WO2023128476A1 - Polyester release film and method for manufacturing same - Google Patents

Abstract

The present invention relates to a polyester release film and a method for manufacturing same. The polyester release film is not only excellent in peelability and coating processability, but also has excellent antistatic properties and has a remarkably low frictional charge voltage of less than 50 V. In addition, the polyester release film prevents static electricity generated during film travel and winding, and can significantly reduce the amount of air or foreign matter introduced due to static electricity.

Description

Polyester release film and manufacturing method thereof

The present invention relates to a polyester release film and a manufacturing method thereof.

[0003] With the trend of larger and thinner displays, the demand for thinning polarizers in image display devices is increasing.

One way to thin the polarizer is to thin a typical polarizer protective material such as polyethylene terephthalate (PET) or triacetyl cellulose (TAC). Another way to thin the polarizer is to replace the polarizer protective material with a coating layer having barrier properties (hereinafter referred to as “barrier coating layer”).

The barrier coating layer is formed through a process of uniformly applying the composition for forming the barrier coating layer on an arbitrary substrate, curing the composition, and then peeling it off.

In order to obtain a high-quality barrier coating layer, the barrier coating layer should be uniformly applied on the substrate and the cured barrier coating layer should be well peeled from the substrate.

When a silicone-based release film is used as the substrate, since the silicone-based release film has low surface energy, it is difficult to form the barrier coating layer with a uniform thickness, and static electricity problems caused by silicon may occur.

One object of the present invention is to provide a polyester release film having excellent peelability, coating processability and antistatic properties and low frictional electrostatic voltage.

Another object of the present invention is to provide a polyester release film capable of preventing static electricity generated during film travel and winding and significantly reducing the amount of air or foreign matter introduced due to static electricity.

Another object of the present invention is to provide a method for producing the polyester release film.

According to one embodiment of the present invention,

A polyester base film, a release layer formed on one side of the base film, and an antistatic layer formed on the other side of the base film, wherein the release layer includes a water-based coating composition including a polyester resin, an acrylic resin, and a polyolefin wax, , The antistatic layer is provided with a polyester release film comprising a water-dispersible antistatic composition containing a conductive polymer.

According to another embodiment of the present invention,

A first step of preparing a polyester base film; A second step of forming a release layer by applying an aqueous coating composition containing a polyester resin, an acrylic resin, and a polyolefin wax to one surface of the base film; A third step of forming an antistatic layer by applying a water-dispersible antistatic composition containing a conductive polymer to the other surface of the base film; And a fourth step of heat-treating while stretching the laminate including the base film and the release layer and the antistatic layer formed on the base film; a method for manufacturing a polyester release film is provided.

The polyester release film according to one embodiment of the present invention has excellent peelability and coating processability, excellent antistatic properties, and a remarkably low frictional electrostatic voltage of less than 50 V.

In addition, the polyester release film according to one embodiment of the present invention can prevent static electricity generated during film travel and winding and significantly reduce the amount of air or foreign matter introduced due to static electricity.

The polyester release film according to one embodiment of the present invention can solve problems such as yield reduction due to unreacted materials generated when a coating layer is formed using the release film and adsorption of foreign substances due to static electricity.

Hereinafter, the present invention will be described in detail.

On the other hand, the embodiments of the present invention can be modified in many different forms, and the scope of the present invention is not limited to the embodiments described below.

In addition, embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

Also, the singular forms used in the specification and appended claims may be intended to include the plural forms as well, unless the context dictates otherwise.

Furthermore, "include" a certain component throughout the specification means that other components may be further included without excluding other components unless otherwise stated.

The polyester release film according to one embodiment of the invention,

A polyester base film, a release layer formed on one surface of the base film, and an antistatic layer formed on the other surface of the base film.

In one embodiment, the release layer may include a water-based coating composition including a polyester resin, an acrylic resin, and a polyolefin wax.

Also, in one embodiment, the antistatic layer may include a water-dispersible antistatic composition containing a conductive polymer.

Also, in one embodiment, the polyester release film may have a frictional electrostatic voltage of less than 50 V.

The inventors of the present invention conducted continuous research on release films used as substrates in the manufacture of optical films such as thin film polarizers.

As a result, a release layer is formed by applying an aqueous coating composition including a polyester resin, an acrylic resin, and a polyolefin wax on the base film in an in-line coating method, and conductivity is formed on the other surface of the base film on which the release layer is not formed. When an antistatic layer is formed by applying a water-dispersible antistatic composition containing a polymer, a polyester release film having excellent coating processability and peelability, excellent antistatic properties and low frictional electrostatic voltage is provided. It was found that it could be, and the present invention was completed.

The polyester release film can exhibit excellent coating processability and peelability in post-processing using the release film (eg, a process of forming a barrier coating layer on the release film, etc.), as well as low friction of less than 50 V. Contamination due to static electricity can be prevented by having a frictional electrostatic voltage.

The polyester release film includes a polyester base film, a release layer formed on one surface of the base film, and an antistatic layer formed on a surface (hereinafter, another surface) of the base film on which the release layer is not formed.

The polyester base film is made of a polyester resin, and conventional ones in the art to which the present invention belongs may be used without particular limitation. For example, the polyester base film may be made of polyethylene terephthalate or polyethylene naphthalate.

As a non-limiting example, the base film made of polyethylene terephthalate having an intrinsic viscosity in the range of 0.6 to 0.8 dl/g may be advantageous in terms of securing weather resistance and hydrolysis resistance.

The release layer may include a water-based coating composition including a polyester resin, an acrylic resin, and a polyolefin wax.

The polyester resin is a resin obtained by condensation polymerization of an acid component containing dicarboxylic acid as a main component and a glycol component containing alkylene glycol as a main component. As the acid component, terephthalic acid or its alkyl esters or phenyl esters may be mainly used, and some of them may be replaced with isophthalic acid, oxyethoxybenzoic acid, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid, sulfoterephthalic acid, etc. and can be used. As the glycol component, ethylene glycol, diethylene glycol, etc. may be mainly used, some of which are propylene glycol, trimethylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-bis It can be used by replacing with oxyethoxybenzene, bisphenol, polyoxyethylene glycol, etc.

As a non-limiting example, the polyester resin is diethylene glycol and ethylene glycol in a molar ratio of 5: 50 mol% glycol component including 5, and terephthalic acid and sulfoterephthalic acid in a molar ratio of 8.5: 50 mol% containing terephthalic acid in a molar ratio of 1.5 It can be obtained by condensation polymerization of an acid component.

