KR100536006B1 - Biaxially oriented polyester film for heat transcription - Google Patents

Abstract

The present invention is a biaxial for thermal transfer ribbon which is excellent in transferability and flammability, has excellent anti-wrinkle performance in manufacturing printer ribbon, and enables clear printing. A stretched polyester film, the film for thermal transfer ribbons which apply | coated the transfer ink layer to the single side | surface of the biaxially-stretched film which consists of polyester resins, and apply | coated the heat-resistant coat layer on the opposite side. WHEREIN: 0.01-1.0 weight% of porous inorganic particles with a pore volume of 0.6-2.0 ml / g and an average particle diameter of 1.3-6.0 micrometer are added to the said polyester resin, and an average particle diameter 0.03 to 1.5% by weight of small particles having a particle size distribution ratio (R) of from 1.1 to 1.2 µm and a particle size distribution ratio (R) of 1.1 to 4.0 represented by the following formula were added, and the surface centerline roughness (SRa) of the film was 20 to 35 nm, with 10 points Average roughness (SRz) is 0.6-1.5㎛, and longitudinal thickness variation does not exceed 15% Biaxially oriented polyester film for thermal transfer ribbons to prevent thermal transfer

It will provide the film for ribbons.

Description

Biaxially oriented polyester film for heat transcription

The present invention is a biaxial for thermal transfer ribbon which is excellent in transferability and flammability, has excellent anti-wrinkle performance in manufacturing printer ribbon, and enables clear printing. It relates to a stretched polyester film.

Biaxially stretched polyester film is widely used as a base film in all fields such as magnetic recording materials, packaging materials, electrical insulation materials, photographic materials, and graphic arts because of excellent mechanical and electrical properties, dimensional stability, transparency, and heat resistance. In particular, in recent years, growth has been outstanding as a base film for thermal transfer ribbons such as OA and FA.

When the ribbon for thermal transfer printers is broadly classified, various pigments are added to a binder such as wax, and a meltable type in which the ink layer is melted by heat and transferred to a transfer object, and a dye having sublimability is added to the binder. It can be classified into a sublimation type in which only the dye is transferred to the aqueous layer of the transfer target in the contact state of.

In recent years, the increasing demand of thermal transfer ribbons for bar codes due to the increase in overall trade volume, the increase in demand for thermal transfer ribbons due to the expansion of digital cameras, the increase in demand for thermal transfer ribbons due to the issue of electronic resident ID cards and ticketing of various receipts Due to the steady increase in demand for thermal transfer ribbons for special small printing, the demand for thermal transfer ribbons and thermal transfer ribbon films is continuously increasing.

In addition, as a result of efforts to reduce the cost of the thermal transfer ribbon manufacturing film, as the thickness of the heat resistant agent and the ink layer is gradually thinned, the surface structure of the thermal transfer ribbon film affects the surface structure of the coating layer. The technique of controlling the surface structure of the film for thermal transfer ribbon has become more important. As such a thermal transfer ribbon film, a polyester film that can be industrially thin and has excellent mechanical properties has been mainly used.

    The polyester film for thermal transfer ribbon production is defined by the mechanical properties, such as US Patent USP 6197430, USP 4675233, USP 6306496, and the like to improve the thermal properties, Japanese Patent Laid-Open No. 10-264337, Japanese Patent Laid-Open No. 11-321127 Etc., and Japanese Patent Application Laid-open No. Hei 10-86543, Japanese Patent Laid-Open No. 2000-108374, etc. are mentioned to improve the characteristics regarding surface roughness. However, the conventional polyester film for thermal transfer ribbon production described above is mainly to improve the slip resistance and heat resistance of the film, it is known that the transfer ribbon made of such a film has the following problems.

First, ribbon cutting occurs on the guide roll or the thermal head of the traveling system due to the increase in the transmission speed and the printing energy in the traveling system inside the transfer printer, and foreign matters generated by the cutting are deposited on the thermal head. The print quality is reduced.

    Secondly, in the case of a ribbon whose surface is smooth in order to solve the above problem, the surface roughness of the film is too flat, resulting in a decrease in processing aptitude, and wrinkles in the transfer ink coating process of the film manufacturing process and the ribbon manufacturing process. Or poor coating.

