JP2019527152A - Polyester multilayer film - Google Patents

Abstract

The present invention relates to a polyester multilayer film, and more particularly, to an optical polyester multilayer film excellent in oligomer blocking properties, antistatic properties, and transparency.

Description

The present invention relates to a polyester multilayer film, and more particularly, to an optical polyester multilayer film that is excellent in oligomer blocking properties and excellent in antistatic properties and transmittance.

In recent years, with the rapid development of various electronic, electrical, and information and communication fields, there have been problems due to static electricity in many fields, from industrial products and household products to which these are applied. The prevention function is an essential function. Antistatic means that the charge accumulated on the surface of the insulator is discharged by an appropriate method.

The reason why such antistatic properties are required is that, in the film manufacturing process and film processing process, static electricity is caused to attach dust and foreign matters to the product, causing a discharge phenomenon, and there is a danger of ignition when using an organic solvent. It is for generating. Therefore, providing antistatic performance is an essential requirement.

The film imparted with antistatic performance is used in the production of electronic materials and optical products. At this time, an antistatic film of a conductive polymer that does not depend on humidity is mainly used. When a conductive polymer is used in order to reduce the generation of static electricity, the light transmittance is reduced. There are limitations to the use for optical and optical films. In addition, when such an antistatic film undergoes a high-temperature process in a subsequent process, the oligomer may migrate to the surface of the film, which may cause a problem that optical properties and charging performance deteriorate.

An object of the present invention is to provide a polyester multilayer film that can be used as an optical film because it has excellent antistatic properties and light transmittance.

Another object of the present invention is to provide a polyester multilayer film that has little change in surface resistance and is excellent in antistatic properties even after undergoing a high temperature and high humidity process.

As a result of researches to achieve the above object, an antistatic layer is formed on one surface using a conductive polymer resin to impart antistatic properties, and a refractive index of 1.4% on the other surface. In the case of forming a primer coating layer of -1.5, it was found that not only the oligomer blocking property but also the transmittance was improved and the optical characteristics were greatly improved, and the present invention was completed.

Specifically, the present invention provides a polyester base film, an antistatic layer formed on one side of the polyester base film, including a conductive polymer and a water-based polyurethane binder, and formed on the other side of the polyester base film. A primer layer having a ratio of 1.4 to 1.5, and the polyester base film includes a base material layer and a skin layer in which at least one layer is laminated on both surfaces of the base material layer. And the content of the oligomer of the polyester resin forming the skin layer is 0.3 to 0.6% by weight, the content of diethylene glycol is 0.1 to 1.2% by weight, and the intrinsic viscosity satisfies the following formula 1. And a polyester multilayer film.

[Formula 1] 1 <Ns / Nc ≦ 1.1

In the formula 1, Ns is the intrinsic viscosity of the polyester resin forming the skin layer, and Nc is the intrinsic viscosity of the polyester resin forming the base material layer.

INDUSTRIAL APPLICABILITY The present invention can provide a polyester film that has little oligomer migration under high temperature and high humidity conditions, little change in surface resistance, excellent silicone adhesion and printability, and excellent transparency.

Since the polyester film of the present invention has antistatic properties and excellent transparency, it can be used as an optical member for various displays.

Hereinafter, the present invention will be described in more detail with reference to specific examples or examples including the accompanying drawings. However, the following specific examples or examples are merely a reference for explaining the present invention in detail, and the present invention is not limited thereto, and can be implemented in various forms.

Also, unless defined otherwise, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the present application is merely for effectively describing a specific example, and is not intended to limit the present invention.

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

In the present invention, the “oligomer” is a by-product generated during polymerization of polyester, more specifically, during the polycondensation reaction of terephthalic acid or a derivative thereof and ethylene glycol, and has a weight average molecular weight of 500 to 10,000 g / mol. It means a dimer, a trimer, a tetramer or the like.

One embodiment of the present invention includes a polyester base film, an antistatic layer formed on one surface of the polyester base film and containing a conductive polymer and a water-based polyurethane binder, and formed on the other surface of the polyester base film. Wherein the polyester base film includes a base material layer and a skin layer in which at least one layer is laminated on each side of the base material layer. The content of the polyester resin oligomer forming the skin layer is 0.3 to 0.6% by weight, the content of diethylene glycol is 0.1 to 1.2% by weight, and the intrinsic viscosity satisfies the following formula 1. The present invention relates to a polyester multilayer film.

[Formula 1] 1 <Ns / Nc ≦ 1.1

In the formula 1, Ns is the intrinsic viscosity of the polyester resin forming the skin layer, and Nc is the intrinsic viscosity of the polyester resin forming the base material layer.

In one aspect of the present invention, the polyester multilayer film has a surface resistance of 105 to 109 Ω / sq before heat treatment, a haze of 2% or less, a total light transmittance of 90% or more, and 85 After maintaining for 72 hours at 85 ° C., the haze change rate ΔH1 satisfies the following formula 2, the light transmittance change rate ΔTT1 satisfies the following formula 3, and the antistatic layer and the primer layer are [Formula 2] ΔH1 <0.5% (in Formula 2, ΔH1 = Hf−Hi, where Hf is maintained at 85 ° C. and 85% for 72 hours. The haze of the film, and Hi is the haze of the film before heating.) [Formula 3] ΔTT1 <0.5% (in Formula 3, ΔTT1 = TTf−TTi, and TTf is 85) Maintained at 85 ° C for 72 hours And TTi is the total light transmittance of the film before heating.) After maintaining at 60 ° C. and 95% for 120 hours, the surface resistance is 105 to 109 Ω / sq. The haze change rate ΔH2 satisfies the following formula 4, the light transmittance change rate ΔTT2 satisfies the following formula 5, and the antistatic layer and the primer layer are held on the polyester base film at the time of adhesion evaluation. There may be.

[Formula 4] ΔH2 <1.0%

In Formula 4, ΔH2 = Hf−Hi, where Hf is the haze of the film after being maintained at 60 ° C. and 95% for 120 hours, and Hi is the haze of the film before heating.

[Formula 5] ΔTT2 <1.0%

In Formula 5, ΔTT1 = TTf−TTi, where TTf is the total light transmittance of the film after being maintained at 60 ° C. and 95% for 120 hours, and TTi is the total light of the film before heating. Transmittance.

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

In one embodiment of the present invention, the antistatic layer has a water contact angle of 90 degrees or more, and a silicone adhesive is applied on the antistatic layer, left in water at 100 ° C. for 2 hours, and then applied to ASTM B905. The silicone coating layer can be retained when the adhesive strength is evaluated according to the above.

In one embodiment of the present invention, the antistatic layer may be formed by applying an antistatic composition containing 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-based organic solvents, aprotic highly polar organic solvents, and amide-based organic solvents. .

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

In one embodiment of the present invention, the conductive polymer may be one in which polyethylene dioxythiophene is doped with polystyrene sulfonate.

In one aspect of the present invention, the primer layer may include any one or more selected from acrylic resins, polyester resins, and urethane resins.

