KR20160080677A - Transparent conductive film and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a transparent conductive film and, more specifically, to a transparent conductive film and a manufacturing method thereof, including: a coextrusion skin layer stacked on one surface or both surfaces of a bare film; and an ITO layer stacked on one upper surface of the skin layer, thereby simplifying a manufacturing process of the transparent conductive film, reducing processing costs, and minimizing defect rates.

Description

TECHNICAL FIELD [0001] The present invention relates to a transparent conductive film,

The present invention relates to a bare film comprising a skin layer laminated on one side or both sides of a bare film, and an ITO (Indium Tin Oxide) layer laminated on one surface of the skin layer laminated on the bare film. Film and a method for producing the same.

The transparent conductive film is used for a liquid crystal display device, a display device using an organic electroluminescent device, and an electrode plate on a display surface side in a flat panel display such as an electronic paper, And is used as an electrode plate of a touch panel. Since the transparent conductive film is required to be conductive and transparent at the same time, a transparent conductive material film is provided on a light-transmissive film. A transparent conductive film obtained by laminating a transparent thin film having a small resistance on a transparent plastic film substrate is one of the key materials of the touch panel, and ITO (Indium Tin Oxide) film is the most widely used among transparent conductive films. If a pattern is formed on the ITO film by an electrostatic capacity method and is adhered together with an optical transparent mounting film (OCA), the touch panel can be finally manufactured.

The ITO film has a structure in which a hard coating layer is formed on both sides of a PET film, an index matching layer is laminated on one surface thereof, and ITO is stacked thereon. The index matching layer is composed of a low refractive index layer and a high refractive index layer, and is laminated using a sputtering method or a wet coating method. In the sputtering method, the thickness of the SiO ₂ layer and the Al ₂ O ₃ layer, which are low refractive layers, become relatively thick, which lowers the overall production rate. The wet coating method has two coating processes to form the high- and low- There is a possibility that defects may occur due to film loss and running problems. Further, in order to form an index matching layer composed of a multi-layered film of a high refractive index layer and a low refractive index layer, various steps are required. As the number of process steps increases, the probability of occurrence of defects in each process is high, which causes not only a decrease in yield but also a rise in process cost. Accordingly, in order to solve such a problem, development of a transparent conductive film having a simplified process has been demanded.

Korean Patent No. 10-0926284

SUMMARY OF THE INVENTION The present invention has been conceived to solve the above problems of the prior art, and it is an object of the present invention to provide a method of manufacturing a transparent conductive film by laminating skin layers instead of laminating the hard coating layer and the index matching layer of the transparent conductive film, It is aimed at minimizing the cost saving and the defect rate.

In order to achieve the above object,

A bare film; A bare film and a skin layer coextruded on one or both sides of the bare film; And a transparent conductive film having a structure in which an ITO (Indium Tin Oxide) layer is laminated on one surface of a skin layer laminated on the bare film.

In addition,

(1) co-extruding a bare film and a skin layer to produce a bare film having a skin layer laminated on one side or both sides of the bare film; And

(2) stacking an ITO layer on one surface of the skin layer laminated on the bare film; And a method for producing the transparent conductive film.

In addition,

And a touch panel made of the transparent conductive film.

The steps of laminating the hard coat layer and the index matching layer in the manufacturing process of the transparent conductive film of the present invention can be omitted, thereby simplifying the process, reducing the process cost, and minimizing the defect rate.

In addition, the transparent conductive film of the present invention can provide a film having excellent optical properties by laminating a skin layer by coextrusion on a bare film to prevent transparency degradation caused by migration of an oligomer.

In addition, the transparent conductive film of the present invention can provide a thin transparent conductive film by laminating only the skin layer instead of the laminate of the hard coating layer and the index matching layer, thereby providing an advantage of being advantageous in thinning the touch panel.

