WO2018004288A2 - Polyester multilayered film - Google Patents

Abstract

The present invention relates to a polyester multilayered film which is an optical polyester multilayered film being excellent in oligomer blocking properties, antistatic properties and transmittance.

Description

Polyester multilayer film

The present invention relates to a polyester multilayer film, and has excellent oligomer barrier property, and relates to an optical polyester multilayer film having excellent antistatic property and excellent transmittance.

In recent years, due to the rapid development of various electronic, electrical, and information communication fields, many fields, such as industrial products and household products, have applied with static electricity, and antistatic functions in these devices and on-site are becoming essential functions. . Antistatic refers to discharging the electric charge accumulated on the insulator surface by an appropriate method.

The reason for requiring such antistatic property is that static electricity is generated in the film manufacturing process or the film processing process to cause dust or foreign matter to adhere to the product, and discharge occurs to generate a risk of ignition when an organic solvent is used. Therefore, providing antistatic performance has become an essential requirement.

Films with antistatic properties are used in the manufacture of electronic materials and optical products. At this time, the conductive polymer antistatic film is mainly used without a humidity dependence, and when the conductive polymer is used to reduce the generation of static electricity, the light transmittance is lowered, and thus there is a limitation in using it as an electronic material and an optical film. In addition, such an antistatic film may have a problem that the oligomer is migrated to the surface of the film when the high temperature process is performed in a later process, thereby deteriorating optical properties and charging performance.

The present invention is to provide a polyester multilayer film that can be used as an optical film with excellent antistatic properties and at the same time excellent light transmittance.

In addition, the present invention provides a polyester multilayer film having a low change in surface resistance and excellent antistatic property even after a high temperature and high humidity process.

As a result of the study to achieve the above object, when forming an antistatic layer using a conductive polymer resin to give an antistatic property on one surface, and a primer coating layer having a refractive index of 1.4 ~ 1.5 on the other surface, The present invention was completed by finding that the transmittance is improved and the optical properties are greatly improved.

Specifically, the present invention is formed on the polyester base film, one surface of the polyester base film and formed on the other surface of the antistatic layer and the polyester base film comprising a conductive polymer and an aqueous polyurethane binder, the refractive index is 1.4 ~ 1.5 A primer layer,

The polyester base film includes a base layer and a skin layer in which at least one layer is laminated on both sides of the base layer, wherein the oligomer content of the polyester resin constituting the skin layer is 0.3 to 0.6 wt%, and diethylene The content of the glycol is 0.1 to 1.2% by weight, and the inherent viscosity relates to a polyester multilayer film satisfying the following formula 1.

[Equation 1]

1 <Ns / Nc ≤ 1.1

In Formula 1, Ns is the intrinsic viscosity of the polyester resin constituting the skin layer, Nc is the intrinsic viscosity of the polyester resin constituting the base layer.

The present invention can provide a polyester film having low oligomer migration, low surface resistance change, excellent silicon adhesion and printability, and excellent transmittance under high temperature and high humidity conditions.

The polyester film of the present invention has antistatic properties and at the same time excellent in transmittance, it can be used as an optical member for various displays.

DETAILED DESCRIPTION Hereinafter, the present invention will be described in more detail with reference to the accompanying examples or embodiments. However, the following specific examples or examples are only one reference for describing the present invention in detail, but the present invention is not limited thereto and may be implemented in various forms.

Also, unless defined otherwise, all technical and scientific terms have the same meanings as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used in the description in the present invention are only for effectively describing specific embodiments and are not intended to limit the present invention.

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

In the present invention, 'oligomer' is a by-product generated during the polycondensation reaction of terephthalic acid or its derivatives and ethylene glycol during polyester polymerization, and has a weight average molecular weight of about 500 to 10,000 g / mol dimer, tri It means a trimer, a tetramer, etc.

One embodiment of the present invention is formed on the polyester base film, and one surface of the polyester base film, an antistatic layer comprising a conductive polymer and an aqueous polyurethane binder and formed on the other surface of the polyester base film, the refractive index is 1.4 ~ 1.5 Phosphorus primer layer,

The polyester base film includes a base layer and a skin layer in which at least one layer is laminated on both sides of the base layer, wherein the oligomer content of the polyester resin constituting the skin layer is 0.3 to 0.6 wt%, and diethylene The content of the glycol is 0.1 to 1.2% by weight, and the inherent viscosity relates to a polyester multilayer film satisfying the following formula 1.

[Equation 1]

1 <Ns / Nc ≤ 1.1

In Formula 1, Ns is the intrinsic viscosity of the polyester resin constituting the skin layer, Nc is the intrinsic viscosity of the polyester resin constituting the base layer.

In one embodiment of the present invention, the polyester multilayer film has a surface resistance of 10 ⁵ to 10 ⁹ Ω / sq, less than 2% haze, total light transmittance of 90% or more before heat treatment,

After 72 hours at 85 ° C. and 85%, the haze change rate ΔH ₁ satisfies the following formula 2, the light transmittance change rate ΔTT ₁ satisfies the following formula 3, and the antistatic layer and the primer layer were the polyester base in the evaluation of the adhesive force. Kept on film,

[Equation 2]

ΔH ₁ <0.5%

ΔH ₁ = H _f −H _i in Equation 2, H _f is the haze of the film after holding at 85 ° C., 85% for 72 hours, and H _i is the haze of the film before heating.

[Equation 3]

TT ₁ <0.5%

ΔTT ₁ = TT _f − TT _i in Formula 3, and TT _f is It is the total light transmittance of a film after hold | maintaining at 85 degreeC and 85% for 72 hours, and TT _i is the total light transmittance of a film before heating.

After 120 hours of maintenance at 60 ° C. and 95%, the surface resistance was 10 ⁵ to 10 ⁹ μs / sq, and the haze change rate ΔH ₂ satisfied the following Equation 4, and the light transmittance change rate TT ₂ satisfied the following Equation 5. In the evaluation of adhesion, the antistatic layer and the primer layer may be maintained on the polyester base film.

[Equation 4]

ΔH ₂ <1.0%

In Formula 4, ΔH ₂ = H _f −H _i , H _f is the haze of the film after holding at 60 ° C., 95% for 120 hours, and H _i is the haze of the film before heating.

[Equation 5]

TT ₂ <1.0%

ΔTT ₁ = TT _f − TT _i in Formula 5, and TT _f is It is the total light transmittance of a film after hold | maintaining at 60 degreeC and 95% for 120 hours, and TT _i is the total light transmittance of a film before heating.

In one embodiment of the present invention, the polyester multilayer film is less than 30 oligomers of the antistatic layer after holding at 85 ℃, 85% 72 hours or 60 ℃, 95% 120 hours, at 85 ℃, 85% 72 After maintaining for 120 hours at 60 ° C. for 95 hours, the number of oligomers in the primer layer may be less than 20.

In one embodiment of the present invention, the antistatic layer has a water contact angle of 90 degrees or more, the silicone adhesive is applied on the antistatic layer, and the silicone coating layer is maintained when the adhesion evaluation according to ASTM B905 after 2 hours in water at 100 ℃ It may be.

In one aspect of the invention, the antistatic layer may be formed by applying an antistatic composition comprising a conductive polymer solution, an aqueous polyurethane binder solution, an organic solvent and water.

In one embodiment of the present invention, the organic solvent may be any one or two or more mixed solvents selected from alcohol organic solvents, aprotic high polar organic solvents and amide organic solvents.

In one embodiment of the present invention, the antistatic layer may include 1 to 30% by weight of the conductive polymer and 70 to 99% by weight of the aqueous polyurethane binder in 100% by weight of the solid content.

In one aspect of the invention, the conductive polymer may be a polystyrene sulfonate doped with polyethylene dioxythiophene.

In one aspect of the invention, the primer layer may be one containing any one or two or more selected from acrylic resin, polyester resin and urethane resin.

In one embodiment of the present invention, the primer layer may include a binder resin having a weight ratio of 20 to 80:80 to 20 of the acrylic resin copolymerized with the glycidyl group-containing radically polymerizable unsaturated monomer and the water-dispersible polyester resin. have.

