JP6464880B2 - Polyester film and method for producing the same - Google Patents

Description

  The present invention relates to a polyester film in which a film has a minute charge over a long section in the longitudinal direction and a method for producing the same.

  Polyester films using polyethylene terephthalate and polyethylene-2,6-naphthalate are excellent in mechanical properties, heat resistance, dimensional stability, chemical resistance, cost performance, etc. It is used. One of them is a thermal transfer ribbon. The thermal transfer recording method is used in fields such as FAX and barcode printing because of its excellent cost performance, maintainability, and operability. In recent years, high-definition and high-quality characteristics have been achieved by using color thermal transfer ink. In addition, it is also used in color thermal transfer printers.

  In recent years, when producing a thermal transfer ribbon, the production line has been increased in speed (400 m / min or more) in order to reduce the production cost. In high-speed ink application, it is necessary to unwind a film roll at a high speed of 400 m / min or more. When the film is unwound from the film roll, peeling electrification occurs. When unwinding at a high speed, the peeling speed between the film and the roll increases, and the amount of charge for peeling increases. When the peel charge amount is serious, it has been pointed out that it may become an ignition source due to electrostatic discharge from the film, and there is a risk of igniting the solvent-based ink. Therefore, when manufacturing a film roll, it is necessary to reduce the charge amount of the film roll itself in advance. Even when the charge amount is at a level that does not cause a problem at a normal unwinding speed, there may be a problem that peeling charge increases due to a small potential in high-speed unwinding.

  In order to reduce the unwinding peeling charge, it is common to use a static eliminator to neutralize the film and to reduce the amount of charge before unwinding when the film is wound into a roll in film formation. Has been taken. As this static eliminator, a voltage application type static eliminator and a voltage application blast type static eliminator are often used. The voltage application type static eliminator has a plurality of electrode needles capable of generating ions by applying a voltage, and neutralizes the film with the ions. The voltage application blower type static eliminator is a combination of the aforementioned voltage application type static eliminator and a blower, and is suitable for static elimination of a film at a distance away from the static eliminator and the film to be neutralized.

  However, in recent years, in order to improve printing accuracy, it has been studied to reduce the thickness of the film. However, if the thickness of the film is reduced, the film forming speed and the slit speed are increased, so that the static elimination is not sufficiently performed. There is a problem that the charge amount of the roll increases and the peeling charge increases.

  For this reason, methods for eliminating static electricity by defining the distance between the static eliminator and the film (Patent Document 1) and using a plurality of static eliminators in opposition (Patent Document 2) have been studied.

JP 2006-290621 A Japanese Patent No. 5029740

  In the voltage application type static eliminator, the static eliminator gives an appropriate amount of ions to the film, and neutralizes the static electricity charged in the film, thereby neutralizing the film. As in Patent Document 1, if the distance between the static eliminator and the film is only specified, excessive ions are applied to the film due to an excessive amount of ions, and the film may be charged. Even if an appropriate amount of ions is set, it is difficult to give the film a minute potential over a long section in the winding longitudinal direction of the film roll. On the other hand, if the amount of ions is too small, there arises a problem that the film is not sufficiently neutralized. In addition, when a static eliminator is used as in Patent Document 2, there is a problem that the installation cost is increased and the installation space becomes large due to the size of existing equipment. Furthermore, since the film is completely neutralized (the non-charged band ratio is almost 100%), there is a problem that a winding defect occurs when winding at a high speed of 300 m / min or more.

  In view of such a problem, the present invention suppresses the occurrence of winding deviation in high-speed winding at 300 m / min or more by giving a film a small potential over a long section in the longitudinal direction, and the film has a small potential. It is an object of the present invention to provide a polyester film and a method for producing the same, in which peeling charge does not increase at a high speed unwinding of 400 m / min or more.

In order to solve the above problems, the present invention has the following configuration.
[I] A polyester film having a maximum value and a minimum value of 55% or more and less than 97% when at least one surface has a non-charged band ratio measured in a longitudinal direction of 800 m.
[II] The polyester film according to [I], wherein the difference between the maximum value and the minimum value is 10% or less when at least one surface has a non-charged band ratio measured in a longitudinal direction of 800 m.
[III] The polyester film according to [II], wherein the film has a thickness of 1 μm or more and 25 μm or less.
[IV] The polyester film according to any one of [I] to [III] used for thermal transfer ribbon applications.
[V] A method for producing a polyester film including a step of neutralizing a film using a voltage application type static eliminator and / or a voltage application blower type static eliminator, wherein the film is subjected to static elimination when the film is neutralized. The manufacturing method of the polyester film which satisfy | fills the following formula, when the absolute value of the ionic current of I is set to I (microampere) and the conveyance speed of a film is set to V (m / min).
5.0 × 10 ⁻² ≦ I ≦ 2.0 (Formula 1)
2.5 × 10 ⁻⁴ ≦ I / V ≦ 7.0 × 10 ⁻³ (Formula 2)
[VI] The method for producing a polyester film according to [V], including a step of neutralizing the film at least twice using a voltage application type static eliminator and / or a voltage application blower type static eliminator.

  The film of the present invention suppresses the occurrence of winding defects such as winding misalignment and wrinkles in high-speed winding at 300 m / min or more by giving the film a minute potential over a long section in the longitudinal direction, and the film has a minute amount. It is possible to provide a polyester film and a method for producing the same, in which the peeling charge does not increase at a high speed unwinding of 400 m / min or more despite having a high potential. When the above film is used as a thermal transfer film, high-speed coating of ink becomes possible.

The figure shows schematically a method for measuring an ionic current at a position where a film is subjected to static elimination when a voltage application type static eliminator is used. 1 schematically shows a method for measuring the amount of peeled charge generated when a film is unwound (potential measurement method).

  Hereinafter, preferred embodiments of the present invention will be described.

  The present invention relates to a polyester film.

