KR100781396B1 - Biaxially oriented polyester laminated film - Google Patents

Abstract

A biaxially oriented polyester laminated film is provided to reduce attachment of the dust by radiating all surface charges generated during a process, by applying an antistatic agent on at least one surface of the film. A biaxially oriented polyester laminated film is composed of: a biaxially oriented polyester film used as a base film; an antistatic layer formed on one surface of the biaxially oriented polyester film and coated with a composition containing water-dispersion acryl copolymer, an epoxy hardening agent, and a surfactant; and a surface layer formed on the other surface of the biaxially oriented polyester film and coated with the water-dispersion acryl copolymer. The surface resistance of the biaxially oriented polyester film coming into contact with the antistatic layer is 9.9x10^5~9.9x10^10ohm/square.

Description

Biaxially Oriented Polyester Laminated Film {BIAXIALLY ORIENTED POLYESTER LAMINATED FILM}

1 is a cross-sectional view of a biaxially oriented polyester laminated film according to the present invention.

The present invention relates to a biaxially oriented polyester laminated film, and more particularly, it is very suitable for an optical product requiring excellent transparency due to its excellent antistatic property and adhesion property with a substrate and friction coefficient, and a conventional antistatic agent is applied. Unlike the method, the biaxially oriented polyester laminated film which can reduce dust adhesion and reduce the process cost by dissipating all surface charges generated during the process by applying to at least one surface of the polyester laminated film during the process It is about.

Conventional transparent biaxially oriented polyester laminated films are not only excellent in transmittance, but also excellent in workability, adhesion, and coefficient of friction, and are widely used as optical materials. Despite these excellent properties, the problem of the transparent biaxially oriented polyester laminated film has become a big problem not only for quality problems but also for safety due to foreign matter adhesion, sparks, and electric shock due to static electricity.

In order to solve such electrostatic problems, various methods of imparting antistatic properties are used. For example, an internal addition method using an organic sulfonate or an organic phosphate, a method of depositing a metal compound, a method of applying conductive inorganic particles, The method of apply | coating anionic or cationic compound, etc. are mentioned.

However, the internal addition method using the organic sulfonate or organophosphate compound has advantages over time and stability, but has the disadvantage of inhibiting the inherent characteristics of the film support and the antistatic effect, and the method of depositing a metal compound; Although the method of apply | coating electroconductive inorganic particle is excellent in antistatic property and is currently used abundantly for the transparent conductive film use, the manufacturing cost is too high and it is used only for a specific use. On the other hand, the coating method using an anionic or cationic compound has been applied very widely because the antistatic effect is relatively good and advantageous in terms of manufacturing cost, but has a disadvantage of high humidity dependence. In addition, the polyester film has a high friction coefficient, which is inherent to the polymer, which makes blocking difficult, and thus it is difficult to handle during running, winding, and slitting. As a solution to these problems, silica, alumina, calcium carbonate, talc, clay, and dioxide are solved. There is a method of adding an inorganic compound such as titanium to the inside of the film, a method of producing internal particles having excellent affinity with PET, and a method of applying organic particles or inorganic particles to the surface of the film. There is a problem that there is a limitation in improvement of runability due to particle dropping or the like.

The present invention has been made to solve the above problems, and an object of the present invention is excellent biaxially oriented polyester lamination is very suitable for optical products that require excellent antistatic properties and adhesion properties and friction coefficient characteristics of the substrate It is to provide a film.

In addition, another object of the present invention is to apply an antistatic agent to at least one surface of the polyester laminated film during the process to dissipate all the surface charges generated during the process to reduce the phenomenon that the dust adheres, the biaxially oriented polyester laminated film By providing an antistatic coating during the process, it is intended to provide a property that can reduce the process process and cost to additionally coat the conventional antistatic layer offline.

The above and other objects and advantages of the present invention will become more apparent from the following description of the preferred embodiments with reference to the accompanying drawings.