In one aspect of the present invention, the primer layer has a weight ratio of 20-80: 80-20 of an acrylic resin copolymerized with a glycidyl group-containing radical polymerizable unsaturated monomer and a water-dispersible polyester resin. A certain binder resin may be included.

In one aspect of the present invention, the water-dispersible polyester resin is obtained by copolymerizing a dicarboxylic acid component containing a sulfonic acid alkali metal salt compound and a glycol component containing diethylene glycol, and the acrylic resin is You may contain 20-80 mol% of glycidyl group containing radically polymerizable unsaturated monomers as a copolymerization monomer in all the monomer components.

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

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

In another aspect of the present invention, an optical device in which any one or more functional coating layers selected from a hard coating layer, a printing layer, an adhesive layer, and a release agent layer are formed on the polyester multilayer film. Related to film.

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

The inventors of the present invention have studied to solve the problem that the total light transmittance of the film is lowered when a conductive polymer is used to improve the antistatic property. As a result, an antistatic layer is formed. It was found that by forming a primer layer having a refractive index of 1.4 to 1.5 on the other surface of the surface, the total light transmittance of the entire film can achieve physical properties of 90% or more, and the present invention is completed. did.

Further, as the polyester base film, using a film of three or more layers in which the base material layer and the skin layer are coextruded and laminated, the skin layer has an oligomer content of 0.3 to 0.6% by weight, By using a polyester resin having a diethylene glycol content of 0.1 to 1.2% by weight, and using a polyester resin having an intrinsic viscosity satisfying the following formula 1, surface resistance, haze change rate, light at high temperature and high humidity The inventors have found that the rate of change in transmittance is small and that the adhesive force between the polyester base film, the antistatic layer and the primer layer is small, and the present invention has been completed.

[Formula 1] 1 <Ns / Nc ≦ 1.1

In the formula 1, Ns is the intrinsic viscosity of the polyester resin forming the skin layer, and Nc is the intrinsic viscosity of the polyester resin forming the base material layer.

That is, the present invention is characterized in that all the desired effects can be achieved by a combination of an antistatic layer, a polyester base film, and a primer layer.

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

In the present invention, the polyester base film may include a base layer and a skin layer laminated on at least one layer on each side of the base layer, and may be composed of three or more layers. It may be formed by extrusion.

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

Further, the content of the base material layer is 60 to 90% by weight of the total film, the content of the skin layer is preferably 10 to 40% by weight, and more preferably the content of the base material layer is 70 to 80% by weight. It is effective that the content of the skin layer is 20 to 30% by weight because the interface stabilization at the time of co-extrusion is excellent and the blocking property of the oligomer is excellent.

The base material layer may be made of a polyester resin, more specifically, a polyethylene terephthalate (PET) resin, but is not limited thereto. At this time, the polyethylene terephthalate resin used preferably has 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 can be lowered, and when it exceeds 1.0, workability can be lowered because raw material processing is not easy.

The skin layer formed by coextruding at least one layer on 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, and the content of diethylene glycol (DEG) may be 0.1 to 1.2% by weight, more preferably 0.7 to 0.8% by weight. When the content of the polyester resin oligomer and diethylene glycol exceeds the above range, the haze value of the initial film increases, and the rate of change in haze increases rapidly when heat-treated. The problem of not being able to fulfill can occur.

Further, the polyester resin of the skin layer can be produced by a synthesis method apparent in the art so that the content of the oligomer and diethylene glycol is in the above-mentioned range. It is effective in reducing the content of diethylene glycol.

The intrinsic viscosity of the polyester resin of the skin layer is preferably 0.6 to 1.0, and more preferably 0.65 to 0.85. When the intrinsic viscosity of the polyethylene terephthalate resin of the skin layer is less than 0.6, heat resistance can be reduced, and when it exceeds 1.0, workability can be reduced because raw material processing is not easy. .

Further, the base material layer and the skin layer may include inorganic particles that are additives added during the production of a normal film.

The polyester base film is formed by coextruding a base material layer and a skin layer, and satisfies the following formula 1 in order to improve workability when the base material layer and the skin layer are coextruded. It is preferable.

[Formula 1] 1 <Ns / Nc ≦ 1.1

In the formula 1, Ns is the intrinsic viscosity of the polyester resin forming the skin layer, and Nc is the intrinsic viscosity of the polyester resin forming the base material layer.

When the ratio of the intrinsic viscosity of the skin layer and the base material layer exceeds 1.1, the problem of interface instability occurs during coextrusion, and a multilayer structure may not be formed. More preferably 1.0 to 1.05 is effective in improving workability.

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

In one embodiment of the present invention, the antistatic layer includes a conductive polymer and an aqueous polyurethane binder. By including these, the water contact angle is 90 degrees or more, the silicone pressure-sensitive adhesive layer is coated on the antistatic layer, left in water at 100 ° C. for 2 hours, and then evaluated for adhesive strength. Can be held.

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

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

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

In addition, the antistatic composition may be a silicone-based wetting agent, a fluorine-based wetting agent, a slip agent, an antifoaming agent, a wetting agent, a surfactant, a thickener, a plasticizer, an antioxidant, an ultraviolet ray, if necessary. Any one or more additives selected from absorbents, preservatives, crosslinking agents and the like may be further included.

In one embodiment of the present invention, the conductive polymer may be a polythiophene-based, polypyrrole-based, polyaniline-based polymer resin, or the like, but is not limited thereto. It is more preferable to use a polythiophene-based conductive polymer resin, and most preferably, the use of polyethylene dioxythiophene doped with polystyrene sulfonate (PEDOT: PSS) is excellent in water dispersibility. The antistatic layer can be formed by the method, and the transparency is not lowered even after the stretching process after the in-line coating process, and the heat resistance and the desired surface resistance are exhibited, but it is not limited thereto. The conductive polymer is preferably used in a range that satisfies the physical properties of a surface resistance of 105 to 109 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 optimum dispersibility. Specifically, for example, when PEDOT: PSS is used, You may mix and use in water, alcohol, and a solvent with a large dielectric constant. As a commercialized example, Clevios P (solid content: 1.2 to 1.4% by weight) manufactured by Heraeus can be used, but is not limited thereto.

The content of the conductive polymer solution in the antistatic composition may be 40 to 90% by weight, more preferably 50 to 70% by weight. When the content is within the above range, it is sufficient to achieve the desired physical properties. Although it is a content, it is not restricted to this.

In one embodiment of the present invention, the water-based polyurethane binder is used by mixing with a conductive polymer, so that it has excellent miscibility, improved surface resistance performance, excellent adhesion to a polyester base film, and high temperature and high humidity. It is possible to form an antistatic layer with little change in physical properties and little yellowing phenomenon under the conditions.

By using a polyurethane binder obtained by reacting a polycarbonate-based polyol and diisocyanate, the water-based polyurethane binder can achieve physical properties that are excellent in heat resistance and have a low surface resistance change rate. More preferably, as a specific example of the diisocyanate, hexamethylene diisocyanate is preferably used from the viewpoint of improving the heat resistance and forming a coating film with less yellowing phenomenon, but is not limited thereto.

