated silicic acid, aluminum oxide, aluminum silicate (including fired products, hydrates, etc.), and monolithium phosphate.

Phosphorus 1!13 Lithium, sodium phosphate, calcium phosphate, barium sulfate, titanium oxide, lithium benzoate, double salts of these compounds (including hydrates), glass powder, viscosity (including kaolin, bentonite, clay, etc.), Examples include talc, diatomaceous earth, and calcium carbonate. Particularly preferred are silicon dioxide, titanium oxide, and calcium carbonate. By selectively including these inert solid fine particles, it is possible to obtain a biaxially oriented film that is even smoother and has better running properties.

The method for producing a biaxially oriented film according to the present invention includes:
It is possible to adopt a method of simultaneously stretching in the longitudinal and lateral directions using general rolls or stenters, a method of simultaneously stretching in the longitudinal and lateral directions, and a method of stretching in at least two or more stages in the longitudinal direction in addition to the transverse direction. The manufacturing method is illustrated below, but is not limited thereto.

After melt extrusion at 280 to 320°C and quenching, the substantially non-oriented unstretched sheet is stretched at a temperature of 110 to 180°C, preferably 115 to 150°C, and a stretching ratio of 3 to 7.5 times in the length and width. The lengthwise magnification may be smaller, larger, or equal to the widthwise magnification (or may be stretched in two or more stages), and heat set at 170 to 260°C.

As the heat-sensitive transferable colored layer in the present invention, a conventionally known heat-sensitive transferable colored layer can be used as it is, and there is no particular limitation.

Such a heat-sensitive transferable colored layer is a composition comprising a colorant and a binder. Dyes and pigments are used as colorants. Examples include inorganic pigments such as carbon black, organic pigments, azo dyes, and anthraquinone dyes. Binding agents include carnauba wax, wood wax, and beeswax.

These compositions include waxes such as ester wax, polymers such as ethyl cellulose, and recording promoters such as dinitrotoluene.

Various compositions that soften upon heating and are transferable can be used. In addition, it may contain softeners such as plasticizers and oils, and other additives for improving weather resistance. The thickness of these heat-sensitive transferable colored layers is 0.5 μm to 20 μm, preferably 0.8 μm to 10 μm, and more preferably 1 μTrL to 5 μm. These colored layers can be formed by melt coating on the base film, or
Alternatively, it can be formed by dispersing or dissolving the composition in a solvent and applying this coating solution.

In the present invention, the effects of the present invention can be sufficiently exhibited even when no heat-resistant protective film is provided on other surfaces of the base film.

However, a body heat protective film may also be provided on one side of the base film.

As the heat-resistant protective film, for example, silicone resin,
Epoxy resin, melamine resin, phenolic resin, fluororesin, polyimide resin, nitrocellulose, acrylic resin, polyester resin, lulose acetate propionate, cellulose acetate butyrate, cellulose acetate, hynylidene fluoride resin, chlorinated rubber, cyclized rubber ,
Polyvinyl alcohol, boron nitride, silica, talc.

Guanamine resin, paraffin wax, amides or salts of higher fatty acids, etc. may be used, and combinations thereof may also be used. There is also a method of providing a metal layer by vapor deposition of aluminum, but the method is not particularly limited.

The thickness of such a heat-resistant protective film is preferably in the range of 0.005 to 10 μm, more preferably in the range of 0.01 to 5 μm, and particularly preferably in the range of 0.05 to 3 μm.

If the thickness becomes thinner, the stick prevention effect will be insufficient,
When the thickness increases, it becomes difficult to increase the printing speed.

By providing the heat-resistant protective film as described above, it becomes possible to further increase the printing speed.

[Effects of the Invention] The thermal transfer recording film of the present invention is suitable for use in thermal printers, and furthermore, even when the speed of a thermal printer is increased, the printing property is good, and the colored layer for thermal transfer recording does not peel or fall off. It also has the characteristic of being difficult to wake up, so
It is also suitable for high-speed printers.

Furthermore, the thermal transfer recording film of the present invention is difficult to cause stick phenomenon and has good slipperiness during running, so it is suitable for use in multiple transfer type thermal printers, and also suitable for use in thermal transfer type color printers. is also suitable.

[Example code] The present invention will be further explained below based on Examples.

Note that various physical property values and characteristics in the present invention were measured and defined as follows.

(1) Cut the Young's modulus measurement film into a sample width of 10M and length of 15cI11, with a chuck distance of 100mm, a tensile speed of 10mm for 1 minute, and a chart speed of 500mm. It was pulled at an Instron type universal tensile test machine for 7 minutes. Young's modulus was calculated from the tangent to the rising portion of the obtained load-elongation curve.

(2) Film density This is a value measured by the float-sink method at 25°C in a mixed solvent of n-hebutane and carbon tetrachloride.

Furthermore, the properties as a thermal transfer recording film were evaluated as follows.

The test pieces were obtained by slitting each film into a tape slit of 8 drum widths to form a thermal transfer ribbon, which was then applied to a thermal printer for practical evaluation.

The occurrence of stick phenomenon, thermal printer slippage, adhesion, and image quality were measured.

