KR100566543B1 - A plastic film for display panel and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a plastic film for a display panel and a method for manufacturing the same, the method for producing a display panel plastic according to the present invention comprises the steps of (a) preparing a plastic transparent film; (b) plasma-reacting the composite inorganic compound precursor containing a hydrocarbon bond by plasma chemical vapor deposition (PECVD) while maintaining a predetermined oxygen partial pressure ratio (partial pressure of oxygen / partial pressure of a composite inorganic compound). Forming an inorganic buffer layer containing; And (c) forming a gas permeation prevention film made of an inorganic material substantially free of carbon on the carbon-containing inorganic buffer layer formed by changing the oxygen partial pressure ratio of step (b) high. According to the manufacturing method of the present invention, it is possible to mass-produce a plastic film for a display panel having a durable gas permeation prevention film in an environmentally friendly and continuous process.

Description

Plastic film for display panel and manufacturing method thereof

1 is an FT-IR spectrum analyzing the chemical composition of the gas permeation barrier and the buffer layer.

The present invention relates to a plastic film used in various display panels and a method of manufacturing the same.

Display panels are widely used in display devices such as electronic calculators, electronic clocks, car navigation systems, office automation devices, mobile phones, laptop computers, and information communication terminals. For example, liquid crystal displays have transparent electrodes and alignment layers formed therein. The liquid crystal is injected between the opposing upper panel and the lower panel.

Conventionally, such a display panel uses a panel made of glass. However, the glass panel has good transparency but lacks impact resistance due to the nature of the glass, which is easily broken by impact and has a limitation in thinning, and has a limitation in light weight due to its large weight per unit volume. Therefore, recently, a panel made of a transparent plastic film having excellent impact resistance and light weight is gradually replacing the glass panel. That is, the display panel of the plastic film material is about 1/3 (compared to 0.7 mm thick glass), the weight is about 1/5 of the glass panel display panel, and the impact resistance is also excellent.

However, since plastic films have greater permeability to oxygen and water vapor than glass, water vapor and oxygen gas permeate due to temperature changes and pressure changes in the surrounding environment, such as liquid crystal injection, high temperature processes, and cooling. There is a risk of deterioration of the quality. Therefore, in order to compensate for these disadvantages of the plastic film used for the display to prevent the permeation of water vapor or oxygen gas by forming a gas permeation prevention film on the surface of the plastic transparent film.

The gas permeation prevention film applied on the plastic transparent film for display panel requires high light transmittance, solvent resistance, surface hardness, heat resistance, etc. in addition to the permeability to oxygen and water vapor, and generally silicon oxide (SiO _x ) and aluminum oxide Transparent inorganic materials such as (Al _x O _y ), tantalum oxide (Ta _x O _y ), titanium oxide (TiO _x ), and the like are used.

The inorganic gas permeation prevention film is generally coated on the surface of the plastic film using a vacuum deposition method such as sol-gel method, plasma-enhanced chemical vapor deposition (PECVD), sputtering, or the like. These coating methods commonly have the feature of forming a thin film layer having a thickness of 100 nm or less on the surface of the plastic film to significantly reduce gas permeation without damaging the optical properties of the film.

However, when such an inorganic gas permeation prevention film is coated on the plastic film as it is, various problems occur because the difference between the modulus of elasticity of the inorganic material and the organic material is very large. For example, the polyether sulfone film has a modulus of elasticity of 3.7 GPa, while silicon dioxide has a value of 70 GPa and alumina of 350 GPa or more. Therefore, when the plastic film coated with the inorganic gas permeation barrier is subjected to bending by an external force, a large internal stress is shown at the interface between the gas permeation barrier and the plastic film. The larger the value, the greater the shearing force at the interface. This shear stress difference not only causes cracking inside the gas permeation barrier thinly coated with tens of nanometers (nanometer), but may also cause peeling of the membrane when the adhesion between the gas permeation barrier and the plastic film is weak. Occurrence of this phenomenon means loss of gas permeation barrier function.

 Therefore, in order to prevent such a phenomenon, a method of introducing a buffer layer is mainly used to overcome the warpage phenomenon or the peeling phenomenon caused by the difference in the thermal expansion coefficient of the plastic film and the inorganic gas permeation prevention film. As a method of introducing the buffer layer, a method of forming a film on the surface of a plastic film by a method such as roll coating or spin coating is obtained by dispersing a solution in which an acrylate monomer, an organic / inorganic hybrid monomer, or the like is dispersed in an organic solvent. However, this method may cause environmental problems because it uses an organic solvent, and since the inorganic gas permeation prevention film must be recoated under vacuum after the buffer layer is formed, it is difficult to apply it in a continuous process when applied to a mass production process.