The water-based polyurethane binder may be dispersed in a solvent, and the solvent is not limited to this, but may be an amide organic solvent and an aprotic highly polar (Aprotic Highly Dipolar, AHD). ) Any one or two or more mixed solvents selected from the group consisting of organic solvents may be used, but are not limited thereto. Commercialized examples include Neo Rez R-860, R-960, and R-972 manufactured by 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, more preferably 10 to 30% by weight. When the content is within the above range, the content is sufficient to achieve the desired physical properties. There is, but is not limited to this.

In one embodiment of the present invention, the organic solvent used in the antistatic composition is any one selected from alcohol-based organic solvents, aprotic highly dipolar (AHD) organic solvents, and amide-based organic solvents. One or two or more mixed solvents may be used.

The content of the organic solvent may be 3 to 50% by weight in the antistatic composition, more specifically 5 to 40% by weight, and more specifically 10 to 30% by weight. In some cases, the content is suitable for improving the dispersibility of the conductive polymer and the polyurethane binder, but is not limited thereto.

More preferably, by using any one or two or more mixed solvents selected from an aprotic highly polar organic solvent and an amide organic solvent together with the alcohol organic solvent, the dispersibility of the conductive polymer can be improved. And the effect of further improving the surface resistance performance by activating the dope.

More specifically, alcoholic organic solvent 1-30 wt%, more specifically 5-20 wt%, any one or two selected from aprotic highly polar organic solvents and amide organic solvents The above mixed solvent may be used in an amount of 2 to 20% by weight, more specifically 5 to 10% by weight.

The alcohol-based organic solvent is not limited thereto, but specific examples include methanol, ethanol, propanol, isopropanol, butanol, and 2-amino-2-methyl-1-propanol. These may be used alone or in admixture of two or more. By using an alcohol-based organic solvent, the mixing property and dispersibility of the conductive polymer and the water-based polyurethane resin can be further improved.

The aprotic highly polar organic solvent is not limited to this, but as a specific example, dimethyl sulfoxide, propylene carbonate, etc. can be used, and may be used alone or in admixture of two or more. Good. By using an aprotic highly polar organic solvent, the conductivity of the conductive polymer can be further improved. When an aprotic highly polar organic solvent is used alone, it may further contain a dispersion stabilizer such as ethylene glycol, glycerin, and sorbitol, but is not limited thereto.

Examples of the amide organic solvent include, but are not limited to, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N-dimethylacetamide, N- Methylpyrrolidone, 2-amino-2-methyl-1-propanol, and the like can be used, and may be used alone or in admixture of two or more. By using an amide organic solvent, the conductivity of the conductive polymer can be further improved.

In one embodiment of the present invention, the antistatic composition further includes a wetting agent, whereby the coating property can be further improved. Specific examples include, but are not limited to, modified silicone wetting agents such as Q2-5212 from Dow Corning, TEGO WET 250 from ENBODIC, BYK 348 from BYK CHEMIE, Zonyl A fluorine-based wetting agent such as FSH can be used, but is not limited thereto. The wetting agent is preferably used in an amount of 0.1 to 2% by weight. When the amount is within the above range, the target coating property can be improved, but the present invention is not limited thereto.

In one aspect of the present invention, the dry coating thickness of the antistatic layer may be 10 to 500 nm. If the dry coating thickness is less than 10 nm, the surface resistance may not be sufficient, and if it exceeds 500 nm, the possibility of occurrence of a blocking (blocking) phenomenon increases, so the above range is advanced. However, it is not limited to this.

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

In one embodiment of the present invention, the primer layer preferably has a refractive index of 1.4 to 1.5, and the antistatic layer is formed using a conductive polymer by satisfying the above range. The total light transmittance is as transparent as 90% or more, and is suitable for use in an optical film. In the case where 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, by forming both the antistatic layer and the primer layer, the total light transmittance is 90% or more, more specifically 90 to 95%, and physical properties with little change in haze are obtained. Both can be satisfied. In addition, a film with little change in total light transmittance and haze can be provided even under high temperature and high humidity conditions.

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

In one aspect of the present invention, the primer layer is formed by applying a water-dispersible resin composition having an oligomer blocking property, and the water-dispersible resin composition having the oligomer blocking property includes: As a specific example, an acrylic resin copolymerized with a glycidyl group-containing radically polymerizable unsaturated monomer and a water-dispersible polyester resin may be included.

In one aspect of the present invention, the water-dispersible resin composition comprises a solid content of an acrylic resin (A) copolymerized with a glycidyl group-containing radical polymerizable unsaturated monomer and a water-dispersible polyester resin (B). (A) :( B) = 20-80: 80-20 may be sufficient. More preferably, it may be used in a weight ratio of 40-60: 60-40. The solid content of the water-dispersible polyester resin (B) is less than 20% by weight, and the solid content of the acrylic resin (A) copolymerized with the glycidyl group-containing radical polymerizable unsaturated monomer is 80% by weight. In the case of exceeding the particle size, the particle size (Particle Size) of the emulsion is increased, so that unevenness occurs during in-line coating, and adhesion and transparency with the polyester base film are deteriorated. The solid content of the water-dispersible polyester resin (B) exceeds 80% by weight, and the solid content of the acrylic resin (A) copolymerized with the glycidyl group-containing radical polymerizable unsaturated monomer is less than 20% by weight. In some cases, a sufficient oligomer blocking effect is not exhibited, and it is not sufficient in improving light transmittance and minimizing changes in haze, surface resistance, etc. under high temperature and high humidity conditions.

The water-dispersible resin composition of the present invention comprises a water-dispersible polyester resin (B) and a binder resin obtained by mixing an acrylic resin (A) copolymerized with a glycidyl group-containing radical polymerizable unsaturated monomer and water. In the aqueous dispersion of the water-dispersible polyester resin (B), the glycidyl group-containing radically polymerizable unsaturated monomer alone or the glycidyl group-containing radically polymerizable unsaturated monomer is used. You may manufacture by superposing | polymerizing the polymerizable radically polymerizable unsaturated monomer. At this time, a surfactant or a polymerization initiator may be used. The surfactant and the polymerization initiator can be used without limitation as long as they are usually used in emulsion polymerization. As a specific example, as the surfactant, an anionic surfactant, a nonionic surfactant, or a non-reactive surfactant can be used, and these may be used in combination. The polymerization initiator is a radical polymerizable initiator, and a peroxide compound or a nitrogen compound such as azobisisobutyronitrile can be used.

The water-dispersed composition of the present invention may further contain an antifoaming agent, a wetting agent, a surfactant, a thickener, a plasticizer, an antioxidant, an ultraviolet absorber, an antiseptic, a crosslinking agent, and the like, if necessary. Good.

