JPH0453197B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a transfer ribbon for printers, and more particularly to a transfer ribbon for printers that has excellent running properties, durability, and transferability. Prior Art Polyester films are widely used as substrates for transfer ribbons for printers because they have excellent properties such as chemical resistance, strength, elastic modulus, heat resistance, crystallinity, and high melting point. However, with conventional ink transfer ribbons using biaxially oriented polyester films, the film may be deformed or elongated due to unprinted areas during transfer using the dot impact method, for example.
Furthermore, the ink layer applied to the polyester substrate is transferred to the opposite surface (running surface) of the ribbon, staining the running surface of the ribbon. In extreme cases, troubles such as the ribbon not moving occur occur, and an improvement is needed. OBJECTS OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a transfer ribbon for printers that has excellent runnability, durability, and transferability. Structure and Effects of the Invention According to the present invention, the object of the present invention is to
A transfer ribbon for printers, which has a transfer ink layer on one side of a 25 μm biaxially oriented polyester film, and the film has a Young's modulus in the longitudinal direction of 450 to 450.
800Kg/mm ² and a heat shrinkage rate of 7% or less at 150℃ in the longitudinal and lateral directions, and the surface on which the transfer ink layer is provided has a protrusion count (Y) measured with a three-dimensional roughness meter. : Ke/mm ² ) and protrusion height (X: μm)
In the area where _{log 10} Y>1.3, the protrusion distribution curve representing the relationship between A printer characterized in that the _maximum value of This is accomplished by using a transfer ribbon. The polyester in the present invention is a polyester containing an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component. Such polyester is substantially linear;
It also has film-forming properties, particularly film-forming properties by melt molding. Aromatic dicarboxylic acids include, for example, terephthalic acid, naphthalene dicarboxylic acid, isophthalic acid, diphenoxyethane dicarboxylic acid,
diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid,
These include diphenylketone dicarboxylic acid and anthracene dicarboxylic acid. Aliphatic glycols include, for example, polymethylene glycols having 2 to 10 carbon atoms such as ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, and decamethylene glycol, or alicyclic diols such as cyclohexanedimethanol. etc. In the present invention, polyesters containing, for example, alkylene terephthalate and/or alkylene naphthalate as main constituents are preferably used. Among such polyesters, for example, not only polyethylene terephthalate and polyethylene-2.6-naphthalate, but also terephthalic acid and/or 2,6-naphthalene dicarboxylic acid account for 80 mol% or more of the total dicarboxylic acid component, and 80 mol% of the total glycol component. Particularly preferred are copolymers in which the above is ethylene glycol. In this case, the dicarboxylic acid accounting for up to 20 mol% of the total acid component can be the above-mentioned aromatic dicarboxylic acids, and also include, for example, aliphatic dicarboxylic acids such as adipic acid and sebacic acid; It can be a cyclic dicarboxylic acid or the like. In addition, less than 20 mol% of the total glycol component is
Can be the above glycols other than ethylene glycol, or aromatic diols such as hydroquinone, resorcinol, 2,2-bis(4-hydroxyphenyl)propane; 1,4
-Aliphatic diols containing aromatics such as dihydroxymethylbenzene; polyalkylene glycols (polyoxyalkylene glycols) such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. In addition, the polyester used in the present invention includes
For example, components derived from oxycarboxylic acids such as aromatic oxyacids such as hydroxybenzoic acid; aliphatic oxyacids such as ω-hydroxycaproic acid are contained in an amount of 20 mol% or less based on the total amount of dicarboxylic acid components and oxycarboxylic acid components. It also includes those containing. Furthermore, the polyester in the present invention contains a trifunctional or more functional polycarboxylic acid or a polyhydroxy compound, such as trimellitic acid, pentaerythritol, in an amount within a substantially linear range, for example, an amount of 2 mol % or less based on the total acid components. Copolymerized products are included. The above polyester is known per se, and can be produced by a method known per se. The above-mentioned polyester preferably has an intrinsic viscosity of about 0.4 to about 0.9 measured as a solution in o-chlorophenol at 35°C. Moreover, the above-mentioned polyester may contain additives such as stabilizers, colorants, and antioxidants, as required. The biaxially oriented polyester film in the present invention is a biaxially oriented film manufactured from the above-mentioned polyester, and the film has a longitudinal Young's modulus of 450 to 800 Kg/mm ² , preferably 500 to 750 Kg/mm 2 .