The technical problem to be achieved by the present invention is to solve the above problems to provide a plastic film for a display panel having a durable gas permeation prevention film.

Another technical problem to be achieved by the present invention is to provide a manufacturing method capable of mass-producing the plastic film for the display panel in an environmentally friendly and continuous process.

In order to achieve the above technical problem, the present invention is a plastic film for a display panel, the buffer layer is formed between a plastic transparent film and a gas permeation prevention film made of an inorganic material, the buffer layer is made of the same inorganic material as the gas permeation prevention film However, to provide a plastic film for a display panel, the inorganic material constituting the buffer layer containing carbon so as to lower the elastic modulus of the buffer layer.

In the plastic film for display panel according to the present invention, the gas permeation prevention film is preferably made of any one inorganic material selected from the group consisting of silicon oxide, aluminum oxide, titanium oxide, tantalum oxide, silicon nitride, aluminum nitride and titanium nitride.

In addition, the present invention in order to achieve the above another technical problem (a) preparing a plastic transparent film; (b) plasma-reacting the composite inorganic compound precursor containing a hydrocarbon bond by plasma chemical vapor deposition (PECVD) while maintaining a predetermined oxygen partial pressure ratio (partial pressure of oxygen / partial pressure of a composite inorganic compound). Forming an inorganic buffer layer containing; And (c) forming a gas permeation prevention film made of an inorganic material substantially free of carbon on the carbon-containing inorganic buffer layer formed by changing the oxygen partial pressure ratio of step (b) to a high value. It provides a method for producing a plastic film for use.

In the manufacturing method of the plastic film for display panels which concerns on this invention, it is preferable to use hexamethyldisiloxane (HMDSO) as a composite inorganic compound precursor containing a hydrocarbon bond.

Hereinafter, a plastic film for a display panel and a method of manufacturing the same according to the present invention will be described in detail.

First, a transparent film for display panel is prepared. Transparent film for display panel used in the present invention is a polycarbonate (polycarbonate, PC), polyimide (polyimide, PI), polyethersulfone (polyethersulfone (PES), polyarylate (PAR), polyethylene) excellent in optical properties It may be prepared from thermoplastic polymer resins such as polyethylene naphthalate (PEN), polyethylene terephthalate (PET), cycloolefin copolymer, and thermosetting polymer resins such as epoxy and unsaturated polyester.

Subsequently, a buffer layer is formed on the surface of the transparent film. The buffer layer is made of the same inorganic material as the gas permeation prevention film described later, but contains carbon so as to have an elasticity modulus lower than that of the gas permeation prevention film that does not substantially contain carbon. The carbon content is controlled by plasma chemical vapor deposition (PECVD), using a composite inorganic compound containing a hydrocarbon bond as a precursor when forming the buffer layer, and the oxygen partial pressure ratio (partial pressure of oxygen / to the extent that the inorganic material constituting the buffer layer may contain carbon). By adjusting the partial pressure of the composite inorganic compound) to effect a plasma reaction. That is, the composite inorganic compound containing a hydrocarbon bond should be supplied with sufficient oxygen during the plasma reaction according to the plasma chemical vapor deposition method so that the carbon present in the molecule is almost removed, such as inorganic oxides, such as silicon oxide ( Metal oxides represented by SiO _x ), aluminum oxide (Al _x O _y ), titanium oxide (TiO _x ), tantalum oxide (Ta _x O _y ), etc., silicon nitride (SiN _x ), aluminum nitride (AlN _x ), and titanium nitride It is coated with the gas permeation prevention film which consists of metal nitrogen compounds, such as (TiN _x ). However, if the oxygen partial pressure ratio (partial pressure of oxygen / partial pressure of the composite inorganic compound) is adjusted to such an extent that oxygen is not sufficiently supplied, a film containing a large amount of carbon groups is formed due to insufficient introduction of oxygen during film formation. Since the membrane made of an inorganic material has an elastic modulus lowered, the membrane has an elastic modulus between the transparent film and the gas permeation prevention layer, thereby acting as a buffer layer. The composite inorganic compound containing a hydrocarbon bond to be used may form a gas permeation prevention film made of an inorganic material by plasma chemical vapor deposition, and the inorganic material constituting the desired gas permeation prevention film according to a change in conditions such as gas composition of the plasma chemical vapor deposition method. Any compound that can selectively contain carbon to the extent that the modulus of elasticity can be lowered can be used. For example, when forming a gas permeation prevention film made of silicon dioxide, a precursor may be a composite inorganic compound having a Si-O bond and a hydrocarbon bond at the same time, for example, hexamethyldisiloxane (HMDSO). When forming the gas permeation prevention film which consists of titanium oxide, a conventional titanium organometallic complex can be used as a precursor.