1 is a schematic view showing a transparent conductive film of the present invention in which a skin layer is laminated on both sides of a bare film and an ITO layer is laminated on one surface of the bare film.
2 is a photograph showing a pattern of the transparent conductive film of Example 1. Fig.
3 is a photograph showing a pattern of the transparent conductive film of Example 2. Fig.

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

The present invention relates to a bare film; A bare film and a skin layer coextruded on one or both sides of the bare film; And a transparent conductive film comprising a structure in which an ITO (Indium Tin Oxide) layer is laminated on one surface of a skin layer laminated on the bare film.

That is, the bare film and the coin-extruded skin layer may be laminated on one side or both sides of the bare film; When the skin layer is laminated on one surface, the ITO layer may be laminated on the upper surface of the one surface, and when the skin layer is laminated on both surfaces, the ITO layer may be laminated on the upper surface of one layer.

In the conventional transparent conductive film, a hard coating layer is laminated on one side or both sides of a bare film, and an index matching layer including a high refractive index layer and a low refractive index layer is laminated on one side of the laminated hard coating layer. . Therefore, there is a disadvantage in that the yield is lowered due to a high probability of occurrence of defects in each step. However, instead of laminating the hard coating layer and the index matching layer on the bare film, the transparent conductive film of the present invention can solve the above problems by laminating only the skin layer on one side or both sides of the bare film, It is possible to make the thickness of the touch panel thin.

The bare film is a film made of a single composition, and each bare film can be laminated to form a bare film layer. The bare film can be used without limitation as long as it is a transparent plastic film. For example, a resin such as a polyester resin, an acetate resin, a polyether sulfone resin, a polycarbonate resin, a polyamide resin, a polyimide resin, a polyolefin resin, a (meth) acrylic resin, a polyvinyl chloride resin, A bare film can be produced from at least one selected from the group consisting of a polyvinylidene chloride resin, a polystyrene resin, a polyvinyl alcohol resin, a polyarylate resin, and a polyphenylene sulfide resin. It is more preferable that the above-mentioned bare film layer is made of a polyethylene terephthalate (PET) resin alone.

The resin used for the bare film preferably has an intrinsic viscosity of 0.5 to 1.0, more preferably 0.6 to 0.8. If the intrinsic viscosity of the bare film resin is less than 0.5, the heat resistance may be reduced. If the intrinsic viscosity is more than 1.0, the raw material processing is not easy and the workability may be decreased.

The thickness of the bare film is preferably 25 to 250 mu m, more preferably 50 to 188 mu m. When the thickness is less than 25 mu m, mechanical properties suitable for the optical film are not realized. When the thickness is more than 250 mu m, the thickness of the film becomes too thick, which is not suitable for thinning the display device. The refractive index of the bare film is preferably 1.55 to 1.85. When the refractive index of the bare film is less than 1.55 or more than 1.85, the index matching is difficult and the ITO pattern is visible to the outside.

The skin layer refers to a layer formed by co-extruding a bare film at the time of extrusion of the bare film and being laminated on one side or both sides of the bare film. Since the skin layer of the present invention is coextruded at the time of extrusion of the bare film and laminated on the bare layer, unlike the conventional primer layer, a separate process step of laminating the bare film on the bare film layer is not necessary, There is an advantage that it can be.

The skin layer can be made of the same material as the bare film, and includes inorganic particles for controlling the refractive index, unlike the bare film. The kind of the inorganic particles is not limited as long as it is an inorganic particle which is obviously used in the technical field. For example, at least one selected from SiO ₂ , Al ₂ O ₃ , zeolite and kaolin can be used.