  The polyester according to the present invention may be a polyester that can be a high-strength film by molecular orientation accompanying stretching, and polyethylene terephthalate or polyethylene-2,6-naphthalate is preferable. These may be polyester copolymers, but preferably 80 mol% or more of the repeating structural units is ethylene terephthalate or ethylene-2,6-naphthalate. Other polyester copolymer components include diol components such as diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol, p-xylene glycol, 1,4-cyclohexanedimethanol, or adipic acid, sebacic acid, phthalic acid, isophthalic acid Examples thereof include dicarboxylic acid components such as acid, 5-sodium sulfoisophthalic acid and 2,6-naphthalenedicarboxylic acid, or polyfunctional dicarboxylic acid components such as trimellitic acid and pyromellitic acid, and p-hydroxyethoxybenzoic acid. Further, in the above polyester, one or more of an alkali metal salt derivative of a sulfonic acid that is not reactive with the polyester, or a polyalkylene glycol or an aliphatic polyester insoluble in the polyester, so long as it does not exceed 5 mol%. For example, it may be copolymerized or blended.

  The present invention relates to a polyester film having a minute potential in the film over a long section in the longitudinal direction. That is, at least one of the surfaces relates to a polyester film having a maximum value and a minimum value of 55% or more and less than 97% when the uncharged band ratio is measured over the longitudinal direction of 800 m. Hereinafter, the non-charging band ratio will be described.

  As a method for confirming the charged state of the polyester film surface, there is a method of visualizing the charge of the film by using a dust figure method (for example, described in the Electrostatic Society edition, electrostatic handbook first edition, page 373). In the dust figure method, after sprinkling the developer on the film surface, the developer is sprinkled off, and the film surface is observed by changing the color of the film surface due to the developer remaining on the film surface due to the charging of the film surface. This is to confirm the charged state. The non-charged band ratio of the present invention is determined by a measurement method described later based on the dust figure method. As the developer, blue toner (Minolta CF toner CF70 / CF80 product number: 8931-728 (manufactured by Konica Minolta)) and red toner (for Canon NP3000 toner NP3025, 3225, 3525, 3725, product number: F41-4012-000 (Canon) A toner with a weight ratio of 1: 1 and a non-charged band ratio of 55% or more and less than 97% means that the surface of the film is at a minute level that cannot be measured by a normal film surface potential meter. In addition, when the uncharged band ratio is measured over 800 m in the longitudinal direction, the maximum value and the minimum value are both 55% or more and less than 97%. Measure the non-charged area ratio at every other 5 locations, and the uncharged area ratio is 55% or more and less than 97% at all 5 places. Representing the Rukoto.

  By giving the film a minute charge, that is, by setting the non-charging band ratio to 55% or more, it is possible to suppress the occurrence of winding defects such as winding deviation and wrinkles in high-speed winding at 300 m / min or more. . In addition, by setting the amount of charge on the film surface to a certain value or less, that is, by setting the non-charging band ratio to less than 97%, the peeling charge does not increase even when the film is unwound at a high speed of 400 m / min or more. It becomes possible. In addition, the film is uniformly charged with a small potential over a long section in the longitudinal direction, that is, the amount charged on the surface of the film over a longitudinal direction of 800 m is set within a certain range, so that the film can be wound at a high speed winding of 300 m / min or more. It is possible to suppress the occurrence of winding defects such as misalignment and wrinkles, and it is possible to prevent the peeling charge from becoming large even when unwinding at a high speed of 400 m / min or more.

  In the polyester film of the present invention, it is preferable that the difference between the maximum value and the minimum value is 10% or less when at least one surface of the polyester film has a non-charged band ratio measured in the longitudinal direction of 800 m. By setting the difference between the maximum value and the minimum value of the non-charged band ratio to 10% or less, it is possible to suppress the occurrence of winding defects such as winding deviation and wrinkles in high-speed winding at 300 m / min or more. More preferably, it is 8% or less, More preferably, it is 6% or less.

  In addition, the polyester film of the present invention measures the surface potential of 20 points every 200 m in the longitudinal direction of the film, and the absolute value of the maximum value of 20 points of the surface potential is 0.2 kV or more and 2.0 kV or less. preferable. More preferably, it is 0.2 kV or more and 1.5 kV or less.

  The thickness of the polyester film in the present invention is preferably 1 μm or more and 25 μm or less. In particular, the thickness is preferably 1.5 μm or more and 10 μm or less in consideration of printing suitability, operation in the thermal transfer ribbon, and ease of handling in general. If the thickness of the film is less than 1 μm, printing wrinkles, perforations and the like may occur.

  The polyester film of the present invention is preferably biaxially oriented. By being oriented biaxially, it is excellent in mechanical strength and printability, and therefore can be suitably used for a thermal transfer ribbon.

  Since the polyester film of the present invention can suppress the occurrence of peeling electrification even when unwound at a high speed of 400 m / min or more, it can be applied at high speed when used for a thermal transfer ribbon. Further, in high-speed winding at 300 m / min or higher, the occurrence of winding defects such as winding deviation and wrinkles is suppressed, so that the transfer characteristics can be improved.

  The method for imparting a minute charge to the surface of the polyester film is not particularly limited, and examples thereof include a method for removing the charge in the film forming step. Examples of the static elimination method in the process of neutralizing the film include a voltage application type static eliminator, a voltage application blower type static eliminator, a self-discharge type static eliminator, a soft X-ray type static eliminator, and a method of static elimination using an ultraviolet type static eliminator. . In particular, since the amount of generated ions is large and can be controlled, and the amount of charge on the film surface can be stably controlled over a long section in the longitudinal direction of the film, the voltage application type static eliminator and / or the voltage application air blow type It is preferable to remove static electricity using a static eliminator. In addition, the voltage application type and the voltage application blower type are preferable because the apparatus is compact, relatively inexpensive, and can be installed on a wide film.

  As for the voltage application type static eliminator and / or the voltage application blower type static eliminator, either AC or DC can be used as the voltage to be applied, but the film surface potential (charge amount) approaches zero, and the film surface In order to make the distribution of the potential (charging amount) more uniform, an AC voltage is preferable. In this case, the applied voltage is preferably 2 to 15 kV. If the voltage is too low, the amount of generated ions tends to be insufficient, and if the voltage is too high, problems such as spark discharge tend to occur.