In one embodiment of the present invention, the water-dispersible polyester-based resin is a copolymer of a dicarboxylic acid component containing a sulfonic acid alkali metal salt compound and a glycol component containing diethylene glycol,

The acrylic resin may be a copolymer monomer containing 20 to 80 mol% of the glycidyl group-containing radical polymerizable unsaturated monomer in all monomer components.

In one embodiment of the present invention, the polyester base film has a thickness of 12 to 250 ㎛, the base layer is 60 to 90% by weight, the skin layer may be 10 to 40% by weight.

In an aspect of the present invention, the antistatic layer may have a dry coating thickness of 10 to 500 nm, and the primer layer may have a dry coating thickness of 20 to 300 nm.

Still another aspect of the present invention is an optical film having at least one functional coating layer selected from a hard coating layer, a printing layer, an adhesive layer, and a release agent layer on the polyester multilayer film.

Hereinafter, the configuration of the present invention will be described in more detail.

The inventors of the present invention have studied to solve the problem that the total light transmittance of the film is lowered when the conductive polymer is used to improve the antistatic property, a primer layer having a refractive index of 1.4 to 1.5 on the other surface where the antistatic layer is formed. The present invention was completed by finding that physical properties of the total light transmittance of the entire film can be achieved by forming more than 90%.

In addition, a base film and a skin layer are co-extruded and laminated using three or more layers of films, and the oligomer content is 0.3 to 0.6% by weight, and the content of diethylene glycol is 0.1 to 1.2% by weight. By using a polyester resin of %% and using a polyester resin having an intrinsic viscosity satisfying the following formula 1, the surface resistance, haze change rate and light transmittance change rate are low under high temperature and high humidity, and the polyester base film, antistatic layer and primer The present invention was completed by finding a small change in adhesion between layers.

[Equation 1]

1 <Ns / Nc ≤ 1.1

In Formula 1, Ns is the intrinsic viscosity of the polyester resin constituting the skin layer, Nc is the intrinsic viscosity of the polyester resin constituting the base layer.

That is, the present invention has a feature that can achieve all the desired effects by the combination of the antistatic layer, the polyester base film and the primer layer.

More specifically, the polyester base film of the present invention will be described.

In the present invention, the polyester base film may be formed of three or more layers, including a skin layer in which at least one or more layers are laminated on both sides of the base layer and the base layer, and may be formed by coextrusion.

The polyester base film preferably has a thickness of 12 to 250 μm, more preferably 50 to 188 μm, but is not limited thereto.

In addition, the content of the base layer is 60 to 90% by weight of the entire film, the content of the skin layer is preferably 10 to 40% by weight, more preferably the content of the base layer is 70 to 80% by weight, the skin layer The content of 20 to 30% by weight is effective because of excellent interfacial stability during coextrusion and excellent barrier property of the oligomer.

The base layer may be made of a polyester resin, more specifically, polyethylene terephthalate (PET) resin, but is not limited thereto. In this case, the polyethylene terephthalate resin used is preferably used having an intrinsic viscosity of 0.5 to 1.0, more preferably 0.60 to 0.80. When the intrinsic viscosity of the polyethylene terephthalate resin is less than 0.5, the heat resistance may be reduced. If the intrinsic viscosity of the polyethylene terephthalate resin is greater than 1.0, it may not be easy to process the raw material, thereby reducing workability.

Skin layer formed by co-extrusion of at least one layer or more on each of both sides of the polyester base layer has an oligomer content of 0.3 to 0.6% by weight, more preferably 0.4 to 0.5% by weight based on the total film weight, diethylene glycol ( The content of DEG) is preferably 0.1 to 1.2% by weight, more preferably 0.7 to 0.8% by weight. When the content of oligomer and diethylene glycol of the polyester resin exceeds the above range, the haze value of the initial film is increased, and the rate of change of haze is sharply increased during heat treatment, thereby achieving optical properties applicable to the optical film. Missing problems can occur.

In addition, the polyester resin of the skin layer may be prepared by a synthetic method known in the art in order to have a content of the oligomer and diethylene glycol in the above range, in particular, that is prepared by the solid-phase polymerization of the oligomer and diethylene glycol Effective in reducing the content.

The intrinsic viscosity of the polyester resin of the skin layer is preferably 0.6 to 1.0, more preferably 0.65 to 0.85. When the intrinsic viscosity of the skin layer polyethylene terephthalate resin is less than 0.6, the heat resistance may be reduced, and if it is more than 1.0, it may not be easy to process the raw material, thereby reducing workability.

In addition, the base layer and the skin layer may include an inorganic particle, such as an additive added during the manufacture of a conventional film.

The polyester base film may be a substrate layer and the skin layer is co-extruded and laminated, it is preferable to satisfy the following formula 1 to improve the workability when co-extruded the base layer and the skin layer.

[Equation 1]

1 <Ns / Nc ≤ 1.1

In Formula 1, Ns is the intrinsic viscosity of the polyester resin constituting the skin layer, Nc is the intrinsic viscosity of the polyester resin constituting the base layer.

When the intrinsic viscosity ratio of the skin layer and the base layer is more than 1.1, the problem of interfacial instability may occur due to coextrusion, so that the multilayer structure may not be formed, and it is preferable to satisfy the above range, more preferably 1.0 to 1.05. It is effective to improve workability.

The present invention includes an antistatic layer on one surface of the polyester base film.

In one aspect of the invention, the antistatic layer is characterized in that it comprises a conductive polymer and an aqueous polyurethane binder, the water contact angle is 90 degrees or more by including them, the silicone pressure-sensitive adhesive on the antistatic layer, water at 100 ℃ After leaving for 2 hours at the evaluation of adhesion may be to maintain the silicone coating layer.

In one embodiment of the present invention, the antistatic layer comprises a conductive polymer and an aqueous polyurethane binder, the conductive polymer of 1 to 30% by weight, the aqueous polyurethane binder of 70 to 99% by weight of the solid content of 100% by weight It may be. More specifically, the conductive polymer may be 5 to 25% by weight, polyurethane binder may be included in 75 to 95% by weight. More specifically, the conductive polymer may be 10 to 20% by weight, polyurethane binder may be included in 80 to 90% by weight.

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

More specifically, for example, the antistatic composition may include 40 to 90 wt% of a conductive polymer solution having a solid content of 1 to 3 wt%, 5 to 50 wt% of an aqueous polyurethane binder solution having a solid content of 30 to 40 wt%, It may include 3 to 50% by weight of the organic solvent and the balance of water.

In addition, the antistatic composition may be any one or two or more additives selected from silicone wetting agents, fluorine wetting agents, slip agents, antifoaming agents, wetting agents, surfactants, thickeners, plasticizers, antioxidants, ultraviolet absorbers, preservatives, crosslinking agents, and the like. It may be to include more.

In one embodiment of the present invention, the conductive polymer may be a polythiophene-based, polypyrrole-based, polyaniline-based polymer resin and the like, but is not limited thereto. It is better to use a polythiophene-based conductive polymer resin, and most preferably, a polystyrene sulfonate doped (PEDOT: PSS) in polyethylene dioxythiophene has excellent water dispersibility, thereby forming an antistatic layer by an inline coating process. Although it is possible to pass through the stretching process after the in-line coating process, the transparency is not lowered, and preferred from the viewpoint of expressing heat resistance and the desired surface resistance, but is not limited thereto. The conductive polymer is preferably used in a range satisfying the physical properties of the surface resistance of 10 ⁵ ~ 10 ⁹ Ω / sq, but is not limited thereto.

The conductive polymer resin may be used as a conductive polymer solution mixed with a solvent in order to express optimal dispersibility. Specifically, for example, when PEDOT: PSS is used, a solvent having a high water, alcohol, and dielectric constant It may be used to mix and the like. Commercialized examples may include, but are not limited to, Clevios P (1.2 to 1.4 wt.% Solids content) from Heraeus.

The content of the conductive polymer solution in the antistatic composition may be 40 to 90% by weight, and more preferably 50 to 70% by weight, but is not limited thereto in a sufficient amount to achieve the desired physical properties in the above range.