Biaxially oriented polyester laminated film according to the present invention for achieving the above object is a base film, a biaxially oriented polyester film, and an antistatic layer formed on one surface of the biaxially oriented polyester film, an aqueous dispersion acrylic copolymer, epoxy An anti-static layer coated with a composition comprising a curing agent and a surfactant, and a surface layer formed on the other side of the biaxially oriented polyester film, consisting of a surface layer coated with a water-dispersible acrylic copolymer, the biaxial contact with the antistatic layer The surface resistance of the surface of the oriented polyester film is characterized by being 9.9x10 ⁵ kV / □ to 9.9x10 ¹⁰ kV / □.

Preferably, the antistatic layer is applied after uniaxial stretching of the biaxially oriented polyester film.

Preferably, the water-dispersible acrylic copolymer of the antistatic layer is a polyfunctional acrylate compound having at least one hydroxyl group, and the antistatic layer is characterized in that the thickness is 0.05 ~ 3.00㎛.

Preferably, the surface of the base film on which the antistatic layer is formed is characterized in that light transmittance of 90% or more, pencil hardness of HB or more, dynamic friction coefficient and static friction coefficient of 0.9 or less and 0.7 or less, respectively.

Hereinafter, the present invention will be described in detail with reference to embodiments and drawings of the present invention. These examples are only presented by way of example only to more specifically describe the present invention, it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples. .

Biaxially oriented polyester laminated film according to the present invention relates to a biaxially oriented polyester laminated film excellent in antistatic properties. It is characterized in that the antistatic agent is added during the manufacturing process of the biaxially oriented polyester laminated film, and the antistatic function performed during the manufacturing process is biaxially oriented so that the antistatic function can be maintained as it is after the coating process in the post processing. It is characterized in that the polyester laminated film. That is, the biaxially oriented polyester laminated film according to the present invention, unlike the conventional biaxially oriented polyester laminated film, by imparting an antistatic function during the manufacturing process, to reduce the economic cost through the improvement of the process, the base film has It maintains the optical properties, and is characterized in that the biaxially oriented polyester laminated film is excellent in antistatic properties, adhesiveness and coefficient of friction.

The biaxially oriented polyester laminated film according to the present invention forms an antistatic coating layer with a coating liquid consisting of an acrylic resin, an epoxy curing agent, and a surfactant on either side of the polyester base layer and the polyester base layer, and the polyester base layer It provides a biaxially oriented polyester laminated film in which the surface layer is laminated on the other side of (see Fig. 1).

The acrylic resin forming the antistatic layer of the biaxially oriented polyester laminated film according to the present invention has three or more, more preferably four or more, even more preferably five or more (meth) acryloyloxy groups in one molecule. A main component is a mixture consisting of at least one of monomers and prepolymers and at least one of monomers having one or two ethylenically unsaturated double bonds in one molecule. More specific examples include pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth ) Acrylic acid, dipentaerythritol hexa (meth) acrylate, trimetholpropane tri (meth) acrylate, pentaerythol triacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene diisocyanate urethane Prepolymer, pentaerythritol triacrylate isophorone diisocyanate urethane prepolymer, etc. can be used. These monomers and the prepolymer can be used 1 type or in mixture of 2 or more types. Especially the polyfunctional acrylate compound which has one or more hydroxyl groups among these is especially preferable because an adhesive of a base film can be improved when an epoxy type hardening | curing agent is used together.

The surfactant forming the antistatic layer of the biaxially oriented polyester laminated film according to the present invention can be used in a water-soluble coating liquid, and a known amount of anionic or nonionic surfactant is required to increase the wettability of the base film and to uniformly apply the coating liquid. It is preferable to apply | coat to a base film using it.

In the present invention, the antistatic coating layer is formed by applying a coating liquid having antistatic properties on the film after the primary stretching together with a resin binder or the like in order to impart antistatic properties. The antistatic agent used in the present invention may challenge the static electricity accumulated on the surface by external or friction with the aqueous dispersion coating liquid of the acrylic copolymer.

