KR20090085859A - Optical antistatic film, manufacturing method thereof and optical film using them - Google Patents

Abstract

A method for manufacturing an optical antistatic film is provided to ensure excellent antistatic property and light transmission by evenly dispersing carbon nanotube to an insulating transparent polymer. A method for manufacturing an optical antistatic film comprises the steps of: mixing 1-8 weight% of highly dispersed carbon nanotube-containing solution and 20-30 weight% of binder resin in the balance of solvent to prepare conductive solution; compounding the conductive solution with an insulating transparent polymer, and injecting the product to form master chips; and extrusion-molding the master chips to prepare the film.

Description

Optical antistatic film, manufacturing method thereof and optical film employing optical antistatic film {OPTICAL ANTISTATIC FILM, MANUFACTURING METHOD THEREOF AND OPTICAL FILM USING THEM}

The present invention relates to an optical antistatic film, a method for manufacturing the same, and an optical film employing the optical antistatic film, and more particularly, compounding a conductive solution containing highly dispersible carbon nanotubes with an insulating transparent polymer. After the injection to form a master chip and extrusion molding, by making the carbon nanotubes highly dispersed in the antistatic film, the antistatic film for optics that can fully exhibit the intrinsic properties of carbon nanotubes, a method of manufacturing and optical It relates to an optical film employing an antistatic film for.

Recently, as flat panel displays (FPDs) compensate for the weaknesses of existing CRT displays and are spread in various display areas of medium and large size, their demand is increasing. In particular, Liquid Crystal Display (LCD) is a representative flat panel display that accounts for more than two-thirds of the flat panel display market. In addition to the growth of the flat panel display market, various types of optical films used in liquid crystal displays are emerging. market).

In the process of forming an image, a liquid crystal display requires two polarizing films on the top and bottom surfaces of a color filter and a thin film transistor (TFT) substrate. In addition, a liquid crystal display such as a viewing angle expanding film, a brightness enhancement film, and a compensation film is required. Various films are used to increase the performance of the film, collectively called optical film.

In general, the optical film is stored with the protective film attached to prevent surface scratches or contamination until it is provided to the user, and the protective film is peeled off after the optical film is mounted on the liquid crystal display. At this time, the peeling charge voltage is generated during the peeling process of the protective film, causing various electrostatic defects such as poor adhesion of foreign matter to the liquid crystal display and breakdown of the circuit of the liquid crystal display panel. In addition, the static electricity affects the alignment of the liquid crystal so that the liquid crystal alignment state is distorted, thereby requiring an additional process to compensate for this.

Thus, in order to solve the problem caused by static electricity, the antistatic property may be given to the optical film surface or the adhesive layer. In general, the method of imparting antistatic properties includes a method of lowering the surface resistivity by including a conductive additive such as a surfactant, conductive carbon black, and a metal filler in the polymer, or using a conductive polymer such as polythiophene, polypyrrole, and polyaniline as an antistatic agent. There is a way.

In the case of the antistatic agent using a surfactant, it has a problem of absorbing moisture in the air to exhibit an antistatic effect, so that it reacts sensitively to moisture and the antistatic performance disappears within a short time [Korea Patent Application No. 2005-0134014] The surfactant may not be applied to electronic materials because there is a problem that ions are transferred to the surface and precipitated on the base film (Korean Patent Application No. 2004-0043439). In addition, in the case of the antistatic agent using the conductive polymer, solubility, light transmittance, thermal stability and external environmental stability has a disadvantage of low [Korean Patent Application No. 2005-0118303].

To improve these disadvantages, Baytron, which has been doped with polyethylene dioxithiophene (PEDOT; Bayer) with polystyrenesulfonic acid, has been manufactured, but since Baytron itself is an aqueous dispersion solution, polymer film, glass The coating property has a low limit due to adhesion to the substrate, strength and dryness.

