KR20170004940A - Uv-cut coating compostion and uv-cut film using same - Google Patents

Abstract

Disclosed in the present invention are a coating composition and a thermoplastic resin film using the same. The coating composition is used to form coating layers on one side or both sides of a substrate film of a thermoplastic resin, such as polyester, typically used for optical films, wherein the coating composition shows excellent UV-shielding properties and optical characteristics with the optical film laminated on the substrate film; and has excellent ink adhesion, stain resistance with respect to the film surface, and excellent surface smoothness. The present invention provides a water-dispersible polymer coating composition, which is used as a coating composition for forming coating layers on one side or both sides of a substrate film of thermoplastic resin, and comprises: 1-40 wt% of a water-dispersible binder resin; 0.1-30 wt% of a UV blocker; 0.1-10 wt% of an inorganic oxide; 0.25-15 wt% of a curing agent; 0.01-5 wt% of a wetting agent; 1-20 wt% of an organic solvent; and 40-97.5 wt% of water. Also, the present invention provides a UV-shielding film using the same.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a UV-blocking coating composition and a UV-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet barrier coating composition and an ultraviolet barrier film using the same, and more particularly to an ultraviolet barrier coating composition for improving ultraviolet barrier properties of an optical film laminated with a primer coating layer.

Generally, a polyester film has a stable chemical structure, has high mechanical strength, is superior in physical properties such as heat resistance, dimensional stability, chemical resistance and transparency, and is used as an optical base film in display fields such as LCD, LED and OLED , Magnetic recording media, capacitors, seasonal insulating materials, packaging, windows, solar back sheets, and the like.

Among them, films for windows, solar photovoltaic sheets and the like are required to have ultraviolet shielding function. Ultraviolet rays reaching the earth from the sun can be classified into ultraviolet A (UVA, wavelength 320 to 390 nm), ultraviolet B (UVB, 280 to 320 nm) and ultraviolet C (UVC, 200 to 280 nm) . Among them, UVC is mostly absorbed by ozone existing in the air layer before reaching the surface of the earth. UVB, which is harmful to the skin, reaches a large amount of the earth surface when the sunlight is strong, and some glass can also penetrate the building glass plate. Since UVA has a long wavelength and high transmittance, it has a large amount reaching the surface of the earth. Compared with UVB and UVC, the destructive strength of the material is weak, but its quantity is very large. Therefore, an ultraviolet ray shielding effect is indispensably required in industrial films such as films for windows and solar back sheets.

In the case of film for windows, it is attached to a window of a home, an office, or a vehicle for the purpose of shielding ultraviolet rays coming into the inside of the vehicle or outside of the building, and is used to block the ultraviolet rays and to provide a visual And stability of vision and ease of securing visibility. In the case of solar back sheets, internal components such as solar cells and EVA fillers inside the module are very vulnerable to external environments such as temperature, humidity, and ultraviolet rays. Therefore, they have durability against external environments such as weather resistance, light resistance and ultraviolet . In addition, it is possible to prevent a yellowing phenomenon of a diffusion sheet or the like which may be caused by ultraviolet rays in a backlight unit (BLU) of a display field, thereby preventing problems such as reduction of BLU luminance and shortening of life due to yellowing. It is possible to apply and use it in the optical and industrial use by adding the ultraviolet ray shielding property to the polyester film.

In Korean Patent No. 1137970, as a conventional technique for ultraviolet ray shielding, ultraviolet ray shielding effect is imparted by blending an ultraviolet screening agent with a resin to prepare a master batch chip. However, in this technology, since a master batch chip is required to be formed in a process, the production efficiency is low in the process and the physical properties of the resin itself are inferior.

In developing a UV-curable film, the in-line coating method or the off-line coating method can be applied as a method of increasing the production efficiency in the process while maintaining the inherent physical properties of the film. Hereinafter, a description will be given of a technique related to a conventional ultraviolet shielding film.