It may be advantageous for the polyester resin to have a weight average molecular weight of 2,000 to 25,000 g/mol to ensure that the release layer has appropriate solvent resistance. Preferably, the weight average molecular weight of the polyester resin may be 2,000 to 25,000 g/mol, or 2,000 to 20,000 g/mol, or 3,000 to 20,000 g/mol, or 3,000 to 15,000 g/mol.

In this specification, a weight average molecular weight means the weight average molecular weight of polystyrene conversion measured by the GPC method. In the process of measuring the weight average molecular weight in terms of polystyrene measured by the GPC method, a conventionally known analyzer and a detector such as a differential refractive index detector and an analysis column may be used, and a commonly applied temperature Conditions, solvents, and flow rates can be applied.

The acrylic resin may contain, as a copolymerization monomer, a radically polymerizable unsaturated monomer containing a glycidyl group in an amount of 20 to 80 mol% based on total monomer components. The glycidyl group-containing radically polymerizable unsaturated monomer is preferred because it can improve the strength of the release layer and prevent outflow of oligomers by a crosslinking reaction. Examples of the glycidyl group-containing radical polymerizable unsaturated monomer include glycidyl acrylate, glycidyl methacrylate, and aryl glycidyl ether.

Examples of the radically polymerizable unsaturated monomer copolymerizable with the glycidyl group-containing radically polymerizable unsaturated monomer include vinyl esters, unsaturated carboxylic acid esters, unsaturated carboxylic acid amides, unsaturated nitriles, unsaturated carboxylic acids, allyl compounds, nitrogen-containing vinyl monomers, and hydrocarbons. A vinyl monomer or a vinyl silane compound, etc. are mentioned. Examples of the vinyl ester include vinyl propionate, vinyl stearate, and vinyl chloride. Examples of the unsaturated carboxylic acid ester include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, ethyl methacrylate, butyl methacrylate, butyl maleate, octyl maleate, butyl fumarate, octyl fumarate, hydroxyethyl methacrylate , hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate and the like can be used. As the unsaturated carboxylic acid amide, acrylamide, methacrylamide, methylol acrylamide, butoxy methylol acrylamide and the like may be used. Acrylonitrile and the like can be used as the unsaturated nitrile. Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, maleic acid ester, fumaric acid acid ester, and itaconic acid acid ester. As the allyl compound, allyl acetate, allyl methacrylate, allyl acrylate, allyl itaconate, diallyl itaconate, and the like can be used. As the nitrogen-containing vinyl monomer, vinyl pyridine, vinyl imidazole, and the like may be used. Ethylene, propylene, hexene, octene, styrene, vinyltoluene, butadiene, etc. may be used as the hydrocarbon vinyl monomer. Examples of the vinyl silane compound include dimethyl vinyl methoxy silane, dimethyl vinyl ethoxy silane, methyl vinyl dimethoxy silane, methyl vinyl diethoxy silane, gamma-methacryloxy propyl trimethoxysilane, and gamma-methacryloxy propyl dimethoxy silane. etc. can be used.

As a non-limiting example, the acrylic resin may be copolymerized with 40 to 60 mol% of glycidyl acrylate and 40 to 60 mol% of vinyl propionate.

The acrylic resin may preferably have a weight average molecular weight of 20,000 to 70,000 g/mol. More preferably, the weight average molecular weight of the acrylic resin may be 20,000 to 60,000 g/mol, or 30,000 to 60,000 g/mol, or 40,000 to 60,000 g/mol, or 45,000 to 55,000 g/mol.

In one embodiment, the weight ratio of the solid content of the polyester resin and the acrylic resin may be 1: 0.1 to 1: 1.5, and more specifically, 1: 0.2 to 1: 1. When the release layer is prepared with a water-based coating composition satisfying the above range, the polyester release film may have an effect of further improving processing coating property as well as excellent release property.

The release layer may include polyolefin wax, and may be dispersed on the polyester resin and the acrylic resin.

The specific type of the polyolefin wax is not particularly limited, but at least one selected from the group consisting of polyethylene wax and polypropylene wax may be preferably used.

The polyolefin wax may be included in 20 to 50 parts by weight or 30 to 40 parts by weight based on 100 parts by weight of the polyester resin. The polyolefin wax is preferably included in an amount of 20 parts by weight or more based on 100 parts by weight of the polyester resin so that the release layer can exhibit an appropriate peeling force. However, when an excessive amount of the polyolefin wax is added to the release layer, a backside transfer problem and a decrease in processing coating properties may be caused. Therefore, the polyolefin wax is preferably included in an amount of 50 parts by weight or less based on 100 parts by weight of the polyester resin.

For example, the polyolefin wax is 20 parts by weight or more, or 25 parts by weight or more, or 30 parts by weight or more based on 100 parts by weight of the polyester resin; And it may be included in 50 parts by weight or less, or 45 parts by weight or less, or 40 parts by weight or less. Specifically, the polyolefin wax is included in 20 to 50 parts by weight, or 25 to 50 parts by weight, or 25 to 45 parts by weight, or 30 to 45 parts by weight, or 30 to 40 parts by weight based on 100 parts by weight of the polyester resin. can

The total content of the polyester resin, acrylic resin, and polyolefin wax included in the water-based coating composition is 1 to 10 wt%, 2 to 9 wt%, 4 to 8 wt%, or 5 to 6 wt% based on solids. desirable.

A polyester release film prepared by satisfying the above range in terms of solid content of the polyester resin, acrylic resin, and polyolefin wax included in the water-based coating composition has excellent transfer characteristics and peelability, as well as frictional electrification voltage (Frictional Electrostatic Voltage) can be significantly lowered to less than 50 V. In addition, the release film manufactured by satisfying the above range can prevent the occurrence of fine pinholes, and thus the processing coating properties can be improved.

In one embodiment of the present invention, the water-based coating composition applied to the release layer is, if necessary, a silicone-based wetting agent, a fluorine-based wetting agent, a curing agent, an acid catalyst, a slip agent, an antifoaming agent, a wetting agent, a surfactant, a thickener, a plasticizer, an oxidizing agent Additives such as an inhibitor, an ultraviolet absorber, an antiseptic, and a crosslinking agent may be further added. The additive may be selectively used within the limit of not impairing the physical properties of the release layer.

The antistatic layer may include a water-dispersible antistatic composition containing a conductive polymer.