In one embodiment of the present invention, the crosslinking agent may include a compound represented by the following Formula 1, but is not limited thereto. By including the crosslinking agent of the following chemical formula 1, the reaction rate is even faster, the primer layer can be formed at a low temperature, and after the formation of the primer layer, some oligomers that can flow out by heating can be completely blocked. it can.

（前記式中、Ａ１〜Ａ３は、それぞれ独立して、化学結合であるか、（Ｃ１−Ｃ１０）アルキレンから選択され、Ｒ１〜Ｒ３は、それぞれ独立して、水素、（Ｃ１−Ｃ１０）アルキルから選択される。）

(Wherein, A1 to A3 are each independently a chemical bond or selected from (C1-C10) alkylene, and R1 to R3 are each independently selected from hydrogen and (C1-C10) alkyl. Selected.)

Said alkyl or alkylene includes both straight or branched chains.

More specifically, A1 to A3 are each independently selected from (C1-C5) alkylene, and R1 to R3 are each independently selected from (C1-C5) alkyl.

As a more specific example of the chemical formula 1, a compound of the following chemical formula 2 may be used.

The compound of Formula 2 has a reaction temperature of 120 to 140 ° C., more specifically about 130 ° C., while increasing the reaction rate, and the reaction occurs in the preheating zone during the polyester film forming process. In this way, it is possible to react with the glycidyl group of the acrylic resin (A) in which the glycidyl group-containing radical polymerizable unsaturated monomer is copolymerized, and to form a primer coating having a denser structure. it can.

Therefore, when the compound of Formula 2 is used, it can be applied in an in-line coating process during the film forming process of the polyester film, which eliminates the need for another primer layer coating process after the film is manufactured. In addition to being simple, the film can be stretched after coating by an in-line coating process to form a uniform coating thickness, and thus a polyester film having excellent optical properties can be produced.

The cross-linking agent is a total solid of an acrylic resin (A) obtained by copolymerizing an aqueous dispersion of a water-dispersible polyester resin (B) and a glycidyl group-containing radical polymerizable unsaturated monomer in an aqueous dispersion composition. It is preferable to use 1 to 40 parts by weight, more preferably 5 to 20 parts by weight with respect to 100 parts by weight of the content. When the amount is less than 1 part by weight, the effect of use is insignificant, and when the amount exceeds 40 parts by weight, the properties of the main binder can be lowered and the adhesive strength can be lowered.

In the water-dispersed composition of the present invention, the water-dispersible polyester resin (B) may be obtained by copolymerization of a dicarboxylic acid component containing a sulfonic acid alkali metal salt compound and a glycol component containing diethylene glycol. Good.

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

Examples of the dicarboxylic acid component include phthalic acid, terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, 2,5-dimethyl terephthalic acid, 2,6-naphthalenedicarboxylic acid, and biphenyldicarboxylic acid. Aliphatic dicarboxylic acids such as adipic acid and sebacic acid, and finger ring dicarboxylic acids such as cyclohexanedicarboxylic acid can be used.

Specific examples of the sulfonic acid alkali metal salt compound include alkali metal salts such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfoisophthalic acid, and 4-sulfonaphthalenic acid-2,7-dicarboxylic acid. 6 to 20 mol% may be used. When it is used at less than 6 mol%, the dispersion time of the resin in water becomes long and the dispersibility is low, and when it is used at more than 20 mol%, the water resistance can be lowered.

As the glycol component, diethylene glycol and aliphatic having 2 to 8 carbon atoms or finger ring glycol having 6 to 12 carbon atoms can be used. Specific examples include ethylene glycol, 1,3-propanediol, 1,2-propylene glycol, neopentyl glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, , 2-cyclohexanedimethanol, 1,6-hexanediol, P-xylene glycol, triethylene glycol and the like can be used. Under the present circumstances, it is preferable to contain diethylene glycol in 20-80 mol% in all the glycol components.

The water-dispersible polyester resin (B) preferably has a number average molecular weight of 1000 to 50000, more preferably 2000 to 30000. When the number average molecular weight is less than 1000, the oligomer blocking effect is negligible, and when it exceeds 50,000, water dispersibility may be difficult.

As the water-dispersible polyester resin (B), water or water containing an aqueous solvent and heated and stirred at 50 to 90 ° C. and uniformly dispersed in water are used. The aqueous dispersion thus produced preferably has a solid concentration of 30% by weight or less, more preferably 10 to 30% by weight, for uniform dispersion. As the aqueous solvent, alcohols such as methanol, ethanol and propanol, polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol and glycerin can be used.

Next, the acrylic resin (A) in which a glycidyl group-containing radical polymerizable unsaturated monomer is copolymerized will be described.

Acrylic resin (A) copolymerized with a glycidyl group-containing radical polymerizable unsaturated monomer can be copolymerized with a homopolymer of a glycidyl group-containing radical polymerizable unsaturated monomer or with a glycidyl group-containing radical polymerizable unsaturated monomer. It is a resin copolymerized with other radical polymerizable unsaturated monomers.

The acrylic resin may contain a glycidyl group-containing radical polymerizable unsaturated monomer as a copolymerization monomer in an amount of 20 to 80 mol% in all monomer components. The glycidyl group-containing radically polymerizable unsaturated monomer improves the strength of the coating film of the primer layer by a crosslinking reaction and increases the crosslinking density, so that the oligomer can be prevented from flowing out. As specific examples, glycidyl ethers such as glycidyl acrylate, glycidyl methacrylate, and aryl glycidyl ether can be used.

Examples of the radical polymerizable unsaturated monomer copolymerizable with the glycidyl group-containing radical polymerizable unsaturated monomer include vinyl ester, unsaturated carboxylic acid ester, unsaturated carboxylic acid amide, unsaturated nitrile, unsaturated carboxylic acid, allyl compound, Examples thereof include nitrogen-containing vinyl monomers, hydrocarbon vinyl monomers, and vinyl silane compounds. As the vinyl ester, vinyl propionate, vinyl stearate, vinyl chloride and the like can be used. As unsaturated carboxylic acid ester, 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, butoxymethylol acrylamide and the like can be used. As the unsaturated nitrile, acrylonitrile or the like can be used. As the unsaturated carboxylic acid, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, maleic acid acidic ester, fumaric acid acidic ester, itaconic acid acidic ester and the like can be used. 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 can be used. As the hydrocarbon vinyl monomer, ethylene, propylene, hexene, octene, styrene, vinyl toluene, butadiene and the like can be used. As the vinylsilane compound, dimethylvinylmethoxysilane, dimethylvinylethoxysilane, methylvinyldimethoxysilane, methylvinyldiethoxysilane, gamma-methacryloxypropyltrimethoxysilane, gamma-methacryloxypropyldimethoxysilane and the like can be used.