mm ² , more preferably 520 to 700 Kg/mm ² . Note that the longitudinal direction of the film coincides with the longitudinal direction of the ink transfer ribbon. If the Young's modulus in the longitudinal direction is less than 450 kg/mm ² , the film tends to stretch and is difficult to recover elastically. Therefore, when used as a transfer ribbon for printing, the printed area will be plastically deformed due to printing pressure, making it thicker than necessary. This is undesirable because the clarity of the print is poor, and the deformation makes it difficult to handle when winding up the transfer ribbon. Also, if the Young's modulus in the longitudinal direction exceeds 800Kg/ ^mm2 ,
Due to the high rigidity, the film tends to tear due to the pressure of printing, which is undesirable. Furthermore, the biaxially oriented film must have a heat shrinkage rate (deformation rate when exposed to hot air at 150°C for 30 minutes under no load) of 7% or less in both the longitudinal and lateral directions, preferably Both are 4% or less, more preferably both are 2% or less. If the heat shrinkage rate of the film exceeds 7%, especially when used as a transfer ribbon for a thermal printer, the ribbon will be severely deformed, resulting in poor print clarity and poor handling when winding the transfer ribbon due to the deformation. Also, even in the dot impact method, if the thermal shrinkage rate exceeds 7%, the printed portion is likely to be deformed, which is undesirable. Further, the thickness of the polyester film in the present invention is generally 1 to 25 μm, preferably 2 to 25 μm.
It is 10 μm, more preferably 3 to 8 μm. If the thickness of the film is thinner than the above-mentioned range, the strength will be insufficient and it will not be suitable for use as a transfer ribbon, and will also be inferior in processing suitability.On the other hand, if the film is thicker than the above-mentioned range, In particular, the thermal transfer method is undesirable because it takes a long time to transfer heat, making it unsuitable for increasing the recording speed and obtaining clear transferred image quality. The biaxially oriented polyester film of the present invention satisfies the above-mentioned Young's modulus in the longitudinal direction, heat shrinkage rate, and thickness, and at the same time, the surface on which the transfer ink layer is provided has a protrusion count (Y: K/ mm ² ) and the protrusion height (X: μm) does not intersect the line expressed by the above formula (1) in the area of log ₁₀ Y > 1.3, and the maximum value of the protrusion distribution The curve in the portion exceeding the maximum value must have surface characteristics within a range that satisfies the above formula (2).
If the film surface roughness falls below the straight line expressed by the formula log ₁₀ = -3.6 ) If the ribbon exhibits a protrusion distribution, when the ink layer is applied and then wound onto a roll, the ink is likely to be transferred to the opposite surface (running surface) of the film, staining the running surface of the ribbon, and causing damage to the ribbon running system. The ink gradually accumulates on the contact parts such as guide posts, which obstructs the running of the ribbon, causing problems such as the ribbon not moving in extreme cases, and other problems such as worsening the slipperiness of the film.
This is undesirable because it causes wrinkles in the film during processing. Also, the surface roughness of the film is expressed by the above formula.
If it is so rough that it exhibits a protrusion distribution that intersects (1), it is not preferable because the sharpness of the print becomes poor and it also causes wear of the thermal head, which poses a practical problem. The above-mentioned film surface also has a number of protrusions (k/mm ² ) measured using a multiple interference reflection microscope (Tl monochromatic light).
and protrusion height (h:μm) is 1.5≧h＞1.0 ...10 pieces/mm ² or less 1.0≧h＞0.75 ...1 to 30 pieces/mm ² 0.75≧h＞0.5 ...15 to 120 pieces/mm ² 0.5≧h＞0.25...It is preferable to satisfy 80 pieces/ ^mm2 or more. Satisfying this surface property is important from the viewpoint of preventing the transfer of the ink layer to the opposite side of the film and from the viewpoint of print clarity.