The polyester release film according to one embodiment of the present invention includes the release layer made of a non-silicone material and the antistatic layer, so that coating workability and peelability are excellent as well as antistatic properties and frictional electrification voltage ( Frictional Electrostatic Voltage) may have a remarkably low characteristic of less than 50 V.

The conductive polymer may be a nano-sized structure having electrical conductivity and polarity. The conductive polymer may include, for example, at least one selected from conductive polymers such as polythiophene, polypyrrole, and polyaniline.

In addition, as an embodiment, a resin composition including a conductive polymer may also be included in the category of the conductive polymer. The resin may be, for example, a water-based resin and may include an ionic polymer.

In the case of the ionic polymer, as a polymer having a group including a cationic or anionic group, it may be an ionic polymer such as polystyrene sulfonate salt or polystyrene ammonium salt, but is not limited thereto. In the case of using the ionic polymer, the content is not limited as long as the object of the present invention is achieved, but for example, it may be used in a weight ratio of 0.01 to 2 with respect to the conductive polymer.

As an embodiment, the conductive polymer may be preferably a polythiophene-based conductive polymer, and may also be polyethylenedioxythiophene:polystyrenesulfonate (PEDOT:PSS). When PEDOT:PSS is used as the conductive polymer, it is suitable for use in an in-line coating process due to its excellent water dispersibility, and transparency is not deteriorated even through a stretching process after the in-line application process, and 10 ¹⁰ Ω/□ or less It is more preferred because it can express the surface resistance of

The water-dispersible antistatic composition may further include a water-based polyurethane resin. By mixing and using the water-based polyurethane resin with a conductive polymer, the miscibility is excellent, the surface resistance performance is improved, the adhesion with the polyester base film is excellent, the physical property change is small under high temperature and high humidity conditions, and the yellowing phenomenon is low. An antistatic layer may be formed. The water-based polyurethane resin can achieve physical properties of excellent heat resistance and low change in surface resistance by using a polyurethane binder in which a polycarbonate-based polyol and diisocyanate are reacted. More preferably, the use of hexamethylene diisocyanate as a specific example of the diisocyanate is good from the viewpoint of forming a coating film with less yellowing by improving heat resistance, but is not limited thereto.

In one embodiment, the water-dispersible antistatic composition may contain 1 to 30 wt% of the conductive polymer and 70 to 99 wt% of the aqueous polyurethane resin in 100 wt% of the solid content of the water-dispersible antistatic composition. More specifically, 5 to 25 wt% of the conductive polymer and 75 to 95 wt% of the polyurethane binder may be included. More specifically, 5 to 20 wt% of the conductive polymer and 80 to 95 wt% of the polyurethane binder may be included.

More specifically, the antistatic layer may be formed by applying a water-dispersible antistatic composition containing a conductive polymer solution, an aqueous polyurethane resin solution, an organic solvent, and water.

More specifically, for example, the water-dispersible antistatic composition comprises 40 to 90 wt% of a conductive polymer solution having a solid content of 1 to 3 wt% and 5 to 50 wt% of an aqueous polyurethane resin solution having a solid content of 30 to 40 wt%. %, an organic solvent of 3 to 50 wt% and the balance of water.

The conductive polymer may be used as a conductive polymer solution mixed in a solvent in order to express optimal dispersibility. Specifically, for example, when PEDOT:PSS is used, water, alcohol, or a solvent having a high dielectric constant, etc. It may be used in combination.

The content of the conductive polymer solution in the antistatic composition may be 40 to 90 wt%, more preferably 50 to 70 wt%, and the content is sufficient to achieve the object of the present invention, but is not limited thereto.

In addition, the water-based polyurethane resin may be dispersed in a solvent, and the solvent is not limited to, but is any one or a mixture of two or more selected from the group consisting of an amide-based organic solvent and an aprotic highly dipolar (AHD) organic solvent. A solvent may be used.

The content of the water-based polyurethane resin in the water-dispersible antistatic composition may be 5 to 50 wt%, more preferably 10 to 30 wt%, but is not limited thereto.

The organic solvent is not particularly limited, but any one or a mixture of two or more selected from the group consisting of an alcohol-based organic solvent and an aprotic highly polar organic solvent may be used, but is not limited thereto.

The content of the organic solvent may be 50 wt% or less, 40 wt% or less, 30 wt% or less, 20 wt% or less, or 10 wt% or less in the water-dispersible antistatic composition, and the lower limit is 1 wt% or 2 wt%. It may be more than that, and the content suitable for improving the dispersibility of the conductive polymer and the water-based polyurethane resin in the above range is not limited thereto.

The alcohol-based organic solvent is not limited, but specifically, for example, methanol, ethanol, propanol, isopropanol, butanol, and 2-amino-2-methyl-1-propanol may be used, alone or in combination of two or more. can be used

The aprotic highly polar organic solvent is not limited, but specifically, for example, dimethyl sulfoxide, propylene carbonate, etc. may be used, and may be used alone or in combination of two or more. The conductivity of the conductive polymer can be further improved by using an aprotic highly polar organic solvent.

Since the water-dispersible antistatic composition includes each material in the above content range, the polyester release film according to an embodiment of the present invention has excellent antistatic property as the frictional electrostatic voltage is significantly lower than 50 V. It can prevent the generation of static electricity generated during film travel and winding, and can significantly reduce the amount of air or foreign matter introduced due to static electricity.

In addition, since the water-dispersible antistatic composition satisfies the above content range, the polyester release film according to an embodiment of the present invention is caused by a decrease in yield due to unreacted substances generated when a coating layer is formed using the same, and a decrease in yield due to static electricity Problems such as adsorption of foreign matter can be solved.

In one embodiment of the present invention, the surface resistance of the antistatic layer may be 10 ¹⁰ Ω/□ or less, and more specifically, 10 ⁹ Ω/□ or less.

In one embodiment of the present invention, the water-dispersible antistatic composition, if necessary, silicone-based wetting agent, fluorine-based wetting agent, slip agent, antifoaming agent, wetting agent, surfactant, thickener, plasticizer, antioxidant, ultraviolet absorber, preservative and crosslinking agent etc. may be further included.

Thicknesses of the base film, the release layer, and the antistatic layer are not particularly limited and may be adjusted according to specific fields of application of the polyester release film.

For example, the base film may have a thickness of 10 to 300 μm, and the release layer and the antistatic layer may have a thickness of 10 to 200 nm, but are not necessarily limited thereto.

