JP4155806B2 - Polyester film package and storage method thereof - Google Patents

Description

【００５４】
表１から明らかなように、本発明によれば保管後のポリエステルフィルム表面へのオリゴマー析出が抑えられ、且つ、ポリエステルフィルムの放電抑止性が良好なものになる。
【００５５】
尚、表１に示した吸湿剤の平均粒径は以下の通りであった。
シリカゲル： ３ｍｍ
炭酸カルシウム： ３ｍｍ
塩化カルシウム： ３ｍｍ
酸化マグネシウム： １ｍｍ
塩化マグネシウム： １ｍｍ
【００５６】
【発明の効果】
本発明によれば、長期間フィルムを保管しても、フィルム表面に実質上オリゴマー析出物や放電、放電跡がなく、磁気記録媒体用基材とした時の磁気記録特性、光学用基材とした時の光学特性に優れたポリエステルフィルムを提供できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polyester film package and a storage method thereof. More specifically, the present invention is substantially free of oligomers on the film surface and is useful for optical substrates typified by substrates for magnetic recording media, reflectors, diffusers, touch panels, and light-emitting elements. The present invention relates to a polyester film package excellent in magnetic recording characteristics when used as a base material for magnetic recording media, optical characteristics when used as a base material for optics, and gas barrier properties, and a storage method thereof.
[0002]
[Prior art]
The polyester film is excellent in performance such as mechanical properties, heat resistance, durability, flexibility, and surface properties. For this reason, it is suitably used for magnetic recording media such as video tapes, audio tapes, memory tapes, magnetic sheets, and magnetic disks. Similarly, for optical use, these characteristics are utilized, and it is suitably used as a reflector for liquid crystal display (hereinafter referred to as LCD), a diffusion plate, a touch panel substrate, and an organic electroluminescence substrate.
[0003]
However, the polyester film has a drawback that oligomers are deposited on the film surface. For example, when a polyester film is used as a base film of a magnetic recording medium, oligomers are deposited on the surface of the polyester film, which is a base film, before being laminated or when the magnetic recording layer is laminated. However, this is a problem because it causes a decrease in magnetic recording output.
[0004]
Moreover, when a polyester film is used as an optical film, the oligomer deposited on the surface of the polyester film causes a decrease in the lifetime of the light emitting element, which is a problem.
[0005]
In addition, even when a polyester film is used as a diffusion plate or a touch panel substrate, oligomers deposited on the substrate surface cause scattering, which causes a decrease in light transmittance, an increase in haze, and an inhibition of adhesion performance when laminated. It is a problem.
[0006]
In order to solve such problems of oligomers, for example, JP-A-8-245811, JP-A-2000-94616, and JP-A-2000-187830 propose a method for reducing oligomers deposited on the surface of a polyester film. Has been. These proposals have an effect of reducing oligomers deposited on the polyester film surface immediately after film formation.
[0007]
However, when these films are stored, there is a phenomenon of oligomer diffusion from the inside of the film to the film surface, so the amount of oligomers deposited on the film surface is small immediately after film formation, but under storage conditions at high temperature and high humidity. The amount of oligomer deposited on the surface increases with time, and as a result, various problems occur when using a polyester film.
[0008]
Patent Document 4 discloses a method for suppressing the diffusion of oligomers from the inside of the film to the film surface by storing the film in a package including a hygroscopic material when the film is stored. However, in this method, the moisture content of the polyester film becomes too low, and when the polyester film is unwound after storage or when various processing is performed on the polyester film, discharge occurs on the film surface, resulting in defects on the film surface. There is a problem that causes the problem to be solved.
[0009]
[Patent Document 1]
Japanese Patent Laid-Open No. 8-245811
[Patent Document 2]
JP 2000-94616 A
[Patent Document 3]
JP 2000-187830 A
[Patent Document 4]
Japanese Patent Laid-Open No. 2002-173270 [0013]
[Problems to be solved by the invention]
The object of the present invention is to solve the above problems when used as a base film of a magnetic recording medium or as an optical film, and is excellent in high signal output or high gas barrier properties, light transmittance, haze, etc. Another object of the present invention is to provide a polyester film package and a method for storing the same.
[0014]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventor can suppress oligomers deposited on the film surface due to oligomer diffusion during film storage, and further when unwinding the polyester film after storage. It has been found that the discharge of the film surface generated when various processing is performed on the polyester film can be suppressed, and the present invention has been completed.