The property of the antistatic agent used in this process is the antistatic property has a value of 9.9 * 10 ¹⁰ or less, excellent compatibility with the resin, and excellent adhesion to the substrate layer. In addition, it should be a level that does not affect the optical properties of the conventional base film. In addition, the friction coefficient is low on one surface of the film to which the antistatic agent is treated, and the property that the viscosity of the antistatic coating solution should not be high is required.

The antistatic agent-treated layer is formed by applying a coating solution made of an epoxy curing agent and a surfactant, etc., in order to improve adhesion to the substrate layer.

At this time, the thickness of the layer to which the antistatic agent is applied is preferably 0.01 to 5.00 µm, more preferably 0.05 to 3.00 µm. If the thickness of the coating is thinner than 0.05㎛ the transparency is good but the adhesion is poor, if the thickness is more than 3㎛ excellent adhesion properties, but the transparency and coating properties are not preferred because it is poor. Additives may be used in the coating solution to improve coating properties and functionality, and organic additives, inorganic particles, antifoaming agents, and the like may be used as such additives.

On the other hand, the surface layer formed on the other side of the biaxially oriented polyester film according to the present invention is applied with a water-dispersible acrylic copolymer, such surface layer improves the optical transmittance of the optical function, and when coated in the post-processing process, Functions to improve adhesion.

EXAMPLE

Manufacturing method of biaxially oriented polyester laminated film

The manufacturing method of the biaxially-oriented polyester laminated | multilayer film which concerns on this invention is demonstrated. First, a polyester laminated film (hereinafter abbreviated as 'PET') will be described as an example of the base film, but the present invention is not limited thereto. Specific examples thereof may be a film made of polyester, polyolefin, polyamide, polyphenylene sulfide, acetate, polycarbonate, acrylic resin, or the like. Among them, a film made of a thermoplastic resin excellent in transparency, mechanical strength, dimensional stability and the like is particularly preferable.

The PET pallet containing 0.2 wt% of silica particles having an average particle diameter of 0.3 µm was vacuum dried at 180 ° C. for about 2 hours to sufficiently remove moisture, then fed to an extruder, melt-extruded at a temperature of 230 to 300 ° C., and T It is molded into a sheet shape from the female mold. The sheet-like article thus obtained is cooled and fixed on a mirrored cooling drum to obtain an unstretched sheet. At this time, it is preferable to use the electrostatic application method for the purpose of improving the adhesiveness with a cast drum. Then, 2 to 5 times extending | stretching is performed in the longitudinal direction of the roll which heated the obtained unstretched film at 70-120 degreeC. Longitudinal stretching is preferably a condition that lowers the crystal orientation and promotes thermal crystallization, and a method of stretching while heating with a radiant heater at the time of stretching is preferable. Subsequently, an antistatic coating layer was applied to the surface of the film uniaxially stretched with a coating liquid consisting of an antistatic resin, an epoxy curing agent, and a surfactant composed of a water-dispersible acrylic copolymer, and the film of the uniaxially stretched film The other surface is applied with a surface layer made of a water-dispersible acrylic copolymer. Thereafter, both ends of the film are gripped with clips, leading to the tenter. After preheating in the tenter, the film is stretched about 2 to 5 times in the width direction. Heat-treatment (approximately, glass transition temperature to melting point temperature of resin, 200 to 245 in case of PET) to complete the crystallization of the base film and curing of the coating film while further performing 3-10% of the lamination film stretched in the width direction. ℃). As the heat required for thermosetting used in the present invention, the air or inert gas, which has been heated to a temperature of at least 140 ° C. using a steam heater, an electric heater, an infrared heater or a far infrared heater, or the like, is sprayed onto the substrate and the coating film using a slit nozzle. The heat applied by contacting is enumerated, and heat by air heated to 200 ° C or higher is preferred, and heat by nitrogen heated to 200 ° C or higher is more preferable since the curing rate is high.