In one aspect of the present invention, by using the water-based polyurethane binder mixed with the conductive polymer, excellent miscibility, surface resistance performance, excellent adhesion to the polyester base film, physical properties change at high temperature and high humidity conditions It is possible to form an antistatic layer with less yellowing and less yellowing.

The water-based polyurethane binder can achieve physical properties with excellent heat resistance and low surface resistance change rate 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 improving heat resistance to form a coating film with less yellowing, but is not limited thereto.

In addition, the aqueous polyurethane binder may be dispersed in a solvent, and the solvent is not limited, but any one or two or more selected from the group consisting of an amide organic solvent and an aprotic highly dipolar (AHD) organic solvent. It may be to use a solvent, but is not limited thereto. Commercialized examples include Neo Rez R-860, R-960, R-972, etc. of Neo Resins, but are not limited thereto.

The content of the water-based polyurethane binder in the antistatic composition may be 5 to 50% by weight, and more preferably 10 to 30% by weight, but is not limited thereto in a sufficient amount to achieve the desired physical properties in the above range. .

In one aspect of the invention, the organic solvent used in the antistatic composition is any one or two or more mixed solvents selected from alcohol-based organic solvents, Aprotic Highly Dipolar (AHD) organic solvents and amide-based organic solvents It may be

The content of the organic solvent may be 3 to 50% by weight, more specifically 5 to 40% by weight, more specifically 10 to 30% by weight of the antistatic composition, the content of the conductive polymer and the polyurethane binder in the above range A content suitable for enhancing acidity is not limited thereto.

More preferably, by using one or two or more mixed solvents selected from an aprotic high polar organic solvent and an amide organic solvent together with an alcoholic organic solvent, the dispersibility of the conductive polymer is improved, and doping is activated to provide surface resistance. The effect which further improves the performance can be expressed.

More specifically 1 to 30% by weight alcoholic organic solvent, more specifically 5 to 20% by weight of any one or two or more mixed solvents selected from aprotic high polar organic solvent and amide organic solvent, more Specifically, it may be to use 5 to 10% by weight.

The alcohol-based organic solvent is not limited, but specifically, for example, methanol, ethanol, propanol, isopropanol, butanol, 2-amino-2-methyl-1-propanol, and the like may be used. Can be used. By using an alcohol-based organic solvent, the mixing and dispersibility between the conductive polymer and the water-based polyurethane resin can be further improved.

The aprotic high polar organic solvent is not limited, but specifically, for example, dimethyl sulfoxide, propylene carbonate, or the like may be used, and may be used alone or in combination of two or more. By using an aprotic high polar organic solvent, the conductivity of the conductive polymer can be further improved. When using an aprotic high polar organic solvent alone, it may further include a dispersion stabilizer such as ethylene glycol, glycerin and sorbitol, but is not limited thereto.

The amide organic solvent is not limited, but specifically, for example, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N-dimethylacetamide, N- Methylpyrrolidone and 2-amino-2-methyl-1-propanol and the like can be used, and can be used alone or in combination of two or more. By using an amide organic solvent, the conductivity of the conductive polymer can be further improved.

In one aspect of the present invention, the antistatic composition may further include a wetting agent to further improve coating properties. Specific examples include, but are not limited to, for example, Dow Corning's Q2-5212, ENBODIC's TEGO WET 250, BYK CHEMIE's BYK 348, and modified silicone-based wetting agents such as ZONyl's FSH and the like. It is not limited. Wetting agent is preferably used in 0.1 to 2% by weight, it is possible to achieve the desired coating properties in the above range, but is not limited thereto.

In one aspect of the invention, the antistatic layer may be a dry coating thickness of 10 ~ 500nm. If the dry coating thickness is less than 10nm, the surface resistance may not be sufficient, and if the dry coating thickness is greater than 500nm, the blocking range is more likely to occur, but the above range is recommended, but is not limited thereto.

The present invention includes a primer layer on the other surface of the antistatic layer is formed.

In one embodiment of the present invention, the primer layer preferably has a refractive index of 1.4 ~ 1.5, even if the antistatic layer is formed by using a conductive polymer by satisfying the above range, the total light transmittance is 90% or more transparent to the optical film Suitable for use When only the antistatic layer is formed without forming the primer layer, the total light transmittance is low, which is not suitable for use as an optical film. More specifically, in the present invention, the antistatic layer and the primer layer are formed at the same time, so that the total light transmittance is 90% or more, more specifically, 90 to 95%, and the physical properties with little change in haze can be satisfied at the same time. In addition, it is possible to provide a film with little change in total light transmittance and haze even under high temperature and high humidity conditions.

In one aspect of the present invention, the primer layer may be formed by applying a water-dispersible resin composition, it may be made of acrylic resin, polyester resin and urethane resin.

In one embodiment of the present invention, the primer layer may be formed by applying a water-dispersible resin composition having an oligomer blocking property, and specifically, for example, a glycidyl group-containing radical polymerization of the water-dispersible resin composition having the oligomer blocking property. The unsaturated unsaturated monomer may be copolymerized acrylic resin and water-dispersible polyester resin.

In one embodiment of the present invention, the water-dispersible resin composition has a solid content weight ratio of acrylic resin (A) copolymerized with a glycidyl group-containing radically polymerizable unsaturated monomer (A) and a water-dispersible polyester resin (B) (A) :( B) = 20 to 80: may be 80 to 20. More preferably, it may be used in a weight ratio of 40 to 60: 60 to 40. If the solids content of the water-dispersible polyester resin (B) is less than 20% by weight and the solids content of the acrylic resin (A) copolymerized with the glycidyl group-containing radically polymerizable unsaturated monomer is greater than 80% by weight, As the particle size increases, staining occurs during inline coating, adhesion and transparency with the polyester base film decrease, and the solid content of the water-dispersible polyester resin (B) is greater than 80 wt%, and glycy When the solid content of the acrylic resin (A) copolymerized with a dill-containing radically polymerizable unsaturated monomer is less than 20% by weight, sufficient oligomer blocking effect cannot be exhibited, and light transmittance is improved and haze, surface resistance, etc. under high temperature and high humidity conditions. It may not be enough to minimize the change.

The water-dispersible resin composition of the present invention may be prepared by mixing a water-dispersible polyester resin (B) and a binder resin mixed with an acrylic resin (A) copolymerized with a glycidyl group-containing radically polymerizable unsaturated monomer, It is also possible to polymerize and produce a glycidyl group-containing radically polymerizable unsaturated monomer alone or a radically polymerizable unsaturated monomer copolymerizable with a glycidyl group-containing radically polymerizable unsaturated monomer in an aqueous dispersion of the water-dispersible polyester resin (B). At this time, surfactant and a polymerization initiator can be used. The surfactant and the polymerization initiator may be used without limitation as long as it is conventionally used in emulsion polymerization. Specifically, for example, as the surfactant, anionic surfactants, nonionic surfactants or non-reactive surfactants can be used, and these can also be used in combination. The polymerization initiator is a radically polymerizable initiator, and nitrogen compounds such as a peroxide initiator or azobis isobutyronitrile can be used.

The water dispersion composition of the present invention may further include an antifoaming agent, a wetting agent, a surfactant, a thickener, a plasticizer, an antioxidant, a UV absorber, a preservative, a crosslinking agent and the like as necessary.

In one embodiment of the present invention, the crosslinking agent may include a compound of Formula 1, but is not limited thereto. By including a crosslinking agent of Formula 1, the reaction rate is faster, a primer layer may be formed at a low temperature, and may completely block an oligomer which may be partially leaked by heating after forming the primer layer.

[Formula 1]

Wherein A ₁ to A ₃ are each independently a chemical bond or are selected from (C1-C10) alkylene, and R ₁ to R ₃ are each independently selected from hydrogen and (C1-C10) alkyl. )

The alkyl or alkylene includes both straight and branched chains.

More specifically, A ₁ to A ₃ are each independently selected from (C ₁ -C 5) alkylene, and R ₁ to R ₃ are each independently selected from (C ₁ -C 5) alkyl.