Thicknesses of the release layer and the antistatic layer may be the same as or different from each other. Specifically, the base film may have a thickness of 10 to 200 μm, 10 to 100 μm, or 10 to 50 μm, and the release layer may have a thickness of 10 to 100 nm, more specifically 50 to 100 nm And, the antistatic layer may have a thickness of 10 to 100 nm, more specifically 20 to 80 nm.

In the polyester release film, the base film is not particularly limited, but may be uniaxially stretched in the machine direction (MD) or transverse direction (TD) or biaxially stretched in the machine direction (MD) and transverse direction (TD) , The release layer and the antistatic layer may be uniaxially or biaxially stretched, but uniaxially stretched in the transverse direction (TD) may be preferred because the properties of the present invention can be better imparted.

As the polyester release film satisfies the above characteristics, it may have excellent peelability as well as excellent antistatic property due to low frictional electrostatic voltage.

For example, the polyester release film may have a peel strength of 350 to 700 gf/inch, or 400 to 650 gf/inch, or 400 to 600 gf/inch. The polyester release film having a peel strength within the above range may have excellent coating processability and peelability in post-processing (eg, a process of forming a barrier coating layer on the release film).

In the present specification, the peel force is measured according to the standard test method of ASTM D 3330. Specifically, the peel force is 70 g / cm by cutting an acrylate-based adhesive tape (manufactured by Nitto Denko, NITTO #31B tape width: 25 mm) into a size of 5 mm X 180 mm and stacking it on the release layer of the polyester release film. After applying a load of ² and leaving it at room temperature for 30 minutes, it can be measured by peeling the tape 180 degrees at a peeling rate of 300 mm/min using a peel tester.

In addition, the polyester release film may have a significantly low frictional electrostatic voltage of less than 50 V, or less than 40 V, or less than 30 V, or less than 20 V, or less than 10 V. The lower limit is not particularly limited, but may be, for example, 1 V or more, 3 V or 5 V or more.

In the present specification, the frictional electrostatic voltage is measured according to the standard test method of KS K 0555. Specifically, the measurement of the frictional electrification voltage may be performed by a method of measuring frictional static electricity for the polyester release film using a conventional rotary static tester. At this time, the amount of static electricity generated by rubbing the A side (the release layer side of the polyester release film) and the B side (the antistatic layer side of the polyester release film) at a rotational speed of 300 rpm for 180 seconds is measured.

Furthermore, the polyester release film may exhibit excellent processing coating properties while having a low haze value.

For example, the polyester release film may have a haze of 3.90% or less. Preferably, the polyester release film may have a haze of 3.50 to 3.90%, 3.60 to 3.90%, or 3.70 to 3.86%.

In addition, the polyester release film may have excellent processing coating properties that satisfy Formula 1 below.

[Equation 1]

N _H = 0

In Equation 1, N _H is the number of pinholes generated per unit area (m ² ) when a UV resin is applied to the release layer of the polyester release film to a thickness of 10 μm and cured.

That is, in any manufacturing process using the polyester release film as a substrate, when an arbitrary resin layer is formed on the release layer, pinholes are not substantially formed on the release layer, resulting in excellent processing coating properties. can

In addition, the polyester release film may exhibit a total light transmittance of 90% to 95%, a water contact angle of 85 ° to 90 °, a diiodomethane contact angle of 50 ° to 60 °, and a surface energy of 30 to 35 mN / m.

In addition, the polyester release film according to one embodiment of the present invention may be a polyester release film for thin film polarizers, but is not limited thereto and can be applied to various fields requiring antistatic, coating workability, and peelability. . For example, in addition to the use of thin film polarizers, cover tape for MLCC (Multi Layer Ceramic Capacitor) Carrier, FPCB (Flexible Printed Circuits Board) process protection, OCA (Optical Clear Adhesive) and OCA protection, optical members for displays (for various display surface protection) etc. can be applied.

In the polyester release film, in particular, the release layer and the antistatic layer may be formed on the polyester base film by in-line coating. The release layer may be formed by applying an aqueous coating composition including the polyester resin, acrylic resin, and polyolefin wax to one surface of the polyester base film by an in-line coating method.

The antistatic layer may be formed by applying the water-dispersible antistatic composition containing the conductive polymer to the other surface of the base film by an in-line coating method.

As the release layer and the antistatic layer are formed by the in-line coating method, the coating thickness is thin, the adhesive strength with the polyester base film is excellent, and the antistatic layer can exhibit excellent resistance to moisture and solvents.

As the polyester release film has excellent coating processability, peelability, and low frictional electrification voltage, it can be suitably used as a base film for release in the manufacture of a thin film polarizer.

As a non-limiting example, when the thin film polarizing plate is manufactured, a barrier coating layer may be formed on the base film of the polyester release film; a polyvinyl alcohol resin layer; adhesive layer; And a resin layer such as polyethylene terephthalate (PET), triacetyl cellulose (TAC), or polymethyl methacrylate (PMMA) may be sequentially laminated to form a laminate.

In addition, the polyester release film may be removed from the laminate.

Hereinafter, the manufacturing method of the polyester release film will be described in detail.

A method for producing a polyester release film according to an embodiment of the present invention,

A first step of preparing a polyester base film; A second step of forming a release layer by applying an aqueous coating composition containing a polyester resin, an acrylic resin, and a polyolefin wax to one surface of the base film; A third step of forming an antistatic layer by applying a water-dispersible antistatic composition containing a conductive polymer to the other surface of the base film; and a fourth step of heat-treating while stretching the laminate including the base film, a release layer and an antistatic layer formed on the base film; can include

The first step is to prepare a polyester base film, and the polyester base film is made of a polyester resin.

As the polyester base film, a conventional one in the art to which the present invention belongs may be used without particular limitation. The polyester base film, but is not necessarily limited thereto, may be prepared as being stretched in the machine direction (MD, or longitudinal direction). Preferably, the polyester base film may be stretched 2 to 5 times in the machine direction (MD). The polyester base film preferably has a thickness of 10 to 300 μm, but is not limited thereto within the limit of achieving the object of the present invention.

The second step is a step of forming a release layer by applying a water-based coating composition containing a polyester resin, an acrylic resin, and a polyolefin wax to one surface of the base film, wherein the water-based coating composition is applied on the polyester base film. It is for forming a release layer.

The water-based coating composition may include the polyester resin, the acrylic resin, and the polyolefin wax, and the above description of the resin and wax may be applied.