Particularly preferred. In addition, the maximum protrusion height on the film surface is 3μm or less,
Furthermore, it is preferably 1.5 μm or less. The biaxially oriented polyester film of the present invention further has a friction coefficient of 0.5 or less, further 0.45 or less, particularly 0.35 to 0.35 on the surface on which the transfer ink layer is not provided.
0.45, and the value of the friction coefficient after 50 consecutive reciprocating tests is preferably less than 150%, more preferably less than 120%, compared to the initial value. Since this surface forms a running surface, if the coefficient of friction is too large, the running properties of the ribbon will deteriorate, and if it is excessive, it will cause ribbon breakage and ink transfer, which is not preferable. The above-mentioned surface roughness of the biaxially oriented polyester film in the present invention is due to the presence of inert inorganic materials in the film.
It is preferable to form by adding organic fine particles or the like. When using this inert fine particle,
0.01 to 5% by weight of particles with an average particle size of 0.01 to 10 μm,
Furthermore, it is preferable to add particles having an average particle size of 0.03 to 4 μm in an amount of 0.01 to 1.5% by weight. At this time, the inert inorganic or organic fine particles added may be a single component, or two or more components may be used simultaneously. In the present invention, the above-mentioned inert fine particles are preferably silicon dioxide (including hydrates, diatomaceous earth, silica sand, quartz, etc.); alumina;
Silicates containing 30% by weight or more of _SiO2 (e.g. amorphous or crystalline clay minerals, aluminosilicate (including calcined products and hydrated products), warm asbestos, zircon, fly ash, etc.), Mg, Oxides of ZnZr and Ti; Sulfates of Ca and Ba; Phosphates of Li, Na, and Ca (including monohydrogen salts and dihydrogen salts);
Benzoate of Li, Na, and K; Ca, Ba,
Zn, and Mn terephthalate; Mg, Ca, Ba,
Titanates of Zn, Cd, Pb, Sr, Mn, Fe, Co and Ni; Chromates of Ba and Pb; Carbon (e.g. carbon black, graphite, etc.); Glass (e.g. glass powder, glass beads, etc.) Ca,
and Mg carbonate; fluorite; and ZnS. More preferably, anhydrous silicic acid, hydrated silicic acid, aluminum oxide, aluminum silicate (including calcined products, hydrates, etc.), monolithium phosphate, trilithium phosphate, sodium phosphate, calcium phosphate, barium sulfate, titanium oxide, Examples include lithium benzoate, double salts of these compounds (including hydrates), glass powder, clay (including kaolin, bentonite, clay, etc.), talc, diatomaceous earth, calcium carbonate, and the like. Polyesters containing these inert particulates are usually reacted to form polyesters by
For example, inert fine particles (preferably as a slurry in glycol) may be used at any time during the transesterification reaction or polycondensation reaction when using the transesterification method, or at any time during the polycondensation reaction when using the direct polymerization method.
It can be produced by adding into the reaction system. Preferably, inert fine particles are added to the reaction system at the beginning of the polycondensation reaction, for example, until the intrinsic viscosity reaches about 0.3. The biaxially oriented polyester film used in the present invention is not particularly limited by its manufacturing method, but
Usually, polyester containing a predetermined proportion of fine particles is melted, extruded into a sheet through a slit die, cooled and solidified in a casting drum to form an unstretched sheet, and then the unstretched sheet is stretched biaxially. The product (film) is manufactured using the same method. At that time, in order to suitably satisfy the requirements of the present invention, the unstretched sheet is first stretched in a uniaxial direction while being heated in a warm bath, and then heated and stretched in a direction perpendicular to the stretching direction in hot air. The method is preferred. In the first stretching in a hot bath, the hot bath is boiling water and the stretching ratio is preferably 2.5 to 6.0 times, more preferably 3.5 to 5.5 times, and in the second stretching, the hot air temperature is 60 to 120 times. ℃, furthermore 75 to 110℃, and the stretching ratio is
It is preferably 2.5 times to 4.0 times, more preferably 2.8 times to 3.7 times. Further, the obtained biaxially stretched film is preferably heat set at a temperature in the range of 150 to 245°C, more preferably 170 to 240°C, for about 1 to 200 seconds. Furthermore,
If necessary, it is also effective to perform a relaxation heat treatment of 1 to 30% after heat setting to improve dimensional stability. The biaxially oriented polyester film thus obtained usually exhibits the same surface characteristics on both the front and back sides.