[0015]
That is, according to the present invention, [1] The entire polyester film roll obtained by winding a polyester film containing polyester as a main component in a roll shape is laminated with a metal film or an inorganic oxide film on at least one side. This can be achieved by a polyester film package that is covered with a plastic film that has been coated with at least one desiccant having a moisture absorption of 10% to 55%.
[0016]
Furthermore, as a preferred embodiment of the present invention,
[2] The polyester film package according to [1], wherein the polyester film is a biaxially oriented film,
[3] The polyester film package according to [1], wherein the polyester is polyethylene terephthalate,
[4] The polyester film package according to [1], wherein the polyester is polyethylene-2,6-naphthalene dicarboxylate,
[5] The polyester film package according to [1], wherein the desiccant is at least one selected from the group consisting of silica gel, calcium chloride, calcium oxide, phosphorus pentoxide, granular soda lime, and magnesium perchlorate.
[6] The polyester film package according to [1], wherein the average particle size of the desiccant is in the range of 10 to 7000 μm.
[7] The polyester film roll is wound around a core, and the moisture content of the core, the plastic film, and the label enclosed in the package is all 15 wt% or less. Polyester film packaging,
[8] The polyester film package according to [7], wherein the material of the core is resin or metal,
[9] The polyester film package according to any one of [1] to [8], wherein the polyester film has a thickness of 2 to 20 μm, and the polyester film is used as a base film for magnetic recording.
[10] The polyester film package according to any one of [1] to [8], in which the polyester film is used as an optical film.
[0017]
Another object of the present invention is to provide the polyester film package according to any one of [11] [1] to [10] under conditions of a temperature of 10 ° C. to 30 ° C. and a relative humidity of 70% or less. This can be achieved by the storage method of the polyester film package stored in the above.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
[0019]
[polyester]
The polyester constituting the polyester film in the present invention is a substantially linear, thermoplastic polyester having film-forming properties, particularly film-forming properties by melt molding, for example, aromatic dicarboxylic acid as a main acid component, It is a thermoplastic polyester having an aliphatic glycol as a main glycol component.
[0020]
Examples of the thermoplastic polyester include polyethylene terephthalate, polyethylene isophthalate, polytetramethylene terephthalate, poly-1,4-cyclohexylenedimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate, and the like. Of these, polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate are preferred. In particular, it is preferable that the polyester is polyethylene-2,6-naphthalenedicarboxylate because the oligomer suppressing effect of the present invention becomes remarkable.
[0021]
The polyester may be a homopolyester or a copolyester. In the case of a copolyester, examples of copolymer components of polyethylene terephthalate and polyethylene-2,6-naphthalene dicarboxylate include diethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, neopentyl glycol, polyoxyethylene glycol, p- Other diol components such as xylene glycol, 1,4-cyclohexanedimethanol, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid (in the case of polyethylene-2,6-naphthalenedicarboxylate), 2, 6-naphthalenedicarboxylic acid (in the case of polyethylene terephthalate), other dicarboxylic acid components such as 5-sodium sulfoisophthalic acid, and oxycarboxylic acid components such as p-oxyethoxybenzoic acid And the like. The amount of the copolymer component is preferably 20 mol% or less, more preferably 10 mol% or less, based on the total acid component.
[0022]
Furthermore, trifunctional or more polyfunctional compounds such as trimellitic acid and pyromellitic acid can be copolymerized. In this case, it is preferable to copolymerize the polymer in a substantially linear amount, for example, 2 mol% or less.
[0023]
It will be readily understood that copolymer components in polyesters other than polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate are also considered as described above. The polyester is known per se and can be produced by a method known per se.
[0024]
[Lubricant]
The polyester film in the present invention may contain a known lubricant. Examples of the lubricant include inorganic particles such as spherical silica, porous silica, calcium carbonate, silica alumina, alumina, titanium dioxide, kaolin clay, barium sulfate and zeolite, or organic particles such as silicon resin particles and crosslinked polystyrene particles. . The inorganic particles are preferably a synthetic product rather than a natural product because the particle size is uniform, and inorganic particles having any crystal form, hardness, specific gravity, and color can be used. The inert particles added to the film may be a single component selected from those exemplified above, or may be a multiple component including two components or three or more components.