The water-dispersible resin composition according to one aspect of the present invention includes an acrylic resin (A) copolymerized with a glycidyl group-containing radical polymerizable unsaturated monomer, which is a binder resin, and a water-dispersible polyester resin (B). A water-dispersible or water-soluble composition having a solid content of 0.5 to 10% by weight is preferred. More specifically, the acrylic resin (A) copolymerized with the glycidyl group-containing radical polymerizable unsaturated monomer and the solid content of the water-dispersible polyester resin (B) of 0.5 to 10% by weight, the balance And, if necessary, may further contain additives such as wetting agents and dispersing agents. The wetting agent is used to improve the coating properties. Specific examples include modified silicones such as Q2-5212 manufactured by Dow Corning, TEGO WET 250 manufactured by ENBODIC, and BYK348 manufactured by BYK CHEMIE. A wetting agent can be used, but is not limited thereto. The wetting agent is preferably used in an amount of 0.1 to 0.5% by weight. When the amount is within the above range, the target coating property can be improved, but is not limited thereto.

In the present invention, the primer layer may have a dry coating thickness of 20 to 300 nm. When the dry coating thickness is less than 20 nm, the oligomer blocking property does not sufficiently appear, and when it exceeds 300 nm, a blocking phenomenon may occur after the film is wound.

The production of the polyester multilayer film including the base material layer and the skin layer of the present invention is not limited thereto, but can be obtained by extrusion melting with at least two or more melt extruders, casting, and biaxial stretching. More specifically, the polyester is extruded by one extruder, and the polyester and additives such as inorganic particles such as silica, kaolin, and zeolite are simultaneously melt-extruded by another extruder, and then the respective melts. Are combined in a feed block and coextruded and cast, cooled, and then biaxially stretched in order.

In the present invention, the antistatic composition and the water-dispersible primer composition may be applied by an in-line application method during the production process of the polyester film. That is, at the time of production of the polyester base film, it can be produced by stretching by applying by an in-line coating method before stretching, or after primary stretching and before secondary stretching, and in the process of secondary stretching and heat setting. Water will evaporate by heating, and a primer layer can be formed. The application method is not limited as long as it is a known application method.

The polyester multilayer film of the present invention has a surface resistance of 105 to 109 Ω / sq before heat treatment, a haze of 2% or less, a total light transmittance of 90% or more, and at 85 ° C. and 85%. After maintaining for 72 hours, the haze change rate ΔH1 satisfies the following formula 2, the light transmittance change rate ΔTT1 satisfies the following formula 3, and the antistatic layer and the primer layer are held on the polyester base film when evaluating the adhesive strength. It can be seen that the optical properties are excellent under high-temperature and high-humidity conditions.

[Formula 2] ΔH1 <0.5%

In Formula 2, ΔH1 = Hf−Hi, where Hf is the haze of the film after being maintained at 85 ° C. and 85% for 72 hours, and Hi is the haze of the film before heating.

[Formula 3] ΔTT1 <0.5%

In Formula 3, ΔTT1 = TTf−TTi, where TTf is the total light transmittance of the film after being maintained at 85 ° C. and 85% for 72 hours, and TTi is the total light of the film before heating. Transmittance.

Further, after maintaining at 60 ° C. and 95% for 120 hours, the surface resistance is 105 to 109 Ω / sq, the haze change rate ΔH2 satisfies the following formula 4, and the light transmittance change rate ΔTT2 is expressed by the following formula 5. It can be seen that, when the adhesive strength is evaluated, both the antistatic layer and the primer layer can satisfy the physical properties held by the polyester base film.

[Formula 4] ΔH2 <1.0%

In Formula 4, ΔH2 = Hf−Hi, where Hf is the haze of the film after being maintained at 60 ° C. and 95% for 120 hours, and Hi is the haze of the film before heating.

[Formula 5] ΔTT2 <1.0%

In Formula 5, ΔTT1 = TTf−TTi, where TTf is the total light transmittance of the film after being maintained at 60 ° C. and 95% for 120 hours, and TTi is the total light of the film before heating. Transmittance.

A hard coating layer, an adhesive layer, a light diffusion layer, an ITO layer, a printing layer, etc. may be formed on the upper part of the polyester film of the present invention, and even after heating after forming such a functional coating layer, Since the outflow of the oligomer is blocked and the optical properties are maintained, the polyester film of the present invention is suitable for use as an optical film.

Hereinafter, based on an Example and a comparative example, this invention is demonstrated in detail. However, the following examples and comparative examples are merely examples for explaining the present invention in more detail, and the present invention is not limited by the following examples and comparative examples.

1) Intrinsic viscosity (IV; dl / g) To 100 ml of a reagent in which phenol and 1,1,2,2-tetrachloroethanol were mixed at a weight ratio of 6: 4, 0.4 g of PET pellet (sample) was added. The solution was transferred to an Ubbelohde viscometer after being dissolved for 90 minutes, maintained in a thermostatic bath at 30 ° C. for 10 minutes, and the falling seconds of the solution were determined using a viscometer and an aspirator. After determining the falling seconds of the solvent by the same method, R.I. V value and I.V. V value was calculated.

In the following mathematical formula, C represents the concentration of the sample.

[Mathematical Formula 1] R.I. V = sample falling seconds / solvent falling seconds

2) Oligomer content (%) As a method for quantifying oligomers, chloroform was added to sample solvent 1,1,1,3,3,3-hexafluoro-2-propanol and dissolved at room temperature. Precipitate as a polymer. Then, after preparing a calibration curve of cyclic trimer CT-3, which is a standard substance, using LC analysis equipment, the purity of the cyclic oligomer is determined by sample analysis. As analytical equipment, LC (liquid chromatography) and Agilent 1100 series were used.

3) Content of DEG (Diethylene glycol) (%) In order to measure the content of diethylene glycol (DEG, Diethylene Glycol), 1 g of a sample was placed in a 50 mL container, 3 mL of monoethanolamine was added, and a hot plate was used. After completely dissolving the sample by heating, the sample was cooled to 100 ° C., a solution prepared by dissolving 0.005 g of 1,6-hexanediol in 20 mL of methanol was added, and neutralized by adding 10 g of terephthalic acid. The obtained neutralized solution was filtered using a funnel and filter paper, and then the filtrate was subjected to gas chromatography to measure the content (% by weight) of DEG. The GC analysis was measured using a Shimadzu GC analyzer according to the Shimadzu GC manual.

4) The test piece of the film formed with haze and total light transmittance was measured using HAZE METER (model: NDH 5000, manufactured by Nippon Denshoku Industries Co., Ltd.).

5) Haze change rate (ΔH) and light transmittance change rate (ΔTT) The film is put in a box having a height of 3 cm, a width of 21 cm, and a length of 27 cm with the upper part opened, and 85 ° C., 85%, 72 Hr, and Each was heat-treated at 60 ° C., 95%, and 120 Hr, and allowed to stand for 5 minutes. Thereafter, the haze change rate (ΔH) and the light transmittance change rate (ΔTT) were measured using HAZE METER (model: NDH 5000, manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS K 715 standard.