Korean Patent Registration No. 0439121 discloses a three-layer structure of a mat layer having a surface gloss of 60% or less of 55% or less and a turbidity of 65% or less, a polyethylene terephthalate base layer, and a coating layer imparted with adhesiveness in a film stretching process Discloses a biaxially stretched polyester film comprising 0.01 to 5% by weight of an ultraviolet light stabilizer in at least one of the layers. However, this patent discloses a biaxially stretched polyester film which contains a UV stabilizer in a polyester film coextruded in a three- And as the content of ultraviolet stabilizer increases, there is a problem that the physical properties of the film are lowered.

Japanese Patent Registration No. 4014446 discloses an aqueous dispersion containing a zinc oxide ultrafine particle aqueous dispersion in an amount of 1 to 400 parts by mass based on 100 parts by mass of a polyolefin resin and being substantially free of a nonvolatile water- Discloses a technique for applying an ultraviolet barrier film to various substrates, in particular, a thermoplastic resin film such as polyethylene terephthalate, polypropylene, or nylon 6, but this patent discloses a technique in which a water-dispersible inorganic zinc oxide dispersion is coated with a polyolefin resin Coating with a mixed water-dispersible coating agent. Since the UV blocking property and the optical characteristic are relatively inversely related to the presence of only the inorganic oxide, there is a problem that it is difficult to meet the appropriate value.

Korean Patent Laid-Open Publication No. 2011-0025405 discloses a method in which a PET film is applied as a base to a vacuum sputtering chamber, and a vapor deposition process is performed on one surface of the film by vacuum sputtering to form an ultraviolet barrier layer, Discloses a film which forms an adhesive layer on the other side of a transparent substrate and provides a thin film having a high blocking ratio of ultraviolet rays and prevents discoloration and oxidation, However, this patent has a problem that the productivity is deteriorated because the ultraviolet barrier layer is formed by a vapor deposition technique using vacuum sputtering.

Korean Patent Laid-Open Publication No. 2011-0135767 discloses an ultraviolet and infrared ray shielding film using inorganic oxides, which comprises a film layer composed of a transparent polyester (PET) film or a transparent film having similar characteristics, and a film layer efficiently blocking ultraviolet rays and infrared rays An ultraviolet barrier coating agent in which an inorganic oxide having an ultraviolet ray absorbing function is dispersed is coated on one surface of the film layer and an infrared ray blocking coating agent in which an inorganic oxide capable of blocking infrared rays is dispersed on the opposite surface is coated with an inorganic oxide A pressure-sensitive adhesive layer is formed to provide a film for blocking ultraviolet rays and infrared rays. In addition, although the ultraviolet shielding inorganic oxide has a structure in which titanium oxide particles having a size of several nanometers to 200 nanometers are coated with calcium phosphate or silicon having an ultraviolet ray absorbing function, Is relatively in inverse proportion, it is not easy to match the appropriate value, and there is a problem that productivity is deteriorated by forming a film by lamination without using a binder.

Korean Patent Publication No. 1406964 discloses a process for producing a PET resin characterized by adding a liquid UV stabilizer mixture containing 25 to 50 wt% of a UV stabilizer during the polycondensation process of the PET resin, The ultraviolet light stabilizer is included, and as the content of the ultraviolet light stabilizer increases, there is a problem that the physical properties of the film are deteriorated.

Korean Patent Registration No. 1297990 discloses an ultraviolet and infrared absorption barrier film including a vacuum glass bead. In this technique, an inorganic oxide is used as an ultraviolet barrier layer and a vacuum glass bead is contained in an infrared barrier layer, , Inorganic oxide and vacuum glass bead particles are used for UV shielding. However, since UV blocking property and optical characteristic are relatively inversely related to each other, it is not easy to meet the appropriate value and a film is formed by lamination without using a binder, There is a falling problem.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to provide a coating composition for forming a coating layer on one side or both sides of a thermoplastic resin base film such as polyester used for an optical film, Which is excellent in ultraviolet barrier property and optical properties, and which is excellent in ink adhesion, prevents stains on the surface of the film, and has excellent surface smoothness, and a thermoplastic resin film using the same.