[0025]
[Polyester film]
The polyester film in the present invention contains polyester as a main constituent. The polyester film in the present invention is preferably a biaxially oriented film. The biaxially oriented polyester film can be formed by a known film forming method. That is, the polyester can be melted with an extruder, extruded into a sheet, cooled and solidified with a cooling roll to form an unstretched film, and then the unstretched film can be further biaxially stretched. For the biaxial stretching, known biaxial stretching methods such as sequential biaxial stretching, simultaneous biaxial stretching, and multistage stretching can be used.
[0026]
[Plastic film]
The plastic film used in the present invention is a plastic film in which a metal film or an inorganic oxide film is laminated on at least one surface thereof. Examples of the metal film include an aluminum film, a silver foil, and a copper foil. Examples of the inorganic oxide film include a silica (silicon oxide) film. The lamination of the metal film or the inorganic oxide film on the plastic base film may be a metal foil or an inorganic oxide foil, preferably laminated via an adhesive layer, or a metal layer or an inorganic oxide layer. May be deposited on a plastic base film by vapor deposition.
[0027]
The base film of the plastic film is preferably selected from at least one of olefin, paraffin, and polyester. Moreover, what uses the bonding film of other materials for a base film is also contained in the plastic film in this invention.
[0028]
[desiccant]
In the present invention, at least one desiccant having a moisture absorption of 55% or less is enclosed inside the package. Examples of the desiccant include silica gel, calcium chloride, calcium oxide, phosphorus pentoxide, granular soda lime, and magnesium perchlorate. When the moisture absorption of the desiccant exceeds 55%, discharge occurs on the film surface when unwinding the polyester film after storage, or when various processes are performed on the polyester film, resulting in defects on the film surface. The moisture absorption of the desiccant is preferably 50% or less from this viewpoint. Further, the lower limit of the moisture absorption of the desiccant is preferably 10% in order to suppress oligomers that precipitate on the surface of the polyester film during storage.
[0029]
These desiccants are preferably packed in the plastic film so as not to contact the surface of the polyester film inside the package, from the viewpoint of preventing moisture absorption.
[0030]
In addition, it is preferable that the desiccant in this invention is a range whose average particle diameter is 10-7000 micrometers. If the average particle size of the desiccant is less than 10 μm, the desiccant tends to adhere to the surface of the polyester film due to static electricity or the like, and the surface characteristics of the film are impaired. On the other hand, when the average particle diameter of the desiccant exceeds 7000 μm, it is difficult to enclose the desiccant inside the package, or the moisture content adjustment of the polyester film inside the package may be hindered.
[0031]
[Packaging materials]
The polyester film roll in the present invention is preferably a roll in which a polyester film is wound around a core. The core used as the packaging material can be selected from a plastic core, a paper core, and a metal core. The stored polyester film is adversely affected by water absorption from the core, label, and cover film (plastic film) used for the packaging material. That is, when the polyester film absorbs water, the plasticization of molecules is promoted inside the polyester film, and the precipitation of oligomers on the surface of the polyester film is promoted. For this reason, it is preferable that the core, label, and cover film used for the packaging material have a moisture content of 15 wt% or less, more preferably 12 wt% or less, particularly 10 wt% or less. . The material is not particularly limited, but a metal core or a plastic core is desirable for the core from the viewpoint of moisture content, strength, and the like.
[0032]
[Storage method]
In the present invention, the entire polyester film roll wound in a roll shape is covered with the plastic film, the desiccant is enclosed inside the package, and preferably a packaging material having a moisture content of 15 wt% or less. It is used and stored in an environment controlled at a temperature of 10 to 30 ° C. and a relative humidity of 70% or less. The storage temperature is preferably 10 to 25 ° C, particularly preferably 10 to 20 ° C. The relative humidity is preferably 65% or less, particularly preferably 55% or less.
[0033]
[Polyester film production]
The polyester film in the present invention can be obtained according to a method conventionally known or accumulated in the industry.