(3) Stick phenomenon The presence or absence of fusion between the thermal transfer ribbon and the heating head was checked.

X: Hostility occurs, and poor ribbon transport is observed △・
...There is a tendency to fuse, but there is no ribbon conveyance failure, and it is practical O...There is a slight tendency to fuse, but it is good ◎...
Very good with no problems (4) Slippage in the printer We checked the ribbon feeding status on the ribbon feeding roller of a thermal printer to see if it slipped or not, and if it wrinkled.

×... Ribbon slips and conveyance failure occurs Δ...
・The ribbon may be wrinkled and may slip slightly, but there are no transport defects and it is usable for practical use.The ribbon may be slightly wrinkled, but it does not slip and there are no transport defects, so it is in good condition. - The feeding condition was good and there were no problems at all (5) Adhesiveness When the ribbon was rubbed by hand, cracking and peeling of the coating film (heat-sensitive transfer colored layer) was observed.

×...The paint film cracks and peels off.△...The paint film cracks, but the peeling is on the surface, so not all of it comes off.○...The paint film cracks on its own, but does not peel off.◎...
No cracking or peeling of the coating film (6) Image quality The fA light and blurring of the image printed by the thermal printer was observed.

×...The image has uneven shading and strong bleeding, which is not practical.Δ...There is a slight difference in shading and there is some bleeding, but it is usable for practical use.○...There is slight bleeding, but the shading is Good without any problems ◎...Very good with no shading or bleeding Example 1 Polyethylene-2,6-naphthalenecarboxylate pellets with an intrinsic viscosity of 0.65 obtained by a conventional method were dried and fed in an extrusion manner, The mixture was melted at 290 to 310°C and extruded onto a rotating drum to obtain an unstretched film. This unstretched film was stretched 3.8 times in the longitudinal direction at 120°C by a roll stretching method, and further stretched 3.8 times in the width direction by a stenter method at 140'C.
Heat treatment was performed at 20° C. for 5 seconds to obtain a biaxially oriented film with a thickness of 2.5 μm. This biaxially oriented film was used as a base film, and the top surface was coated with 30 parts of carnauba wax, 35 parts of paraffin wax, 5 parts of oil black HBB (an oil-soluble dye made by Orient Kagaku Kogyo (Tai)), 25 parts of carbon black, and lanolin. Mix 5 parts and heat melt to 4 μm.
A heat-sensitive transfer recording film was obtained by hot-melt coating to a thickness of n.

This thermal transfer recording film was slit into a width of 8M and was evaluated using a thermal printer using a thermal transfer ribbon. The results are shown in Table 1.

There was no sticking phenomenon, the image quality was clear and good, the slipperiness when running on the thermal printer was good, and the adhesion was also good.

Examples 2 to 4 and Comparative Example 1 In Example 1, the stretching ratios in the length direction and width direction were adjusted to obtain biaxially oriented films with different Young's moduli. Using this as a base film, a thermal transfer recording film was obtained in the same manner as in Example 1, and the evaluation results are shown in Table 1.

When the Young's modulus decreased, the stick phenomenon occurred and the slipperiness in the printer also deteriorated. - In Example 4, the stretchability of the base film was poor, and there were many breaks during film formation, resulting in low productivity.

Example 5.6 and Comparative Example 2 In Example 1, the thickness of the unstretched film and the stretching ratio were adjusted to obtain biaxially oriented films with different thicknesses. Using this as a base film, a thermal transfer recording film was obtained in the same manner as in Example 1, and evaluated in the same manner as in Example 1. The results are shown in Table 1.

When the base film becomes thinner, even when the Young's modulus is high, wrinkles tend to occur when running on a thermal printer, and slipperiness tends to deteriorate. Furthermore, as the thickness of the base film increased, the image began to bleed, and there were more uneven shadings, resulting in a decrease in image quality.

(Left below) Examples 7 to 9 and Comparative Example 3 In Example 1, the heat treatment temperature and stretching ratio were adjusted to obtain biaxially oriented films with different densities.

Using this as a base film, a thermal transfer recording film was obtained in the same manner as in Example 1, and evaluated in the same manner as in Example 1. The results are shown in Table 2.

When the density of the base film was lowered, fusion with the heating head was more likely to occur. As the density of the base film increased, cracking and peeling of the heat-sensitive transferable colored layer became more likely to occur.

(Margin below) Table 2

Claims (2)

[Claims] (1) In a heat-sensitive transfer recording film equipped with a heat-sensitive transfer colored layer that melts when heated on the surface of a base film,
As a base film, the sum of the Young's modulus in the length direction and the Young's modulus in the width direction is 1200 Kg/mm^2 or more, the thickness is 0.5 μm to 8 μm, and the density is 1.345
A film for thermal transfer recording, characterized in that it uses a biaxially oriented polyethylene-2,6-naphthalene dicarboxylate film having a film density of g/cm^3 to 1.365 g/cm^3. (2) The dry heat transfer recording film according to claim 1, wherein a heat-resistant protective film is provided on the surface of the base film on which no colored layer is provided.