In order to solve the above problems, the present invention provides a coating composition for forming a coating layer on one side or both sides of a thermoplastic resin base film, comprising: 1 to 40% by weight of an aqueous dispersion binder resin; 0.1 to 30% by weight of an ultraviolet screening agent; 0.1 to 10% by weight of an inorganic oxide; 0.25 to 15% by weight of a hardener; 0.01 to 5 wt% wetting agent; 1 to 20% by weight of an organic solvent; And 40 to 97.5% by weight of water.

The thermoplastic resin may be selected from the group consisting of a polyester resin, a cellulose resin, an acetate resin, a polyether sulfone resin, a polycarbonate resin, a polyamide resin, a polyimide resin, a polyolefin resin and an acrylic resin And at least one kind of water-dispersible polymer coating composition.

Dispersible binder resin is a resin having at least one functional group selected from the group consisting of a carbonyl group, a hydroxyl group, an acrylic group, a urethane group, a carboxyl group, an amide group and an imide group do.

Also, the UV blocking agent is one or more ultraviolet blocking agents selected from the group consisting of hindered amine type, salicylic acid type, benzophenone type, benzotriazole type and cyano acrylate type.

Also, the present invention provides an aqueous dispersion type polymer coating composition characterized in that the inorganic oxide is zirconium oxide (ZrO ₂ ) particles having a UV absorption capacity of 1 to 1,000 nm.

The curing agent may be a water-soluble thermosetting melamine resin, a water-soluble thermosetting melamine formaldehyde resin, an epoxy-based curing resin, a silane coupling agent, an aziridine-based curing agent, an oxazoline-based curing agent, a carbodiimide carbodiimide-based curing agent and blocked isocyanate. The present invention also provides an aqueous dispersion coating composition comprising the same.

And the wetting agent is a nonionic surface active agent or an anionic surface active agent.

And the organic solvent is isopropyl alcohol or ethanol.

According to another aspect of the present invention, there is provided a thermoplastic resin film having a coating layer formed on one side or both sides of a thermoplastic resin base film, wherein the coating layer is a primer coating layer formed of the coating composition.

According to the present invention, a primer coating layer is formed with a water-dispersible coating composition comprising an optimal amount of a specific water-dispersed binder resin, an ultraviolet screening agent, an inorganic oxide, a curing agent, a wetting agent, an organic solvent and water on the surface of a thermoplastic resin- A coating composition excellent in ultraviolet light shielding property, optical property and ink adhesion property with a laminated optical film, prevention of stain on the film surface and excellent in surface smoothness, and a thermoplastic resin film using the same can be provided .

Unlike coating of inorganic oxide and dye as a laminated film, the water dispersion coating liquid containing a UV blocking agent is easy to apply as an in-line coating as well as an off-line coating in addition to the addition of a UV blocking agent to an existing polyester film resin. A thermoplastic resin film having enhanced ultraviolet shielding effect, durability, adhesion performance and the like can be provided.

Hereinafter, preferred embodiments of the present invention will be described in detail. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Throughout the specification, when an element is referred to as "including " an element, it means that it can include other elements, not excluding other elements, unless specifically stated otherwise.

The present inventors have found that a coating composition for forming a coating layer on one side or both sides of a thermoplastic resin base film such as polyester used for an optical film and which is excellent in ultraviolet barrier property and optical property with an optical film laminated on a base film As a result of studies for development, it has been found that a primer coating layer is formed with a water-dispersible coating composition comprising a specific water-dispersed binder resin, ultraviolet screening agent, inorganic oxide, curing agent, wetting agent, organic solvent and water, And optical properties, as well as to provide a coating composition which is excellent in ink adhesiveness, prevention of occurrence of stains on the film surface and also in surface smoothness. Thus, the present invention has been achieved.