The water-based coating composition may be prepared by uniformly mixing the above-described components and water. The solid content of the water-based coating composition may be preferably 20 to 60 wt% to secure the efficiency of the coating process.

The release layer may be formed on one surface of the polyester base film by an in-line coating method using the aqueous coating composition. As the release layer is formed by the in-line coating method, the adhesive strength with the polyester base film is excellent even though the coating thickness is thin, and excellent resistance to moisture and solvents can be exhibited.

The in-line coating method may be performed using a conventional device.

In performing the in-line coating, the water-based coating composition may be applied to a thickness of 20 to 200 nm after final stretching and drying of the release layer. Specific details regarding the thickness and other characteristics of the release layer may be applied as described above.

After the water-based coating composition is applied on the polyester base film, the release layer may be formed by removing moisture from the water-based coating composition and curing the water-based coating composition.

The third step is a step of forming an antistatic layer by applying a water-dispersible antistatic composition containing a conductive polymer to the other surface of the base film, the water-dispersible antistatic composition may further include a water-based polyurethane resin, Specific details regarding the conductive polymer, the water-based polyurethane resin, and the like may be applied as described above.

The water-dispersible antistatic composition may be prepared by uniformly mixing the above-described components and water. The solid content of the antistatic composition may be preferably 5 to 50 wt% to secure the efficiency of the coating process.

The water-dispersible antistatic composition may further include an organic solvent, and the above-described information regarding this may be applied.

The antistatic layer may be formed on the other surface of the polyester base film by an in-line coating method using the water-dispersible antistatic composition, and the specific details of the in-line coating method are as described above in the release layer. can be applied

The fourth step is a step of heat-treating the laminate including the base film, the release layer and the antistatic layer formed on the base film while stretching in the machine direction (MD) or the transverse direction (TD).

In one embodiment, but not necessarily limited thereto, when the laminate is stretched 2 to 5 times in the transverse direction (TD), it is suitable for achieving the desired physical properties of one embodiment of the present invention and is preferred.

For example, after forming the release layer and the antistatic layer on the polyester base film uniaxially stretched in the machine direction (MD), it may be stretched in the transverse direction (TD). Through this stretching process, the polyester base film may be biaxially stretched in the machine direction and the transverse direction, and the release layer and the antistatic layer may be uniaxially stretched in the transverse direction.

The fourth step may be performed using a conventional heat treatment device such as a tenter. In the fourth step, the laminate may continuously pass through the tenter.

The laminate may be preheated while passing through the front end of the tenter, stretched in the transverse direction (TD) while passing through the middle part of the tenter, and heat treated while passing through the rear end of the tenter. The heat treatment may be performed while maintaining tension applied to the laminate during the transverse direction stretching.

Preferably, the fourth step may be performed by passing the laminate through a heat treatment device having a total heat capacity of 222,000 kcal/min to 229,000 kcal/min of air supplied to the passing section. The laminated body passing through the heat treatment device is subjected to the stretching and heat treatment while being exposed to the total heat amount range.

Specifically, in the fourth step, the total heat of the air supplied to the entire passing section is 222,000 kcal/min to 229,000 kcal/min, or 225,000 kcal/min to 229,000 kcal/min, or 226,000 kcal/min to 229,000 kcal/min , or 226,000 kcal / min to 228,000 kcal / min, or 226,000 kcal / min to 227,000 kcal / min may be performed by passing the laminate through a heat treatment device.

In the fourth step, the total heat amount (kcal) of air supplied to the entire section through which the laminate passes is the temperature of the section (℃), the mass of air supplied to the heat treatment device (kg/min), It can be calculated from data such as specific heat (kcal/kg °C). The air mass (kg/min) can be obtained from the air volume flow rate (Nm ³ /min) and air density (kg/Nm ³ ).

For example, the density of air supplied to a certain zone in the heat treatment device is 1.286 kg/Nm ³ , the specific heat of air is 0.24 kcal/kg°C, and the volumetric flow rate of air is 380 Nm ³ /min. , When the initial temperature of the air is 20 ℃ and the set temperature of the section is 220 ℃, the total heat (kcal) of the air supplied to the section can be obtained as 23,456.64 kcal / min by the following formulas 1 and 2 there is.

[Calculation 1]

Mass of air (kg/min) = Volume flow rate of air (Nm ³ /min) X Density of air (kg/Nm ³ )

[Calculation 2]

Heat of air (kcal/min) = mass of air (kg/min) X specific heat of air (kcal/kg℃) X temperature change (℃)

And, when the passage length of the section is 3 m and the laminate passes through the section at a speed of 100 m/min, the amount of heat exposed to the laminate in the section is obtained as 7,037 kcal/zone by Equation 3 below. can

[Calculation 3]

Heat amount exposed to the laminate (kcal/zone) = Heat amount of air (kcal/min) X Passing length of the section (m/zone) X Speed of the laminate (m/min)

According to one embodiment of the invention, the step of preheating the laminate by passing through a section in which a heat amount of 44,000 kcal / min to 46,000 kcal / min is supplied; stretching the preheated laminate in the machine direction (MD) or transverse direction (TD) while passing through a section where a heat amount of 62,000 kcal/min to 64,000 kcal/min is supplied; and a step of heat treating the stretched laminate while passing it through a section in which a heat amount of 114,000 kcal/min to 120,000 kcal/min is supplied.

Preferably, the preheating process may be performed while passing the laminate through a section where a heat amount of 45,000 kcal/min to 46,000 kcal/min is supplied.

Preferably, the stretching process may be performed while passing the preheated laminate through a section where a heat amount of 63,000 kcal/min to 64,000 kcal/min is supplied.

And, preferably, the step of heat treating the stretched laminate is 115,000 kcal/min to 120,000 kcal/min, or 115,000 kcal/min to 119,000 kcal/min, or 116,000 kcal/min to 119,000 kcal/min, Alternatively, 117,000 kcal/min to 118,500 kcal/min, or 118,000 kcal/min to 118,500 kcal/min may be performed while passing through a section in which heat is supplied.

In the fourth step (particularly, in the heat treatment zone after stretching), when the total heat amount of the air supplied to the passing section is too low, the release property and transfer characteristics of the polyester release film may deteriorate and the frictional electrification voltage may increase. And, in the fourth step (particularly, in the heat treatment zone after the transverse stretching), when the total heat amount of the air supplied to the passing section is too high, the surface energy of the polyester release film is lowered, and thus the processing coating property may be lowered. .