As a more specific example of Formula 1, a compound of Formula 2 may be used.

[Formula 2]

The compound of Formula 2, while the reaction rate is fast, the reaction temperature is 120 ~ 140 ℃, more specifically 130 ℃ in the preheating zone (Preheating Zone) during the film forming process of the polyester film, accordingly glycidyl group It is possible to react with the glycidyl group of the acrylic resin (A) in which the containing radically polymerizable unsaturated monomer is copolymerized, thereby forming a primer coating film having a more dense structure.

Therefore, in the case of using the compound of Formula 2, it is possible to apply in the in-line coating process during the film forming process of the polyester film, and thus, the process is simplified since the process of applying the primer layer separately after film production is not necessary. Since it can be stretched after coating by the coating process to form a uniform coating film thickness, it is possible to produce a polyester film having excellent optical properties.

The crosslinking agent is 1 to 40 parts by weight based on 100 parts by weight of the total solid content of the acrylic resin (A) in which the aqueous dispersion of the water-dispersible polyester resin (B) and the glycidyl group-containing radically polymerizable unsaturated monomer in the water dispersion composition are copolymerized. It is preferable to use a weight part, More preferably, it is 5-20 weight part. If it is less than 1 part by weight, its use effect is insignificant, and when it is used in excess of 40 parts by weight, the properties of the main binder may be lowered, thereby lowering the adhesive strength.

In the water dispersion composition of the present invention, the water-dispersible polyester-based resin (B) may be a copolymer of a dicarboxylic acid component containing a sulfonic acid alkali metal salt compound and a glycol component containing diethylene glycol.

More specifically, as the dicarboxylic acid component, an aromatic dicarboxylic acid and a sulfonic acid alkali metal salt compound may be used, and the sulfonic acid alkali metal salt compound may contain 6 to 20 mol% of the total acid component.

The dicarboxylic acid component is an aromatic dicarboxylic acid such as phthalic acid, terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalic acid, 2,5-dimethyl terephthalic acid, 2,6-naphthalene dicarboxylic acid, biphenyldicarboxylic acid and the like. Aliphatic dicarboxylic acids, such as an acid, adipic acid, a sebacic acid, alicyclic dicarboxylic acids, such as cyclohexane dicarboxylic acid, etc. can be used.

Specific examples of the sulfonic acid alkali metal salt compound include alkali metal salts such as sulfoterephthalic acid, 5-sulfo isophthalic acid, 4-sulfo isophthalic acid, 4-sulfo naphthalic acid-2,7-dicarboxylic acid, and the like. , 6 to 20 mol% may be used. When using less than 6 mol%, the dispersion time of resin to water becomes long, dispersibility is low, and when it uses more than 20 mol%, water resistance may fall.

As the glycol component, diethylene glycol and aliphatic glycols having 2 to 8 carbon atoms or alicyclic glycols having 6 to 12 carbon atoms may be used. Specifically, for example, ethylene glycol, 1,3-propanediol, 1,2-propylene glycol, neopentyl glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol , 1,2-cyclohexanedimethanol, 1,6-hexanediol, P-xylene glycol, triethylene glycol and the like can be used. At this time, it is preferable to contain 20-80 mol% of diethylene glycol among all the glycol components.

It is preferable that the number average molecular weights of the said water-dispersible polyester resin (B) are 1000-50000, More preferably, the number average molecular weights are 2000-30000. When the number average molecular weight is less than 1000, the oligomer blocking effect is insignificant, and when the number average molecular weight is more than 50000, water dispersibility may be difficult.

The water-dispersible polyester-based resin (B) is used by uniformly dispersing by heating and stirring the water or water containing an aqueous solvent at 50 ~ 90 ℃. The aqueous dispersion thus prepared has a solid content of 30 wt% or less, more preferably 10 to 30 wt%, for uniform dispersion. The aqueous solvent may be alcohols such as methanol, ethanol, propanol, polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, glycerin, and the like.

Next, the acrylic resin (A) to which the glycidyl group containing radically polymerizable unsaturated monomer was copolymerized is demonstrated.

Acrylic resin (A) copolymerized with a glycidyl group-containing radically polymerizable unsaturated monomer is a homopolymer of a glycidyl group-containing radically polymerizable unsaturated monomer or another radically polymerizable unsaturated monomer copolymerizable with a glycidyl group-containing radically polymerizable unsaturated monomer. It is resin copolymerized.

The acrylic resin may be a copolymer monomer containing 20 to 80 mol% of the glycidyl group-containing radical polymerizable unsaturated monomer in all monomer components. Since the glycidyl group-containing radically polymerizable unsaturated monomer improves the strength of the coating film of the primer layer by the crosslinking reaction and increases the crosslinking density, it is possible to block the outflow of the oligomer. Specifically, for example, glycidyl ethers such as glycidyl acrylate, glycidyl methacrylate, and arylglycidyl ether can be used.

Radical polymerizable unsaturated monomers copolymerizable with glycidyl group-containing radical polymerizable unsaturated monomers include vinyl esters, unsaturated carboxylic acid esters, unsaturated carboxylic acid amides, unsaturated nitriles, unsaturated carboxylic acids, allyl compounds, nitrogen-containing vinyl monomers and hydrocarbon vinyl monomers. Or a vinyl silane compound. Vinyl propionate, vinyl stearate, vinyl chloride, etc. can be used as vinyl ester. Unsaturated carboxylic acid esters 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, methacrylate hydroxypropyl, hydroxypropyl acrylate and the like can be used. As the unsaturated carboxylic acid amide, acrylamide, methacrylamide, metyrolacrylamide, butoxy methirol acrylamide, and the like can be used. Acrylonitrile etc. can be used as unsaturated nitrile. As the unsaturated carboxylic acid, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, maleic acid acid ester, fumaric acid acid ester, itaconic acid acid ester and the like can be used. As the allyl compound, allyl acetate, allyl methacrylate, allyl acrylate, allyl itaconic acid, diallyl itaconic acid and the like can be used. Vinylpyridine, vinyl imidazole, etc. can be used as a nitrogen-containing vinyl monomer. As the hydrocarbon vinyl monomer, ethylene, propylene, hexene, octene, styrene, vinyltoluene, butadiene and the like can be used. As a vinyl silane compound, dimethyl vinyl methoxy silane, dimethyl vinyl ethoxy silane, methyl vinyl dimethoxy silane, methyl vinyl diethoxy silane, gamma-methacryloxy propyl trimethoxysilane, gamma-methacryloxy propyl dimethoxy silane, etc. Can be used.

The water-dispersible resin composition according to one embodiment of the present invention has a solid content of 0.5 to 10 weight of the acrylic resin (A) and the water-dispersible polyester resin (B) copolymerized with a glycidyl group-containing radical polymerizable unsaturated monomer as a binder resin. It is preferable that it is a water dispersible or water-soluble composition which is%. More specifically, the solid content of the acrylic resin (A) and the water-dispersible polyester resin (B) copolymerized with the glycidyl group-containing radically polymerizable unsaturated monomer is 0.5 to 10% by weight, and the remainder includes water. It may further include additives such as a wetting agent, a dispersing agent. The wetting agent is used to improve the coating property. Specifically, for example, a modified silicone wetting agent such as Dow Corning's Q2-5212, ENBODIC's TEGO WET 250, BYK CHEMIE's BYK 348, etc. may be used. It doesn't happen. Wetting agent is preferably used in 0.1 to 0.5% by weight, it is possible to achieve the desired coating properties in the above range, but is not limited thereto.

In the present invention, the primer layer may be a dry coating thickness of 20 ~ 300nm. When the dry coating thickness is less than 20 nm, the oligomer blocking property may not be sufficiently exhibited. When the dry coating thickness is greater than 300 nm, a blocking phenomenon may occur after winding the film.

The production of the polyester multilayer film including the base layer and the skin layer of the present invention is not limited, but may be obtained by extrusion fusion and casting by biaxial stretching in at least two melt extruders. In more detail, one extruder is used to extrude polyester, and another extruder is melt extruded simultaneously with additives such as polyester, inorganic particles such as silica, kaolin, and zeolite, and each melt is coextruded in the feed block. After casting, casting, cooling and then biaxial stretching in sequence.