The average particle diameter of the inorganic particles is 0.3 to 3.0 占 퐉, and the refractive index of the skin layer is adjusted by including the concentration of less than 100 ppm. The surface roughness (R _a ) is formed in the range of 0.1 to 20 nm to provide a transparent conductive film having improved slipperiness and winding property in the production of a film. When the average particle size of the inorganic particles is less than 0.3 탆, it is difficult to form a sufficient surface roughness, and blocking phenomenon may occur between the films during production of the film. Further, because in the average particle diameter of the inorganic particles when they exceed 3.0㎛, and / or concentration is more than 100ppm, the transparency is decreased rapidly to form in excess of the surface roughness (R _a) 20nm, the surface smoothness decreases Which may not be suitable for optical applications such as touch screen or ITO process.

 The bare film and the skin layer can serve as a high refractive index layer and a low refractive index layer and serve as an index matching layer for adjusting the refractive index of the transparent conductive film. Therefore, in order to perform the above- And the refractive index should be controlled. The refractive index of the skin layer is 1.35 to 1.60, preferably 1.35 to 1.50. If it is out of the above range, it is difficult to perform the role of the index matching layer, and the pattern is visually observed after the etching process of the ITO layer.

When a skin layer is laminated on both sides of the bare film layer, it is also possible to form a skin layer having the above refractive index on one side and a skin layer having another refractive index on the other side.

The thickness of the skin layer is 5 to 60 nm, and more preferably 10 to 40 nm. If it is out of the above range, it becomes difficult to perform the role of the index matching layer and the pattern is visually recognized after the etching process of the ITO layer for manufacturing the touch panel.

In addition, the skin layer of the present invention plays a role of enhancing adhesion and blocking moisture in a transparent conductive film. In addition to this, it is possible to prevent the whitening phenomenon caused by the migration of the oligomer upon heating, thereby preventing the transparency of the film from deteriorating and manufacturing a transparent conductive film having better optical properties.

The ITO layer may be formed of indium tin oxide (ITO), which is a compound of tin oxide (ln ₂ O ₃ And SnO ₂ ). ITO can exhibit properties of conductivity and transparency, and thus is mainly used for a screen display device such as a touch screen.

The ITO layer has a thickness of 15 to 50 nm, more preferably 18 to 40 nm, and a refractive index of 1.9 to 2.2. When the thickness is out of the above range, a required resistance can not be obtained, cracks and curls of the ITO layer are generated, and light transmittance is lowered. When the refractive index is less than 1.9 or more than 2.2, there is a problem in matching with the index matching layer due to the lower bare film or skin layer, and the pattern is visually observed after the ITO etching.

In the present invention, the refractive index of the bare film is 1.55 to 1.85, the refractive index of the skin layer is 1.35 to 1.60, and the refractive index of the ITO layer is 1.9 to 2.2. That is, in the transparent conductive film of the present invention, the refractive index decreases in the order of the ITO layer, the bare film, and the skin layer. In the above sequence, the skin layer alone can serve as an index matching layer, And it is possible to make the transparent conductive film thinner.

Further, the transparent conductive film of the present invention

(1) co-extruding a bare film and a skin layer to produce a bare film having a skin layer laminated on one side or both sides of the bare film; And

(2) stacking an ITO layer on one surface of the skin layer laminated on the bare film; Based on the total weight of the transparent conductive film.

The co-extrusion step of step (1) may be carried out by an extrusion method well known in the art. For example, it can be extrusion melted and cast by at least two uniaxial melt extruders or biaxial melt extruders. As an example, a resin having an oligomer content of 1.0 to 1.4% by weight in the first extruder and an intrinsic viscosity of 0.6 to 0.8 is extruded; Extruding the additive such as a resin and an inorganic particle having an oligomer content of 0.3 to 0.6 wt% and an intrinsic viscosity of 0.65 to 0.8 in a second extruder, and then causing each melt to coextrusion in the feed block, Method can be used.

The step (2) for laminating the ITO layer may be carried out according to a method commonly used in the art.

After the step (2), a step of laminating an adhesive layer laminate or release film on the upper surface of the ITO layer may be further included. The laminate or the laminate may be heated to crystallize the constituent components of the ITO layer to prepare a transparent conductive film can do.