Accordingly, the present invention provides a coating composition for forming a coating layer on one side or both sides of a thermoplastic resin base film, comprising: 1 to 40% by weight of an aqueous dispersion binder resin; 0.1 to 30% by weight of an ultraviolet screening agent; 0.1 to 10% by weight of an inorganic oxide; 0.25 to 15% by weight of a hardener; 0.01 to 5 wt% wetting agent; 1 to 20% by weight of an organic solvent; And 40 to 97.5% by weight of water; and a thermoplastic resin film formed from the primer coating layer. Hereinafter, the thermoplastic resin applicable to the present invention and the components constituting the coating composition according to the present invention will be described in detail.

Examples of the thermoplastic resin applicable to the present invention include polyester resins, cellulose resins, acetate resins, polyether sulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, And a transparent polymer such as an acrylic resin. Of these, a polyester resin is preferable. Examples of the polyester resin include polyethylene terephthalate and polyethylene naphthalate, and polyethylene terephthalate is particularly preferable as described later. The film substrate may be used as a laminate body of one kind or two or more kinds of film materials, or a uniaxial or biaxially drawn product of the film may be used. In the present invention, the thickness of the thermoplastic resin film may be 5 to 500 μm or less, preferably 10 to 250 μm. If the thickness of the film is less than 5 탆, rigidity or mechanical strength may be insufficient, and if it is more than 500 탆, transparency may be deteriorated and it may be disadvantageous in terms of cost efficiency. Further, the thermoplastic resin film can be subjected to various surface treatments such as corona treatment.

When the base film on which the coating layer is formed by the coating composition according to the present invention is made of a polyester resin, the polyester resin can be obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol, and the aromatic dicarboxylic acid is not limited There may be used, for example, ethylene glycol, diethylene glycol, and the like. The aliphatic glycol may be, for example, ethylene glycol, diethylene glycol, have. Examples of such a polyester resin include polyethylene terephthalate and polyethylene-2,6-naphthalene dicarboxylate. However, the polyester resin is not limited thereto, and is preferably composed of polyethylene terephthalate in terms of balance of physical properties and cost , And the base film made of polyethylene terephthalate can be remarkably improved in chemical resistance, heat resistance, mechanical strength and the like by uniaxial or biaxial stretching.

The coating composition used for forming the primer coating layer on the thermoplastic resin base film according to the present invention is mainly composed of a water-dispersed binder resin serving as a binder for imparting the adhesiveness of the coating composition. Herein, the main component means a base resin except for water and additives among the components except for the solvent, in the coating composition formed of the water dispersion mixture liquid.

The water-dispersible binder resin is preferably a water-dispersible or water-soluble binder resin having a functional group such as a carbonyl group, a hydroxyl group, an acrylic group, a urethane group, a carboxyl group, an amide group or an imide group, Resin, and it is most preferable to use a polyurethane binder resin in consideration of the improvement of the UV barrier property.

The water-dispersed binder resin is contained in the coating composition in an amount of 1 to 40% by weight, preferably 5 to 30% by weight, more preferably 15 to 25% by weight. If the content of the water-dispersed binder resin is less than 1% by weight, the binder resin content is too low to uniformly form a thin coating layer on the surface of the film, which may result in a lot of unevenness in appearance, If it is more than 40% by weight, the coating layer becomes excessively thick due to the excessive content of the binder resin, and the viscosity of the coating solution may increase, and uneven coating may occur in the coating layer.

In the present invention, the ultraviolet screening agent is not particularly limited as long as it is uniformly dispersed in the water-dispersed binder resin and absorbs ultraviolet rays and is stable to ultraviolet rays. Examples of the ultraviolet screening agent include hindered amine type, salicylic acid type, benzophenone type, benzotriazole type, Acrylate-based ultraviolet screening agents can be preferably used.

Such an ultraviolet screening agent is contained in an amount of 0.1 to 30% by weight, preferably 5 to 25% by weight, more preferably 10 to 20% by weight in the entire coating composition. If the content of the ultraviolet screening agent is less than 0.1% by weight, the ultraviolet ray shielding effect may be insufficient. If the content of the ultraviolet screening agent is more than 30% by weight, unstable reaction with the binder resin may cause coagulation, Characteristics and the like may be degraded.