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

[Calculation Formula 1] ΔH = Hf−Hi

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

[Calculation Formula 2] ΔTT = TTf−TTi In the above formula, TTf is the total light transmittance of the film after being maintained at 85 ° C., 85% for 72 hours or 60 ° C., 95% for 120 hours, and TTi 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 measuring method, the surface resistance was measured under the conditions of 25 ° C., 50% Rh, 10 V, 10 seconds using ST-4 equipment manufactured by Simco.

Further, after the sample was maintained at 85 ° C. and 85% for 72 hours or at 60 ° C. and 95% for 120 hours, the change in surface resistance was also measured.

7) Measurement of coating thickness The coating thickness was measured using a TEM equipment.

8) Drop shape analyzer DSA100 (manufactured by KRUSS Co., Ltd.) was used as a water contact angle contact angle measuring device, 4 μl of water was dropped, and measurement was performed by the tangent method. When the contact angle is 90 ° or more, it indicates that the usage standard is met.

9) Measurement of silicone adhesive strength Adhesive strength was measured according to ASTM B905.

After production of the film, Momentive PSA6574 was applied as a silicone adhesive to the surface coated with the antistatic coating composition, and dried at 150 ° C. for 4 minutes to form a silicone coating layer having a thickness of 30 μm. After the adhesive-coated film was placed in hot water for 2 hours, the presence or absence of dropping was confirmed during rubbing, and the adhesion between the antistatic coating layer and the silicone adhesive layer was evaluated.

○: The silicone adhesive layer is maintained as it is. X: A part of the silicone adhesive layer is dropped or completely dropped.

10) Evaluation of the degree of migration of oligomers in the primer layer and the antistatic layer After the polyester film was cut into a size of 100 mm × 100 mm, it was kept at 85 ° C., 85% for 72 hours or 60 ° C., 95% for 120 hours, a constant temperature and humidity chamber Aging. Then, using a reflection mode of a microscope (Leica, DM 2500M), 27000 μm 2 was observed when observed at a magnification of 500 times. The surface of such an area was observed 10 times, and the number of oligomer particles observed 10 times was averaged. The average size of the oligomer particles is 15 ± 5 μm, and is observed like black dots during observation.

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

11) Adhesive strength of base film, primer layer and antistatic layer A metal plate with a width of 25 mm x 25 mm and a weight of 915 g is placed on an ultrafine fiber cloth and rubbed 10 times. Force evaluation was performed.

○: The coating layer is maintained as it is. X: A part or all of the coating layer is dropped.

12) Refractive index The refractive index was measured using an ABBE refractometer (manufactured by ATAGO, DR-M2) in accordance with ASTM D1218.

[Production Example 1] Production of water-dispersible antistatic composition (1) Clevios P (manufactured by Heraeus, solid content 1.3 wt%) 60 wt%, water 6 wt%, isopropyl alcohol 5 wt% as a conductive polymer aqueous dispersion Is added to a mixing vessel and stirred for 1 hour, and 2 wt% of 2-amino-2-methyl-1-propanol (Alfa aesar, 95%) is further added to the mixing vessel and further stirred for 1 hour, and as an aqueous polyurethane binder resin. 20 wt% of NeoRez R-972 (Neo resins, solid content 34 wt%) was added and stirred again for 30 minutes, and then 5 wt% of dimethyl sulfoxide and 1 wt% of silicone wetting agent (BYK, BYK 348) were added to the mixing container. A primary antistatic composition was prepared by adding 1 wt% of a slip agent (Q8-8211, manufactured by Dow corning) and further stirring for 1 hour.

Then, the primary antistatic composition was subjected to secondary dilution production. At this time, the water-dispersible antistatic composition (1) is produced by mixing 40 wt% of the primary antistatic composition, 59.6 wt% of water, and 0.4 wt% of a fluorine-based wetting agent (Zonyl FSH). did.

[Production Example 2] As a production binder for the water-dispersible primer composition (2), an acrylic resin (A) copolymerized with a glycidyl group-containing radical polymerizable unsaturated monomer and a water-dispersible polyester resin (B). A binder having a solid content weight ratio of (A) :( B) = 50: 50 was used.

The acrylic resin (A) contains 50 mol% of a glycidyl group-containing radical polymerizable unsaturated monomer as a copolymerization monomer in all monomer components, and the water-dispersible polyester resin contains diethylene glycol in all glycol components. The sulfonic acid alkali metal salt compound was contained in an amount of 10 mol% in the total acid component, and the weight average molecular weight was 32,000.

The water-dispersible polyester resin (B) is 50 mol% of diethylene glycol and 50 mol% of glycol component of 50 mol% of ethylene glycol, and 50 mol of acid component of 15 mol% sulfoterephthalic acid and 85 mol% terephthalic acid. %, Which was polymerized using a polymer having a weight average molecular weight of 12,000.

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

[Production Example 3] Production of water-dispersible antistatic composition (2) Clevios P (manufactured by Heraeus, solid content 1.3 wt%) 30 wt%, water 6 wt%, isopropyl alcohol 5 wt% as a conductive polymer aqueous dispersion Is added to a mixing vessel and stirred for 1 hour, and 2 wt% of 2-amino-2-methyl-1-propanol (Alfa aesar, 95%) is further added to the mixing vessel and further stirred for 1 hour, and as an aqueous polyurethane binder resin. NeoRez R-972 (manufactured by Neo resins, solid content 34% by weight) was added to 50 wt% and stirred again for 30 minutes, and then dimethyl sulfoxide 5 wt%, silicone wetting agent (BYK, BYK 348) 1 wt% in the mixing container. A primary antistatic composition was prepared by adding 1 wt% of a slip agent (Q8-8211, manufactured by Dow corning) and further stirring for 1 hour.

Then, the primary antistatic composition was subjected to secondary dilution production. At this time, the water-dispersible antistatic composition (2) was manufactured by mixing 40 wt% of the primary antistatic composition, 59.6 wt% of water, and 0.4 wt% of a fluorine-based wetting agent (Zonyl FSH). .

[Example 1] Production of polyester film Polyethylene having an intrinsic viscosity of 0.63, a diethylene glycol content of 0.96% by weight, and an oligomer content of 1.4% by weight as the base layer (B) The terephthalate chip was put into an extruder and melt extruded. The skin layer (A) has a polyethylene terephthalate chip having an intrinsic viscosity of 0.67, a diethylene glycol content of 0.8% by weight and an oligomer content of 0.5% by weight, and an average particle size of 0. Sheets were prepared by coextrusion casting with 3 layers of A / B / A using 5 μm silica particles at 50 ppm relative to the total weight of polyethylene terephthalate.

The sheet was stretched 3 times in the machine direction (MD) at 120 ° C. Thereafter, the water-dispersible antistatic composition (1) produced in Production Example 1 was coated on one side by the Bar Coating method, and the water-dispersible primer composition (2) produced in Production Example 2 was coated on the other side. After coating by a bar coating method, the film was stretched 3.5 times in the transverse direction (TD) at 150 ° C. Thereafter, heat treatment was performed at 230 ° C. with a five-stage tenter and 10% relaxation was performed at 200 ° C. in the machine direction and the transverse direction, thereby producing a 75 μm biaxially stretched film coated on both sides.