In the present invention, the antistatic composition and the water dispersible primer composition may be applied by an in-line coating method of the polyester film manufacturing process. In other words, the polyester base film may be prepared by applying an in-line coating method before stretching or before the second stretching after the primary stretching, or by stretching. Water is evaporated by heating during the secondary stretching and heat setting. Layers can be formed. The coating method is not limited as long as it is a known coating method.

The polyester multilayer film of the present invention has a surface resistance of 10 ⁵ to 10 ⁹ Ω / sq, a haze of 2% or less, a total light transmittance of 90% or more before the heat treatment,

After 72 hours at 85 ° C. and 85%, the haze change rate ΔH ₁ satisfies the following formula 2, the light transmittance change rate ΔTT ₁ satisfies the following formula 3, and the antistatic layer and the primer layer were the polyester base in the evaluation of the adhesion. It can be seen that the optical properties in the high temperature and high humidity conditions are satisfied by satisfying the physical properties maintained in the film.

[Equation 2]

ΔH ₁ <0.5%

ΔH ₁ = H _f −H _i in Equation 2, H _f is the haze of the film after holding at 85 ° C., 85% for 72 hours, and H _i is the haze of the film before heating.

[Equation 3]

TT ₁ <0.5%

ΔTT ₁ = TT _f − TT _i in Formula 3, and TT _f is It is the total light transmittance of a film after hold | maintaining at 85 degreeC and 85% for 72 hours, and TT _i is the total light transmittance of a film before heating.

In addition, 60 ℃, then at 95% maintained 120 hours, and a surface resistance of ^{10 5 ~ 10 9 Ω / sq} , a haze rate of change △ satisfies the H ₂ is the following formula 4 and, △ light transmittance change rate TT ₂ to have the formula 5 It can be seen that the antistatic layer and the primer layer satisfy all of the physical properties maintained in the polyester base film when the adhesive force is evaluated.

[Equation 4]

ΔH ₂ <1.0%

In Formula 4, ΔH ₂ = H _f −H _i , H _f is the haze of the film after holding at 60 ° C., 95% for 120 hours, and H _i is the haze of the film before heating.

[Equation 5]

TT ₂ <1.0%

ΔTT ₁ = TT _f − TT _i in Formula 5, and TT _f is It is the total light transmittance of a film after hold | maintaining at 60 degreeC and 95% for 120 hours, and TT _i is the total light transmittance of a film before heating.

Hard coating layer, pressure-sensitive adhesive layer, light diffusing layer, ITO layer, printing layer, etc. may be formed on the polyester film of the present invention, and even after heating the functional coating layer, the outflow of the oligomer is blocked to provide optical properties. Since it can be maintained, the polyester film of this invention is suitable for use as an optical film.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the following Examples and Comparative Examples are only examples for explaining the present invention in more detail, the present invention is not limited by the following Examples and Comparative Examples.

1) intrinsic viscosity (I.V .; dl / g)

Into 100 ml of a mixture of phenol and 1,1,2,2-tetrachloroethanol at a weight ratio of 6: 4, 0.4 g of PET pellet (sample) was dissolved for 90 minutes, and then transferred to a Uberode viscometer and placed in a 30 ° C thermostat. The solution was held for 10 minutes, and the number of seconds of the drop of the solution was determined using a viscometer and an aspirator. The number of falling seconds of the solvent was also determined in the same manner, and then R.V and I.V values were calculated by the following equations (1) and (2).

In the following equation, C represents the concentration of the sample.

[Equation 1]

R.V = number of drops of sample / number of drops of solvent

[Equation 2]

2) oligomer content (%)

Oligomer By quantitative method, chloroform is added to 1,1,1,3,3,3-hexafluoro-2-propanol, a sample solvent, dissolved at room temperature, and then acetonitrile is precipitated as a polymer. After that, a calibration curve of the cyclic trimer CT-3, which is a standard material, is prepared by using an LC analyzer, and cyclic oligomer purity is determined through sample analysis. As analytical equipment, LC (liquid chromatography) and Agilent's 1100 series were used.

3) DEG (Diethylene glycol) content (%)

Diethylene Glycol (DEG) content is 1 g of a sample in a 50 mL container, 3 mL of monoethanolamine is added and heated using a hot plate to completely dissolve the sample, then cooled to 100 ℃ 1 A solution of 0.005 g of 6-hexanediol dissolved in 20 mL of methanol was added, followed by neutralization by addition of 10 g of terephthalic acid. The obtained neutralized liquid was filtered using a funnel and filter paper, and the filtrate was subjected to gas chromatography (Gas Chromatography) to measure the DEG content (% by weight). GC analysis was measured using a Shimadzu GC analyzer and in accordance with the Shimazu GC manual.

4) Haze and total light transmittance

Specimens of the film formed were measured using a HAZE METER (model name: Nipon denshoku, Model NDH 5000).

5) Haze change rate (△ H) and light transmittance change rate (△ TT)

The film was placed in a box having a height of 3 cm, a width of 21 cm, and a height of 27 cm with an open top, and then heat-treated at 85 ° C., 85%, 72 Hr and 60 ° C., 95%, 120 Hr, and left for 5 minutes. Then, haze change rate (ΔH) and light transmittance change rate (ΔTT) were measured using a HAZE METER (Nipon denshoku, Model NDH 5000) according to JIS K 715.

The haze change rate was calculated according to the following formula 1, and the light transmittance change rate was calculated according to the following formula 2.

[Calculation 1]

ΔH = H _f -H _i

In the above formula, H _f is the haze of the film after holding at 85 ° C., 85% for 72 hours or 60 ° C., 95% for 120 hours, and Hi is the haze of the film before heating.

[Calculation 2]

△ TT = TT _f -TT _i

In the above formula, TT _f is the total light transmittance of the film after holding at 85 ° C., 85% for 72 hours or 60 ° C., 95% for 120 hours, and TT _i is the total light transmittance of the film before heating.

6) surface resistance

The surface resistance of the antistatic layer of the present invention was evaluated. As a measurement method, surface resistance was measured at 25 ° C., 50% Rh, 10 V, and 10 seconds using a Simco ST-4 device.

In addition, after maintaining the sample at 85 ° C., 85% at 72 hours or 60 ° C., 95% at 120 hours, the surface resistance change was also measured.

7) Coating thickness measurement

Coating thickness was measured using a TEM instrument.

8) Water contact angle

Drop shape analyzer DSA100 (KRUSS Co., Ltd.) was used as the contact angle measuring instrument, and 4 μl of water was dropped on the basis of the Tangent Method. If the contact angle is more than 90 °, it indicates the use criteria.

9) Silicone Adhesion Measurement

Adhesion was measured according to ASTM B905.

After the film was prepared, Momentive PSA6574 was coated on the surface coated with the antistatic coating composition with a silicone adhesive and dried at 150 ° C. for 4 minutes to form a silicon coating layer having a thickness of 30 μm. The adhesive coated film was placed in boiling water for 2 hours, and then checked for dropping during rubbing to evaluate the adhesion between the antistatic coating layer and the silicone adhesive layer.

○: The silicone adhesive layer is kept as it is

X: The silicone adhesive layer is partially dropped or completely dropped

10) Evaluation of the degree of oligomer migration of the primer layer and the antistatic layer

The polyester film was cut to a size of 100 mm × 100 mm and then aged in a constant temperature and humidity chamber at 85 ° C., 85% for 72 hours or 60 ° C., 95% for 120 hours. Then, using a reflection mode of the microscope (Leica, DM 2500M) can be observed 27000㎛ ² when observed at 500 times magnification, the surface area observed 10 times, the number of oligomer particles observed surface 10 times Averaged. The average size of the oligomer particles is 15 ± 5 μm and observed as black dots when observed.