On the other hand, the benzophenone-based ultraviolet screening agents are widely used because of their excellent compatibility with resins, but ultraviolet ray absorbing ability of 340 nm or more is lower than that of benzotriazole based ultraviolet screening agents. Benzotrazole-based ultraviolet light absorbers have absorption ability over a wide area, and are mainly used in colorless products and high-grade products. In addition to the above ultraviolet screening agents, there are ultraviolet screening agents such as resorcinol monobenzoate, hydroxybenzoate and formamidine. Unlike ultraviolet absorbers, hindered amine-based ultraviolet screening agents are excellent in surface protection and can be applied to products having a thin cross section. The aromatic nucleus disclosed in U.S. Patent No. 4,446,262 and a cyclic imino ester compound having two carbon atoms forming part of an imino ester ring may be used as a UV blocking agent. In the case of iminoester-based ultraviolet screening agents, excellent thermal stability and oxidation stability have been reported.

In the present invention, the inorganic oxide is dispersed in an aqueous dispersion binder resin together with an ultraviolet screening agent as zirconium oxide (ZrO ₂ ) particles having a UV absorbing function and a size of 1 nm to 1,000 nm, preferably 1 to 200 nm . Zirconium oxide (ZrO ₂ ) absorbs ultraviolet rays having a wavelength of 280 to 390 nm at high efficiency, thereby increasing ultraviolet ray shielding efficiency and enhancing chemical durability, thereby providing a film having enhanced ultraviolet shielding performance and improved durability can do. Further, when a polyester film base material is used, the refractive index of the coating layer due to the zirconium oxide particles is increased to reduce the refractive index difference with respect to the polyester base material, thereby reducing the interference pattern (rainbow) caused by light .

Such inorganic oxides are contained in an amount of 0.1 to 10 wt%, preferably 0.5 to 5 wt%, and more preferably 1 to 2.5 wt% in the entire coating composition. If the content of the inorganic oxide is less than 0.1% by weight, the ultraviolet ray shielding effect and the durability are not greatly improved, and the refractive index can be hardly controlled. If the inorganic oxide content is more than 10% by weight, The haze of the film itself can be increased.

In the present invention, the curing agent is contained in an amount of 0.25 to 15% by weight, preferably 0.5 to 10% by weight, more preferably 0.5 to 2% by weight in the coating composition for curing between the water-dispersed binder resin and the film have. If the content of the curing agent is less than 0.25% by weight, a sufficient curing reaction may not be exhibited and whitening may occur. If the content of the curing agent is more than 15% by weight, the coating layer may become hard and the adhesion may be reduced.

The curing agent is not particularly limited but is preferably a water-soluble thermosetting melamine resin, a water-soluble thermosetting melamine formaldehyde resin, an epoxy-based curing resin, a silane coupling agent, an aziridine-based curing agent, oxazoline based curing agent, carbodiimide based curing agent, blocked isocyanate and the like can be used.

In the present invention, the surface tension of the coating liquid is changed to improve the wetting characteristics of the two phases to impart surface smoothness. To uniformly apply the coating liquid to the surface of the polyester film, a wetting agent is added in an amount of 0.01 to 5 wt% By weight, preferably 0.05 to 2% by weight, more preferably 0.1 to 0.5% by weight. If the content of the wetting agent is less than 0.01% by weight, the wettability may be decreased and the coating may be uneven. If the content of the wetting agent is more than 5% by weight, the viscosity of the coating liquid may increase.

The wetting agent is not particularly limited, but known non-ionic surfactants or anionic surfactants of the reactive type can be used.

In the present invention, the organic solvent is contained in an amount of 1 to 20% by weight, preferably 2 to 15% by weight, more preferably 3 to 20% by weight based on the coating composition for minimizing the wetting agent content and minimizing uniform application and bubble generation. To 10% by weight. If the content of the organic solvent is less than 1% by weight, the wettability may decrease and the coating may be uneven and the bubble inhibiting effect may not be exhibited. If the organic solvent content is more than 20% by weight, environmental pollution may be caused.