Recently, in the case of a thermal transfer ribbon for printing an automobile label or an electronic resident card, a sharper printing quality is required, and as the printing speed increases, the cutting system in the thermal printer needs to have fewer cuttings and a processability. At the same time, it is necessary to satisfy the mutually opposing characteristics such as being excellent.

The present invention improves the thermal dimensional characteristics of the film or ribbon, thereby preventing the occurrence of all defects such as wrinkles and coating failure when manufacturing or processing the film for thermal transfer ribbon, transferability and flammability An object of the present invention is to provide a biaxially oriented polyester film having excellent sealability and excellent processability.

In order to achieve the above object, the film for thermal transfer ribbon of the present invention is 0.01 to 1.0 of porous inorganic particles having a pore volume of 0.6 to 2.0 ml / g and an average particle size of 1.3 to 6.0 µm in a polyester resin. A biaxially oriented film containing from about 0.0% to about 1.5% by weight of particles having an average particle diameter of 0.01 to 1.2 µm and a particle size distribution ratio (R) of 1.1 to 4.0, wherein the center line average roughness (SRa) ) Is 20 to 35 nm, and 10-point average roughness (SRz) is 0.6 to

By setting the thickness variation in the longitudinal direction to 15% or less, it was possible to obtain a biaxially oriented polyester film for thermal transfer ribbons having excellent print quality, no wrinkles, and excellent workability. EMBODIMENT OF THE INVENTION Hereinafter, preferable embodiment of this invention is described.

In the present invention, the polyester composition includes not only a polyester resin monolith but also a blend of other kinds of polymers. In the case of blending, at least 50% by weight is made of polyester resin.

The polyester resin used for this invention is a polymer containing the ester group obtained by the condensation-polymerization of dicarboxylic acid and diol. Dicarboxylic acids are, for example, terephthalic acid, isophthalic acid, adipic acid, sebacic acid, 2, 6-naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, bis-α, β (2-chlorophenoxy) ethane-4, Aliphatic and aromatic dicarboxylic acids such as 4'-dicarboxylic acid can be used. As the diol, for example, ethylene glycol, 1,4-butanediol, diethylene glycol, polyethylene glycol, neopentyl glycol, cyclohexanemethanol and the like can be used.

Two or more types of said dicarboxylic acid and diol may be used, respectively.

On the other hand, the intrinsic viscosity of such a polyester is preferably 0.4 to 2, more preferably 0.5 to 1, measured in orthochlorophenol at 25 ° C.

If the polyester resin used for this invention is less than 10 mol% other than the said dicarboxylic acid and diol, another monomer and polymer may be copolymerized. In addition, two or more kinds of polyester resins are melted. It may be mixed. In addition, other kinds of polymers, ultraviolet absorbers, lubricants, pigments, antioxidants, heat stabilizers, flame retardants, antistatic agents, and the like may be contained within the scope of not impairing the object of the present invention.

On the other hand, particularly preferred as the polyester resin used in the present invention are polyethylene terephthalate, polyethylene-2,6-naphthalate, polyethylene-α, β (2-chlorophenoxy) ethane-4,4'-dicarboxyl Rate.

In this invention, a film is shape | molded using polyester resin as above. Next, the film of the present invention needs to be oriented at least biaxially or more.

In the present invention, the thickness of the biaxially oriented film is not particularly limited, but in general, the thermal transfer ribbon preferably has a thickness of 2.0 to 8.0 µm, more preferably 2.5 to 7.0 µm, and even more preferably 2.5 to 6.0 µm. Is good. If the thickness of the film exceeds 8.0㎛, it takes time for heat conduction and is not suitable for high speed factor. On the contrary, when the thickness is less than 2.0 mu m, the strength is inferior, resulting in poor workability, and the ribbon lacks strength characteristics, which is not preferable.