In addition, the present invention can provide a touch panel made of the transparent conductive film, and the touch panel can facilitate thinning.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the following examples and comparative examples are intended to further illustrate the present invention, and the scope of the present invention is not limited by the following examples and comparative examples. The following examples and comparative examples can be suitably modified or changed by those skilled in the art within the scope of the present invention.

≪ Preparation of transparent conductive film &

Example  One.

A polyethylene terephthalate (PET) chip having an intrinsic viscosity of 0.65, a DEG content of 1.3% and an oligomer content of 1.3% was melt extruded into an extruder. The skin layer had an intrinsic viscosity of 0.67 and a DEG content of 0.9 use of an oligomer content of 0.6% in the solid state polymerization of polyethylene terephthalate (PET) chips, were co-extruded and cast by using a mean particle diameter of the inorganic particles (SiO ₂₎ 50ppm 1.6㎛ to prepare a non-stretched sheet. The unstretched sheet was stretched in the machine direction (MD) and then sequentially stretched in the transverse direction (TD). The stretch ratio was 3% in the width direction at 230 DEG C and 1.5% The thickness and the refractive index of the bare film layer were 100 탆 and 1.60, respectively, and the thickness and the refractive index of the skin layer were 25 nm and 1.55, respectively.

Using the sintered body of indium oxide and 7 wt% of tin oxide in an atmosphere of a mixed gas (0.4 Pa) of 98% argon gas and 2% oxygen gas, a sintered body material having a thickness of 23 nm and a refractive index of 1.9 Lt; / RTI > layer.

A pressure-sensitive adhesive sheet was laminated on the rear surface of the prepared transparent conductive film on which ITO was formed using a laminator.

Example  2.

A multilayer film was prepared in the same manner as in Example 1 except that 70 ppm of inorganic particles (SiO ₂ ) having an average particle size of 2.0 탆 was co-extruded to prepare a multilayer film. At this time, the refractive index of the skin layer was 1.50, and the transparent conductive film was produced by forming ITO through sputtering in the same manner as in Example 1.

Example  3.

A multilayer film was produced in the same manner as in Example 1 except that the skin layer used was coextruded with 100 ppm of inorganic particles (SiO ₂ ) having an average particle size of 3.0 μm to prepare a multilayer film. At this time, the refractive index of the skin layer was 1.47. In the subsequent steps, ITO was formed through sputtering as in Example 1 to prepare a transparent conductive film.

Example  4.

A multilayer film was prepared in the same manner as in Example 1 except that the skin layer used was coextruded with 100 ppm of inorganic particles (SiO ₂ ) having an average particle size of 2.0 μm to prepare a multilayer film. At this time, the refractive index of the skin layer was 1.45. In the subsequent steps, ITO was formed through sputtering as in Example 1 to prepare a transparent conductive film.

Example  5.

A transparent conductive film was prepared by forming an ITO layer having a thickness of 40 nm and a refractive index of 2.2 by preparing a multilayer film in the same manner as in Example 1 above.

Example  6.

A multilayered film was produced in the same manner as in Example 1 except that the thickness and the refractive index of the bare film layer were 80 탆 and 1.70, respectively, and the thickness and the refractive index of the skin layer were 45 nm and 1.60, respectively.

Comparative Example  One.

A hard coat layer was coated on both sides of a PET film (manufactured by Kolon, U43R) manufactured through a series of processes. A coating layer having a refractive index of 1.45 was formed thereon to a thickness of 35 nm, and a coating layer having a refractive index of 1.70 was formed thereon .

Using the sintered body of indium oxide and 7 wt% of tin oxide in an atmosphere of a mixed gas of argon gas and argon gas of 2% (0.4 Pa), a sintered body of 23 nm in thickness and 1.9 in refractive index ITO layer was formed.

A pressure-sensitive adhesive sheet was laminated on the rear surface of the prepared transparent conductive film on which ITO was formed using a laminator.