The organic solvent is not particularly limited, but an alcohol-based organic solvent such as isopropyl alcohol or ethanol may be used.

The coating composition according to the present invention comprises 40 to 97.5% by weight of the above components and water, preferably 45 to 80% by weight, more preferably 50 to 70% by weight. In addition, the coating composition according to the present invention may further contain another additive depending on each use within the scope of the present invention. As additional additives, a curing catalyst, a fluorescent dye, a plasticizer, an ultraviolet absorber, a pigment dispersant, a defoamer, and an antistatic agent may be added alone or in combination of two or more in a generally used range. 0.1 to 10 parts by weight based on 100 parts by weight of the composition.

The coating composition may be applied to one side or both sides of the polyester base film in a thickness of 1 to 20 탆, preferably 5 to 10 탆, and is preferably 10 to 1,000 nm, more preferably 50 to 500 nm, When the coating layer is formed to a thickness of 100 to 300 nm, sufficient adhesion can be exhibited while maintaining the UV barrier property and the optical property of the polyester film. If the thickness after the drying is less than 10 nm, the UV barrier property and adhesion may be deteriorated. If the thickness exceeds 1,000 nm, the optical characteristics of the film may be deteriorated, and blocking may occur when the film is wound.

The method for forming the coating layer is not particularly limited as long as it is known in the art and includes, for example, coating using a roll such as a gravure roll, a reverse roll, a reverse gravure roll, A coating method using a bar such as a Meyer bar or a coating method such as an air knife method may be used.

The formation of the coating layer in the present invention can be performed, for example, by coating the film in-line after the film coating, for example, after the longitudinal stretching, or by applying an off-line coating after the biaxially oriented film is produced.

On the other hand, the production of the polyester base film is not particularly limited and may be carried out by a method commonly known in the art to which the present invention belongs. For example, polyethylene terephthalate is melt-extruded on a rotary cooling drum maintained at 15 to 25 ° C to prepare an unstretched film (sheet), subjected to 2 to 5 times of longitudinal stretching at 100 to 130 ° C, The film is transversely stretched at 2 to 5 times at 150 DEG C and heat-set at 200 to 260 DEG C to produce a biaxially stretched polyester film.

Hereinafter, a specific embodiment of the present invention will be described.

Example 1

(I) a solution quantitatively determined to be 0.15% by weight of a nonionic surfactant as a wetting agent and 1% by weight of a water-soluble thermosetting methylation melamine formaldehyde resin (solid content concentration of about 98% by weight) as a curing agent, ) Is sufficiently dispersed in distilled water quantitatively determined to have a content of 63.75% by weight, such that 10% by weight of the benzotriazole-based ultraviolet screening agent and 0.1 to ₂ % by weight of zirconium oxide (ZrO ₂ ) particles having a size of 10 to 200 nm are contained. (Iii) The polyurethane resin is added to the solution (ii) in which the ultraviolet screening agent and the zirconium oxide (ZrO ₂ ) particles are dispersed in an amount of 20% by weight, and the mixture is stirred at 300 rpm for 20 minutes or more. (Iv) (iii) isopropyl alcohol was added to the solution in an amount of 5% by weight, and stirred at a speed of 300 rpm for at least 20 minutes to prepare a coating composition.

Example 2

A coating composition was prepared in the same manner as in Example 1, except that the amount of the ultraviolet ray blocking agent was 20% by weight, the amount of zirconium oxide particles was 0.5% by weight, and the amount of distilled water was 53.35% by weight.

Example 3

A coating composition was prepared in the same manner as in Example 1, except that the amount of the ultraviolet ray blocking agent was 20% by weight, the amount of zirconium oxide particles was 1% by weight, and the amount of distilled water was 52.85% by weight.

Example 4

A coating composition was prepared in the same manner as in Example 1 except that the amount of the ultraviolet ray blocking agent was 20% by weight, the amount of zirconium oxide particles was 2.5% by weight, and the amount of distilled water was 51.35% by weight.