In addition, in the fourth step, the laminate is subjected to the heat treatment device at a speed of 80 m/min to 120 m/min, 90 m/min to 110 m/min, or 90 m/min to 100 m/min. It is desirable to pass

In performing the fourth step, in order to expose the laminate to an appropriate amount of heat in each section and to sufficiently perform the transverse stretching and heat treatment, the laminate is subjected to the heat treatment within the speed range It is desirable to pass through the device.

The fourth step may be performed at 120 °C to 245 °C. For example, the fourth step may include preheating the laminate at 120 °C to 150 °C; transversely stretching the preheated laminate at 130° C. to 150° C.; and a process of heat treating the stretched laminate at 215 °C to 245 °C.

In particular, the step of heat treating the stretched laminate is 215 °C or higher, 220 °C or higher, 225 °C or higher, or 230 °C or higher; And it can be carried out at 245 ℃ or less, or 240 ℃ or less. Specifically, the process of heat treating the stretched laminate may be performed at 215 to 245 °C, 220 to 245 °C, 220 to 240 °C, 225 to 240 °C, or 230 to 240 °C.

When the temperature of the heat treatment process for the stretched laminate satisfies the above range, not only the release property of the polyester release film is excellent, but also the frictional electrostatic voltage can be lowered, and the polyester release film Since fine pinholes do not occur during manufacturing, processing coating properties can be improved.

After performing the fourth step, a process of relaxing by 2 to 10% in the machine direction and the transverse direction at 150 ° C. to 200 ° C. may be performed.

The final thickness of the polyester release film obtained through the above processes may be 20 to 100 μm, or 30 to 80 μm, or 30 to 50 μm.

Hereinafter, manufacturing examples, examples and experimental examples of the present invention will be specifically illustrated and described. However, Examples and Experimental Examples to be described later are merely illustrative of a part of the present invention, and the present invention is not limited thereto.

<Preparation Example 1> Preparation of a first water-based coating composition

(1) Preparation of the first resin composition

A first polyester resin obtained by condensation polymerization of 50 mol% of a glycol component containing diethylene glycol and ethylene glycol in a molar ratio of 5: 5, and 50 mol% of an acid component containing terephthalic acid and sulfoterephthalic acid in a molar ratio of 8.5: 1.5 was obtained (weight average molecular weight 10,000 g/mol).

100 parts by weight of the first polyester resin and 25 parts by weight of polyethylene wax (Wax No.1, Takamatsu, Japan) were added to distilled water and stirred for 30 minutes to prepare a first resin composition (solid content: 20 wt%).

(2) Preparation of the second resin composition

A second polyester resin obtained by condensation polymerization of 50 mol% of a glycol component containing diethylene glycol and ethylene glycol in a molar ratio of 5: 5, and 50 mol% of an acid component containing terephthalic acid and sulfoterephthalic acid in a molar ratio of 8.5: 1.5 (Weight average molecular weight 3,000 g/mol).

60 mol% of glycidyl acrylate and 40 mol% of vinyl propionate were copolymerized to obtain an acrylic resin (weight average molecular weight: 50,000 g/mol).

50 parts by weight of the second polyester resin, 50 parts by weight of the acrylic resin, and 25 parts by weight of polyethylene wax were added to distilled water and stirred for 30 minutes to prepare a second resin composition (solid content: 20 wt%).

(3) Preparation of water-based coating composition

The first resin composition 14.3 wt% (solid content 20 wt%), the second resin composition 14.3 wt% (solid content 20 wt%), silicone-based wetting agent 0.2 wt% (Dow Corning, Q2-5212, solid content 90 wt%) , 0.2 wt% of a fluorine-based wetting agent (DuPont, FS-31, 25 wt% solid content), and the remaining amount of water were mixed to prepare a first aqueous coating composition.

<Preparation Example 2> Preparation of a second water-based coating composition

A second aqueous coating composition was prepared in the same manner as in Preparation Example 1, except that the first resin composition prepared in Preparation Example 1 was not used and the amount of the second resin composition was further used. That is, the second water-based coating composition according to Preparation Example 2 includes 28.6 wt% of the second resin composition.

<Preparation Example 3> Preparation of the first antistatic coating composition

60 wt% of conductive polymer aqueous dispersion (Heraeus, Clevios P solid content: 1.3 wt%), 6 wt% of water, and 5 wt% of isopropyl alcohol (IPA) were put in a mixing container, stirred for 1 hour, and 2-amino-2- After adding 2 wt% of methyl-1-propanol (Alfa aesar, 95%) to the mixing container and stirring for another hour, a water-based polyurethane resin (Neo resins Neo rez R-960, solid content 31 wt%) was added. After adding 20 wt% and re-stirring for 30 minutes, 5 wt% of dimethyl sulfoxide and 2 wt% of a silicone-based wetting agent (BYK 348) were added to the mixing container and further stirred for 1 hour to form the first water-dispersible antistatic composition (solid content 6.98 wt%). %) is produced. Then, the first water-dispersible antistatic composition is prepared by secondary dilution. In this case, 30 wt% of the first water-dispersible antistatic composition, 69.6 wt% of water, 0.2 wt% of a silicone-based wetting agent (Dow Corning, Q2-5212, 90 wt% of solid content), and 0.2 wt% of a fluorine-based wetting agent (DuPont, FS-31, solid content 25 wt%) was mixed to prepare a first antistatic coating composition.

<Comparative Preparation Example 1> Preparation of a third water-based coating composition

20 wt% silicone release main material (Wacker 400E, solid content 55 wt%) and curing agent 1.1 wt% (Wacker V-72, solid content 40 wt%) 0.18 wt% silicone wetting agent (Dow Corning, Q2-5212, solid content 90 wt%), 5 wt% of isopropyl alcohol (IPA) and the balance of water to prepare a third water-based coating composition.

<Comparative Preparation Example 2> Preparation of the fourth water-based coating composition

A fourth aqueous coating composition was prepared in the same manner as in Preparation Example 1, except that the amount of the first resin composition was further used without using the second resin composition prepared in Preparation Example 1. That is, the fourth water-based coating composition according to Comparative Preparation Example 1 includes 28.6 wt% of the first resin composition.