The manufactured polyester multilayer film has 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 is 50 nm, The dry coating thickness of the primer layer was 50 nm.

The physical properties were measured and shown in Table 1 and Table 2 below.

[Example 2] A polyester multilayer film was produced in the same manner as in Example 1 except that the dry coating thickness of the primer layer was changed to 100 nm.

The physical properties were measured and shown in Table 1 and Table 2 below.

[Example 3] A polyester multilayer film was produced in the same manner as in Example 1 except that the dry coating thickness of the primer layer was changed to 150 nm.

The physical properties were measured and shown in Table 1 and Table 2 below.

[Example 4] The same method as in Example 1, except that the base material layer was changed to 80% by weight of the total film weight and the skin layer was changed to 20% by weight of the total film weight. Thus, a polyester multilayer film was produced.

The physical properties were measured and shown in Table 1 and Table 2 below.

[Example 5] In Example 1, 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 is used as the base material layer (B). A polyester multilayer film was produced in the same manner as in Example 1 except that it was used.

The physical properties were measured and shown in Table 1 and Table 2 below.

[Example 6] Polyethylene terephthalate chips having an intrinsic viscosity of 0.63, a diethylene glycol content of 0.96% by weight, and an oligomer content of 1.4% by weight as the base layer (B) were put into an extruder. And melt extruded. The skin layer (A) includes a polyethylene terephthalate chip having an intrinsic viscosity of 0.67, a diethylene glycol content of 0.8% by weight, and an oligomer content of 0.5% by weight, and silica particles having an average particle size of 0.5 μm. Was used at 50 ppm based on the total weight of polyethylene terephthalate, and a sheet was produced by coextrusion casting with three layers of A / B / A.

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

Thereafter, heat treatment was performed at 230 ° C. with a five-stage tenter and 10% relaxation was performed at 200 ° C. in the machine direction and the transverse direction, thereby producing a 75 μm biaxially stretched film coated on both sides.

The manufactured polyester multilayer film has 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 is 50 nm, The dry coating thickness of the primer layer was 50 nm.

The physical properties were measured and shown in Table 1 and Table 2 below.

[Comparative Example 1] As the base material layer (B), a polyethylene terephthalate chip having an intrinsic viscosity of 0.63, a diethylene glycol content of 0.96 wt%, and an oligomer content of 1.4 wt% was charged into an extruder. And melt extruded. The skin layer (A) includes a polyethylene terephthalate chip having an intrinsic viscosity of 0.67, a diethylene glycol content of 0.8% by weight, and an oligomer content of 0.5% by weight, and silica particles having an average particle size of 0.5 μm. Was used at 50 ppm based on the total weight of polyethylene terephthalate, and a sheet was produced by coextrusion casting with three layers of A / B / A.

The sheet was stretched 3 times in the machine direction (MD) at 120 ° C. Thereafter, the water-dispersible antistatic composition (1) produced in Production Example 1 was coated on one surface by the Bar Coating method and then stretched 3.5 times in the transverse direction (TD) at 150 ° C.

Thereafter, heat treatment was performed at 230 ° C. with a five-stage tenter and 10% relaxation was performed at 200 ° C. in the machine direction and the transverse direction, thereby producing a 75 μm biaxially stretched film coated on one side.

In the manufactured polyester multilayer film, the base material layer 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. .

[Comparative Example 2] As the base material layer (B), a polyethylene terephthalate chip having an intrinsic viscosity of 0.63, a diethylene glycol content of 0.96 wt%, and an oligomer content of 1.4 wt% was charged into an extruder. And melt extruded. The skin layer (A) includes a polyethylene terephthalate chip having an intrinsic viscosity of 0.67, a diethylene glycol content of 0.8% by weight, and an oligomer content of 0.5% by weight, and silica particles having an average particle size of 0.5 μm. Was used at 50 ppm based on the total weight of polyethylene terephthalate, and a sheet was produced by coextrusion casting with three layers of A / B / A.

The sheet was stretched 3 times in the machine direction (MD) at 120 ° C. Thereafter, the water-dispersible antistatic composition (1) produced in Production Example 1 was coated on both sides by the Bar Coating method and then stretched 3.5 times in the transverse direction (TD) at 150 ° C.

Thereafter, heat treatment was performed at 230 ° C. with a five-stage tenter and 10% relaxation was performed at 200 ° C. in the machine direction and the transverse direction, thereby producing a 75 μm biaxially stretched film coated on both sides.

In the manufactured polyester multilayer film, the base layer 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 each. It was.

[Comparative Example 3] As the polyester base film, a single layer polyester film was used without co-extrusion with 3 layers as in Example 1.

A polyethylene terephthalate film 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 is charged into an extruder and melt extruded to produce a single layer polyethylene terephthalate film. A film was produced in the same manner as in Example 1, except that it was used.

[Comparative Example 4] As the base material layer (B), a polyethylene terephthalate chip having an intrinsic viscosity of 0.63, a diethylene glycol content of 0.96% by weight, and an oligomer content of 1.4% by weight was put into an extruder. And melt extruded. The skin layer (A) includes a polyethylene terephthalate chip having an intrinsic viscosity of 0.67, a diethylene glycol content of 0.8% by weight, and an oligomer content of 0.5% by weight, and silica particles having an average particle size of 0.5 μm. Was used at 50 ppm based on the total weight of polyethylene terephthalate, and a sheet was produced by coextrusion casting with three layers of A / B / A.

The sheet was stretched 3 times in the machine direction (MD) at 120 ° C. Thereafter, the water-dispersible antistatic composition (1) produced in Production Example 1 is coated on one surface by the Bar Coating method, and then water-dispersed containing a polyurethane binder having a refractive index of 1.58 on the other surface. The primer composition was coated by the Bar Coating method and then stretched 3.5 times in the transverse direction (TD) at 150 ° C.

Thereafter, heat treatment was performed at 230 ° C. with a five-stage tenter and 10% relaxation was performed at 200 ° C. in the machine direction and the transverse direction, thereby producing a 75 μm biaxially stretched film coated on one side.

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

[Comparative Example 5] A polyethylene terephthalate chip having an intrinsic viscosity of 0.63, a diethylene glycol content of 0.96% by weight, and an oligomer content of 1.4% by weight was placed in the extruder as the base material layer (B). And melt extruded. The skin layer (A) includes a polyethylene terephthalate chip having an intrinsic viscosity of 0.67, a diethylene glycol content of 1.3% by weight and an oligomer content of 0.7% by weight, and silica particles having an average particle size of 0.5 μm. Was used at 50 ppm based on the total weight of polyethylene terephthalate, and a sheet was produced by coextrusion casting with three layers of A / B / A.

The sheet was stretched 3 times in the machine direction (MD) at 120 ° C. Thereafter, the water-dispersible antistatic composition (1) produced in Production Example 1 was coated on one side by the Bar Coating method, and the water-dispersible primer composition (2) produced in Production Example 2 was coated on the other side. After coating by a bar coating method, the film was stretched 3.5 times in the transverse direction (TD) at 150 ° C.