In addition, when the polyester film of the present invention is produced by a production method including a step of removing a film using a voltage application type static eliminator and / or a voltage application blower type static eliminator, the film is eliminated when the film is neutralized. When the absolute value of the ionic current at the position where the film is received is I (μA) and the film conveyance speed is V (m / min), it is preferable to satisfy the following equation.
5.0 × 10 ⁻² ≦ I ≦ 2.0 (Formula 1)
2.5 × 10 ⁻⁴ ≦ I / V ≦ 7.0 × 10 ⁻³ (Formula 2)
The voltage application type static eliminator and the voltage application blower type static eliminator perform static elimination by generating positive ions (plus ions) and negative ions (minus ions). At this time, although the value may be different between the positive ion current amount and the negative ion current amount, it is preferable that each absolute value satisfies the above formula. The positive ion current and the negative ion current are preferably balanced, and the difference between the absolute values of the positive ion amount and the negative ion amount is preferably 0.5 μA or less. By producing by a production method including a static elimination step that satisfies the above formula, a small amount of charge can be imparted to the film surface stably over a long section in the longitudinal direction of the film. (Formula 1) is more preferably 2.0 × 10 ⁻¹ ≦ I ≦ 1.0, and (Formula 2) is more preferably 5.0 × 10 ⁻⁴ ≦ I / V ≦ 3. 5 × 10 ⁻³ .

Moreover, it is preferable to pass through at least two static eliminators in the step of neutralizing the film. When the number of static eliminators is two or more, the ionic current I and the film transport speed at the position where the film is subjected to static elimination when the film is neutralized by each static eliminator satisfy the above formulas 1 and 2. Is preferred. (For example, the ion current at the position where the film is subjected to charge removal when the charge is removed by the first charge remover is I ₁ , the film transport speed at that time is V _1, and the film is removed when the charge is removed by the second charge remover. Assuming that the ion current at the position where the charge is removed is I ₂ , and the film transport speed at that time is V ₂ , I ₁ and I ₂ preferably satisfy Formula 1 respectively, and I ₁ / V ₁ , I ₂ / Each V ₂ preferably satisfies Formula 2. Further, when the film is neutralized, the sum of the absolute values of the ionic current I at the position where the film is subjected to static elimination is It (It = I ₁ + I ₂ +. I _n ), It is preferably 0.5 μA or more, more preferably It is 1.5 μA or more and 10 μA or less, and the ion current amount is a positive ion current and a negative ion current. If they are different, the one having a larger absolute value is employed to obtain the total current It of the ionic currents, and the phase of the static eliminator located next is preferably shifted by 1/3 to 2/3.

  Next, the manufacturing method of the preferable polyester film of this invention is shown. Although it can manufacture by the process shown below, this invention is not limited to this example.

  As a method of biaxially stretching the polyester film of the present invention, an unstretched thermoplastic resin film is stretched in the longitudinal direction or the width direction, and then sequentially biaxially stretched in a direction orthogonal to the previous stretching direction. Simultaneous biaxial stretching in which the film is stretched at once in the longitudinal direction and the width direction is employed.

  In the case of sequential biaxial stretching, the polyester resin is melted using a known extruder, extruded into a sheet form from a die having a slit-like discharge port, and cooled in the form of a cooling roll to obtain an amorphous film. Subsequently, the amorphous film is heated to a temperature equal to or higher than the glass transition temperature of the polyester film by a known method such as a method of passing the amorphous film through several temperature-controlled rolls or heating by radiant heat of a heater such as an infrared heater. And it extends | stretches in a longitudinal direction using the circumferential speed difference etc. of the roll to front and back. The heating temperature at this time is preferably 80 to 130 ° C. The stretching ratio is about 2 to 8 times, and the stretching may be performed in one step or stepwise in two or more steps. A strongly oriented film can be obtained. In this way, a uniaxially stretched film is obtained.

  The film stretched in the longitudinal direction is once cooled and then stretched in the width direction by a known stenter oven. While the film is held by a clip running on a rail in the stenter oven, the film is heated again above the glass transition temperature of the resin in the oven and stretched in the width direction as the rail travels. The draw ratio in the width direction is about 2 to 5 times. The film stretched in the longitudinal direction and the width direction is subsequently heat treated. The heat treatment may be performed in the same stenter oven following the stretching in the width direction, or may be performed in an oven different from the stenter oven that has been stretched in the width direction. The temperature of the heat treatment is preferably 180 ° C to 250 ° C. It is preferable to perform the heat treatment because the dimensional stability when exposed to high temperatures during use as a subsequent processing step or final product is improved. Further, it is desirable to relax the film in the longitudinal direction and / or the width direction by 0 to 8% after the heat treatment in order to further improve the dimensional stability.

  The biaxially stretched film is once wound up as an intermediate product by a wide winder. The neutralization is preferably performed at least once before being wound up by the intermediate product. The static elimination electrode is installed with the film sandwiched so as to be perpendicular to the traveling direction of the film at a position where the film does not flutter and to be parallel to the surface of the film. Thereafter, it is cut into a necessary width and length by a known slitter to obtain a final product. Also in this slitter transport system, at least one static elimination electrode is installed at a position where the film does not flutter so as to be perpendicular to the film traveling direction and parallel to the film surface. It is preferable. In addition, it is not necessarily limited to the manufacturing method shown here.

  For the purpose of imparting head runnability as an ink ribbon and the purpose of improving the winding property and improving the productivity, a two-layer laminated film in which the slippery layer side is a rough surface type can also be used. Furthermore, an easy-adhesion coating layer can be applied to the transfer surface for the purpose of enhancing the adhesion between the ink layer and the polyester film. When the coating is applied, it can be provided either during the production process of the biaxially oriented polyester film or after the production, but in the latter case, it is industrially inefficient and difficult to apply uniformly. In addition, since the dust tends to be a defect at the time of printing by entraining dust, it is preferable to adopt the former method. Application in the manufacturing process may be performed at any stage as long as it is in a state before the orientation crystallization is completed, and finally in an unstretched film, a film after uniaxial stretching, and a low magnification stretched state. It can be provided on any of the films before re-stretching.