Accordingly, recently, various methods for improving mechanical strength and conductivity by adding carbon nanotubes as fillers to insulating polymers have been developed, and carbon nanotubes using excellent chemical, mechanical, electrical and thermal properties of carbon nanotubes have been developed. Applications of conductive polymers using tube / polymer composites have been in the spotlight. However, the nano-size particles of carbon nanotubes have a very large increase in surface area of the same volume as compared to micro-sized particles, so that the attractive force (van der Waals force) between the particles is very large and the particles are agglomerated with each other. As a result, the formation of the carbon nanotube / polymer composite prevents the formation of a three-dimensional network structure that can improve physical properties, thereby preventing the excellent properties of the carbon nanotubes from being sufficiently expressed in the composite.

Accordingly, the present inventors have endeavored to obtain an optical antistatic film exhibiting sufficient intrinsic properties of carbon nanotubes. As a result, a conductive solution containing highly dispersed carbon nanotubes was compounded with an insulating transparent polymer and then injected into a master chip. The present invention was completed by forming an optically antistatic film having sufficient physical properties inherent to carbon nanotubes by forming and extruding the carbon nanotubes in the optically antistatic film.

An object of the present invention is to provide an optical antistatic film in which carbon nanotubes are uniformly dispersed in an insulating transparent polymer and a method for producing the optical antistatic film using high dispersion carbon nanotubes.

Another object of the present invention is to provide a method for producing a highly dispersed carbon nanotube solution.

Still another object of the present invention is to provide an optical film employing the optical antistatic film.

In order to achieve the above object, the present invention provides a conductive solution containing 1 to 8% by weight of a highly dispersible carbon nanotube-containing solution, 20 to 30% by weight of a binder resin and a residual amount of a solvent in a film manufacturing process of insulating transparent polymer. Injecting to provide an optically antistatic film extruded. In this case, the conductive solution is in the form of a master chip compounded with the insulating transparent polymer.

In addition, the present invention is an optical antistatic coating a conductive solution comprising a high dispersion of carbon nanotube-containing solution 1 to 8% by weight, a binder resin 20 to 30% by weight and a residual amount of the solvent is coated on at least one side of the insulating transparent polymer Provide a film.

The insulating transparent polymer is any one selected from the group consisting of polyester, polyamide, polycarbonate, polystyrene, polymethyl methacrylate and acrylonitrile butadiene styrene.

The carbon nanotubes are any one selected from the group consisting of single-walled carbon nanotubes (SWNT), multi-walled carbon nanotubes (MWNT) and carbon nanofibers having a particle size of 0.002 to 0.04㎛.

The highly dispersed carbon nanotubes are surface-modified by acid treatment, neutralized, and then uniformly dispersed by ultrasonication. The binder resin is selected from the group consisting of phenol, melamine, xylene, epoxy, aniline, and polyurethane. The solvent may be any one selected from the group consisting of water, alcohols, ketones and ethers, or a mixture of two or more thereof.

The surface resistance of the optical antistatic film prepared using the conductive solution is 10 ⁵ to 10 ⁹ Ω / area.

The present invention further prepares a conductive solution by mixing 1 to 8% by weight of the highly dispersible carbon nanotube-containing solution in 20 to 30% by weight of the binder resin and the remaining amount of solvent, and compounding the conductive solution with an insulating transparent polymer. And injection molding to form a master chip, and extrusion molding the master chip to provide a method for producing the optical antistatic film. At this time, the thickness of the extruded film is 100 to 500㎛, in the compounding step is added to 5 to 8% by weight of the conductive solution and 92 to 95% by weight of the insulating transparent polymer.

The highly dispersed carbon nanotube solution is supported by carbon nanotubes in a mixed solvent of nitric acid: sulfuric acid, and then surface-modified by stirring, neutralizing the resulting carbon nanotube solution to pH 7, and then dimethylacetamide , Dimethylformamide and N-pyrrolidone are added to any one of the organic solvents selected from the group prepared by sonication for 2 to 10 hours under 20 to 60% output of 4 to 20KHz ultrasonic apparatus.

