KR20100118219A - Flexible substrate for display panel and manufacturing method of the same - Google Patents

Abstract

PURPOSE: A flexible substrate for a display panel and a method for manufacturing the same are provided to reduce the thermal expansion coefficient of a substrate through the bonding of heat-resistant resins. CONSTITUTION: A flexible substrate(100) for a display panel comprises an inorganic particle filler pattern(110) recessed in a harden heat-resistant resin(120). The inorganic particle filler pattern is formed through plasticization after forming the pasted inorganic particle fillers in a certain pattern. The inorganic particle filler pattern is a grid pattern which is repeatedly formed over the surface of the pattern. The heat-resistant resin is one of polysulfone, polyether, Polyether lmide, PAR:polyarylate, Polyether lmide and PAR:polyarylate.

Description

Flexible substrate for display panel and manufacturing method therefor {FLEXIBLE SUBSTRATE FOR DISPLAY PANEL AND MANUFACTURING METHOD OF THE SAME}

The present invention relates to a flexible substrate for a display panel and a method of manufacturing the same, and more particularly, through a film structure in which a paste-formed inorganic particle filler pattern is transferred into a heat resistant resin, the coefficient of transparency is low, and the coefficient of thermal expansion is low. The present invention relates to a flexible substrate for display panel having excellent heat resistance and surface roughness, and a method of manufacturing the same.

Currently, a display device (for example, a liquid crystal display device) that is widely used uses a transparent electrode substrate made of a glass material. However, glass substrates have limitations in thinning and lightening display devices due to their thick thickness and heavy weight, and are vulnerable to impact resistance, and are particularly unsuitable for use in flexible displays due to the brittleness of glass materials.

Accordingly, a flexible substrate made of a plastic optical film material is in the spotlight as a material to replace a conventional glass substrate, and the flexible substrate is used in next-generation display devices such as liquid crystal displays, organic ELs, and e-paper. It has very suitable properties.

Compared to the glass substrate used as a conventional display panel, the flexible substrate made of plastic optical film material has a thin, light, flexible ductility, and can be processed in various forms, thereby reducing weight, thickness, and curved surface, which are essential for next-generation display devices. The display function can be implemented.

Due to the advantages of the flexible substrate as described above, various researches and developments are being made on materials and structures of the flexible substrate.

In detail, in the initial stage of development, there is an example in which a transparent film material made of a plastic polymer is used, and an epoxy resin, an acid anhydride-based curing agent, a composition using an alcohol curing catalyst, or the like is applied as a material of the flexible substrate.

However, the flexible substrate composed of the above materials has a large coefficient of linear expansion, and especially when applied to an active matrix display element substrate, it causes problems such as warpage and disconnection of aluminum wiring in the manufacturing process, and is more resistant to heat than the glass substrate. Thermal characteristics such as coefficient of thermal expansion (CTE) and optical characteristics such as transparency and refractive index are weak, and thus there is a limit to use as a flexible substrate.

Therefore, in order to use the plastic optical film material as a display panel substrate, in particular, a liquid crystal display device substrate, heat resistance and high transmittance must be satisfied, and above all, a plastic optical film material having a low coefficient of thermal expansion and a low surface roughness of the film surface. It is essential to develop.

Looking at the conventionally known technology for reducing the coefficient of thermal expansion of plastic optical film material according to this requirement, it is understood that the present invention relates to a composite film structure composed of an inorganic filler such as glass powder or glass cloth. Can be.

For example, Japanese Patent Application Laid-Open No. 2004-51960 proposes a resin sheet containing an epoxy resin and a glass fiber in the form of glass fabric, and Japanese Patent Publication No. 2004-233851 presents a transparent substrate made of glass cloth and resin. Doing.

However, the conventional composite film structure and its manufacturing method which produce a transparent substrate by impregnating glass cloth with resin had some problems.

First, the process of producing glass fibers in the form of a fabric is not simple, and especially when the film is made large by using a hot press method, the process becomes long and complicated because it causes film curl. There was a problem that the production of large films is difficult because the production cost is increased.

Second, when manufacturing a glass cloth impregnated film using a UV-curing resin, due to the structural characteristics of the glass fiber in the form of a fabric and shrinkage phenomenon of the glass cloth, the finished film is not flat surface roughness is very rough display There was a problem that caused poor image quality of the device.

The present invention has been made to solve the above problems, an object of the present invention is to provide a flexible substrate that can ensure the optimum image quality of the display device by improving the surface roughness problem of the substrate.