  The polyester film thus formed suppresses the occurrence of winding deviation at a high speed winding of 300 m / min or more, and has a peeling charge at a high speed unwinding of 400 m / min or more even though the film has a minute potential. Since it does not become large, when producing a thermal transfer ribbon, high-speed coating of ink can be performed.

[Measurement and evaluation methods of physical properties]
(1) Method for measuring electric potential of film surface The electric potential is measured using a digital electrostatic potential measuring device KSD-1000 manufactured by Kasuga Electric. A measurement location unwinds a film from a film roll, and makes it a winding outer surface and the width direction center part in the position 2 m away from the roll. The distance between the film and the potential measuring device is 50 mm. Measure for 5 seconds and adopt the maximum value. This is measured at 20 points every 200 m in the longitudinal direction of the film, and the maximum value of 20 points is taken as the potential.

(2) Measuring method of non-charged band ratio The charged state of the film was visualized by the following method by the dust figure method (edited by the Electrostatic Society, Electrostatic Handbook 1st Edition, page 373).
(I) Cut into 5 samples and a size of 0.4 m × 1.0 m every 200 m in the longitudinal direction. (Hereinafter referred to as evaluation film.)
(Ii) From the top of the evaluation film in an environment with a relative humidity of 50% RH, blue toner (Minolta CF toner CF70 / CF80 product number: 8931-728 (manufactured by Konica Minolta)) and red toner (Canon NP3000 toner NP3025, 3225) 3525, 3725 Part No .: F41-4012-000 (manufactured by Canon Inc.) in a weight ratio of 1: 1 is added 1 g of toner.
(Iii) The evaluation film is vibrated with the film floating, and excess toner is shaken off.
(Iv) The evaluation film is divided every 20 cm × 20 cm.
(V) A masking sheet (manufactured by Bunkodo) is cut into a size of 20 cm × 20 cm, and is sufficiently neutralized with a wearable compact ionizer (model: TAS-10WC, manufactured by Takayanagi Laboratories).
(Vi) The masking sheet and the evaluation film are bonded together and slowly peeled off.
(Vii) Each masking sheet is read with a color scanner (GT-X750 (manufactured by Epson)) and converted into digital data. The resolution is 400 dpi, each RGB color is 16 bits, and the moire removal function is used as image quality adjustment. When reading with a scanner, the masking sheet adhesive surface (toner adhesion surface) is faced up, and the wearable compact ionizer (model: TAS-10WC, Takayanagi Laboratories) between the masking sheet adhesive surface (toner adhesion surface) and the scanner cover. TP PAPER (manufactured by Ricoh Co., Ltd.) that has been sufficiently neutralized with
(Viii) This image data is binarized by photo retouching software (JTrim ver. 1.53). The threshold value for the binarization boundary is set to 230. The area ratio of the number of white pixels obtained from this image is calculated as the non-charged band ratio. The average value, the maximum value, and the minimum value of the measurement of five samples were obtained, and the average value, the maximum value, and the minimum value of the uncharged band ratio over the longitudinal direction of 800 m were obtained.

(3) Measuring method of absolute value of ion current at position where film is subjected to charge removal The absolute value of ion current at a position where the film is subjected to charge removal is measured using an ion ammeter MSW-001 (manufactured by Kasuga Denki). The ion ammeter includes a sensor unit and a main body, and the sensor unit includes a charging plate that measures the amount of ion current from the static eliminator. Since the total area of the charging plate and the ionic current value are in a proportional relationship, a charging plate having the same area is always used for measurement. In this measurement, the charging plate is made of steel and has a total area of 66 cm ² .

  As shown in FIG. 1, an ion ammeter MSW-001 is installed at a position where the film is subjected to static elimination, and the ion current of the static eliminator is measured. Since the ionic current value has a positive current value and a negative current value, each is measured. When the absolute value of the positive current value is different from the absolute value of the negative current value, the larger absolute value was adopted.

(4) Occurrence rate of wrinkles / winding deviation The final product is slit at a speed of 600 mm in width, 5000 m in length, and 300 m / min. Each occurrence rate was determined by the following equation.
Wrinkle generation rate (%) = number of wrinkles (number) / total number (100) × 100
Winding deviation occurrence rate (%) = winding deviation occurrence number (pieces) / total number (100 pieces) × 100
The following criteria were used for evaluation.
○: Incidence rate is less than 5%.
X: Rate of occurrence 5% or more (5) Unwinding test In the unwinding of the film shown in FIG. 2, the final product was unwound 3000 m at a speed of 100 m / min, 400 m / min, and 700 m / min. . The unwinding and winding tensions are both 80 N / m. The potential was measured using a digital electrostatic potential measuring device KSD-1000 manufactured by Kasuga Electric, and the maximum absolute value was adopted. The distance between the film and the potential measuring device was 20 mm, and was measured at the center in the width direction of the film. Evaluation was performed according to the following criteria.
A: The potential is an absolute value of less than 1 kV.
○: Potential is 1 kV or more and less than 2 kV in absolute value.
Δ: Potential is 2 kV or more and less than 3 kV.
X: Potential increase is 3 kV or more.

(6) Evaluation of printability The melt type ink shown below, melted and stirred at 120 ° C. on the surface of the polyester film, is about 100 by a hot melt coater so that the thickness of the finally obtained ink layer becomes 0.5 μm. Coating was performed at 0 ° C. to obtain a thermal transfer ribbon.

(Melting ink)
Carnauba wax (Carnauba No. 1, manufactured by Toyo Adre): 30 parts by weight Paraffin wax (HNP-10, manufactured by Nippon Seiwa Co., Ltd.): 35 parts by weight Carbon black (MA-8, manufactured by Mitsubishi Chemical Corporation): 15 parts by weight Ethylene-vinyl acetate copolymer (MB-11, manufactured by Sumitomo Chemical Co., Ltd.): 10 parts by weight Printed thermal transfer ribbon with thermal transfer printer (high-definition printer Color Printer 2 8-tone software “PALMIX” manufactured by Seiko Denshi Kogyo Co., Ltd.) The images were visually confirmed and evaluated according to the following criteria.
A: Good print density.
○: Print density is slightly low, but there is no practical problem.
(Triangle | delta): Print density is low and may become a problem practically.