[0034]
For example, polyester is heated and melted in an extruder, the polyester is filtered with high precision before the extrusion die, and then formed into a film at a temperature of the melting point Tm ° C. to (Tm + 70) ° C. (where Tm is the melting point of the polyester). After extrusion, it is rapidly cooled and solidified with a cooling roll of 20 to 90 ° C. to obtain an unstretched film. Thereafter, the unstretched film is uniaxially (longitudinal or transverse) according to a conventional method at a temperature of (Tg-10) to (Tg + 70) ° C. (where Tg is the glass transition temperature of the polyester), 2.5 to 8 The film is stretched at a magnification of 0.0, preferably at a magnification of 3.0 to 7.5, and then at a magnification of 2.5 to 8.0 at a temperature of Tg to (Tg + 70) ° C. in a direction perpendicular to the above direction. The film is preferably stretched at a magnification of 3.0 to 7.5 times. Further, if necessary, the film may be stretched again in the machine direction and / or the transverse direction. That is, two-stage, three-stage, four-stage, or multistage stretching may be performed. The total draw ratio is usually 9 times or more, preferably 12 to 42 times as the area draw ratio. Subsequently, excellent dimensional stability is imparted by thermally fixing crystallization of the biaxially oriented film at a temperature of (Tg + 70) to (Tm-10) ° C., for example, 180 to 250 ° C. The heat setting time is preferably 1 to 60 seconds.
[0035]
[Coating layer]
The polyester film in the present invention can be provided with a coating layer on at least one side thereof. The coating layer is preferably applied by applying a coating solution to the surface of the polyester film before the final stretching treatment, and after coating, the film is preferably stretched at least in a uniaxial direction. The coating film is dried before or during the stretching. Among them, the coating is preferably performed on an unstretched laminated film or a longitudinal (uniaxial) stretched laminated film, particularly a longitudinal (uniaxial) stretched laminated film. Although it does not specifically limit as a coating method, For example, a roll coat method, a die coat method, etc. are mentioned.
[0036]
The solid content concentration of the coating liquid, particularly the aqueous coating liquid, is preferably 0.2 to 8.0 wt%, and more preferably 0.3 to 6.0 wt%. In the coating liquid (preferably aqueous coating liquid), other components, for example, other surfactants, stabilizers, dispersants, UV absorbers, thickeners, etc., as long as the effects of the present invention are not hindered. Can be added.
[0037]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited by these Examples. In the examples and comparative examples, “parts” and “%” are based on weight unless otherwise specified. The physical property values and characteristics in the present invention are each measured and defined by the following methods.
[0038]
[Hygroscopic absorption of desiccant]
About 100 g of unused desiccant is stored for 1 hour in an atmosphere of 25 ° C. and 60% RH, and the weight is measured. The weight value is defined as W ₀ (g). The desiccant is stored for one day in an atmosphere of 40 ° C. and 90% RH. After storage for one day, return to the atmosphere of 25 ° C. and 60% RH, store for 1 hour, measure the weight, and let the weight value be W ₁ (g). From the obtained result, the moisture absorption of the desiccant was calculated by the following formula.
[0039]
Hygroscopicity of desiccant = [(W ₁ −W ₀ ) / W ₀ ] × 100
[Average particle size of desiccant]
The photograph of each particle | grain is image | photographed with the magnification according to the size of the desiccant with the optical microscope, and it calculates with the average value (10 measurement points) of a projected particle diameter using image analysis processing apparatus Luzex 500 (made by a Japan regulator).
[0040]
[Oligomer content]
A biaxially oriented polyester film was cut into a size of 38 mm × 38 mm and immersed in 25 ml of chloroform at 25 ° C. for 1 hour. A calibration curve of the oligomer was drawn in advance with an absorbance meter, and the amount of oligomer eluted in chloroform was determined from the absorbance after immersion for 1 hour. The unit is shown in mg / m ² / hr.
[0041]
[Total light transmittance]
Measurement was carried out based on JIS K6714-1958.
[0042]
[Moisture content]
For the film, core, and label, take a slice sample, measure the original weight (X), hold at 110 ° C. for 3 hours, then measure the weight (Y) after holding, and obtain by the following formula (1). It was.
[0043]
[Expression 1]
Moisture content (%) = {(XY) / X} · 100 (1)
[Discharge prevention]
The film 20m was unwound 3 times from the stored polyester film roll at a speed of 15m / min, and it was observed whether or not a discharge occurred, and the discharge traces on both sides of the film were sprinkled with toner on the film surface and visually observed. Evaluated by criteria.