The biaxially oriented film of the present invention needs to contain porous large particles having a pore volume of 0.6 to 2.0 ml / g. Preferably, by containing large particles having a pore volume of 0.8 to 1.5 ml / g, it is possible to satisfy the suitability in film production and processing, and the wear resistance in the running system after ribbon production. If the pore volume is less than 0.6 ml / g, after the ribbon is manufactured, large particles are cut off in the traveling system of the thermal printer during thermal transfer, resulting in poor printing, voids during stretching of the film due to insufficient affinity between the large particles and the resin composition. (Void) is generated, and there is a problem that stress is concentrated on the voids in the heat setting step and the film breaks. In addition, when the pore volume exceeds 2.0 ml / g, the surface energy of the particles becomes excessively large, which makes it difficult to disperse the particles, which leads to the formation of undesirable aggregates. Even if the film is not broken, it is not preferable because a problem arises that the printing is cut off from the traveling system during thermal transfer printing after the ribbon is manufactured and the printability is poor. It is preferable that the average particle diameter of a large particle is 1.3-6.0 micrometers, More preferably, it is 1.6-5.0 micrometers. If the average particle diameter of the particles is less than 1.3㎛, the surface roughness of the film is too low, and the handling properties of the film manufacturing process and the ribbon processing deteriorate, causing problems such as wrinkles or coating defects, 6.0㎛ If larger, surface roughness becomes too high, the number of coarse particles increases, and the pressure of the filter increases too rapidly during the film manufacturing process, requiring frequent replacement of the filter, frequent breakage in the stretching process, or the traveling system inside the thermal transfer printer. There is a drawback that the quality of the factor is reduced due to the increased cutting in the. Moreover, as for the addition amount of the porous large particle which has a pore, 0.01 to 1.0 weight% is preferable. More preferably, 0.03-0.6 weight% is preferable.

If the added amount is less than 0.01% by weight, it is not preferable because of poor handleability during film production and ribbon processing, which may cause wrinkles, protrusions, coating defects, and the like. The pressure rises sharply and frequent filter replacement is required, resulting in low productivity, frequent breaks during film stretching, and after processing with ribbons, wear resistance inside the traveling system is reduced, and particles are cut out, and the cut-out particles are thermoelectric. It is not preferable because it accumulates in the yarn head part and degrades the quality of printing. In addition, the porous large particles having a pore volume may include silica, calcium phosphate, alumina, and the like, and among these, precipitated silica and hydroxy apatite calcium phosphate are preferable.

The biaxially oriented film of the present invention contains small particles having at least one or more average particle diameters of 0.01 to 1.2 µm in addition to the porous large particles having the above-mentioned pores, and having a particle size distribution ratio (R) of 1.1 to 4.0 represented by the following formula. do.

Particle size distribution ratio (R) = particle size when the integrated weight of the particles is 25%

Particle diameter when the integrated weight of the particles is 75%

The small particles are not particularly limited, but, for example, calcium carbonate particles, organic particles, colloidal silica particles, titanium oxide particles, alumina particles, and the like are preferable, and at least one selected from calcium carbonate particles, colloidal silica particles, and alumina particles. Particles of more than a kind are preferable. Although it does not specifically limit as a crystal form of a calcium carbonate particle, A calcitic type, a vaterite type, etc. are used.

The organic particles are not particularly limited, but di-vinylbenzene particles, silicon particles and the like are preferable. Di-vinylbenzene particle means that it mainly uses di-vinylbenzene as a crosslinking component. Di-vinylbenzene is preferably 51% or more, preferably 60% or more, more preferably 75% or more of the particle component. Here, the crosslinking degree is the weight% of the crosslinkable component in the organic particle composition. In addition, silica particles are mainly composed of organopolysiloxane (CH ₃ -SiO _3/2). The average particle diameter of the small particles mentioned above is 0.01-1.2 micrometer, More preferably, it is 0.06-0.8 micrometer. If the average particle diameter is less than 0.01 µm, the projections