The present invention further provides an optical film employing the optical antistatic film in any one selected from the group consisting of a viewing angle expanding film, a brightness enhancing film and a compensation film.

The present invention can provide an optical antistatic film applying a conductive solution containing high dispersion carbon nanotubes to an insulating transparent polymer, and carbon nanotubes by making the carbon nanotubes highly dispersed in the optical antistatic film The inherent physical properties can be sufficiently exhibited to provide an optical antistatic film having improved physical properties compared to conventional carbon nanotube composites.

In addition, the present invention can provide an optical film employing the method of manufacturing the optical antistatic film and the optical antistatic film.

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

Generally, carbon nanotubes have a resistance of 10 ^-4 to It has a very good conductivity of 10 ^-3 Ω / cm, but the surface tension between molecules is large, which causes it to agglomerate itself and lose its inherent properties. .

Accordingly, the present invention provides an antistatic film for optically expressing the physical properties of the carbon nanotubes by applying a conductive solution containing a highly dispersed carbon nanotubes to the insulating transparent polymer.

According to a first embodiment of the present invention, a film of a transparent insulating polymer is prepared by using a conductive solution containing 1 to 8% by weight of a highly dispersible carbon nanotube-containing solution, 20 to 30% by weight of a binder resin and a residual amount of a solvent. It is put into a process to provide an optically antistatic film extruded. At this time, the conductive solution is in the form of a master chip compounded and injected with the insulating transparent polymer, the final mixed state of the conductive solution and the insulating transparent polymer is in the form of a master chip is easy to store and the film extrusion step is simple.

According to a second embodiment of the present invention, a conductive solution containing 1 to 8% by weight of a highly dispersible carbon nanotube-containing solution, 20 to 30% by weight of a binder resin, and a residual amount of a solvent includes at least one insulating transparent polymer. It provides an optical antistatic film coated on one side.

The highly dispersible carbon nanotubes of the present invention are acid-treated to neutralize the carbon nanotubes to include a carboxyl group, neutralized, and uniformly dispersed by ultrasonication in an organic solvent. The highly dispersible carbon nanotube-containing solution is preferably 1 to 8% by weight, and when the highly dispersible carbon nanotube-containing solution is less than 1% by weight, the content of carbon nanotubes in the final molded antistatic film is sufficient. If the antistatic function is poor, and the carbon nanotube-containing solution exceeds 8% by weight, as the concentration of the carbon nanotubes increases, it becomes difficult to control fine dispersion, which may lower the transparency and light transmittance of the antistatic film. There is a problem that stains occur during coating.

At this time, the shape and size of the carbon nanotubes are not limited, but preferably a group consisting of single-walled carbon nanotubes (SWNT), multi-walled carbon nanotubes (MWNT) and carbon nanofibers having a particle size of 0.002 to 0.04㎛. It is effective to increase the light transmittance in the visible region using any one selected from.

The binder resin serves to improve the uniformity of the bond between the carbon nanotube-containing conductive solution and the insulating transparent polymer, improving adhesion, and improving the change over time for the antistatic function of the conductive solution. At this time, the binder resin When less than 20% by weight, the bonding uniformity and adhesion between the conductive solution and the insulating transparent polymer are deteriorated or the characteristics of the conductive solution are not changed over time, and the binder resin is If it exceeds 30% by weight, the surface resistance of the conductive solution is increased, the antistatic function is poor, the dispersibility of the carbon nanotubes are reduced, there is a problem that a stain occurs during coating.

As the binder resin, any one selected from the group consisting of phenol, melamine, xylene, epoxy, aniline and polyurethane is used.

In addition, the insulating transparent polymer used in the present invention is any one selected from the group consisting of polyester, polyamide, polycarbonate, polystyrene, polymethyl methacrylate and acrylonitrile butadiene styrene.