After the formation of the buffer layer is completed, the plasma partial pressure ratio is changed to high enough to supply sufficient oxygen so that carbon present in the molecular structure of the composite inorganic compound including hydrocarbon bonds is completely removed. Likewise, a gas permeation prevention film made of an inorganic material substantially free of carbon may be formed on the buffer layer.

As such, by introducing a buffer layer having the same carbon content as the gas permeation prevention film but having a high carbon content between the transparent film and the gas permeation prevention film to have an intermediate modulus of elasticity, the shear stress generated at the interface between the transparent film and the gas permeation prevention film is alleviated. Cracking and peeling of the gas permeation prevention film can be suppressed. This method is not only environmentally friendly because it uses a plasma chemical vapor deposition method that does not use an organic solvent, and since the formation process of the buffer layer and the gas permeation prevention film can be performed continuously, a continuous process is possible and suitable for mass production.

In the method for producing a plastic film for display panel according to the present invention, when hexamethyldisiloxane (HMDSO) is used as the composite inorganic compound precursor containing a hydrocarbon bond, the oxygen partial pressure ratio at the time of buffer layer formation is 1-10. When the gas permeation barrier is formed, the oxygen partial pressure ratio may be 15 to 30, thereby producing a plastic film for display panel having excellent durability and gas permeability. A buffer layer-forming inorganic material containing an appropriate amount of carbon is represented by Formula 1 below. Can be displayed.

SiO _x C _y H _z

In Formula 1, x is 0.5 to 1.5, y is 1.5 to 3, z is 4.5 to 9.

Hereinafter, examples will be described in detail to help understand the present invention. However, embodiments according to the present invention can be modified in many different forms, the scope of the invention should not be construed as limited to the following examples. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

Experimental Example 1

In order to analyze the chemical properties of the thin film, KBr powder was used as a substrate by compression molding into a disc shape. The thin film was obtained by plasma reaction of hexamethyldisiloxane (HMDSO) using an RF power source (Advanced Energy, RFX-600) in the presence of oxygen using chemical vapor deposition. Using a 6 "diameter flat electrode, a KBr substrate was placed on the ground electrode at a distance of 50 mm and reacted with an energy of 200 W. The partial pressure ratio of hexamethyldisiloxane and oxygen Po ₂ / P _HMDSO was (a) was made to react as 20.0 and (b) 5.0, and the total pressure was less than 100 mtorr.

The chemical structure and composition of the thin film formed on the KBr substrate were shown in FIG. 1 using a Mattson FT-IR spectrometer (32 scan, 8 cm ^-1 resolution). (a) shows the case where the Po ₂ / P _HMDSO partial pressure is 20 and (b) shows the case where a thin film is formed with the partial pressure of five. In (a), it can be seen that most of the peaks due to the carbon compounds are not exhibited except for the Si-O peaks that appear strongly at 1033 cm −1. It can be seen from this that the thin film has a SiO ₂ inorganic structure that is substantially free of carbon. In contrast, in (b), it can be seen that a peak of 3400 cm ^-1 -OH and a peak of -CHx at 2800 cm ^-1 appear. This means that Si-C and CH compounds such as Si-OH and Si-CH ₃ , and -CHx remain in the thin film. These results suggest that oxygen is insufficient in the formation of the membrane, so that a large amount of carbon groups remain in the HMDSO molecules.

Comparative Example 1

As a plastic film for display, polyether sulfone (PES) of 200 micrometers in thickness was used. AFM analysis of the film surface had a planar smoothness of 3.0 nm. The film was obtained by plasma reaction of hexamethyldisiloxane (HMDSO) using an RF power source (Advanced Energy, RFX-600) in the presence of oxygen using plasma chemical vapor deposition. The substrate was placed on the ground electrode at a distance of 50 mm using a 6 "diameter flat electrode and reacted with an energy of 250 W. The partial pressure ratio of hexamethyldisiloxane and oxygen of Po ₂ / P _HMDSO was 20.0. And the total pressure reacted at less than 100 mtorr.