Comparative Example 1

The coating composition was prepared in the same manner as in Example 1, except that the ultraviolet screening agent and the zirconium oxide particles were not mixed and the content was determined to be 73.85 wt% of distilled water.

Comparative Example 2

A coating composition was prepared in the same manner as in Example 1, except that 30% by weight of an ultraviolet screening agent was used instead of zirconium oxide particles, 2.5% by weight of silica sol was replaced with 41.35% by weight of distilled water.

Comparative Example 3

A coating composition was prepared in the same manner as in Example 1, except that 20% by weight of the ultraviolet screening agent was used instead of zirconium oxide particles, 5% by weight of silica sol was replaced by 48.85% by weight of distilled water.

Comparative Example 4

A coating composition was prepared in the same manner as in Example 1, except that 30% by weight of an ultraviolet screening agent was used in Example 1, 5% by weight of silica sol was used instead of zirconium oxide particles, and 38.85% by weight of distilled water was used.

Comparative Example 5

The coating composition was prepared in the same manner as in Example 1, except that the polyurethane resin was not mixed in Example 1, and the amount was determined to be 20% by weight of the ultraviolet screening agent, 2.5% by weight of the zirconium oxide particles and 71.35% Respectively.

The composition (unit: wt%) of the coating composition prepared according to the above Examples and Comparative Examples is shown in Table 1 below.

Test Example

In order to evaluate the optical characteristics, appearance, ink adhesion and the like of the polyester film having the primer coating layer formed from the coating composition according to the present invention, the coating composition prepared according to Examples and Comparative Examples was used to prepare a primer coating layer To prepare a polyester film. The produced films were evaluated according to the following measurement methods, and the results are shown in Table 2 below. Together with the evaluation of the physical properties of the film, the liquid stability of the coating composition was also evaluated.

[Film making and primer coating]

Polyethylene terephthalate was melt-extruded onto a rotating cooling drum maintained at about 20 캜 to prepare an unoriented film. The unstretched film is heated to about 2 to 5 times in the longitudinal direction at 100 to 130 DEG C by heating with heated rolls and an infrared heater, and then the coating composition is coated on one side of the in-line longitudinally stretched polyester film, The film was cured by thermal drying at 250 ° C., stretched in the transverse direction about 2 to 5 times at 130 to 150 ° C., and heat-set at 200 to 260 ° C. to prepare a biaxially stretched polyester film.

[Measurement and evaluation method]

(1) liquid stability

After the coating composition was mixed, the solution was stirred at 200 to 500 rpm for about 1 hour, and the solution was evaluated as " O "in the case of no coarse foreign matter and" X "

(2) Appearance

When the coated surface of the film was visually observed by using various light sources such as a fluorescent lamp, a halogen lamp, and an incandescent lamp, the size and the number of the uncoated portion were compared and evaluated according to the following criteria. The area of the uncoated area exceeded 1 mm x 3 mm and the inspection area was 1 m2. Quot ;, "? "For 2 to 3, and"? &Quot; for 4 to 10, respectively.

(3) Ink adhesion property

The coating is lightly coated on the coated surface with ink made by Shachiha Co., Ltd., dried for 1 minute, and then adhered to the CT-24 of the niche plate cell. After making two rounds of reciprocation with a 2 kg roller once, it is left for 2 minutes and then peeled 180 degrees at a peeling speed of 0.5 MPM using a peeling force tester. &Quot; "when the ink printed on the coated surface was not peeled off, and " X" when the ink printed on the coated surface was peeled or transferred by cell tape.

(4) Transmittance

Test method The total light transmittance of each polyester film was measured using a haze meter (NDH5000, Nippon Shokuhin Co., Ltd.) according to JIS K 7361.

(5) Haze

The haze of each polyester film was measured using a haze meter (NDH5000, manufactured by Nippon Shokuhin Co., Ltd.) according to the test method JIS K 7361.