<Comparative Preparation Example 3> Preparation of the second antistatic coating composition

Acrylic water dispersion (ATX-014 from Takamatsu, Japan, solid content 40 wt%) 5.1 wt%, anionic polymer antistatic agent (Jinbo, ICP-323, molecular weight 100,000 g / mol or more, solid content 25.5 wt%), 9 wt%, A second antistatic coating composition was prepared by mixing 2 wt% of a silicone-based wetting agent (BYK 384) and the remaining amount of water.

<Example 1>

(1) PET chips from which moisture was removed to 100 ppm or less were injected into a melting extruder, melted, and rapidly cooled and solidified using a casting drum having a surface temperature of 20 ° C while extruding through a T-die to prepare a PET sheet. The prepared PET sheet was stretched 3.5 times in the machine direction at 110° C. and then cooled to room temperature to obtain the PET base film.

(2) Applying the first aqueous coating composition according to Preparation Example 1 using a gravure coater to one side of the PET base film to a thickness of 70 nm after final drying to form a release layer, and first charging according to Preparation Example 3 An antistatic layer was formed by applying the antistatic coating composition to the other surface of the PET base film to a thickness of 50 nm after final drying.

(3) Then, in a tenter partitioned into a preheating zone, a stretching zone, and a heat treatment zone, a heat treatment step is performed while stretching the laminate on which the release layer and the antistatic layer are formed 4 times in the transverse direction (TD) It became.

The heat treatment while passing the laminate (initial width 5.12 m, initial thickness 152 μm) at a moving speed of 100 m/min through the tenter having a total length of 33 m including a preheating zone, a stretching zone, and a heat treatment zone in sequence step was performed.

The heat treatment step was performed by passing the laminate through the tenter having a total heat quantity of 226,400 kcal/min of air supplied to the passing section.

The density of air supplied to the tenter was 1.286 kg/nm ³ , the specific heat of air was 0.24 kcal/kg° C., and the volumetric flow rate of air was adjusted within the range of 270 to 680 nm ³ /min.

Specifically, the laminate passed through the preheating zone (passing length: 7.5 m) at a temperature of about 120 °C to 130 °C and supplied with a heat amount of 45,000 kcal/min. Subsequently, the preheated laminate was stretched 4 times in the transverse direction while passing through the stretching zone (passing length of 10.5 m) supplied with a heat amount of 63,200 kcal/min at a temperature of about 130°C to 140°C. Continuously, the stretched laminate was subjected to heat treatment while passing through the heat treatment zone (passing length of 15 m) supplied with a heat amount of 118,200 kcal/min at a temperature of 230 to 235°C.

(4) After the heat treatment step, a polyester release film having a total thickness of 38 μm was prepared by heat-setting at 200° C. by 10% relaxation in each of the machine and transverse directions.

<Example 2>

In Example 2, a polyester release film having a total thickness of 38 μm was prepared in the same manner as in Example 1, except that the release layer of Example 1 was coated with the second aqueous coating composition according to Preparation Example 2. manufactured.

<Comparative Example 1>

In Comparative Example 1, except that the antistatic layer of Example 1 was not formed. In the same manner as in Example 1, a polyester release film having a total thickness of 38 μm was prepared.

<Comparative Example 2>

In Comparative Example 2, except that the release layer of Example 1 was formed by coating the third aqueous coating composition according to Comparative Preparation Example 1, the polyester release film having a total thickness of 38 μm was carried out in the same manner as in Example 1. was manufactured.

<Comparative Example 3>

In Comparative Example 3, a polyester release film having a total thickness of 38 μm was prepared in the same manner as in Comparative Example 2, except that the antistatic layer of Comparative Example 2 was not formed.

<Comparative Example 4>

In Comparative Example 4, except that the antistatic layer of Example 1 was coated with the second antistatic coating composition according to Comparative Preparation Example 3, the same procedure as in Example 1 was performed, and a polyester release having a total thickness of 38 μm A film was made.

<Comparative Example 5>

In Comparative Example 5, a polyester release film having a total thickness of 38 μm was carried out in the same manner as in Example 1, except that the release layer of Example 1 was coated with the fourth aqueous coating composition according to Comparative Preparation Example 2. was manufactured.

<Evaluation items>

The measured values of the following properties of Examples and Comparative Examples are shown in Table 1 below.

1. Optical properties

Haze and total light transmittance (TT) of the films of Examples and Comparative Examples were measured using a haze meter (Nipon denshoku, NDH 5000).

2. Transfer test

After laminating an untreated PET base film on the release layer of the polyester release film, applying a load of 50 gf/inch, and leaving it in an oven at 45 ° C. for 24 hours, if the difference in water contact angle is greater than △2 °, transfer is present. It was marked as , and when there was no difference in water contact angle, it was marked as no transfer.

The same transfer test was performed on the antistatic layer of the polyester release film to indicate the presence or absence of transfer.

3. Water contact angle

The water contact angle for the release layer of the film was measured using a contact angle measuring instrument (KRUSS, DSA 100). 3 μl of pure water (S1, Volume mode) was dropped on the film specimen and the average water contact angle for 15 seconds was measured. A total of 5 measurements were performed and the average value was shown.

4. Diiodomethane contact angle

The contact angle of diiodomethane on the release layer of the film was measured using a contact angle meter (KRUSS, DSA 100). 1 μl of diiodomethane (S1, Volume mode) was dropped on the film specimen and the average contact angle of diiodomethane for 15 seconds was measured. A total of 5 measurements were performed and the average value was shown.

5. Surface Energy

The surface energy of the release layer of the film was calculated using the Owens-Wendt method from the measurement results of the water contact angle and the diiodomethane contact angle.

6. Processing coating properties

UV resin (Miwon Specialty Chemical Co., MIRAMER M1130) was applied on the release layer of the film to a thickness of 10 μm to prepare a UV cured sample. The process coating properties of the samples were evaluated according to the criteria below.

* Grade 1 - No pinholes per unit area (㎡)

* Class 2 - less than 2 pinholes per unit area (㎡)

* Class 3 - Less than 5 pinholes per unit area (㎡)

* Grade 4 - Less than 10 pinholes per unit area (㎡)

* Grade 5 - More than 10 pinholes per unit area (㎡)

7. Peel force

preparing a first sample by attaching an acrylate-based adhesive tape (Nitto Denko NITTO #31B tape width: 25 mm) on the release layer of the polyester release film; preparing a second sample by cutting the first sample into a size of 5 mm X 180 mm; and applying a load of 70 g/cm ² to the second sample, leaving it at room temperature for 30 minutes, and then peeling the tape 180 degrees at a peel rate of 300 mm/min using a peel tester; The peel force was measured by a method including.