The solvent is one or two or more mixed solvents selected from the group consisting of water, alcohols, ketones and ethers.

In addition, the conductive solution may optionally further include additives such as dispersants, stabilizers and fillers.

The optical antistatic film prepared by using the conductive solution has a surface resistance of 10 ⁵ to 10 ⁹ Ω / area and a light transmittance of 85% or more, showing optical properties of 90% or more.

The present invention also provides a method for producing the optical antistatic film.

More specifically, 1 to 8% by weight of the highly dispersible carbon nanotube-containing solution is mixed with 20 to 30% by weight of the binder resin and the remaining amount of solvent to prepare a conductive solution, and the conductive solution is compounded with an insulating transparent polymer. Thereafter, injection is performed to form a master chip and extrusion molding of the master chip.

The highly dispersed carbon nanotubes are supported by carbon nanotubes in a 1: 3 volume ratio mixed solution of nitric acid and sulfuric acid, stirred, and surface-modified to include a carboxyl group (-COOH), and the acidified carbon nanotubes become pH7. Neutralize until it is put into any one organic solvent selected from the group consisting of dimethylacetamide (DMAc), dimethylformamide (DMF) and N-methylpyrrolidone (NMP), and then prepared by sonication.

The carbon nanotubes are acid-treated by being supported in a mixed solution of nitric acid and sulfuric acid to introduce polar groups on the surface of the carbon nanotubes, thereby reducing interfacial tension with the polymer. That is, the functional group is introduced into the hydrophobic carbon nanotube to impart hydrophilicity, and thus it may be easily dispersed in the solvent. The carbon nanotubes subjected to the acid treatment step have structural defects at the same time as the functional groups are introduced to the surface, thereby undergoing a neutralization step to prevent the physical properties of the carbon nanotubes from deteriorating.

The sonication is to uniformly disperse the carbon nanotubes in the organic solvent. In the nonpolar solvent, the carbon nanotubes are aggregated and precipitated, so dimethylacetamide (DMAc), dimethylformamide (DMF), and N-methylpyrroli A polar solvent such as ton (NMP) is used.

The sonication is performed for 2 to 10 hours at 20 to 60% power of the 4 to 20 kHz ultrasonic device. Ultrasonic waves in the frequency region above 20 kHz have a high penetration but low cavitation, and vice versa in the frequency region below 4 kHz. Therefore, by performing alternating frequencies within the above range it is possible to obtain a highly dispersed carbon nanotubes.

The compounding step is a mixture of 5 to 8% by weight of the conductive solution and 92 to 95% by weight of the insulating transparent polymer through a compounder, when the conductive solution is less than 5% by weight of the carbon nanotubes in the final antistatic film formed optical The antistatic function is not efficient because the content is not sufficient, and if the conductive solution exceeds 8% by weight, the antistatic function is excellent, but the dispersion control is difficult due to the high content of carbon nanotubes in the optical antistatic film. And it is not preferable because there exists a problem that light transmittance falls.

The thickness of the optical antistatic film prepared according to the above production method is 100 to 500㎛.

The present invention further provides an optical film employing the optical antistatic film in any one selected from the group consisting of a viewing angle expanding film, a brightness enhancing film and a compensation film.

Hereinafter, the present invention will be described in detail by way of examples.

The following examples are merely illustrative of the present invention, but the scope of the present invention is not limited to the following examples.

< Production Example > Preparation of High Dispersion Carbon Nanotube Solution

10 g of multi-walled carbon nanotubes (CM 95 manufactured by Iljin Nanotech Co., Ltd.) were added to 450 ml of a mixture of nitric acid and sulfuric acid in a volume ratio of 1: 3, stirred for 4 hours, and neutralized until the pH was 7 using NaOH solution. After coarse, it was put into an organic solvent of dimethylformamide and sonicated for 3.5 hours with a sonicator having a frequency of 20 kHz and an energy of 300 W to prepare a solution of highly dispersed carbon nanotubes.