Number of oligomers per unit area (10000 μm ² ) = (number of oligomer particles per observation / 2.7)

11) Adhesion between base film, primer layer and antistatic layer

After placing a metal plate having a width of 25 mm × 25 mm and a weight of 915 g on the microfiber cloth and rubbing ten times, the adhesive layer was evaluated by checking whether the coating layer was dropped.

○: The coating layer is maintained as it is

X: part or all of the coating layer is peeled off

12) refractive index

According to ASTM D1218, the refractive index was measured using an ABBE refractometer (DRGO, ATAGO Co., Ltd.).

Preparation Example 1 Preparation of Water Dispersible Antistatic Composition (1)

As a conductive polymer aqueous solution, Heraeus, Clevios P (solid content 1.3 wt%), 60 wt%, water 6wt%, isopropyl alcohol 5wt% were put in a mixed container and stirred for 1 hour, 2-Amino-2-methyl-1-propanol 2 wt% (Alfa aesar, 95%) was added to the mixing vessel and stirred for another 1 hour, followed by adding 20 wt% of NeoRez R-972 (34 wt% solid) of Neo resins with aqueous polyurethane binder resin and restirring for 30 minutes. Then, 5 wt% of dimethyl sulfoxide, 1 wt% of a silicone-based wetting agent (BYK company BYK 348), and 1 wt% of a slip agent (Dow corning company, Q8-8211) were added to the mixed container and further stirred for 1 hour to prepare a primary antistatic composition. Prepared.

And the first antistatic composition was prepared in a second dilution. At this time, the water-dispersible antistatic composition (1) was prepared by mixing 40 wt% of the primary antistatic composition, 59.6 wt% of water, and 0.4 wt% of fluorine-based wetting agent (Zonyl FSH).

Preparation Example 2 Preparation of Water Dispersible Primer Composition (2)

As the binder, a binder having a solid content weight ratio of acrylic resin (A) copolymerized with a glycidyl group-containing radically polymerizable unsaturated monomer and a water-dispersible polyester resin (B) (A) :( B) = 50: 50 was used.

The acrylic resin (A) contains 50 mol% of glycidyl group-containing radically polymerizable unsaturated monomer as a copolymerization monomer in all monomer components, and the water-dispersible polyester resin contains 50 mol% of diethylene glycol in all glycol components. A sulfonic acid alkali metal salt compound containing 10 mol% of all the acid components and having a weight average molecular weight of 32000 were used.

The water-dispersible polyester-based resin (B) is 50 mol% of sulfoterephthalic acid and 85 mol% of terephthalic acid with respect to 50 mol% of diethylene glycol and 50 mol% of ethylene glycol 50 mol%. As the resin polymerized using, a weight average molecular weight of 12000 was used.

A water dispersible primer composition 2 was prepared by mixing 2 wt% of the solid content of the binder, 0.3 wt% of a silicone-based wetting agent (BYK 348 by BYK CHEMIE), and the balance of water.

Preparation Example 3 Preparation of Water Dispersible Antistatic Composition (2)

As a conductive polymer aqueous solution, Heraeus, Clevios P (solid content 1.3 wt%), 30 wt%, water 6wt%, isopropyl alcohol 5wt% were added to the mixing vessel and stirred for 1 hour, 2-Amino-2-methyl-1-propanol 2 wt% (Alfa aesar, 95%) was added to the mixing vessel and stirred for another 1 hour, followed by adding 50 wt% of NeoRez R-972 (34 wt% solid) of Neo resins with an aqueous polyurethane binder resin and restirring for 30 minutes. Then, 5 wt% of dimethyl sulfoxide, 1 wt% of a silicone-based wetting agent (BYK company BYK 348), and 1 wt% of a slip agent (Dow corning company, Q8-8211) were added to the mixed container and further stirred for 1 hour to prepare a primary antistatic composition. Prepared.

And the first antistatic composition to prepare a second dilution. At this time, 40 wt% of the primary antistatic composition, 59.6 wt% of water, and 0.4 wt% of a fluorine-based wetting agent (Zonyl FSH) were prepared to prepare a water dispersible antistatic composition (2).

Example 1 Preparation of Polyester Film

As the base material layer (B), polyethylene terephthalate chips having an intrinsic viscosity of 0.63, a content of diethylene glycol of 0.96% by weight, and an oligomer content of 1.4% by weight were introduced into an extruder to melt extrusion. The skin layer (A) has an intrinsic viscosity of 0.67, a content of diethylene glycol of 0.8% by weight, an oligomer content of 0.5% by weight of polyethylene terephthalate chips and an average particle diameter of 0.5 µm to the total polyethylene terephthalate weight. A sheet co-extruded to the A / B / A three layer using 50 ppm was prepared.

The sheet was stretched three times in the machine direction (MD) at 120 ° C. Thereafter, the water-dispersible antistatic composition (1) prepared in Preparation Example 1 was coated on one surface by a bar coating method, and the water-dispersible primer composition (2) prepared in Preparation Example 2 was applied to the other surface by a bar coating method. After coating, the film was stretched 3.5 times in the transverse direction (TD) at 150 ° C. Thereafter, heat treatment was performed at 230 ° C. in a five-stage tenter, and at 200 ° C., 10% was relaxed in the longitudinal and transverse directions to prepare a 75 μm biaxially stretched film coated on both sides.

The prepared polyester multilayer film was 60% by weight of the total film weight, the skin layer was 40% by weight of the total film weight, the dry coating thickness of the antistatic layer is 50 nm, the dry coating thickness of the primer layer is 50 nm.

Physical properties were measured and shown in Tables 1 and 2 below.

Example 2

A polyester multilayer film was manufactured in the same manner as in Example 1, except that the dry coating thickness of the primer layer was changed to 100 nm in Example 1.

Physical properties were measured and shown in Tables 1 and 2 below.

Example 3

A polyester multilayer film was manufactured in the same manner as in Example 1, except that the dry coating thickness of the primer layer was changed to 150 nm in Example 1.

Physical properties were measured and shown in Tables 1 and 2 below.

Example 4

A polyester multilayer film was manufactured in the same manner as in Example 1, except that the base layer was 80% by weight of the total film weight in Example 1, and the skin layer was changed to be 20% by weight of the total film weight.

Physical properties were measured and shown in Tables 1 and 2 below.

Example 5

In Example 1, except that polyethylene terephthalate having an intrinsic viscosity of 0.65, a diethylene glycol content of 1.2% by weight, and an oligomer content of 1.5% by weight was used as the base layer (B). A polyester multilayer film was prepared.

Physical properties were measured and shown in Tables 1 and 2 below.

Example 6

As the base material layer (B), polyethylene terephthalate chips having an intrinsic viscosity of 0.63, a content of diethylene glycol of 0.96% by weight, and an oligomer content of 1.4% by weight were introduced into an extruder to melt extrusion. The skin layer (A) has an intrinsic viscosity of 0.67, a content of diethylene glycol of 0.8% by weight, an oligomer content of 0.5% by weight of polyethylene terephthalate chips and an average particle diameter of 0.5 µm to the total polyethylene terephthalate weight. A sheet co-extruded to the A / B / A three layer using 50 ppm was prepared.

The sheet was stretched three times in the machine direction (MD) at 120 ° C. Thereafter, the water-dispersible antistatic composition (2) prepared in Preparation Example 3 was coated on one surface by a bar coating method, and the water-dispersible primer composition (2) prepared in Preparation Example 2 was applied to the other surface by a bar coating method. After coating, the film was stretched 3.5 times in the transverse direction (TD) at 150 ° C.

Thereafter, heat treatment was performed at 230 ° C. in a five-stage tenter, and at 200 ° C., 10% was relaxed in the longitudinal and transverse directions to prepare a 75 μm biaxially stretched film coated on both sides.

The prepared polyester multilayer film was 60% by weight of the total film weight, the skin layer was 40% by weight of the total film weight, the dry coating thickness of the antistatic layer is 50 nm, the dry coating thickness of the primer layer is 50 nm.

Physical properties were measured and shown in Tables 1 and 2 below.