Comparative Example  2.

A multilayer film was produced in the same manner as in Example 1 except that the thickness and the refractive index of the bare film layer were 80 mu m and 1.70, respectively, and a transparent conductive film without a skin layer was prepared.

< Experimental Example >

Experimental Example  1. Reflectometry

The transparent conductive films prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were heated at 150 DEG C for 60 minutes to crystallize the constituent components of the ITO layer to measure the reflectance of the transparent conductive film. The reflectance was measured using a 100 Conc UV-VIS Spectrometer (Varian Technology) and the reflection spectrum was measured at an incident angle of 8 °. The reflectance difference of the transparent conductive film at a wavelength of 550 nm was calculated. The results are shown in Table 1.

Experimental Example  2. Pattern change by etching

The transparent conductive films prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were heated at 150 DEG C for 60 minutes to crystallize the constituent components of the ITO layer and then patterned in a stripe pattern on the ITO layer of the transparent conductive film After forming a resist film, the substrate was immersed in a 5% hydrochloric acid aqueous solution at 25 占 폚 for 1 minute, and then the ITO layer was etched. The obtained ITO layer had a pattern width of 5 mm and a pattern pitch of 5 mm. The patterned transparent conductive film was placed on a black sheet, and visually confirmed whether the pattern was visually observed.

Experimental Example  3. Turbidity evaluation

The ITO layer of the transparent conductive films prepared in Examples 1 to 6 and Comparative Examples 1 and 2 was immersed in a 5% hydrochloric acid aqueous solution at 25 占 폚 for 1 minute without using a photoresist film, and then the entire surface of the ITO layer was etched . The entire surface of the ITO film was heated at 150 ° C for 60 minutes, and turbidity changes were measured before and after the heat treatment of the film using Hazemeter (NDH-2000, Nippon Denshoku).

Experimental Example  4. Evaluation of transmittance

The transparent conductive films prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were heated at 150 DEG C for 60 minutes to crystallize the constituent components of the ITO layer to measure the transmittance of the transparent conductive film. After crystallizing the constituent components of the ITO layer and forming a photoresist film on the ITO layer of the transparent conductive film, the ITO layer was etched after immersing in a 5% hydrochloric acid aqueous solution for 1 minute at 25 ° C. The transmittance of the film was measured on the surface of the etched film, and the difference in transmittance at a wavelength of 550 nm before and after etching was measured. The specific method was carried out using NDH-1001DP manufactured by Nippon Denshoku Kogyo Co., Ltd. in accordance with JIS K7316.

Item Reflectance difference (550 nm) Whether the pattern is visible Turbidity change (%) Difference in transmittance (550 nm) Example 1 0.2% X 0.1% 0.4% Example 2 0.5% X 0.4% 0.7% Example 3 0.2% X 0.3% 0.7% Example 4 0.4% X 0.6% 0.3% Example 5 0.3% X 0.1% 0.9% Example 6 0.4% X 0.2% 0.6% Comparative Example 1 0.3% X 0.4% 0.6% Comparative Example 2 4.3% ○ 4.7% 3.9%

As shown in Table 1, in the case of the transparent conductive films prepared in Examples 1 to 6, the reflectance difference between the transparent conductive film and the PET film was 0.2 to 0.5% at a wavelength of 550 nm. The reflectance difference was less than 3%, and the intensity of the reflected light between the ITO pattern and the non-patterned portion after the ITO patterning was similar, so that the ITO pattern could not be visually confirmed. As shown in Table 1, the transparent conductive films prepared in Examples 1 to 6 had a difference in transmittance of the transparent conductive film at a wavelength of 550 nm from that of the film after etching to less than 3%, and the ITO pattern was not visually observed .