In this case, the surface on which the transfer ink layer is provided may be the front or back surface. In the present invention, the transfer ink layer is not particularly limited, and any known one can be used. That is, it is composed of a binder component, a coloring component, etc. as the main components, and an appropriate amount of a softener, a flexibilizing agent, a dispersant, a smoothing agent, etc. added as necessary. To explain the above-mentioned main components in more detail, first, as the binder component, well-known waxes such as carnauba wax and varafine wax, and various low-melting point polymer substances are used;
The coloring agent is mainly carbon black, and various other dyes or organic or inorganic pigments are used. In some cases, the transfer ink may also include a sublimation type. The transfer ink layer can be formed by a conventional method, for example, a solution coating method such as gravure, reverse, or slit die method in a state in which a solvent is added, or hot melt coating. At this time, the biaxially oriented polyester film may be subjected to pretreatment such as corona discharge treatment or subbing coating with a binder, if necessary. The transfer ribbon for printers of the present invention has the excellent properties originally possessed by biaxially oriented polyester films, such as high chemical resistance, strength, modulus of elasticity, heat resistance, and high melting point, as well as ink on the running surface. This eliminates problems such as ink stains being transferred and stains, and ink stains accumulating on the running system such as guide posts, which prevents the ribbon from running, and when used for impact printing, plastic deformation such as leftover marks due to printing is also small. , and is a ribbon with excellent transfer image quality. Examples Hereinafter, the present invention will be further explained with reference to Examples.
Note that various physical property values and characteristics in the present invention were measured and defined as follows. (1) Protrusion distribution measurement method Using a three-dimensional roughness meter (SE-3CK) manufactured by Kosaka Laboratory, needle diameter 2μmR, needle pressure 30mg, measurement length 1mm, sampling pitch 2μm, cutoff 0.25mm, vertical magnification 2 The protrusion distribution was measured under the conditions of 10,000 times, 200 times lateral magnification, and 150 scans, and the protrusion height (x axis) is the protrusion height (z) at the point where the area ratio from the reference level is 70%. Level) was set as 0 level, the difference from that height was set as the protrusion height, and the corresponding number of protrusions was plotted on the y-axis. (2) Young's Modulus Measurement The film was cut into sample widths of 10 mm and lengths of 15 cm, and stretched using an Instron type universal tensile tester at a chuck spacing of 100 mm at a tensile speed of 10 mm/min and a chatch speed of 500 mm/min. Young's modulus was calculated from the tangent to the rising portion of the obtained load-elongation curve. (3) Number of surface protrusions Aluminum was uniformly vacuum-deposited on the surface of the film to a thickness of 400 to 500 Å or less, and collodion was applied to the opposite non-vapor-deposited surface (film surface), followed by drying. An arbitrary 100 cm ² of the aluminum vapor-deposited surface was observed at a magnification of 100 times using a Tl monochromatic light multiple interference reflection microscope (for example, manufactured by Carl Zeiss JENA). The number of protrusions with interference fringes generated corresponding to the protrusion height of the protrusions in the microscopic field of view was counted. (4) Heat shrinkage rate 300mm for a film sample cut out to a width of 20mm
Mark gauge marks at the distances between the gauges, hang them without a load in a circulating hot air fan heated to 150°C for 30 minutes, then take them out and leave them to cool, then read the length between the gauge marks. Then, the ratio of the difference from the original length to the original length is expressed as a percentage. Heat shrinkage rate (%) = (original length) - (length after heating) / (original length) x 1
00 (5) Ink transferability A transfer ink composition consisting of carbon black 15 parts by weight carnauba wax 35〃 ester wax 32〃 polytetrahydrofuran 13〃 silicone oil 5〃 is applied to one side of a 10 μm thick film in a layer thickness A film sample of 10 mm width x 20 cm length was covered with a transfer sheet obtained by coating with the gravure method to a thickness of 18 μm, and the sample was pressed 20 times with a 5 cm diameter hard chrome-treated roll weighing 1 kg. The surface in contact with the transfer ink layer was traced with a cotton swab moistened with ethyl alcohol, and the degree of ink adhesion to the cotton swab (staining degree) was visually evaluated on a five-point scale. <5-level evaluation> ◎...No ink adhesion is observed.○...Ink adhesion is almost not observed.△...Ink adhesion is somewhat observed.×...Ink adhesion is considerable. Recognized XX...Severe ink adhesion is observed (6) Running properties Measured as follows using the apparatus shown in Figure 1. In Figure 1, 1 is the load cell and 2 is the surface roughness.