[Example 1]
Toray polyethylene terephthalate having an intrinsic viscosity of 0.61 containing 0.05% by mass of silicon dioxide particles having a number average particle size of 2.6 μm manufactured by Fuji Silysia Co., Ltd. was melted at 285 ° C. in an extruder, and then from the die to a sheet form The film was melt-extruded to 25 ° C. and brought into close contact with a rotary cooling drum at 25 ° C. to solidify, thereby obtaining an unstretched film. Using the difference in peripheral speed of the heated roll, the film is stretched 2.4 times (first stage stretching) at 125 ° C. in the longitudinal direction, and then stretched 2.5 times at 115 ° C. in the longitudinal direction (second stage). Stretched) to obtain a uniaxially stretched film.
Next, both ends of this film are gripped with clips, guided to a tenter, preheated at 105 ° C., stretched 4.0 times in the width direction, further heat treated at 230 ° C., and 4 in the width direction at 150 ° C. The film was wound after being relaxed by 0.0% to obtain a biaxially oriented polyester film roll (intermediate product) having a thickness of 4.5 μm.

The obtained polyester film roll (intermediate product) was unwound while performing static elimination under the following conditions, and wound while slitting a longitudinal direction of 10,000 m with a slitter. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: polyester film roll unwinding section, film roll winding section (2 in total)
V (film transport speed): 400 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 5.0 × 10 ⁻¹ [μA]
I _{1 /} V: 1.3 × 10 ⁻³
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding unit: 9.5 × 10 ⁻¹ [μA]
I _{2 /} V: 2.4 × 10 ⁻³
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 1.5 [μA]
[Example 2]
In the same manner as in Example 1, a film was formed to a thickness of 4.5 μm to obtain a polyester film roll (intermediate product). The obtained polyester film roll (intermediate product) was unwound while performing static elimination under the following conditions, and wound while slitting a longitudinal direction of 10,000 m with a slitter. The measurement of ion current used MSW-001 made by Kasuga Electric. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: polyester film roll unwinding section, film roll winding section (2 in total)
V (film transport speed): 500 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 5.0 × 10 ⁻¹ [μA]
I _{1 /} V: 1.0 × 10 ⁻³
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding part: 7.5 × 10 ⁻¹ [μA]
I _{2 /} V: 1.5 × 10 ⁻⁴
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 1.3 [μA]
[Example 3]
In the same manner as in Example 1, a film was formed to a thickness of 2.5 μm to obtain a polyester film roll (intermediate product). The obtained polyester film roll (intermediate product) was unwound while performing static elimination under the following conditions, and wound while slitting a longitudinal direction of 10,000 m with a slitter. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: polyester film roll unwinding section, film roll winding section (2 in total)
V (film transport speed): 300 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 5.0 × 10 ⁻¹ [μA]
I _{1 /} V: 1.7 × 10 ⁻³
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding part: 7.5 × 10 ⁻¹ [μA]
I ₂ / V: _2.5 × 10 ⁻³
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 1.3 [μA]
[Example 4]
In the same manner as in Example 1, a film was formed to a thickness of 4.5 μm to obtain a polyester film roll (intermediate product). The obtained polyester film roll (intermediate product) was unwound while performing static elimination under the following conditions, and wound while slitting a longitudinal direction of 10,000 m with a slitter. The measurement of ion current used MSW-001 made by Kasuga Electric. Table 1 shows the properties of the film of the final product wound up.
SIMCO SS-50 (AC voltage application type static eliminator), SIMCO BLUE BAR (AC voltage application type static eliminator)
Static eliminator mounting position: Film roll unwinding part (SIMCO BLUE BAR), film roll winding part (SIMCO SS-50) (two in total)
V (film transport speed): 400 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 5.0 × 10 ⁻¹ [μA]
I _{1 /} V: 1.3 × 10 ⁻³
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding part: 7.5 × 10 ⁻¹ [μA]
I _{2 /} V: 1.9 × 10 ⁻³
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 1.3 [μA]
[Example 5]
In the same manner as in Example 1, a film having a thickness of 7.5 μm was formed to obtain a polyester film roll (intermediate product). The obtained polyester film roll (intermediate product) was unwound while performing static elimination under the following conditions, and wound while slitting a longitudinal direction of 10,000 m with a slitter. The measurement of ion current used MSW-001 made by Kasuga Electric. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: polyester film roll unwinding section, film roll winding section (2 in total)
V (film transport speed): 300 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 5.0 × 10 ⁻¹ [μA]
I _{1 /} V: 1.7 × 10 ⁻³
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding unit: 9.5 × 10 ⁻¹ [μA]
I _{2 /} V: 3.2 × 10 ⁻³
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 1.5 [μA]
[Example 6]
Toray polyethylene terephthalate having an intrinsic viscosity of 0.61 containing 0.05% by mass of silicon dioxide particles having a number average particle size of 2.6 μm manufactured by Fuji Silysia Co., Ltd. was melted at 285 ° C. in an extruder, and then from the die to a sheet form The film was melt-extruded to 25 ° C. and brought into close contact with a rotary cooling drum at 25 ° C. to solidify, thereby obtaining an unstretched film. Using the difference in peripheral speed of the heated roll, the film is stretched 1.4 times in the longitudinal direction at 123 ° C. (first stage stretching), and then stretched 2.5 times in the longitudinal direction at 111 ° C. (second stage). Stretched) to obtain a uniaxially stretched film.

  Next, both ends of this film are gripped with clips, guided to a tenter, preheated at 105 ° C., stretched 4.0 times in the width direction, further heat-treated at 227 ° C., and 4 in the width direction at 150 ° C. The film was wound after being relaxed by 0.0% to obtain a biaxially oriented polyester film roll (intermediate product) having a thickness of 12 μm.

  The obtained polyester film roll (intermediate product) was unwound while performing static elimination under the following conditions, and wound up while slitting a longitudinal direction of 10,000 m with a slitter. Table 1 shows the properties of the film of the final product wound up.

Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: film roll unwinding section, film roll winding section (two in total)
V (film transport speed): 300 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 5.0 × 10 ⁻¹ [μA]
I _{1 /} V: 1.7 × 10 ⁻³
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding unit: 9.5 × 10 ⁻¹ [μA]
I _{2 /} V: 3.2 × 10 ⁻³
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 1.5 [μA]
[Example 7]
In the same manner as in Example 1, a film was formed to a thickness of 4.5 μm to obtain a polyester film roll (intermediate product). The obtained polyester film roll (intermediate product) was unwound while performing static elimination under the following conditions, and wound up while slitting a longitudinal direction of 10,000 m with a slitter. Table 1 shows the properties of the film of the final product wound up. Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: polyester film roll unwinding section, film roll winding section (2 in total)
V (film transport speed): 400 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 5.0 × 10 ⁻¹ [μA]
I / V: 1.3 × 10 ⁻³
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding part: 1.7 [μA]
I / V: 4.3 × 10 ⁻³
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 2.2 [μA]
[Example 8]
In the same manner as in Example 1, a film was formed to a thickness of 4.5 μm to obtain a polyester film roll (intermediate product). The obtained polyester film roll (intermediate product) was unwound while performing static elimination under the following conditions, and wound up while slitting a longitudinal direction of 10,000 m with a slitter. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: polyester film roll unwinding section, film roll winding section (2 in total)
Static eliminator mounting position: film roll unwinding section, film roll winding section (two in total)
V (film transport speed): 450 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 1.7 [μA]
I _{1 /} V: 3.8 × 10 ⁻³
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding part: 1.7 [μA]
I _{2 /} V: 3.8 × 10 ⁻³
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 3.4 [μA]
[Example 9]
In the same manner as in Example 1, a film was formed to a thickness of 4.5 μm to obtain a polyester film roll (intermediate product). The obtained polyester film roll (intermediate product) was unwound while performing static elimination under the following conditions, and wound while slitting a longitudinal direction of 10,000 m with a slitter. The measurement of ion current used MSW-001 made by Kasuga Electric. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: polyester film roll unwinding section, film roll winding section (2 in total)
V (film transport speed): 400 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 1.7 [μA]
I _{1 /} V: 4.3 × 10 ⁻³
Absolute value (I ₂ ) of ion current at the position where the film is subjected to charge removal by the charge eliminator installed in the winding unit: 5.0 × 10 ⁻¹ [μA]
I _{2 /} V: 1.3 × 10 ⁻³
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 2.2 [μA]
[Example 10]
In the same manner as in Example 1, a film was formed to a thickness of 4.5 μm to obtain a polyester film roll (intermediate product). The obtained polyester film roll (intermediate product) was unwound while performing static elimination under the following conditions, and wound while slitting a longitudinal direction of 10,000 m with a slitter. The measurement of ion current used MSW-001 made by Kasuga Electric. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: polyester film roll unwinding section, film roll winding section (2 in total)
V (film transport speed): 400 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 5.0 × 10 ⁻¹ [μA]
I _{1 /} V: 1.3 × 10 ⁻³
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding unit: 1.0 × 10 ⁻¹ [μA]
I ₂ / V: _2.5 × 10 ⁻⁴
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 6.0 × 10 ⁻¹ [μA]
[Example 11]
In the same manner as in Example 1, a film was formed to a thickness of 4.5 μm to obtain a polyester film roll (intermediate product). The obtained polyester film roll (intermediate product) was unwound while performing static elimination under the following conditions, and wound while slitting a longitudinal direction of 10,000 m with a slitter. The measurement of ion current used MSW-001 made by Kasuga Electric. Table 1 shows the properties of the film of the final product wound up. The SIMCO IQ Power was used in manual mode with an ion balance of + 50 / -50.
Static eliminator: SIMCO SS-50 (AC voltage application type static eliminator), SIMCO IQ power (DC voltage application type static eliminator)
Static eliminator mounting position: polyester film roll unwinding part (IQ Power made by SIMCO), film roll winding part (SS-50 made by SIMCO) (two in total)
V (film transport speed): 400 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 5.0 × 10 ⁻¹ [μA]
I _{1 /} V: 1.3 × 10 ⁻³
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding unit: 1.0 × 10 ⁻¹ [μA]
I ₂ / V: _2.5 × 10 ⁻⁴
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 6.0 × 10 ⁻¹ [μA]
[Example 12]
In the same manner as in Example 1, a film was formed to a thickness of 4.5 μm to obtain a polyester film roll (intermediate product). The obtained polyester film roll (intermediate product) was unwound while performing static elimination under the following conditions, and wound while slitting a longitudinal direction of 10,000 m with a slitter. The measurement of ion current used MSW-001 made by Kasuga Electric. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: polyester film roll unwinding section, film roll winding section (2 in total)
V (film transport speed): 400 [m / min]
Absolute value (I ₁ ) of ion current at the position where the film is subjected to charge removal by the charge eliminator installed at the unwinding section: 1.0 × 10 ⁻¹ [μA]
I _{1 /} V: 2.5 × 10 ⁻⁴
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding unit: 1.0 × 10 ⁻¹ [μA]
I ₂ / V: _2.5 × 10 ⁻⁴
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 2.0 × 10 ⁻¹ [μA]
[Example 13]
In the same manner as in Example 1, a film was formed to a thickness of 4.5 μm to obtain a polyester film roll (intermediate product). The obtained polyester film roll (intermediate product) was unwound while performing static elimination under the following conditions, and wound while slitting a longitudinal direction of 10,000 m with a slitter. The measurement of ion current used MSW-001 made by Kasuga Electric. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: polyester film roll unwinding section, film roll winding section (2 in total)
V (film transport speed): 400 [m / min]
Absolute value (I ₁ ) of ion current at the position where the film is subjected to charge removal by the charge eliminator installed at the unwinding section: 1.0 × 10 ⁻¹ [μA]
I _{1 /} V: 2.5 × 10 ⁻⁴
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding part: 0.5 × 10 ⁻¹ [μA]
I _{2 /} V: 1.3 × 10 ⁻³
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 6.0 × 10 ⁻¹ [μA]
[Example 14]
Toray polyethylene terephthalate having an intrinsic viscosity of 0.61 containing 0.05% by mass of silicon dioxide particles having a number average particle size of 2.6 μm manufactured by Fuji Silysia Co., Ltd. was melted at 285 ° C. in an extruder, and then from the die to a sheet form The film was melt-extruded to 25 ° C. and brought into close contact with a rotary cooling drum at 25 ° C. to solidify, thereby obtaining an unstretched film. Using the difference in the peripheral speed of the heated roll, the film was stretched 1.2 times in the longitudinal direction at 123 ° C. (first stage stretching), and then stretched 2.5 times in the longitudinal direction at 111 ° C. (second stage). Stretched) to obtain a uniaxially stretched film.