Comparative Example 1

As the base material layer (B), polyethylene terephthalate chips having an intrinsic viscosity of 0.63, a content of diethylene glycol of 0.96% by weight, and an oligomer content of 1.4% by weight were introduced into an extruder to melt extrusion. The skin layer (A) has an intrinsic viscosity of 0.67, a content of diethylene glycol of 0.8% by weight, an oligomer content of 0.5% by weight of polyethylene terephthalate chips and an average particle diameter of 0.5 µm to the total polyethylene terephthalate weight. A sheet co-extruded to the A / B / A three layer using 50 ppm was prepared.

The sheet was stretched three times in the machine direction (MD) at 120 ° C. Thereafter, the water-dispersible antistatic composition (1) prepared in Preparation Example 1 was coated on one surface by a bar coating method, and then stretched 3.5 times in a transverse direction (TD) at 150 ° C.

Thereafter, heat treatment was performed at 230 ° C. in a 5-stage tenter, and 10% relaxation was performed at 200 ° C. in the longitudinal and transverse directions to prepare a 75 μm biaxially stretched film coated on one surface.

The prepared polyester multilayer film had a base layer of 60% by weight of the total film weight, a skin layer of 40% by weight of the total film weight, and a dry coating thickness of the antistatic layer was 50 nm.

Comparative Example 2

As the base material layer (B), polyethylene terephthalate chips having an intrinsic viscosity of 0.63, a content of diethylene glycol of 0.96% by weight, and an oligomer content of 1.4% by weight were introduced into an extruder to melt extrusion. The skin layer (A) has an intrinsic viscosity of 0.67, a content of diethylene glycol of 0.8% by weight, an oligomer content of 0.5% by weight of polyethylene terephthalate chips and an average particle diameter of 0.5 µm to the total polyethylene terephthalate weight. A sheet co-extruded to the A / B / A three layer using 50 ppm was prepared.

The sheet was stretched three times in the machine direction (MD) at 120 ° C. Thereafter, the water-dispersible antistatic composition (1) prepared in Preparation Example 1 was coated on both sides by a bar coating method, and then stretched 3.5 times in a transverse direction (TD) at 150 ° C.

Thereafter, heat treatment was performed at 230 ° C. in a five-stage tenter, and at 200 ° C., 10% was relaxed in the longitudinal and transverse directions to prepare a 75 μm biaxially stretched film coated on both sides.

The prepared polyester multilayer film was 60% by weight of the total film weight, the skin layer was 40% by weight of the total film weight, and the dry coating thickness of the antistatic layer was 50 nm, respectively.

Comparative Example 3

As the polyester base film, a single-layer polyester film was used without co-extrusion into three layers as in Example 1.

A polyethylene terephthalate having an intrinsic viscosity of 0.63, a diethylene glycol content of 0.96% by weight, and an oligomer content of 1.8% by weight was added to an extruder to melt extrusion to prepare a single layer polyethylene terephthalate film. A film was prepared in the same manner as in Example 1.

[Comparative Example 4]

As the base material layer (B), polyethylene terephthalate chips having an intrinsic viscosity of 0.63, a content of diethylene glycol of 0.96% by weight, and an oligomer content of 1.4% by weight were introduced into an extruder to melt extrusion. The skin layer (A) has an intrinsic viscosity of 0.67, a content of diethylene glycol of 0.8% by weight, an oligomer content of 0.5% by weight of polyethylene terephthalate chips and an average particle diameter of 0.5 µm to the total polyethylene terephthalate weight. A sheet co-extruded to the A / B / A three layer using 50 ppm was prepared.

The sheet was stretched three times in the machine direction (MD) at 120 ° C. Thereafter, the water-dispersible antistatic composition (1) prepared in Preparation Example 1 was coated on one surface by a bar coating method, and then the other surface was coated with a water-dispersible primer composition including a polyurethane-based binder having a refractive index of 1.58. After coating by the (Bar Coating) method, it was stretched 3.5 times in the transverse direction (TD) at 150 ℃.

Thereafter, heat treatment was performed at 230 ° C. in a 5-stage tenter, and 10% relaxation was performed at 200 ° C. in the longitudinal and transverse directions to prepare a 75 μm biaxially stretched film coated on one surface.

The prepared polyester multilayer film was 60% by weight of the total film weight, the skin layer was 40% by weight of the total film weight, the dry coating thickness of the antistatic layer is 50 nm, the dry coating thickness of the primer layer is 50 nm.

[Comparative Example 5]

As the base material layer (B), polyethylene terephthalate chips having an intrinsic viscosity of 0.63, a content of diethylene glycol of 0.96% by weight, and an oligomer content of 1.4% by weight were introduced into an extruder to melt extrusion. In the skin layer (A), the polyethylene terephthalate chip having an intrinsic viscosity of 0.67, the content of diethylene glycol of 1.3% by weight, the oligomer content of 0.7% by weight, and the silica particles having an average particle diameter of 0.5 µm are compared with the total polyethylene terephthalate weight. A sheet co-extruded to the A / B / A three layer using 50 ppm was prepared.

The sheet was stretched three times in the machine direction (MD) at 120 ° C. Thereafter, the water-dispersible antistatic composition (1) prepared in Preparation Example 1 was coated on one surface by a bar coating method, and the water-dispersible primer composition (2) prepared in Preparation Example 2 was applied to the other surface by a bar coating method. After coating, the film was stretched 3.5 times in the transverse direction (TD) at 150 ° C.

Thereafter, heat treatment was performed at 230 ° C. in a five-stage tenter, and at 200 ° C., 10% was relaxed in the longitudinal and transverse directions to prepare a 75 μm biaxially stretched film coated on both sides.

The prepared polyester multilayer film was 60% by weight of the total film weight, the skin layer was 40% by weight of the total film weight, the dry coating thickness of the antistatic layer is 50 nm, the dry coating thickness of the primer layer is 50 nm.

Physical properties were measured and shown in Tables 1 and 2 below.

	Haze (%)			Total light transmittance (%)			Adhesive force of antistatic layer			Adhesion of Primer Layer			Oligomer Number of Antistatic Layers		Oligomer Number of Primer Layers
	Early	△ H 1	△ H 2	Early	△ TT 1	△ TT 2	Early	One)	2)	Early	One)	2)	One)	2)	One)	2)
Example 1	1.15	0.3	0.3	91.20	0.14	0.14	○	○	○	○	○	○	12	14	8	10
Example 2	1.17	0.2	0.2	92.30	0.11	0.11	○	○	○	○	○	○	8	9	5	6
Example 3	1.19	0.1	0.1	93.20	0.08	0.08	○	○	○	○	○	○	4	4	2	2
Example 4	1.05	0.5	0.5	91.40	0.26	0.26	○	○	○	○	○	○	28	29	16	18
Example 5	1.16	0.4	0.4	91.50	0.24	0.24	○	○	○	○	○	○	26	27	12	14
Example 6	1.15	0.5	0.5	91.90	0.15	0.15	○	○	○	○	○	○	20	21	8	10
Comparative Example 1	1.10	2.5	2.7	89.00	0.34	0.34	○	○	○	-	-	-	42	46	-	-
Comparative Example 2	1.12	2.0	2.0	87.60	0.28	0.28	○	○	○	-	-	-	37	38	-	-
Comparative Example 3	1.33	4.5	4.5	90.20	1.12	1.14	○	○	○	○	○	○	92	96	58	58
Comparative Example 4	1.14	3.5	3.7	88.70	0.44	0.44	○	○	○	○	○	○	42	46	32	37
Comparative Example 5	1.25	2.6	2.6	91.20	0.34	0.35	○	○	○	○	○	○	42	44	28	30

In Table 1, ΔH ₁ is a haze change rate measured after 85 ° C. and 85% 72 hours, and ΔH ₂ is a haze change rate measured after 60 ° C. and 95% 120 hours.

ΔTT ₁ is the rate of change in total light transmittance measured after 85 ° C. and 85% 72 hours, and ΔTT ₂ is the rate of change in total light transmittance measured after 120 hours at 60 ° C., 95%.