8. Frictional electrification

Frictional static electricity on the polyester release film was measured using a rotary static tester (Daiei Kagaku Seiki MFG, RST-300a). At this time, the amount of static electricity generated by rubbing the A side (the release layer side of the polyester release film) and the B side (the antistatic layer side of the release film) at a rotational speed of 300 rpm for 180 seconds was measured.

9. Surface resistance

The surface resistance of the antistatic layer of the films prepared in Examples and Comparative Examples was evaluated. The measurement method is Mitsubishi Chemical Corp. Surface resistance was measured using Hiresta-Up MCP-HP450 equipment under conditions of 25 ℃, 50% RH, 10 V, and 10 seconds.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Waterborne coating composition used for side A ^* Preparation Example 1 Preparation Example 2 Preparation Example 1 Comparative Preparation Example 1 Comparative Preparation Example 1 Preparation Example 1 Comparative Preparation Example 2 A-side physical properties water contact angle
(°) 87.0 89.8 87.0 112.0 112.0 87.0 71.5 Surface energy (mN/m) 35 34 35 18 18 35 54 processing coating 1st class Grade 2 1st class 5 stars 5 stars 1st class 1st class Peel force (gf/inch) 420 380 420 16 16 420 682 warrior traits nothing nothing nothing nothing nothing have nothing Antistatic coating composition used for side B ^* Preparation Example 3 Preparation Example 3 - Preparation Example 3 - Comparative Preparation Example 3 Preparation Example 3 Side B ^* Properties warrior traits nothing nothing nothing nothing nothing nothing nothing surface resistance
(Ω/□) 10 ⁹ 10 ⁹ - 10 ⁹ - 10 ⁹ 10 ⁹ common properties Haze (%) 3.86 3.98 3.63 3.97 3.74 3.90 3.75 Total light transmittance (%) 90.36 90.38 90.12 90.48 90.02 0.27 90.77 Friction electrification voltage between A side and B side (V) 10 10 274 50 1,420 112 20 Side A: release layer formed on one side of the base film
Side B: antistatic layer formed on the other side of the base film

Referring to Table 1, the polyester release film according to the examples has excellent transfer properties, peelability, and coating processability, as well as excellent antistatic properties and a triboelectric charge voltage of less than 50 V compared to the release films of comparative examples. was found to be significantly lower.

Therefore, the polyester release film of the present invention includes a release layer comprising a water-based coating composition including a polyester resin, an acrylic resin and a polyolefin wax, and an antistatic layer comprising a water-dispersible antistatic composition comprising a conductive polymer, It not only has excellent peelability and coating processability, but also has excellent antistatic properties and a remarkably low frictional electrification voltage of less than 50 V. The amount of foreign matter can be significantly reduced.

In addition, the polyester release film of the present invention can solve problems such as yield reduction due to unreacted substances generated when the coating layer is formed using the release film and adsorption of foreign substances due to static electricity, so that when manufacturing optical films such as thin film polarizers It is suitable for use as a substrate.

Claims (17)

A polyester base film, a release layer formed on one side of the base film, and an antistatic layer formed on the other side of the base film, The release layer includes a water-based coating composition including a polyester resin, an acrylic resin, and a polyolefin wax, The antistatic layer is a polyester release film comprising a water-dispersible antistatic composition containing a conductive polymer. According to claim 1, The polyester release film has a triboelectric potential of less than 50 V, the polyester release film. According to claim 1, A weight ratio of the solid content of the polyester resin and the acrylic resin is 1:0.1 to 1:1.5, a polyester release film. According to claim 1, The release layer comprises 20 to 50 parts by weight of polyolefin wax based on 100 parts by weight of the polyester resin, a polyester release film. According to claim 1, The polyolefin wax is at least one wax selected from the group consisting of polyethylene wax and polypropylene wax, polyester release film. According to claim 1, The conductive polymer is a polyester release film comprising at least one selected from polythiophene-based, polypyrrole-based and polyaniline-based. According to claim 1, The water-dispersible antistatic composition further comprises a water-based polyurethane resin, a polyester release film. According to claim 7, The solid content of the water-dispersible antistatic composition is a polyester release film comprising 1 to 30 wt% of a conductive polymer and 70 to 99 wt% of a water-based polyurethane resin. According to claim 1, The surface resistance of the antistatic layer is 10 ¹⁰ Ω / □ or less, a polyester release film. According to claim 1, A polyester release film having a haze of 3.90% or less and a processing coatability satisfying the following formula 1: [Equation 1] N _H = 0 In Equation 1, N _H is the number of pinholes generated per unit area (m ² ) when a UV resin is applied to the release layer of the polyester release film to a thickness of 10 μm and cured. According to claim 1, The release layer is formed by in-line coating the water-based coating composition, The antistatic layer is formed by in-line coating of the water-dispersible antistatic composition, a polyester release film. According to claim 1, The base film is biaxially stretched, and the release layer and the antistatic layer are uniaxially stretched in the transverse direction (TD), a polyester release film. According to claim 1, The base film has a thickness of 10 to 300 μm, and the release layer and the antistatic layer have a thickness of 10 to 200 nm, a polyester release film. According to claim 1, The polyester release film is for protecting a polarizing plate, a polyester release film. A first step of preparing a polyester base film; A second step of forming a release layer by applying an aqueous coating composition containing a polyester resin, an acrylic resin, and a polyolefin wax to one surface of the base film; A third step of forming an antistatic layer by applying a water-dispersible antistatic composition containing a conductive polymer to the other surface of the base film; and A method for producing a polyester release film comprising a; fourth step of heat-treating while stretching the laminate including the base film and the release layer and the antistatic layer formed on the base film. According to claim 15, The fourth step is to pass the laminate through a heat treatment device having a total heat amount of 222,000 kcal / min to 229,000 kcal / min of air supplied to the passing section, and stretching and heat treatment. Method for producing a polyester release film. According to claim 15, The fourth step is a process of preheating the laminated body by passing through a section in which a heat amount of 44,000 kcal/min to 46,000 kcal/min is supplied; stretching the preheated laminate in a transverse direction (TD) while passing through a section where a heat amount of 62,000 kcal/min to 64,000 kcal/min is supplied; and a step of subjecting the stretched laminate to the heat treatment while passing it through a section where a heat amount of 114,000 kcal/min to 120,000 kcal/min is supplied; Method for producing a polyester release film, which is carried out including a.