As a result of checking whether the pattern was visually observed, the pattern of the stripe pattern was not confirmed in the transparent conductive film produced in Example 1 (Fig. 2). In addition, in the transparent conductive film prepared in Example 2, a stripe-shaped pattern was hardly observed (FIG. 3), and the difference in reflectance was less than 3% in Experimental Example 1, I could.

Also in the case of Comparative Example 1 manufactured by the conventional method of producing a transparent conductive film, the ITO pattern was not visually recognized with a reflectance difference of 0.3%, but the difference in reflectance was 4.3% in Comparative Example 2 in which no skin layer was laminated, There is a problem that the ITO pattern is visible to the naked eye because the difference in reflected light between the ITO pattern and the non-patterned portion after ITO patterning is large.

In Examples 1 to 6 and Comparative Example 1, the difference in reflectance was less than 3%. In the conventional method as in Comparative Example 1, a hard coating layer was formed on a PET film, an index matching layer was formed thereon in two layers The pattern is not verified unless it is subjected to a complicated process for producing ITO by depositing it, so that it does not meet the object of the present invention.

On the other hand, it was confirmed that the transparent conductive film of the present invention exhibits the performance realized by the conventional method without any difference or even better in a simple process structure. That is, it was found that the skin layer of the transparent conductive film of the present invention can serve as an index matching layer through the result of the reflectance difference in Experimental Example 1 and the visual confirmation of the pattern in Experimental Example 2.

On the other hand, as a result of Comparative Example 2 in which the skin layer was not laminated, the reflectance difference was 4.3%, the ITO pattern was visually confirmed, and unlike Examples 1 to 6 in which the turbidity change was less than 1% And it was confirmed that it was not appropriate.

In addition, when the results of Experimental Example 4 in which the difference in the transmittance before and after etching were evaluated, it was confirmed that all of Examples 1 to 6 were at an appropriate level of 1.0% or less, but in Comparative Example 2, 3.9% .

As described above, the transparent conductive film of the present invention has a simple structure that does not include a hard coating layer and an index matching layer, but it can exhibit the performance realized in the transparent conductive film produced by the conventional method with no difference or better . Also, it was confirmed from the results of Experimental Examples 1 to 4 that the skin layer of the transparent conductive film of the present invention can serve as a conventional index matching layer and a hard coating layer.

1: ITO layer
2: Skin layer
3: Bare film layer

Claims (10)

A bare film; A bare film and a skin layer co-extruded on one or both sides of the bare film; A transparent conductive film comprising a structure in which an ITO (Indium Tin Oxide) layer is laminated on one surface of a skin layer laminated on the bare film. The method according to claim 1,
Wherein the refractive index of the bare film is 1.55 to 1.85, the refractive index of the skin layer is 1.35 to 1.60, and the refractive index of the ITO layer is 1.9 to 2.2;
Wherein the refractive index is decreased in the order of the ITO layer, the bare film and the skin layer. The method according to claim 1,
Wherein the thickness of the bare film is 20 to 250 占 퐉, the thickness of the skin layer is 5 to 60 nm, and the thickness of the ITO layer is 15 to 50 nm. The method according to claim 1,
Wherein a difference between a reflectance of the skin film and a reflectance of the transparent conductive film is less than 3.0%. The method according to claim 1,
Wherein the transparent conductive film further comprises an adhesive layer on the upper surface of the ITO layer. The method of claim 5,
Wherein the transparent conductive film further comprises a release film on the upper surface of the adhesive layer. (1) co-extruding a bare film and a skin layer to produce a bare film having a skin layer laminated on one side or both sides of the bare film; And
(2) stacking an ITO layer on one surface of the skin layer laminated on the bare film; And a transparent conductive film. The method of claim 7,
Further comprising the step of laminating an adhesive layer laminate and a release film on the upper surface of the ITO layer of the transparent conductive film after the step (2). The method of claim 7,
Wherein the refractive index of the skin layer is 1.35 to 1.60. A touch panel made of the transparent conductive film of claim 1.

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