  Next, both ends of this film are gripped with clips, guided to a tenter, preheated at 105 ° C., stretched 4.0 times in the width direction, further heat-treated at 227 ° C., and 4 in the width direction at 150 ° C. The film was wound after being relaxed by 0.0% to obtain a biaxially oriented polyester film roll (intermediate product) having a thickness of 20 μm.

The obtained polyester film roll (intermediate product) was unwound while performing static elimination under the following conditions, and wound while being slit in a longitudinal direction with a 10,000 m slitter. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: film roll unwinding section, film roll winding section (two in total)
V (film transport speed): 300 [m / min]
Absolute value (I ₁ ) of ion current at the position where the film is subjected to charge removal by the charge eliminator installed at the unwinding section: 1.0 × 10 ⁻¹ [μA]
I _{1 /} V: 3.3 × 10 ⁻⁴
Absolute value (I ₂ ) of ion current at the position where the film is subjected to charge removal by the charge eliminator installed in the winding unit: 5.0 × 10 ⁻¹ [μA]
I _{2 /} V: 1.7 × 10 ⁻³
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 6.0 × 10 ⁻¹ [μA]
[Comparative Example 1]
The polyester film roll (intermediate product) formed into a thickness of 4.5 μm in the same manner as in Example 1 was unwound while performing static elimination under the conditions shown below, and the longitudinal direction was 10,000 m slitted with a slitter. I wound it up. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: film roll unwinding section, film roll winding section (two in total)
V (film transport speed): 300 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 5.0 × 10 ⁻² [μA]
I _{1 /} V: 1.7 × 10 ⁻⁴
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding unit: 5.0 × 10 ⁻² [μA]
I _{2 /} V: 1.7 × 10 ⁻⁴
Total sum of absolute values of ion currents It (I ₁ + I ₂ ): 1.0 × 10 ⁻¹ [μA]
[Comparative Example 2]
The polyester film roll (intermediate product) formed into a thickness of 4.5 μm in the same manner as in Example 1 was unwound while performing static elimination under the conditions shown below, and the longitudinal direction was 10,000 m slitted with a slitter. I wound it up. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: film roll unwinding section, film roll winding section (two in total)
V (film transport speed): 400 [m / min]
Absolute value (I ₁ ) of ion current at the position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 2.1 [μA]
I _{1 /} V: 5.3 × 10 ⁻³
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding part: 2.1 [μA]
I _{2 /} V: 5.3 × 10 ⁻³
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 4.2 [μA]
[Comparative Example 3]
The polyester film roll (intermediate product) formed into a thickness of 4.5 μm in the same manner as in Example 1 was unwound while performing static elimination under the conditions shown below, and the longitudinal direction was 10,000 m slitted with a slitter. I wound it up. The SIMCO IQ Power was used in manual mode with an ion balance of + 60 / −40. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SIMCO SS-50 (AC voltage application type static eliminator), SIMCO IQ power (DC voltage application type static eliminator)
Static eliminator mounting position: film roll unwinding section, film roll winding section (two in total)
V (film transport speed): 400 [m / min]
Absolute value (I ₁ ) of ion current at the position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 2.1 [μA]
I _{1 /} V: 5.3 × 10 ⁻³
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding part: 2.1 [μA]
I _{2 /} V: 5.3 × 10 ⁻³
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 4.2 [μA]
[Comparative Example 4]
The polyester film roll (intermediate product) formed into a thickness of 4.5 μm in the same manner as in Example 1 was unwound while performing static elimination under the conditions shown below, and the longitudinal direction was 10,000 m slitted with a slitter. I wound it up. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: film roll unwinding section, film roll winding section (two in total)
V (film transport speed): 400 [m / min]
Absolute value (I ₁ ) of ion current at the position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 2.1 [μA]
I _{1 /} V: 5.3 × 10 ⁻³
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding part: 1.6 [μA]
I _{2 /} V: 4.0 × 10 ⁻³
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 3.7 [μA]
[Comparative Example 5]
The polyester film roll (intermediate product) formed into a thickness of 4.5 μm in the same manner as in Example 1 was unwound while performing static elimination under the conditions shown below, and the longitudinal direction was 10,000 m slitted with a slitter. I wound it up. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: film roll unwinding section, film roll winding section (two in total)
V (film transport speed): 350 [m / min]
Absolute value (I ₁ ) of ion current at the position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 2.1 [μA]
I _{1 /} V: 6.0 × 10 ⁻³
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding unit: 5.0 × 10 ⁻² [μA]
I _{2 /} V: 1.4 × 10 ⁻⁴
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 2.2 [μA]
[Comparative Example 6]
The polyester film roll (intermediate product) formed into a thickness of 4.5 μm in the same manner as in Example 1 was unwound while performing static elimination under the conditions shown below, and the longitudinal direction was 10,000 m slitted with a slitter. I wound it up. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: film roll unwinding section, film roll winding section (two in total)
V (film transport speed): 300 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 2.3 [μA]
I _{1 /} V: 7.7 × 10 ⁻³
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding unit: 5.0 × 10 ⁻² [μA]
I _{2 /} V: 1.7 × 10 ⁻⁴
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 2.4 [μA]
[Comparative Example 7]
The polyester film roll (intermediate product) formed into a thickness of 4.5 μm in the same manner as in Example 1 was unwound while performing static elimination under the conditions shown below, and the longitudinal direction was 10,000 m slitted with a slitter. I wound it up. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: film roll unwinding section, film roll winding section (two in total)
V (film transport speed): 300 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 2.3 [μA]
I _{1 /} V: 7.7 × 10 ⁻³
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding part: 2.5 [μA]
I _{2 /} V: 8.2 × 10 ⁻³
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 4.8 [μA]
[Comparative Example 8]
The polyester film roll (intermediate product) formed into a thickness of 4.5 μm in the same manner as in Example 1 was unwound while performing static elimination under the conditions shown below, and the longitudinal direction was 10,000 m slitted with a slitter. I wound it up. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: film roll unwinding section, film roll winding section (two in total)
V (film transport speed): 350 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 3.0 × 10 ⁻² [μA]
I _{1 /} V: 8.6 × 10 ⁻⁵
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding part: 3.0 × 10 ⁻² [μA]
I _{2 /} V: 8.6 × 10 ⁻⁵
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 6.0 × 10 ⁻² [μA]
[Comparative Example 9]
The polyester film roll (intermediate product) formed into a thickness of 4.5 μm in the same manner as in Example 1 was unwound while performing static elimination under the conditions shown below, and the longitudinal direction was 10,000 m slitted with a slitter. I wound it up. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: film roll unwinding section, film roll winding section (two in total)
V (film transport speed): 300 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 5.0 × 10 ⁻² [μA]
I _{1 /} V: 1.7 × 10 ⁻⁴
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding unit: 5.0 × 10 ⁻² [μA]
I _{2 /} V: 1.7 × 10 ⁻⁴
Total sum of absolute values of ion currents It (I ₁ + I ₂ ): 1.0 × 10 ⁻¹ [μA]
[Comparative Example 10]
In the same manner as in Example 6, the polyester film roll (intermediate product) formed into a film having a thickness of 10 μm was unwound while performing neutralization under the conditions shown below, and the longitudinal direction was 10,000 m while slitting with a slitter. Winded up. The properties of the wound film are shown in Table 1.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: film roll unwinding section, film roll winding section (two in total)
V (film transport speed): 300 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 5.0 × 10 ⁻² [μA]
I _{1 /} V: 1.7 × 10 ⁻⁴
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding unit: 5.0 × 10 ⁻² [μA]
I _{2 /} V: 1.7 × 10 ⁻⁴
Total sum of absolute values of ion currents It (I ₁ + I ₂ ): 1.0 × 10 ⁻¹ [μA]
[Comparative Example 11]
The polyester film roll (intermediate product) formed into a thickness of 4.5 μm in the same manner as in Example 1 was unwound while performing static elimination under the conditions shown below, and the longitudinal direction was 10,000 m slitted with a slitter. I wound it up. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (AC voltage application type static eliminator)
Static eliminator mounting position: film roll unwinding section, film roll winding section (two in total)
V (film transport speed): 300 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 5.0 × 10 ⁻² [μA]
I _{1 /} V: 1.7 × 10 ⁻⁴
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding part: 2.5 [μA]
I _{2 /} V: 8.2 × 10 ⁻³
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 2.5 [μA]
[Comparative Example 12]
The polyester film roll (intermediate product) formed into a thickness of 4.5 μm in the same manner as in Example 1 was unwound while performing static elimination under the conditions shown below, and the longitudinal direction was 10,000 m slitted with a slitter. I wound it up. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (voltage application type static eliminator)
Static eliminator mounting position: film roll unwinding section, film roll winding section (two in total)
V (film transport speed): 300 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 3.0 × 10 ⁻² [μA]
I _{1 /} V: 1.0 × 10 ⁻⁴
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding part: 2.5 [μA]
I _{2 /} V: 8.2 × 10 ⁻³
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 2.5 [μA]
[Comparative Example 13]
In the same manner as in Example 14, the polyester film roll (intermediate product) formed into a film having a thickness of 25 μm was unwound while performing neutralization under the conditions shown below, and the longitudinal direction was 10,000 m while slitting with a slitter. Winded up. Table 1 shows the properties of the film of the final product wound up.
Static eliminator: SS-50 made by SIMCO (voltage application type static eliminator)
Static eliminator mounting position: film roll unwinding section, film roll winding section (two in total)
V (film transport speed): 300 [m / min]
Absolute value (I ₁ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed at the unwinding section: 3.0 × 10 ⁻² [μA]
I _{1 /} V: 1.0 × 10 ⁻⁴
Absolute value (I ₂ ) of ion current at a position where the film is subjected to static elimination by the static eliminator installed in the winding part: 2.5 [μA]
I _{2 /} V: 8.2 × 10 ⁻³
Sum of absolute values of ion currents It (I ₁ + I ₂ ): 2.5 [[μA]