Example 1

In Example 1, 12.5% by weight of an antistatic resin consisting of a water-dispersible acrylic copolymer, 0.5% by weight of an epoxy curing agent, and 0.2% by weight of a surfactant were added to an agitator containing 86.8% by weight of water, followed by stirring. After preparing an antistatic coating solution, it is applied to one surface of the primary stretched film in the method of manufacturing the biaxially oriented polyester laminated film to form an antistatic coating layer, the other surface of the uniaxially stretched film on the other surface An acrylic copolymer was applied to form a surface layer, and then a biaxially oriented polyester laminated film was prepared.

 Example 2

The biaxially oriented polyester was prepared in the same manner as in Example 1, except that 4.2 wt% of an antistatic resin and 95.1 wt% of water (the amount of the epoxy watch hardener and the surfactant) of the water-dispersible acrylic copolymer were used. A biaxially oriented polyester laminated film was prepared according to the method for producing a laminated film.

Example 3

The biaxially oriented poly was prepared in the same manner as in Example 1 except that 20.9% by weight of an antistatic resin and 78.4% by weight of water (the amount of the epoxy clock curing agent and the surfactant) of the water-dispersible acrylic copolymer were used. A biaxially oriented polyester laminated film was prepared according to the method for producing an ester laminated film.

Example 4

The biaxial orientation was carried out in the same manner as in Example 1, except that 41.7% by weight and 57.6% by weight of an antistatic resin composed of an aqueous dispersion acrylic copolymer was used (the amount of the epoxy clock curing agent and the surfactant was the same). A biaxially oriented polyester laminated film was prepared according to the method for producing a polyester laminated film.

Example 5

The biaxial orientation was carried out in the same manner as in Example 1, except that 83.3 wt% and 16.0 wt% of an antistatic resin composed of an aqueous dispersion acrylic copolymer was used (the amount of the epoxy clock curing agent and the surfactant was the same). A biaxially oriented polyester laminated film was prepared according to the method for producing a polyester laminated film.

[Comparative Example]

Except that the antistatic layer was not applied, the biaxially oriented polyester laminated film prepared according to the method for producing the biaxially oriented polyester laminated film was used as a comparative example.

Experimental Example 1

The surface resistance of the films prepared in Examples 1 to 5 and Comparative Examples was measured. The film was allowed to stand for 24 hours under a condition of a temperature of 23 ° C. and a relative humidity of 50%, and then a surface resistance was measured by applying an applied voltage of 500 V using a surface resistance meter model R-503 of Kawaguchi, Japan.

Experimental Example 2

The light transmittance (%) of the films prepared in Examples 1 to 5 and Comparative Examples was measured. The difference between the haze value of the untreated film after measuring the haze value of the scattered light to incident light in% value using a C-light source with a haze meter (model NDH-1001 of Japan Densoku Kogyo Co., Ltd.). Indicated. The smaller the deviation of the haze, the better the transparency of the film.

Experimental Example 3

The adhesion between the adhesive film and the antistatic layer of the film prepared in Examples 1 to 5 and Comparative Examples was measured. An acrylate adhesive test sample was applied to the surface to which the antistatic layer was attached using a # 4 wire bar, and dried at 150 ° C. for 30 seconds in a drying oven. A cutting line is then made on the film coated with the antistatic layer with a cutter to place 2 mm x 2 mm squares in a 10 x 10 matrix. The cut lines are made deep enough to reach the substrate film through the adhesive layer. The cellophane tape (No. 405, product of NICHIBAN; width: 24 mm) is attached to the film with a cutting line, and it is strongly attached to a film by rubbing a tape with an eraser. Then remove the tape vertically. The area of the antistatic layer remaining in the adhesive layer was visually observed, and the adhesive force was calculated based on the following equation (1).

[Equation 1]

Experimental Example 4

The storage stability (pH) of the coating liquid used for the films prepared in Examples 1 to 5 and Comparative Examples was evaluated. The storage stability of the antistatic coating solution was measured as storage stability was measured by the change in pH over time.

Experimental Example 5

The optical properties of the coating liquid used in the films prepared in Examples 1 to 5 and Comparative Examples were measured. Optical properties were measured by dividing the combat rate and Hz using methods commonly used in the art.