○: No discharge or trace of discharge was observed in all three times. (Good discharge prevention)
X: Discharge at one or more places or traces of discharge are observed. (Discharge prevention failure)
[Glass transition temperature (Tg), melting point (Tm)]
A 20 mg sample was sealed in an aluminum pan, set in a differential scanning calorimeter (DuPont Instrument 910 DSC), and measured at room temperature to 20 ° C./min.
[0044]
[Example 1]
Polyethylene terephthalate (PET) substantially free of inert particles was obtained by a conventional polymerization method. This polyethylene terephthalate was dried at 170 ° C. for 3 hours, then supplied to an extruder, melted at a melting temperature of 290 ° C., extruded into a sheet form from a die, and rapidly cooled to obtain an unstretched film. The obtained unstretched film is preheated, further stretched 3.5 times in the machine direction at a film temperature (Tg + 15) ° C. between low-speed and high-speed rolls, quenched, and then on one side of the longitudinally stretched film the aqueous coating liquid of the coating layer B of the composition of a water-soluble coating liquid of the coating layer a on the other side, coated respectively 3.8 g / m ^2, so that a coating weight of 1.5 g / m ^2, Then, it supplied to the stenter and extended | stretched 4.2 times in the horizontal direction at 100 degreeC. The obtained biaxially stretched film was heat-fixed with hot air at 210 ° C. for 4 seconds to obtain a biaxially oriented polyester film having a thickness of 6.5 μm.
[0045]
The obtained biaxially oriented polyester film was wound up to a length of 10,000 m on an aluminum cylindrical core while slitting to a width of 550 mm. Cover this roll with a film cover (polyethylene terephthalate film), affix a label, and cover the bag with 200 g of silica gel (average particle size 3000 μm) with adhesive tape so as not to touch the biaxially oriented polyester film as a product directly After being mounted inside, it was packed with aluminum foil so that the product surface was not exposed. The moisture content data at this time is shown in the table. This package is stored in a warehouse controlled at 20 ° C and 50% relative humidity for 3 months, and then the amount of oligomer is measured by sampling the most core part of the product film (the part closest to the core) and the film on the outermost layer. did. Further, the total light transmittance of the biaxially oriented polyester film collected from the most core portion was measured.
[0046]
Coating was performed by adjusting the average particle diameter of fine particles in the water-soluble coating liquid used for forming the coating layers A and B, the composition, the composition of the siloxane copolymer acrylic resin, and the coating weight of the water-soluble coating liquid as follows. .
[0047]
Water-soluble coating liquid used for forming coating layer A: solid content concentration 1.0%
Solid content composition / binder resin Acrylic modified polyester IN-170-B manufactured by Takamatsu Yushi Co., Ltd. 57.8 parts / inactive particles Cross-linked acrylic resin particles (average particle size 15 nm) 5.2 parts / surfactant SANYO KASEI KOGYO ( NAROACTY N85 27 parts, parting agent Shin-Etsu Chemical Co., Ltd. Siloxane copolymer acrylic resin X-22-8053 10 parts Water-soluble coating liquid used for forming coating layer B: solid content concentration 2.3 %
Solid composition / binder resin Takamatsu Yushi Co., Ltd. acrylic modified polyester SH551BK 49 parts / binder resin Shin-Etsu Chemical Co., Ltd. methyl cellulose SM15 20 parts / inactive particles Cross-linked acrylic resin particles (average particle size 40 nm) 18 parts / interface Activator Sanyo Kasei Kogyo Co., Ltd. NAROACTY N85 10 parts Release agent Shin-Etsu Chemical Co., Ltd. Siloxane copolymer acrylic resin X-22-8053 3 parts [Examples 2-5 and Comparative Examples 1-5]
A polyester film package was prepared in the same manner as in Example 1 except that the changes were made as shown in Table 1 and evaluated after 3 months. The evaluation results are shown in Table 1.
[0048]
[Example 6]
In Example 1, the thickness of the biaxially oriented polyethylene terephthalate film was changed to 3000 m when the thickness of the 125 μm film slit was changed to 10 g / m of a water-soluble 3% coating composition having the following composition from the coating layers A and B. Except that ² was coated on one side, it was carried out as shown in Table 1 to prepare a polyester film package. The polyester film package was evaluated after 3 months. The evaluation results are shown in Table 1.