(6) Transmittance (@ 365 nm wavelength)

The transmittance of each polyester film in the wavelength region of 365 nm was measured using a UV-Vis Spectrophotometer (UV-2450, Shimadzu) according to JIS K 7361 Test Method.

Referring to Table 2, it can be seen that the ultraviolet absorbing performance at a wavelength of 365 nm is remarkably lower in the case of the film prepared using the coating composition not containing the ultraviolet screening agent and the inorganic oxide (Comparative Example 1).

Even when an ultraviolet ray blocking agent is used, when the silica sol is used in an amount of 2.5 to 5 wt% instead of the zirconium oxide particle as the inorganic oxide (Comparative Examples 2 and 4), the transmittance at 365 nm wavelength is slightly reduced, Liquid stability, appearance, ink adhesion or haze characteristics are deteriorated.

In addition, when the polyurethane resin is not used (Comparative Example 5), the appearance and the ink adhesion property are deteriorated.

On the other hand, it can be confirmed that the primer-coated film (Examples 1 to 4) with the coating composition of the composition range according to the present invention has excellent ultraviolet barrier properties and optical properties, and is excellent in stability of the liquid bath, appearance and ink adhesion .

The preferred embodiments of the present invention have been described in detail above. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the meaning, range, and equivalence of the claims are included in the scope of the present invention Should be interpreted.

Claims (8)

A coating composition for forming a coating layer on one side or both sides of a thermoplastic resin base film,
15 to 25% by weight of an aqueous dispersion binder resin; 10 to 20% by weight of an ultraviolet screening agent; 1 to 2.5% by weight of an inorganic oxide; 0.5 to 2% by weight of a hardener; 0.1 to 0.5 wt% wetting agent; 3 to 10% by weight of an organic solvent; And 50 to 70% by weight of water, wherein the inorganic oxide is composed of zirconium oxide (ZrO ₂ ) particles having a size of 1 to 1,000 nm and having an ultraviolet ray absorbing function, Wherein the total light transmittance according to the method is not less than 90.64% and the transmittance in a wavelength region of 365 nm is not more than 3%.
[Total light transmittance measurement method]
Test method The total light transmittance of the film is measured using a haze meter (NDH5000, manufactured by Nippon Shokuhin Co., Ltd.) according to JIS K 7361.
[Measurement method of transmittance in 365 nm wavelength region]
Test method The transmittance of the film in the wavelength region of 365 nm was measured using a UV-Vis spectrophotometer (UV-2450, Shimadzu) according to JIS K 7361. The method of claim 1, wherein
Wherein the thermoplastic resin is selected from the group consisting of a polyester resin, a cellulose resin, an acetate resin, a polyether sulfone resin, a polycarbonate resin, a polyamide resin, a polyimide resin, a polyolefin resin and an acrylic resin At least one kind of water-dispersible polymer coating composition. The method according to claim 1,
Wherein the water-dispersed binder resin is a resin having at least one functional group selected from the group consisting of a carbonyl group, a hydroxyl group, an acrylic group, a urethane group, a carboxyl group, an amide group and an imide group. The method according to claim 1,
Wherein the ultraviolet screening agent is at least one ultraviolet screening agent selected from the group consisting of a hindered amine type, a salicylic acid type, a benzophenone type, a benzotriazole type, and a cyanoacrylate type. The method according to claim 1,
The curing agent is selected from the group consisting of a water-soluble thermosetting melamine resin, a water-soluble thermosetting melamine formaldehyde resin, an epoxy curing resin, a silane coupling agent, an aziridine curing agent, an oxazoline curing agent, a carbodiimide ) Based curing agent, and blocked isocyanate. ≪ RTI ID = 0.0 > 11. < / RTI > The method according to claim 1,
Wherein the wetting agent is a nonionic surfactant or an anionic surfactant. The method according to claim 1,
Wherein the organic solvent is isopropyl alcohol or ethanol. A thermoplastic resin film having a coating layer formed on one side or both sides of a thermoplastic resin base film, wherein the coating layer is a primer coating layer formed from the coating composition of any one of claims 1 to 7.