Adhesion of the antistatic layer 1) is the adhesion of the antistatic layer to the base film measured after 85 ℃, 85% 72 hours, adhesion of the antistatic layer 2) is the antistatic layer to the base film measured after 60 ℃, 95% 120 hours Of adhesion.

The adhesion of the primer layer 1) is the adhesion of the primer layer to the base film measured after 85 ℃, 85% 72 hours, the adhesion of the primer layer 2) is the primer layer to the base film measured after 60 ℃, 95% 120 hours Of adhesion.

The number of oligomers of the antistatic layer 1) is the number of oligomers of the antistatic layer relative to the base film measured after 85 ° C., 85% 72 hours, and the number of oligomers of the antistatic layer 2) is the base film measured after 60 ° C., 95% 120 hours. Is the number of oligomers of the antistatic layer.

Oligomer number 1) of the primer layer is the number of oligomers of the primer layer for the base film measured after 85 ℃, 85% 72 hours, oligomer number 2) of the primer layer was measured on the base film measured after 60 ℃, 95% 120 hours Is the number of oligomers of the primer layer.

As shown in Table 1, Examples 1 to 6 by forming an antistatic layer on one side, and a primer coating layer on the other side, there is little change in surface resistance even after a high temperature and high humidity process, excellent antistatic properties At the same time, it can be seen that the light transmittance is remarkably improved as compared with the comparative example, and the number of oligomers of the antistatic layer and the primer layer is significantly reduced.

In the case of Comparative Example 1, even though the water-dispersible antistatic composition having the same composition as in Example 1 was used, when only the antistatic layer was formed on one surface, the light transmittance rapidly decreased, and thus it was impossible to use it as an electronic material and an optical film. It was confirmed that the oligomer number was found to increase.

It was found that the number of oligomers increased even when the water-dispersible antistatic composition was applied to both surfaces as in Comparative Example 2.

	Antistatic layer					Primer layer refractive index
	Water contact angle (degrees)	Surface resistance (Ω / sq)			Silicone adhesion
		Early	One)	2)
Example 1	92	10 5.8	10 6.2	10 6.4	○	1.48
Example 2	96	10 5.5	10 5.8	10 6.0	○	1.48
Example 3	100	10 5.2	10 5.4	10 5.6	○	1.48
Example 4	92	10 5.8	10 6.7	10 6.8	○	1.48
Example 5	92	10 5.8	10 6.6	10 6.8	○	1.48
Example 6	90	10 8.2	10 8.6	10 8.8	○	1.48
Comparative Example 1	92	10 5.8	10 7.4	10 7.6	○	-
Comparative Example 2	92	10 5.8	10 7.2	10 7.4	○	-
Comparative Example 3	92	10 5.8	10 7.8	10 8.0	○	1.48
Comparative Example 4	92	10 5.8	10 7.4	10 7.7	○	1.58
Comparative Example 5	92	10 5.8	10 7.9	10 7.2	○	1.48

In Table 2, the surface resistance 1) is the surface resistance measured after 85 ° C. and 85% 72 hours, and the surface resistance 2) is the surface resistance measured after 60 ° C. and 95% 120 hours.

As shown in Table 2, Examples 1 to 6 was confirmed that the change in the surface resistance is small even after the high temperature and high humidity process, and excellent in antistatic properties.

Claims (13)

1. It includes a polyester base film, an antistatic layer formed on one surface of the polyester base film and a conductive polymer and an aqueous polyurethane binder, and a primer layer formed on the other surface of the polyester base film and having a refractive index of 1.4 to 1.5. ,

   The polyester base film includes a base layer and a skin layer in which at least one layer is laminated on both sides of the base layer, wherein the oligomer content of the polyester resin constituting the skin layer is 0.3 to 0.6 wt%, and diethylene The content of glycol is 0.1 to 1.2% by weight, the intrinsic viscosity of the polyester multilayer film satisfying the following formula 1.

   [Equation 1]

   1 <Ns / Nc ≤ 1.1

   In Formula 1, Ns is the intrinsic viscosity of the polyester resin constituting the skin layer, Nc is the intrinsic viscosity of the polyester resin constituting the base layer.
2. The method of claim 1,

   The polyester multilayer film has a surface resistance of 10 ⁵ to 10 ⁹ Ω / sq before heat treatment, a haze of 2% or less, a total light transmittance of 90% or more,

   After 72 hours of holding at 85 ° C. and 85%, the haze change rate ΔH ₁ satisfies the following equation 2 and the light transmittance change rate ΔTT ₁ satisfies the following equation 3

   [Equation 2]

   ΔH ₁ <0.5%

   ΔH ₁ = H _f −H _i in Equation 2, H _f is the haze of the film after holding at 85 ° C., 85% for 72 hours, and H _i is the haze of the film before heating.

   [Equation 3]

   TT ₁ <0.5%

   ΔTT ₁ = TT _f − TT _i in Formula 3, and TT _f is It is the total light transmittance of a film after hold | maintaining at 85 degreeC and 85% for 72 hours, and TT _i is the total light transmittance of a film before heating.

   After 120 hours of maintenance at 60 ° C. and 95%, the surface resistance was 10 ⁵ to 10 ⁹ μs / sq, the haze change rate ΔH ₂ satisfied the following formula 4, and the light transmittance change rate ΔTT ₂ satisfied the following formula 5. Polyester multilayer film.

   [Equation 4]

   ΔH ₂ <1.0%

   In Formula 4, ΔH ₂ = H _f H _i , H _f is the haze of the film after holding at 60 ° C., 95% for 120 hours, and H _i is the haze of the film before heating.

   [Equation 5]

   TT ₂ <1.0%

   ΔTT ₁ = TT _f − TT _i in Formula 5, and TT _f is It is the total light transmittance of a film after hold | maintaining at 60 degreeC and 95% for 120 hours, and TT _i is the total light transmittance of a film before heating.
3. The method of claim 1,

   The polyester multilayer film is less than 30 oligomers of the antistatic layer after holding at 85 ℃, 85% 72 hours or 60 ℃, 95% 120 hours, 85 ℃, 85% 72 hours or 60 ℃, 95% The polyester multilayer film having a number of oligomers of the primer layer after 20 hours in less than 20.
4. The method of claim 1,

   The antistatic layer has a water contact angle of 90 degrees or more, a polyester multilayer film is applied on the antistatic layer and the silicone coating layer is maintained upon evaluation of adhesion according to ASTM B905 after 2 hours in water at 100 ° C. .
5. The method of claim 1,

   The antistatic layer is a polyester multilayer film formed by applying an antistatic composition comprising a conductive polymer solution, an aqueous polyurethane binder solution, an organic solvent and water.
6. The method of claim 5,

   The organic solvent is any one or two or more mixed solvents selected from alcohol organic solvents, aprotic high polar organic solvents and amide organic solvents.
7. The method of claim 1,

   The antistatic layer is a polyester multilayer film comprising 1 to 30% by weight of the conductive polymer and 70 to 99% by weight of the aqueous polyurethane binder in 100% by weight of solids.
8. The method of claim 1,

   Wherein the conductive polymer is a polystyrene sulfonate doped with polyethylene dioxythiophene (PEDOT: PSS) polyester multilayer film.
9. The method of claim 1,

   The primer layer is a polyester multilayer film containing any one or two or more selected from acrylic resin, polyester resin and urethane resin.
10. The method of claim 1,

    The primer layer is a polyester multilayer film comprising a binder resin having a weight ratio of 20 to 80: 80 to 20 of the acrylic resin copolymerized with glycidyl group-containing radically polymerizable unsaturated monomer and water-dispersible polyester resin.
11. The method of claim 1,

    The polyester base film has a thickness of 12 ~ 250 ㎛,

    The base layer is 60 to 90% by weight, the skin layer is 10 to 40% by weight of the polyester multilayer film.
12. The method of claim 1,

    The antistatic layer has a dry coating thickness of 10 to 500 nm,

    The primer layer has a dry coating thickness of 20 to 300 nm polyester multilayer film.
13. An optical film having at least one functional coating layer selected from a release coating layer, an adhesive layer, a hard coating layer, and a printing layer on the polyester multilayer film of any one of claims 1 to 12.