Insufficient ability to form, leading to an increase in the contact area with the guide roll in the traveling system inside the thermal transfer printer, which is undesirable due to poor wear resistance. When the thickness exceeds 1.2 µm, the number of protrusions decreases, and the number of coarse particles It is not desirable to increase the wear resistance in reverse. The particle size distribution ratio R of the small particles is preferably 1.1 to 4.0, more preferably 1.3 to 3.7. If the particle size distribution ratio R is less than 1.1, it is preferable in view of the effect of the present patent, but it is uneconomical because the filtration treatment to reduce the particle size distribution ratio must be performed highly. In addition, when the particle size distribution ratio exceeds 4.0, the particle size distribution is wide, so that the number of small-sized protrusions decreases, and thus the wear resistance decreases. The content of elementary particles is preferably 0.03 to 1.5% by weight, preferably 0.05 to 1.2% by weight, more preferably 0.1 to 1.0% by weight. If the content is less than 0.03% by weight, it is not preferable because the effect of improving the wear resistance by the small particles is not sufficiently expressed. On the contrary, if the content exceeds 1.5% by weight, the effect of increasing the wear resistance is beyond the saturation point, which is not economical.

The biaxially oriented film of the present invention may contain non-porous large particles in addition to the porous large particles and small particles having the above-mentioned pores in terms of printability, wear resistance, aptitude during ribbon processing, and the like. Although it does not specifically limit as a nonporous large particle, The crystalline form is a delta type, (theta) type, (eta) type, (gamma) type alumina, zirconia, a silica, etc. are preferable. Herein, non-porous means a large particle having an average particle size of 1.0 μm or more which is less than 0.5 ml / g of pore volume and less than the lower limit of the pore volume set forth in the present patent. In terms of wear resistance, such non-porous large particles are preferably secondary aggregated particles in which primary particles are aggregated. The primary particle size is not particularly limited, but is 5 to 100 nm, preferably 10 to 80 nm, and the aggregated secondary particle diameter is not particularly limited, but is 1.0 to 4.0 μm, preferably 1.3 to 3.5 μm, and the content is not particularly limited, but is 0.005. It is preferable to set it as -0.5 weight%, Preferably it is 0.01 to 0.3 weight%.

The biaxially stretched film of this invention refers to the film which biaxially stretched the said composition.

The monoaxial or unstretched film is not preferable because of its poor wear resistance. Although the degree of such stretching is not particularly limited, wear resistance is further improved when the elastic modulus, which is a measure of the stretching of the polymer, is 350 kgf / mm ² or more in both the longitudinal direction and the width direction. Moreover, as for the elasticity modulus which is a measure of extending | stretching, 1500 kgf / mm <^2> normally becomes a manufacturing limit.

In the biaxially oriented film of the present invention, the elastic modulus is within the above range, for example, the orientation of the polymer molecules near the surface layer is unoriented or uniaxially aligned, that is, the molecular orientation of the entire portion in the thickness direction. In this biaxial orientation, the wear resistance is further improved. The biaxially oriented film of the present invention needs to have a center line average roughness SRa of 20 to 35 nm and a 10-point average roughness SRz of 0.6 to 1.5 µm. If the center line average illuminance is 20 nm or less or the 10-point average illuminance is 0.6 μm or less, there is a problem that the printing becomes difficult due to the sticking phenomenon in which the thermal head is fused during printing, and the center line average roughness is 35 nm. When the average value of 10 points or more exceeds 1.5 µm, the number of coarse particles increases, which leads to deterioration in wear resistance of the traveling system inside the thermal printer, and thermal conductivity of the thermal head.

Center line average roughness SRa and 10-point average roughness SRz can be achieved by adjusting the average thickness, average particle diameter, and amount of inert particles added to the polyester resin in order to maintain the above range.

The biaxially oriented film of the present invention needs to have a thickness variation in the longitudinal direction of 15% or less, more preferably 13% or less. In the case where the thickness variation rate is 15% or more, wrinkles or poor coating occur easily during ribbon processing, which is not preferable. In order to keep the thickness variation in the longitudinal direction of 15% or less, the molding conditions in the production of the unstretched film, the stretching temperature and the stretching ratio in the longitudinal stretching process must be controlled. Among these, the molding conditions especially during the production of the unstretched film are important, and it is important to set the distance between the polymer sheet discharged from the die on the slit and the wire electrode to which the voltage is applied to an appropriate range.