0.5μm plastic fixing rod (outer diameter 5mmφ)
3 is the load (100gr), 5 and 6 are sample fixtures,
4 indicates a sample (ribbon). The surface opposite to the transfer ink coated surface (running The friction coefficient was read by making the load cell 1 contact the fixed rod 2 at 90° and moving the load cell 1 horizontally over a length of 30 cm at a speed of 30 mm per second. The running performance was judged on a three-level scale by comparing the friction coefficient obtained immediately after the start of measurement with the friction coefficient obtained during 50 consecutive reciprocating runs. <Three-stage judgment> ○...The friction coefficient after 50 repeated reciprocating runs is less than 120% of the initial friction coefficient, and the friction coefficient does not increase much due to repeated running. △…The friction coefficient when running back and forth repeatedly 50 times is 120% or more and less than 150% with respect to the initial friction coefficient,
A slight increase in the coefficient of friction is observed due to repeated running. ×...The friction coefficient after 50 repeated reciprocating runs is 150% or more with respect to the initial friction coefficient, and a significant increase in the friction coefficient is observed with repeated running. (7) Print clarity The transfer ink layer consisting of the composition shown in (4) above is
Using an electric typewriter IBM82C, type the letter "Q" in alpha alphabet on the opposite side of the ink-coated side of the transfer ribbon coated to a thickness of 18 μm onto regular typewriter paper. The clarity, print thickness, and shading were visually evaluated in three stages. <Three-level judgment> ○...Printing is not thick, there are no shading spots, and it is clear △...Printing is a little thick, but it is clear ×...Printing is quite thick, and there are some areas (8) Degree of film deformation The same spot was struck 5 times in a row using the method described in (6) above, and the marks on the film were visually judged on a three-grade scale. <Three-stage evaluation> ○...Almost no scratches are observed △...Some scratches are observed ×...Example: few scratches are observed Example 1 Ethylene glycol (hereinafter abbreviated as EG) 90
After adding 10 parts by weight of kaolin (average particle size 1.2 μm) to the parts by weight, mixing and stirring were performed to obtain a slurry. Next, 100 parts by weight of dimethyl terephthalate and
After transesterifying 70 parts by weight of EG in a conventional manner using 0.035 parts by weight of manganese acetate tetrahydrate as a catalyst, the kaolin obtained above (concentration 0.4% by weight to polymer) was added under stirring. Subsequently, 0.03 parts by weight of trimethyl phosphate and 0.03 parts by weight of antimony trioxide were added, and then a polycondensation reaction was carried out in a conventional manner under high temperature vacuum to obtain polyethylene terephthalate pellets having an intrinsic viscosity of 0.620. Furthermore, this polyethylene terephthalate (hereinafter
After drying the pellets (abbreviated as PET) at 170℃ for 3 hours, the pellets are fed to the extruder hopper and melted at a melting temperature of 280 to 300℃.The molten polymer is passed through a 1 mm slit die with a surface finish of about 0.3S and a surface temperature of 20℃. The film was molded and pressed onto a rotating cooling drum to obtain an unstretched film with a thickness of about 110 μm. Subsequently, as shown in FIG. 2, this unstretched film is preheated with four heating rolls 31, 32, 33, and 34, and immediately the film is heated in a hot water bath 37, and rolls 35 and 36 in the hot water bath are heated. The film was stretched 3.6 times in the longitudinal direction in one step. Subsequently, the first-stage stretched film was stretched 3.9 times in the transverse direction at a temperature of 110°C in hot air, and then stretched 15 times at a temperature of 230°C.