[0049]
Polyester: The acid component is composed of 63 mol% of 2,6-naphthalenedicarboxylic acid / 32 mol% of isophthalic acid / 5 mol% of 5-sodium sulfoisophthalic acid, and the glycol component is composed of 90 mol% of ethylene glycol / 10 mol% of diethylene glycol. (Manufactured according to the method described in Example 1 of JP-A-06-116487)
Acrylic; composed of 30% by mole of methyl methacrylate / 2% by mole of 2-isopropenyl-2-oxazoline / 10% by mole of polyethylene oxide (n = 10) methacrylate / 30% by mole of acrylamide (Japanese Unexamined Patent Publication No. 63-37167, Production Example 1) -Manufactured according to the method described in 3)
Fine particles: silica and titania composite inorganic particles (average particle size: 100 nm). (Manufactured according to the method described in JP-A-7-2520, Production Examples and Examples)
Additives; Carnauba wax (trade name Cellosol 524, manufactured by Chukyo Yushi Co., Ltd.)
Wetting agent; polyoxyethylene (n = 7) lauryl ether (trade name NAROACTY N-70, manufactured by Sanyo Chemical Co., Ltd.)
The composition ratio of polyester / acrylic / fine particles / additive / wetting agent was 67/20/3/5/5 (% by weight).
[0050]
[Comparative Example 6]
A polyester film package was prepared in the same manner as in Example 6 except that the conditions were changed as shown in Table 1, and evaluated after 3 months. The evaluation results are shown in Table 1.
[0051]
[Examples 7 and 8 and Comparative Example 7]
A polyester film package was prepared in the same manner as in Example 1 except that the raw material polyethylene terephthalate used for film formation in Example 1 was changed to polyethylene-2,6-naphthalate and the conditions were changed as shown in Table 1. And the evaluation after 3 months was performed. The evaluation results are shown in Table 1.
[0052]
[Comparative Example 8]
A polyester film package was prepared in the same manner as in Example 8 except that the desiccant was changed as shown in Table 1 and evaluated after 3 months. The evaluation results are shown in Table 1.
[0053]
[Table 1]

[0054]
As is apparent from Table 1, according to the present invention, oligomer precipitation on the surface of the polyester film after storage is suppressed, and the discharge suppression property of the polyester film is good.
[0055]
In addition, the average particle diameter of the hygroscopic agent shown in Table 1 was as follows.
Silica gel: 3mm
Calcium carbonate: 3mm
Calcium chloride: 3mm
Magnesium oxide: 1mm
Magnesium chloride: 1mm
[0056]
【The invention's effect】
According to the present invention, even when the film is stored for a long period of time, the film surface is substantially free from oligomer precipitates, discharges, and traces of discharge. It is possible to provide a polyester film having excellent optical characteristics when it is applied.

Claims (11)

A polyester film package in which a whole polyester film roll obtained by winding a polyester film mainly composed of polyester into a roll is covered with a plastic film in which a metal film or an inorganic oxide film is laminated on at least one side, A polyester film package in which at least one desiccant having a moisture absorption of 10% to 55% is enclosed in the package.   The polyester film package according to claim 1, wherein the polyester film is a biaxially oriented film.   The polyester film package according to claim 1, wherein the polyester is polyethylene terephthalate.   The polyester film package according to claim 1, wherein the polyester is polyethylene-2,6-naphthalenedicarboxylate.   The polyester film package according to claim 1, wherein the desiccant is at least one selected from the group consisting of silica gel, calcium chloride, calcium oxide, phosphorus pentoxide, granular soda lime, and magnesium perchlorate.   The polyester film package according to claim 1, wherein the desiccant has an average particle size in the range of 10 to 7000 µm.   The polyester film packaging according to claim 1, wherein the polyester film roll is wound around a core, and the moisture content of the core, the plastic film, and the label enclosed in the package is 15 wt% or less. body.   The polyester film package according to claim 7, wherein a material of the core is resin or metal.   The polyester film package according to any one of claims 1 to 8, wherein the polyester film has a thickness of 2 to 20 µm, and the polyester film is used as a base film for magnetic recording.   The polyester film package according to any one of claims 1 to 8, wherein the polyester film is used for an optical film.   A method for storing a polyester film package, wherein the polyester film package according to any one of claims 1 to 10 is stored under conditions of a temperature of 10 ° C to 30 ° C and a relative humidity of 70% or less.