That is, if the distance is too long for the distance between the wire electrode and the cooling drum surface, the potential gradient formed between the wire electrode and the cooling drum is lowered so that sufficient charge is not emitted from the wire electrode, thereby reducing the electrostatic force applied to the polymer sheet. As a result, sufficient adhesion cannot be obtained on the cooling drum, and hence the thickness variation rate increases.

On the contrary, if this distance is too short, the potential gradient is excessive, which leads to the problem of insulation breakdown of the polymer sheet and the occurrence of discharge, which is not preferable. In addition, when the wire electrode is provided upstream than the position where the molten polymer sheet discharged from the die lands on the surface of the cooling drum, the coulomb acting between the polymer sheet and the wire electrode is located in the direction in which the polymer sheet of the wire electrode is drawn. The repulsive force and the vibration of the peripheral device are combined to cause the polymer sheet to shake, resulting in an increase in thickness variation. On the contrary, if it is provided downstream from the landing point, the surface of the cooling drum side of the polymer sheet is already cooled to some extent, and the polymer sheet is not sufficiently adhered to the cooling drum, which is not preferable because there is a problem that a defect occurs.

Hereinafter, the manufacturing method of the film for liver heat transfer of this invention is demonstrated.

   First, the method of adding particles to the polyester may be added at any stage of the polyester manufacturing process or the molding process, but a polycondensation to obtain a polymer having a film forming ability in a reduced pressure or inert air stream with a relatively low molecular weight intermediate It is preferable for the dispersibility to the obtained polyester resin and the prevention of the coloring of a polymer to add immediately before or just before reaction. Moreover, addition is preferably made to disperse | distribute to ethylene glycol of a diol component as a slurry, and to polymerize this ethylene glycol with the predetermined dicarboxylic acid component. Of course, the water slurry of the particles is directly mixed with a predetermined polyester pellet and kneaded in polyester using a vented twin screw extruder to prepare a masterbatch, which is diluted with other polyester to form a film. The content of may be adjusted.

Subsequently, the pellet containing the predetermined amount of particles is dried as necessary, extruded into a sheet form in a known slit-like die and cooled to solidification on a casting roll to form an unstretched film. Subsequently, the non-oriented film is biaxially oriented by biaxially stretching in the longitudinal direction and the transverse direction, but a successive biaxial stretching method or a simultaneous biaxial stretching method is used as the stretching method. However, the longitudinal stretching is first performed, and then the longitudinal stretching is divided into two or more stages by using a sequential biaxial stretching method in which the stretching is performed in the width direction, and the stretching temperature is 80 to 150 ° C., and the total longitudinal stretching ratio is 3.0 to It is preferable to set it as 6.5 times and a extending | stretching speed in the range of 5,000-50,000% / min.

The stretching method in the width direction is preferably a method using a stenter, the stretching temperature is preferably 80 to 160 ° C, the stretching ratio is 3.5 to 6.0 times, and the stretching speed is in the range of 1,000 to 20,000% / min. The stretched film is then heat treated. In this case, the heat treatment temperature is preferably 200 to 245 ° C, more preferably 210 to 240 ° C, and more preferably 0.5 to 30 seconds.

In the case of the relaxation treatment, the treatment is performed after the heat treatment and until it is wound on the roll. In the lateral relaxation treatment, the width of the stenter is reduced between the heat treatment zones and the cooling zones in the direction of film width in the film width direction from the heat treatment zone. It is preferable to perform 10% relaxation treatment. As a longitudinal relaxation treatment method, the both ends of the film are cut out, and the pulling speed is lower than the feed rate of the film under the temperature conditions of Tg or more and below the melting temperature of the film. Heating rollers with different feed rolls, or passing the heating zone by a heating oven or infrared heater to reduce the speed of the roll after the heating zone to less than the speed of the roll before the heating zone. Either way or any method may be used, the relaxation process is carried out with a reduction ratio of the take-out speed as 0 to 5% relative to the speed on the supply side.

Moreover, the polyester composition which comprises the film of this invention may contain a part of the composition collect | recovered by recycling. The recycled recovered composition refers to a polyester composition composed of trimming parts, quality non-conforming products or waste products generated in the manufacturing process of the film.