A biaxially oriented film with a thickness of 7.5 μm was obtained by heat treatment for seconds. Note that the stretching speed at this time was 20 m/min. Young's modulus of this film, heat shrinkage rate at 150℃,
The surface roughness protrusion distribution curve, maximum protrusion height, ink transferability, runnability, print clarity, and film deformation of the transfer ribbon after coating with the ink layer were all at a good level, and the overall The evaluation was also good. These results are shown in Table-1. Example 2 In Example 1, calcium carbonate (average particle size 1.5 μm) was added as an additive lubricant in an amount of 0.4% by weight based on the polymer.
A biaxially oriented film of 7.5 μm was obtained under the same conditions except for the addition. The surface projection distribution curve of this biaxially oriented film was rougher than that of the film obtained in Example 1, and as a result, the ink transferability and runnability were even better, and the overall evaluation was also very good. These results are shown in Table-1. Example 3 A biaxial film with a thickness of 7.2 μm was prepared in the same manner as in Example 2, except that the stretching ratio was 4.2 times in the longitudinal direction and 3.2 times in the lateral direction, and the heat setting temperature after the lateral stretching was 235° C. An oriented film was obtained. The results are shown in Table 1, and all items were very good. Example 4 A biaxially oriented film with a thickness of 7.3 μm was obtained by processing under the same stretching and heat setting conditions as in Example 3, except that the polymer of Example 1 was used. The results are shown in Table 1, and all items were good. Example 5 Stretching and heat setting were performed under the same conditions as in Example 2, except that the heat setting temperature was 215°C, and the thickness was
A biaxially oriented film of 7.5 μm was obtained. The results are shown in Table 1, and all items were good. Example 6 In Example 1, 0.45% by weight of calcium carbonate (average particle size 1.5 μm) and 0.25% by weight of silica (average particle size 0.6 μm) were used as additive lubricants, and 4.5% by weight of silica (average particle size 0.6 μm) was used in the longitudinal direction.
A biaxially oriented film with a thickness of 7.2 μm was obtained in the same manner as in Example 1, except that the film was stretched twice and then stretched 3.6 times in the transverse direction. The results are shown in Table 1, and all items were good. Example 7 Of Example 6, silica (average particle size 2.0 μm)
The thickness was
A biaxially oriented film of 7.2 μm was obtained. The results are shown in Table 1, and all items were good.

【table】

[Table] * Overall evaluation ◎...Very good, ○...Good, △...Slightly poor, ×...Poor Comparative example 1 The unstretched film obtained in Example 1 was preheated at 75°C, and further rolled at low speed and high speed. From 15mm above between
Heated with one infrared heater with a surface temperature of 900℃, and due to the difference in surface speed between the low speed and high speed rolls
Stretched twice, then fed to a stenter and heated to 110℃
The film was stretched 3.8 times in the transverse direction. The obtained biaxially stretched film was further heat-set at 210° C. for 15 seconds to obtain a film with a thickness of 7.7 μm. The evaluation results for each item after coating the obtained biaxially oriented film and ink layer to form a ribbon are shown in Table 2.