Thereafter, heat treatment was performed at 230 ° C. with a five-stage tenter and 10% relaxation was performed at 200 ° C. in the machine direction and the transverse direction, thereby producing a 75 μm biaxially stretched film coated on both sides.

The manufactured polyester multilayer film has 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 is 50 nm, The dry coating thickness of the primer layer was 50 nm.

The physical properties were measured and shown in Table 1 and Table 2 below.

In Table 1, ΔH1 is the haze change rate measured after 85 ° C., 85%, 72 hours, and ΔH2 is the haze change rate measured after 60 ° C., 95%, 120 hours.

ΔTT1 is the change rate of the total light transmittance measured after 85 ° C., 85%, 72 hours, and ΔTT2 is the change rate of the total light transmittance measured after 60 ° C., 95%, 120 hours.

The adhesion 1) of the antistatic layer is the adhesion of the antistatic layer to the base film measured after 85 ° C., 85%, 72 hours, and the adhesion 2) of the antistatic layer is 60 ° C., 95%, 120 It is the adhesive force of the antistatic layer to the base film measured after time.

The primer layer adhesion 1) is the adhesion of the primer layer to the base film measured after 85 ° C., 85%, 72 hours, and the primer layer adhesion 2) is measured after 60 ° C., 95%, 120 hours. It is the adhesive force of the primer layer with respect to the base film.

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

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

As shown in Table 1, in Examples 1 to 6, the antistatic layer is formed on one surface and the primer coating layer is formed on the other surface, so that the surface resistance changes even after the high temperature and high humidity process. It was found that the number of oligomers in the antistatic layer and the primer layer was remarkably reduced.

As in Comparative Example 1, when the water-dispersible antistatic composition having the same composition as in Example 1 was used, when only the antistatic layer was formed on one side, the light transmittance was drastically increased. It was confirmed that it could not be used as an electronic material or optical film, and the number of oligomers was found to increase.

As in Comparative Example 2, it was found that the number of oligomers also increased when the water-dispersible antistatic composition was applied on both sides.

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

As shown in Table 2, it was confirmed that Examples 1 to 6 had little change in surface resistance and excellent antistatic properties even after undergoing a high temperature and high humidity process.

Claims (13)

A polyester base film, an antistatic layer formed on one surface of the polyester base film and containing a conductive polymer and an aqueous polyurethane binder, and formed on the other surface of the polyester base film, having a refractive index of 1.4 to 1. The polyester base film comprises a base material layer, and a skin layer in which at least one layer is laminated on both surfaces of the base material layer, and forms the skin layer. A polyester multilayer film having an oligomer content of 0.3 to 0.6% by weight, a diethylene glycol content of 0.1 to 1.2% by weight, and an intrinsic viscosity satisfying the following formula 1. [Formula 1] 1 <Ns / Nc ≦ 1.1 (In Formula 1, Ns is the intrinsic viscosity of the polyester resin constituting the skin layer, and Nc is the intrinsic viscosity of the polyester resin constituting the base material layer. ) The surface resistance before heat treatment is 105 to 109 Ω / sq, the haze is 2% or less, the total light transmittance is 90% or more, and the haze change rate is maintained at 85 ° C. and 85% for 72 hours. ΔH1 satisfies the following formula 2, the light transmittance change rate ΔTT1 satisfies the following formula 3, and [formula 2] ΔH1 <0.5% (in formula 2, ΔH1 = Hf−Hi, Hf is the haze of the film after being maintained at 85 ° C. and 85% for 72 hours, and Hi is the haze of the film before heating.) [Formula 3] ΔTT1 <0.5% (Formula 3 ΔTT1 = TTf−TTi, where TTf is the total light transmittance of the film after being maintained at 85 ° C. and 85% for 72 hours, and TTi is the total light transmittance of the film before heating. After maintaining for 120 hours at 60 ° C. and 95%, the surface resistance is 105-10. Omega / a sq, haze change rate △ H2 satisfies the following formula 4, the light transmittance rate of change △ TT2 satisfies the following equation 5, the polyester multilayer film of claim 1. [Formula 4] ΔH2 <1.0% (In the above Formula 4, ΔH2 = Hf−Hi, where Hf is the haze of the film after being maintained at 60 ° C. and 95% for 120 hours. Is the haze of the film before heating.] [Formula 5] ΔTT2 <1.0% (in Formula 5, ΔTT1 = TTf−TTi, where TTf is 60 ° C. and 95% for 120 hours. (The total light transmittance of the film after being maintained, and TTi is the total light transmittance of the film before heating.) After maintaining at 85 ° C, 85% for 72 hours or 60 ° C, 95% for 120 hours, the number of oligomers in the antistatic layer is less than 30, and 85 ° C, 85% for 72 hours or 60 ° C, 95% The polyester multilayer film according to claim 1, wherein the number of oligomers in the primer layer is less than 20 after being maintained for 120 hours. The antistatic layer has a water contact angle of 90 ° or more, and a silicone adhesive was applied on the antistatic layer, left in water at 100 ° C. for 2 hours, and then evaluated for adhesive strength according to ASTM B905. The polyester multilayer film of claim 1, wherein the silicone coating layer is sometimes retained. The polyester multilayer film according to claim 1, wherein the antistatic layer is formed by applying an antistatic composition containing a conductive polymer solution, an aqueous polyurethane binder solution, an organic solvent, and water. The polyester multilayer film according to claim 5, wherein the organic solvent is any one or two or more mixed solvents selected from alcohol-based organic solvents, aprotic highly polar organic solvents, and amide-based organic solvents. . The said antistatic layer is a polyester multilayer film of Claim 1 containing 1-30 weight% of conductive polymers and 70-99 weight% of water-based polyurethane binders in solid content of 100 weight%. The polyester multilayer film according to claim 1, wherein the conductive polymer is polyethylene dioxythiophene doped with polystyrene sulfonate (PEDOT: PSS). The polyester multilayer film according to claim 1, wherein the primer layer includes any one or two or more selected from an acrylic resin, a polyester resin, and a urethane resin. The primer layer includes a binder resin in which a weight ratio of an acrylic resin copolymerized with a glycidyl group-containing radical polymerizable unsaturated monomer and a water-dispersible polyester resin is 20 to 80:80 to 20. A polyester multilayer film as described in 1. The polyester multilayer film according to claim 1, wherein the polyester base film has a thickness of 12 to 250 μm, a base material layer of 60 to 90% by weight, and a skin layer of 10 to 40% by weight. The polyester multilayer film according to claim 1, wherein the dry coating thickness of the antistatic layer is 10 to 500 nm, and the dry coating thickness of the primer layer is 20 to 300 nm. The polyester multilayer film according to any one of claims 1 to 12, wherein at least one functional coating layer selected from a release coating layer, an adhesive layer, a hard coating layer, and a printing layer is formed on the polyester multilayer film. An optical film formed.