ESCA analysis of the plasma-coated film has a SiOxCyHz structure, where x is 1.8 and y has a value of 0.1 or less, and it is confirmed that there are almost no CHx functional groups. The deposition rate of the plasma coating film was 45 nm / min, and the thickness of the coated film was 0.33 micron. The internal stress of the membrane was 5x10 ⁹ dynes / cm ^2, and the curling occurred severely due to the apparent stress.

Example 1

As a plastic film for display, polyether sulfone (PES) of 200 micrometers in thickness was used. AFM analysis of the film surface had a planar smoothness of 3.0 nm. Using plasma chemical vapor deposition, hexamethyldisiloxane (HMDSO) was obtained by plasma reaction using RF power (Advanced Energy, RFX-600) in the presence of oxygen. The substrate was placed on the ground electrode at a distance of 50 mm using a 6 "diameter flat electrode and reacted with an energy of 200 W. The partial pressure ratio of hexamethyldisiloxane and oxygen of Po ₂ / P _HMDSO was 5.0 The total pressure was less than 100 mtorr, and the deposition rate of the plasma coating layer was 45 nm / min, and the thickness of the coated buffer layer was 0.25 micron.

Membranes for imparting gas permeation prevention properties on the buffer layer were continuously produced in the same manner. The energy used was 250W, the partial pressure ratio of hexamethyldisiloxane and oxygen was Po ₂ / P _HMDSO was 20.0, and the total pressure was reacted at less than 100 mtorr. At this time, the deposition rate of the plasma coating film was 45nm / min, the thickness of the coated film was 0.3micron. The coating film thus prepared was hardly observed curling phenomenon.

ESCA analysis of the plasma coated membrane showed that when the chemical structure of the membrane was expressed as SiOxCyHz, the buffer layer had x of 1.1, y of 2.3, and z of 6.4, and the gas permeation barrier had x of 1.8 and y of 0.1 or less. It was confirmed that it was almost absent.

In order to compare the performance durability of the prepared plastic films for display panels of Comparative Example 1 and Example 1, the oxygen permeability change of these films was observed using a torsional motion device. The torsional motion device was manufactured on the basis of ASTM D2236, and the sample size was 100 mm x 30 mm, and the length direction of the sample was always determined by the machine direction of the film. The frequency of the torsional motion was fixed at 0.25 Hz, the angular displacement was (1/24) π, and the number of vibrations was fixed at 1,000 times per sample.

Table 1 shows the results of measuring the oxygen permeability (OTR) before and after performing the torsional motion for each sample.

Sample Number Oxygen Permeability (cc / ㎡day) Before torsion After torsional exercise Comparative Example 1 0.9 53 Example 1 0.7 1.1

Referring to Table 1, the display panel film of Example 1 having a buffer layer between the film and the gas permeation barrier according to the present invention does not significantly increase oxygen permeability even after the torsional movement, unlike the film of Comparative Example 1 having no buffer layer. It can be seen that.

According to the manufacturing method of the present invention, a plastic film for display panel having a durable gas permeation prevention film is formed between the plastic film and the gas permeation prevention film by forming a buffer layer of the same kind as the gas permeation prevention film and containing an inorganic substance containing carbon. Can be. In addition, the manufacturing method of the present invention is environmentally friendly and does not use an organic solvent, it is possible to mass-produce a plastic film for display panel having a durable gas permeation prevention film in a continuous process.

Claims (7)

delete delete delete (a) preparing a plastic transparent film; (b) plasma-reacting the composite inorganic compound precursor containing a hydrocarbon bond by plasma chemical vapor deposition (PECVD) while maintaining a predetermined oxygen partial pressure ratio (partial pressure of oxygen / partial pressure of a composite inorganic compound). Forming an inorganic buffer layer containing; And (c) forming a gas permeation prevention film made of an inorganic material substantially free of carbon on the carbon-containing inorganic material buffer layer formed by changing the oxygen partial pressure ratio of step (b) to a high value; Method for producing a plastic film. The method of claim 4, wherein the composite inorganic compound precursor containing a hydrocarbon bond is hexamethyldisiloxane (HMDSO). The method of claim 5, wherein the oxygen partial pressure ratio of the step (b) is 1 to 10, and the oxygen partial pressure ratio of the step (c) is 15 to 30. The plastic film for display panel according to claim 4, wherein the gas permeation prevention film is made of any one inorganic material selected from the group consisting of silicon oxide, aluminum oxide, titanium oxide, tantalum oxide, silicon nitride, aluminum nitride, and titanium nitride. Manufacturing method.

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