  The film for thermal transfer ribbons of this invention apply | coats the transfer ink layer of a molten type or a sublimation type to the single side | surface of the biaxially-oriented film which consists of polyester compositions. The transfer ink layer is a well-known composition mainly composed of a pigment or dye colorant and a binder made of a polymer compound. The transfer ink layer is formed by applying a known method or hot melt coating to form a transfer ink layer on a polyester film. do. Although the thickness of a transfer ink layer is not specifically limited, It is preferable to set it as 2 micrometers or less. When the thickness of the ink layer is 2 µm or more, there is a problem in that the remodelability is insufficient. Moreover, when thickness is 2 micrometers or less, four or more sets of remodeling expressions can be made easy. The opposite side of the transfer ink layer is formed by applying a heat resistant layer. The heat resistant layer is for preventing sticking due to heat when contacted with the thermal head, and known ones known in the art can be used here. As a typical heat-resistant coating layer, various waxes, cellulose resins, modified acrylic resins such as acrylic silicone, butyral resins, silicone resins, imide resins, silicone oils, various mineral oils, phosphoric acid compounds and the like can be used. In addition, various organic particles and inorganic particles may be added to the heat-resistant coating layer. Although the thickness of this heat-resistant coating layer is not specifically limited, It is preferable to set it as 0.01-1.0 micrometer, especially 0.02-0.3 micrometer from a thermal head contamination and heat resistance. In addition, the method of coating is not particularly limited, but a predetermined coating may be applied to a uniaxial stretched or unstretched film, followed by drying or stretching, stretching to two or more axes, and then applying to a film subjected to the necessary heat treatment, It may be dried. Typical coating methods include gravure method, reverse method, metering bar method, die coating method, gap coating method and the like.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated concretely based on an Example.

Example

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail based on an Example.

In the present invention, the characteristic values were applied to the following measurement methods and evaluation criteria.

One) Average particle size and particle size distribution ratio of particles:

    The measurement was carried out using "CP-50 type Centrifugal Particle Size Analyser" manufactured by Shimadzu Corporation, Japan. The cumulative curve of each particle size particle and the amount of abundance computed based on the obtained centrifugal sedimentation curve was grasped | ascertained and the numerical value was made into the average particle diameter. The particle size distribution ratio was calculated based on the centrifugal sedimentation curve obtained in the measurement of the average particle diameter, and was calculated by calculating a Cumulative curve between the particle size and the amount present. The cumulative weight of the particles corresponds to 25% by weight and the cumulative weight of the particles is calculated. The particle size corresponding to 75 weight% was grasped, and the former value was divided by the latter value, and the particle size distribution ratio R of each particle was calculated.

2) Pore Volume:

    A pore volume with a pore size of 17 to 3000 mm 3 was obtained by BJH method by nitrogen adsorption desorption using a high-speed specific surface area and pore distribution measuring instrument "Asapu 2400" manufactured by Shimadzu Corporation, Japan.

3) Center line average roughness (SRa), 10-point average roughness (SRz):

    It measured according to DIN-4768. Using a 5 micrometer R needle, it measured with 2.5 mm of measurement length, 40 sheets of scanning number, and 0.25 mm of cutoff values. Four repeated measurements of the same sample were made as the average of the remaining three data except for the largest one.

4) Thickness variation:

    The film thus prepared was sampled at a width of 5 cm in the longitudinal direction, set in a film traveling device, and then continuously run over 5 meters, and the film thickness was measured with an Anritsu film thickener "KG601A type", and the value was measured. Continuous writing was performed and the thickness (maximum thickness min minimum thickness) / average thickness x 100 (%) was expressed as the longitudinal thickness variation.

5) Factor (印字 性):

    Using a high-precision printer manufactured by Seiko Electronics Co., Ltd. as a thermal transfer printer, the sharpness of the print was observed by visual observation and 100-fold stereoscopic microscope.

    As shown in Table 1, the case where the printed character had no defects such as scratching, sagging, deformation, etc., and there was no unnecessary factor in the portion other than the printing was indicated by ○.