As shown in Figure 2, the ink transferability and runnability were at a reasonably good level, but the degree of film deformation and print clarity were poor, and the overall evaluation was also poor. Comparative Example 2 The unstretched film obtained in Example 2 was biaxially stretched under the stretching conditions of Comparative Example 1, and then heat-set at a temperature of 215°C to obtain a biaxially oriented film with a thickness of 7.7 μm. The evaluation results of the obtained biaxially oriented film and ribbon are as shown in Table 2, and although the ink transferability and runnability are at a better level than Comparative Example 1, the overall evaluation is inferior. It was hot. Comparative Example 3 An unstretched film obtained by adding 0.5% by weight of kaolin (average particle size 0.5 μm) to the polymer as an additive lubricant was stretched to a longitudinal stretching ratio of 3.6 times that of Comparative Example 1, and the heat setting temperature was A biaxially oriented film with a thickness of 7.5 μm was obtained by stretching and heat setting under the same conditions as in Comparative Example 1 except that the temperature was 230°C. The properties of the obtained biaxially oriented film are as shown in Table 2, and the surface protrusion distribution curve was below the preferred range, the ink transferability and runnability were poor, and the overall evaluation was poor. Comparative Example 4 Calcium carbonate (average particle size
The unstretched film obtained by adding 0.8% by weight of 1.5 μm) to the polymer was
4.2 times, horizontal stretching ratio 3.5 times, heat setting temperature 230
A biaxially oriented film with a thickness of 7.5 μm was obtained by processing under the same conditions as in Comparative Example 1 except that the temperature was changed to ℃. The evaluation results for each item of the obtained biaxially oriented film are as shown in Table 2, and the number of curvatures in the distribution of surface protrusions was too rough, the printing clarity was poor, and the overall evaluation was poor. Comparative Example 5 Calcium carbonate (average particle size
An unstretched film with a thickness of 150 μm obtained by adding 0.4% by weight of 1.5 μm) to the polymer was heated under the conditions of Comparative Example 1, using an infrared heater with a surface temperature of 750°C, on the surface of low-speed and high-speed rolls. It was stretched at a speed ratio of 3.0 times in the longitudinal direction, then stretched in the transverse direction at a stretching ratio of 3.7 times in hot air at 95°C, and then heated again in the longitudinal direction with an infrared heater with a surface temperature of 1000°C to a stretching ratio of 1.8. The film was stretched at a double speed and then heat-set at 220°C to obtain a biaxially oriented film with a thickness of 7.5 μm. Each item of the obtained biaxially oriented film is as shown in Table 2. When printing with a printer, the film was torn in the vertical direction due to the printing pressure, making it impossible to print clearly, and the overall evaluation was poor. It was hot. Comparative Example 6 A biaxially oriented film with a thickness of 7.5 μm was obtained under the same conditions as in Comparative Example 2 except that the heat setting temperature was 180°C. The characteristics of the obtained biaxially oriented film are as shown in Table 2. The film was severely deformed due to the printing pressure, the printing was thick, and the clarity was poor, so the overall evaluation was poor. It was hot.

[Table] * Overall evaluation ◎...Very good, ○...Good, △...
Slightly inferior, ×…inferior

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a device for measuring the runnability of a transfer ribbon. FIG. 2 is a schematic diagram of a longitudinal stretching machine used in an example of the present invention. FIG. 3 is a diagram showing the relationship between the height of protrusions on the film surface (Y: μm) and the number of protrusions (X: x/mm ² ) determined by a three-dimensional roughness meter.

Claims (1)

[Claims] 1. A transfer ribbon for printers, comprising a biaxially oriented polyester film with a thickness of 1 to 25 μm and a transfer ink layer provided on one side, the film having a Young's modulus in the longitudinal direction of 450 to 800 Kg/mm ² and the heat shrinkage rate at 150°C in the longitudinal and lateral directions is 7% or less, and the surface on which the transfer ink layer of the film is provided has a protrusion count (Y: x/mm) measured with a three-dimensional roughness meter. ² ) and the protrusion height (X: μm).
In the area of log ₁₀ Y > 1.3, it does not intersect the line expressed by the following formula (1) log ₁₀ Y = -1.8 A transfer ribbon for a printer, characterized in that the curve of the curved portion thereof has surface characteristics in a range that satisfies the following formula (2): log ₁₀ Y≧−3.6×+2.8 (2). 2 The number of protrusions (ke/mm ² ) and protrusion height (h: μm) measured using a multiple interference reflection microscope (Tl monochromatic light) on the surface of the polyester film on which the transfer ink layer is to be provided.
is 1.5≧h＞1.0 …10 pcs/mm ² or less 1.0≧h＞0.75 …1 to 30 pcs/mm ² 0.75≧h＞0.5 …15 to 120 pcs/mm ² 0.5≧h＞0.25 ……80 Claim 1, which is characterized in that it satisfies not less than x/ ^mm2 .
Transfer ribbon for printers described in section. 3. The surface of the polyester film on which the transfer ink layer is not provided has a coefficient of friction of 0.5 or less, and the value of the coefficient of friction after 50 consecutive reciprocating tests is less than 150% of the initial value. A transfer ribbon for a printer according to claim 1 or 2.