< Example  1>

1) 1.5 g of the highly dispersed carbon nanotube prepared above, 17 g of a urethane binder, and 65 ml of a mixed solvent in which ethyl alcohol and isopropyl alcohol were mixed in a 1: 1 mixture were mixed in a bowl mixer at 60 rpm for 1 hour to form a conductive solution. It was.

2) After compounding 30 g of the conductive solution and 500 g of acrylonitrile butadiene styrene (ABS) insulating transparent polymer chip, a master chip was obtained through a twin screw injection machine.

3) The master chip was put into an extruder of a single screw to prepare an optical antistatic film having a thickness of 200 μm.

< Example  2>

An optically antistatic film was prepared in the same manner as in Example 1 except that the amount of the highly dispersed carbon nanotube solution was 2.5 g.

< Example  3>

An optically antistatic film was prepared in the same manner as in Example 1 except that the amount of the highly dispersed carbon nanotube solution was 3.5 g.

< Example  4>

An optical antistatic film was prepared in the same manner as in Example 1 except that the amount of the conductive solution was 40 g.

< Example  5>

An optical antistatic film was prepared in the same manner as in Example 2 except that the amount of the conductive solution added was 40 g.

< Comparative example  1>

5 g of carbon nanotubes were immersed in an aqueous solution of strong acid mixed with sulfuric acid and nitric acid, acid treated for 4 hours, filtered through a filter, and washed several times with distilled water until neutral. The washed carbon nanotubes were evaporated in a hot air dryer at 65 ° C. to form a powder, and 3.5 g of the dried carbon nanotubes were obtained in the form of a master chip together with 500 g of the insulating transparent polymer chip, followed by extrusion to obtain a thickness of 200 μm. An optical antistatic film was prepared.

< Comparative example  2>

An aqueous solution containing 5 parts by weight of poly (3,4-ethylenedioxythiophene, PEDOT) as the conductive polymer and 100 parts by weight of polyester resin and 7 parts by weight of polystyrene sulfonic acid as the binder resin (solid content 0.8 %) The aqueous solution was coated on a polyester film to a thickness of 1 μm, and then dried at 100 ° C. for 2 minutes to prepare an antistatic film for optics.

< Experimental Example  1> Optical Antistatic Film Characterization

One. Light transmittance  And Haze  How to measure

The purpose of this experiment is to find out the light transmission performance and the light diffusion performance of Examples 1 to 5 and Comparative Examples 1 to 2 of the present invention. A light diffusing film sampled in a size of 10 cm x 10 cm was placed vertically on an AUTOMATIC DIGITAL HAZEMETER manufactured by Nippon Densoku Co., Ltd., Japan. Measured.

At this time, the light transmittance value was calculated using Equation 1 below.

In addition, the haze value was computed using the following formula (2).

2. Antistatic measuring method

Surface resistance was measured to check the antistatic properties of the film surface prepared in Examples 1 to 5 and Comparative Examples 1 to 2. The test was carried out using an advanced test, the Adventest Test Co., Ltd., at a temperature of 23 ° C and a humidity of 50% RH (relative humidity) and applying a 100V voltage. The surface resistance after charging for 40 seconds was measured.

If the surface resistance of the antistatic film is 10 ¹² GPa / area or less, there is no problem in practical use. If the surface resistance is 10 ¹⁰ GPa / area or 10 ⁹ GPa / area or less, excellent antistatic property is exhibited. The optical antistatic film of the present invention exhibits antistatic properties of surface resistance of 10 ⁵ Ω / area to 10 ⁹ Ω / area and at the same time exhibits optical transmittance of 85% or more and 90% or more of optical properties, and powdery carbon nano The optical antistatic film of Comparative Example 1 prepared using a tube and the optical antistatic film of Comparative Example 2 prepared using a conventional conductive polymer exhibit excellent effects.