Although no defects or unnecessary factors were identified visually, the case where it was confirmed on a 100-fold stereomicroscope was indicated by △, and the case that was confirmed by both the naked eye and 100-time microscope was indicated by x.

Table 1

Factor The sharpness of the argument Visually Stereomicroscope ○ △ × ○○ × ○ ××

6) Aptitude for thermal ribbon processing:

After applying the following coating solution to the one side of the biaxially oriented film with a heat resistant layer using a metering bar method so that the coating thickness after drying is 0.2 μm, the solvent under the conditions of the film tension 20MPa, heating temperature 130 ℃, heating time 15 seconds Was dried and crosslinking was carried out.

[Composition of Heat Resistant Layer]

    Polyacrylic acid ester: 13.4 wt%

        Amino modified silicone: 6.5 wt%

         Isocyanate: 0.1 wt%

         Toluene: 35.0 wt%

         Methyl ethyl ketone: 45.0 wt%

Subsequently, a transfer ink of the following composition was applied on the opposite side of the heat resistant layer using a gravure coater with a thickness of 1.5 μm, and the tension applied to the film was 20 MPa, a heating temperature of 110 ° C., and a heating time of 12 seconds. Dried.

[Composition of Transfer Ink]

        Ethylene Vinyl Acetate Copolymer: 28 wt%

        Water-based rosin wax: 7 wt%

        Carbon black: 15 wt%

        Toluene: 47 wt%

        Ethylene Glycol Monomethyl Ether: 3 wt%

In the processing of such ribbons, whether or not normal processing was possible was observed in the process, or the processed ribbons were visually examined to distinguish them as follows.

        (Circle): Wrinkles do not generate | occur | produce at all in a process, and application | coating defects do not arise either.

Not,

         △: fine wrinkles occur in the process, but does not lead to poor coating,

X: Wrinkles generate | occur | produce severely in a process, and coating defect also arises.

7) Abrasion Resistance of Film:

   Fixed guide pin made of SUS material using a tape running tester ("TBT300D / H" manufactured by Yokohama Systems Japan) under the condition that the film was cut into a tape of 1/2 inch width at a temperature of 20 ° C and a relative humidity of 60%. [Surface roughness (Ra): 0.1㎛] Friction by driving on the top. [Running speed: 50mpm, Guide pin contact angle: 60 ° crimp tension: 50 grams] Wear powder adhered to the fixing guide pin after 10 passes of the film. The state of was evaluated based on the following criteria.

      (Circle): No abrasion powder is seen at all,

      (Triangle | delta): The area of the abrasion powder adhered is 1/10 of the apparent contact area of a pin and a film.

If less than

X: The area of abrasion adhered is 1/10 of the apparent contact area between the pin and the film

If more than

Example 1

(1) Preparation of Polyester Resin Composition:

    1 part by weight of porous silica particles having an average particle diameter of 2.5 μm and a pore volume of 1.6 ml / g were mixed with each other by 90 parts by weight of ethylene glycol, followed by high-speed stirring at room temperature for 3 hours to obtain silica particles / ethylene glycol slurry (a).

    On the other hand, after adding 0.06 parts of magnesium acetate as a catalyst to 100 parts by weight of dimethyl terephthalate and 64 parts by weight of ethylene glycol, and performing a transesterification reaction while gradually raising the temperature between 150 ° C and 240 ° C, the slurry prepared before the reaction product ( a) After adding the addition amount shown in Table 1, 0.03 parts by weight of antimony trioxide as a condensation catalyst and 0.04 parts by weight of trimethyl phosphate were added. The condensation reaction was carried out to obtain a polyethylene terephthalate composition having an intrinsic viscosity of 0.625.