  The polyester film of the present invention can be suitably used for a thermal transfer ribbon, but its application range is not limited thereto.

1: Static eliminator 2: Ion ammeter 3: Conveying roll 4: Film position 5: Electrometer 6: Unwinding roll 7: Winding roll

Claims (5)

At least one surface, along the longitudinal direction 800 m, when the uncharged band index was measured, the maximum value, Ri the minimum value are both 55% or more but less than 97% der, polyester film used in the thermal transfer ribbon application. The polyester film used for the thermal transfer ribbon application according to claim 1, wherein the difference between the maximum value and the minimum value is 10% or less when at least one surface has a non-charged band ratio measured in a longitudinal direction of 800 m. The polyester film used for the thermal transfer ribbon application according to claim 1 or 2, wherein the film has a thickness of 1 µm to 25 µm. A method for producing a polyester film comprising a step of neutralizing a film using a voltage application static eliminator and / or a voltage application blower type static eliminator, wherein the ion current at a position where the film is subjected to static elimination when the film is neutralized A method for producing a polyester film satisfying the following formula where I is the absolute value of I (μA) and the film transport speed is V (m / min).
5.0 × 10 ⁻² ≦ I ≦ 2.0 (Formula 1)
2.5 × 10 ⁻⁴ ≦ I / V ≦ 7.0 × 10 ⁻³ (Formula 2) The manufacturing method of the polyester film of Claim 4 including the process of neutralizing a film using a voltage application type static elimination device and / or a voltage application ventilation type static elimination device at least twice.

Images