The present invention forms a master chip by compounding a conductive solution containing highly dispersed carbon nanotubes with an insulating transparent polymer and then extruding the surface to have a surface resistance of 10 ⁵ to 10 ⁹ Ω / area and a light transmittance of 85 It can provide more than 90% or more excellent antistatic film for optical and an optical film employing the same.

The present invention can also provide a method for producing an optical antistatic film that applies highly dispersed carbon nanotubes to an antistatic film and an optical film employing an optical antistatic film.

Although the present invention has been described in detail only with respect to the embodiments described, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and modifications belong to the appended claims.

Claims (14)

An optically characterized in that the conductive solution comprising a high dispersion carbon nanotube-containing solution 1 to 8% by weight, a binder resin 20 to 30% by weight and a residual amount of the solvent is added to the film manufacturing process of the insulating transparent polymer Antistatic film. The optical antistatic film of claim 1, wherein the conductive solution is in the form of a master chip compounded with an insulating transparent polymer. An antistatic film for optics, characterized in that a conductive solution comprising a highly dispersible carbon nanotube-containing solution 1 to 8% by weight, a binder resin 20 to 30% by weight and a residual amount of a solvent is coated on at least one surface of the insulating transparent polymer . The method of claim 1 or 3, wherein the insulating transparent polymer is any one selected from the group consisting of polyester, polyamide, polycarbonate, polystyrene, polymethyl methacrylate and acrylonitrile butadiene styrene. The optical antistatic film. According to claim 1 or 3, wherein the carbon nanotubes are selected from the group consisting of single-walled carbon nanotubes (SWNT), multi-walled carbon nanotubes (MWNT) and carbon nanosum flow path having a particle size of 0.002 to 0.04㎛ The optical antistatic film, characterized in that any one. 4. The optical antistatic film according to claim 1 or 3, wherein the highly dispersed carbon nanotubes are surface-modified and neutralized by acid treatment, and then uniformly dispersed by ultrasonication. 4. The optical antistatic film according to claim 1 or 3, wherein the binder resin is any one selected from the group consisting of phenol, melamine, xylene, epoxy, aniline, and polyurethane. The optical antistatic film according to claim 1 or 3, wherein the solvent is any one or two or more mixed solvents selected from the group consisting of water, alcohols, ketones and ethers. 4. The optical antistatic film according to claim 1 or 3, wherein the surface resistance of the optical antistatic film prepared using the conductive solution is 10 ⁵ to 10 ⁹ kPa / area. 1 to 8% by weight of the highly dispersed carbon nanotube-containing solution was mixed with 20 to 30% by weight of the binder resin and the remaining amount of solvent to prepare a conductive solution. Compounding the conductive solution with an insulating transparent polymer, and then injected into a master chip, The method of manufacturing an optical antistatic film of claim 1, wherein the master chip is extrusion molded to produce a film. The method of claim 10, wherein the extruded film has a thickness of 100 to 500 µm. The method of claim 10, wherein 5 to 8% by weight of the conductive solution and 92 to 95% by weight of the insulating transparent polymer are added to the compounding step. The method of claim 10, wherein the highly dispersed carbon nanotube solution The carbon nanotubes were supported on a mixed solvent of nitric acid and sulfuric acid, and then surface-modified by stirring. Neutralize the resulting carbon nanotube solution until pH7, It is composed of dimethyl acetamide, dimethylformamide and N-pyrrolidone in one of the organic solvents selected from the group consisting of sonication for 2 to 10 hours under 20 to 60% output of a 4-20KHz ultrasonic apparatus. Method for producing the optical antistatic film characterized in that. The optical film of claim 1 or 3, wherein the optical antistatic film is employed in any one selected from the group consisting of a viewing angle expanding film, a brightness enhancing film and a compensation film.