(2) Preparation of Biaxially Oriented Polyester Film:

    The obtained polyester resin was vacuum at 160 degreeC and 3 torr for 6 hours. Dried. The polymer was fed to an extruder, melted and extruded at 285 ° C, and formed into a sheet in a slit-type die on a cooling drum whose surface temperature was controlled at 28 ° C. At this time, the gap between the die and the cooling drum is set to 27 mm, the vertical distance between the cooling drum and the wire electrode is 4 mm, and the horizontal distance between the wire electrodes in the die vertical direction is 52 mm, while the sheet is brought into close contact with the drum surface by the electrostatic application method. Direct voltage is 8.5KV and cooled at 45m / min. It solidified and obtained the unstretched sheet. The unstretched sheet was stretched in the longitudinal direction by 1.7 times at 121 ° C., 1.4 times at 120 ° C., and 2.1 times at 115 ° C., and the resulting uniaxially stretched film was sent to the stenter and stretched in the transverse direction at 125 ° C. and 3.9 times, after stretching. Heat treatment was performed at 230 ° C. and 3.8% relaxation treatment was performed in the transverse direction. As a result, a biaxially oriented film of 4.6 µm was obtained.

About the obtained biaxially-oriented film, center line roughness SRa, 10-point average roughness SRz, thickness variation rate, and abrasion resistance were evaluated. The evaluation results are shown in Table 2.

Subsequently, the heat transfer agent layer and the transfer ink layer were apply | coated to the single side | surface and the opposite surface of the obtained biaxially-oriented film like the said composition, and the transfer ribbon was manufactured, and the printing property and the aptitude at the time of ribbon processing were evaluated. The evaluation results are shown in Table 2.

Examples 2-7, Comparative Examples 1-6, and Comparative Examples 8-9

In the same manner as in Example 1, the film was prepared by changing the type, average particle size, and addition amount of the porous large particles, the small particles, and the non-porous large particles. As shown in Table 2 and Table 3, the film of the present invention has good printability, abrasion resistance, and aptitude during ribbon processing, and it is impossible to achieve printability, abrasion resistance, and aptitude during ribbon processing outside of this range. .

Comparative Example 7

In preparing the film as in Example 2, the film was made closer to the discharged polymer by setting the distance between the die and the cooling drum to 18 mm and the distance between the electrode wires in a straight line parallel to the die discharge part to 42 mm. As shown in Table 3, the thickness variation was increased, resulting in poor aptitude during ribbon processing.

TABLE 2

TABLE 3

In the film for thermal transfer ribbon of the present invention, the pore volume is from 0.6 to the polyester resin.

A range of specific surface roughness is obtained by adding an appropriate amount of porous inorganic particles having an average particle diameter of 1.3 to 6.0 µm and small particles having an average particle diameter of 0.01 to 1.2 µm and a particle size distribution ratio (R) of 1.1 to 4.0. In addition, by defining the thickness variation in the longitudinal direction in a specific range, it is possible to manufacture a biaxially oriented polyester film for thermal transfer ribbons having excellent wear resistance, printability and processability.

Claims (4)

In the film for thermal transfer ribbons which apply | coated the transfer ink layer to the single side | surface of the biaxially-stretched film which consists of polyester resins, and apply | coated the heat-resistant coat layer on the opposite surface, the said polyester-type resin 0.01 to 1.0% by weight of porous inorganic particles having a pore volume of 0.6 to 2.0 ml / g and an average particle size of 1.3 to 6.0 µm, and an average particle diameter of 0.01 to 1.2 µm, 0.03 to 1.5% by weight of the small particles having a particle size distribution ratio (R) of 1.1 to 4.0 represented by the formula is added so that the surface centerline roughness (SRa) of the film is 20 to 35 nm, and the ten point average roughness (SRz) is 0.6 to A 1.5 탆, biaxially oriented polyester film for thermal transfer ribbons, characterized in that the longitudinal thickness variation does not exceed 15%. Particle size distribution ratio (R) = particle size when the integrated weight of the particles is 25% Particle diameter when the integrated weight of the particles is 75% The biaxially oriented polyester film for thermal transfer ribbons according to claim 1, wherein the porous inorganic particles are porous silica, calcium phosphate or alumina by a wet method. The biaxially oriented polyester film for thermal transfer ribbons according to claim 1, wherein the small particles include calcium carbonate particles, clodal silica particles, titanium oxide particles, or alumina particles. The biaxially oriented polyester film for thermal transfer ribbons according to claim 1, wherein the thickness of the transfer ink layer does not exceed 2.0 µm.