 [Table 1] Measurement results of the antistatic coating solution and the coated film

Item Comparative example Example 1 Example 2 Example 3 Example 4 Example 5 pH (1day) 5.89 5.19 5.57 5.75 5.91 6.12 Battle rate 88.4 91.94 90.43 91.96 91.48 91.47 Hz 0.82 1.43 1.35 1.33 1.36 1.42 Front 0% 100% 100% 100% 100% 100% Friction Coefficient (US) 0.92 0.58 0.54 0.63 0.86 0.86 Friction Coefficient (UK) 0.71 0.33 0.40 0.36 0.38 0.50 Surface resistance 1.31E + 15 1.34E + 10 3.07E + 09 1.34E + 09 8.57E + 08 3.84E + 08 Pencil hardness H HB HB HB HB HB

As can be seen in Table 1, the storage stability (pH) of the antistatic coating solution is a pH change with the change of time, in Comparative Examples 1 to 5, the width of the change of the pH is not large for 1 day It can be seen that the storage stability is excellent. In the table, the optical properties were measured by dividing the battle rate and Hz, and the results are shown separately.

Experimental Example 6

The viscosity of the coating liquid used in the films prepared in Examples 1 to 5 and Comparative Examples was measured. Viscosity was measured using a # 00 spindle in a 23 ° C. thermostat using a Brooklyn model DV-I + viscometer. The results are shown in Table 2 below.

[Table 2] Viscosity of Antistatic Coating Solution

sample cps (dyne / ㎠) torque (%) Uniqueness Comparative example 1.98 24.5 100 rpm Example 1 3.37 56.1 100 rpm Example 2 2.01 33.5 100 rpm Example 3 4.96 82.7 100 rpm Example 4 12.34 61.7 30 rpm Example 5 185.20 77.2 2.5 rpm

According to the biaxially oriented polyester laminated film according to the present invention, it has excellent antistatic properties, and is excellent in adhesion properties and friction coefficient properties with a substrate, which is very suitable for optical products requiring transparency.

In addition, while the conventional antistatic agent is applied after processing, in the present invention, by applying the antistatic agent to at least one surface of the polyester laminated film during the process, it is not necessary to perform an additional antistatic coating after processing, when coating in a conventional post-processing process There is an advantage that can be improved by applying an antistatic coating in the film manufacturing process coating defects on the film surface. This has the effect of reducing the process cost, by reducing the coating process of the post-processing process. In addition, the antistatic property in the post-processing process improves the electrical conductivity of the polyester laminated film in the film manufacturing process to dissipate all surface charges generated during the process, thereby attracting less dust particles, thereby preventing dust from sticking. It works.

Claims (4)

As a base film, A biaxially-oriented polyester film, An antistatic layer formed on one surface of the biaxially oriented polyester film, an antistatic layer coated with a composition comprising a water-dispersible acrylic copolymer, an epoxy curing agent and a surfactant; As a surface layer formed on the other side of the biaxially oriented polyester film, made of a surface layer coated with a water-dispersible acrylic copolymer, A biaxially oriented polyester laminated film, characterized in that the surface resistance of the surface of the biaxially oriented polyester film in contact with the antistatic layer is 9.9 x 10 ⁵ Ω / □ to 9.9 x 10 ¹⁰ Ω / □. The method of claim 1, The antistatic layer is biaxially oriented polyester laminated film, characterized in that the coating is applied after uniaxial stretching of the biaxially oriented polyester film. The method of claim 1, The water-dispersive acrylic copolymer of the antistatic layer is a polyfunctional acrylate compound having at least one hydroxyl group, The antistatic layer is a biaxially oriented polyester laminated film, characterized in that the thickness is 0.05 ~ 3.00㎛. The method of claim 1, The biaxially oriented polyester laminated film, characterized in that the surface of the base film on which the antistatic layer is formed has a light transmittance of 90% or more, a pencil hardness of HB or more, a dynamic friction coefficient and a static friction coefficient of 0.9 or less and 0.7 or less, respectively.

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