Another object of the present invention is to provide a flexible substrate that can improve the surface roughness of the substrate and at the same time ensure a low coefficient of thermal expansion, thereby minimizing the phase difference change of the pattern cell due to shrinkage expansion of the substrate during high temperature processing. will be.

The flexible substrate for a display panel according to the present invention for achieving the above object includes an inorganic particle filler pattern impregnated in the cured heat-resistant resin, the inorganic particle filler pattern is formed of a paste patterned inorganic particle filler in a predetermined pattern And then calcined and formed.

Still another object of the present invention is a method of manufacturing a flexible substrate for a display panel, the method comprising the steps of preparing an inorganic particle filler having a thermal expansion coefficient of 8 ppm or less, a second step of pasting the prepared inorganic particle filler, and a paste-formed inorganic particle filler. The third step of printing in a plaid pattern shape on the plate-like member, the fourth step of firing to remove the binder and the organic material in the printed paste, and the liquid heat-resistant resin is poured and immersed in the completed inorganic particle filler pattern And a fifth step of transferring the inorganic particle filler pattern printed on the plate member to the inside of the heat resistant resin and removing the heat resistant resin from which the transfer of the inorganic particle filler pattern is completed from the plate member. Achieved by a flexible substrate manufacturing method for a display panel Neunghada.

According to the present invention, a flexible substrate for a display panel and a method of manufacturing the same can provide a method of reducing the coefficient of thermal expansion of the substrate and at the same time preventing surface roughness reduction through organic bonding of the pasted inorganic particle filler pattern and the heat resistant resin. Therefore, it is possible to improve the dimensional stability of the display panel substrate, to ensure the optimum image quality of the display device, and to perform a continuous manufacturing process of a roll type, thereby improving productivity.

In addition, unlike glass cloth composed of a conventional glass fiber in the form of a fabric, there is no variation in height, and in particular, when the grid pattern is configured in a square, a thermal swelling is uniformly generated as the opening surfaces having the same length ratio are arranged at equal intervals. It can be induced so that the uniformity of the thermal difference coefficient can be ensured.

In addition, the surface roughness of the substrate can be minimized by the impregnating material as the height is constant over the entire surface of the pattern, and there is a remarkable effect of increasing the transmittance of the substrate.

1 (a) to (d) is a view showing a manufacturing process of a flexible substrate for a display panel according to the present invention, Figures 2 (a) and (b) is a final completed flexible substrate through the manufacturing process of FIG. 3 is a plan view and a cross-sectional view of FIG. 100, and FIG. 3 is a block flow diagram showing a workflow of the method for manufacturing a flexible substrate for a display panel according to the present invention.

Prior to the description, preferred embodiments described below are directed to the best flexible substrates and manufacturing methods for panels requiring transparent substrates, such as liquid crystal displays, among various display devices including liquid crystal displays, organic EL and electronic paper. It is revealed.

That is, the flexible substrate 100 according to the present invention provides an optical characteristic of "85% or more transmittance" and a technical characteristic of improving the resin sheet to secure a thermal characteristic of "coefficient of thermal expansion of 20 ppm or less".

Therefore, when the flexible substrate 100 of the present invention is to be applied to a panel (for example, an organic EL, a touch panel, an electronic paper, a solar cell, an optical circuit board, etc.) that does not need to consider the transmittance of the substrate, Technical features that affect the transmittance of the flexible substrate 100 need not be considered, and of course, only a configuration for improving thermal characteristics may be combined and applied.

Hereinafter, with reference to FIGS. 1 to 3 will be described in detail the features, preferred embodiments and advantages of the flexible substrate according to the present invention.

The flexible substrate for a display panel according to the present invention is formed by pasting an inorganic particle filler to print to have a predetermined pattern shape, firing the same, and then immersing the inorganic particle filler in the liquid resin 120. The inorganic particle filler having a pattern shape suggests a plastic optical film structure impregnated to be included in the cured liquid resin 120.

By improving the physical properties of the resin sheet through the film structure as described above, while ensuring the proper transmittance, and above all to secure a strength that can overcome the limitation of the thermal expansion coefficient reduction of the conventional plastic flexible substrate.

Specifically, the flexible substrate 100 according to the present invention is to improve the physical properties of the resin sheet by printing an inorganic particle filler having a predetermined pattern shape, and by impregnating the printed inorganic particle filler inside the resin 120 Made through the steps.

First, the step of printing the inorganic particle filler in a predetermined pattern shape will be described.

The printing of the inorganic particle filler in a predetermined pattern shape may include the steps of preparing an inorganic particle filler that satisfies a predetermined condition, pasting the prepared inorganic particle filler, and pasting the prepared inorganic particle filler into a glass plate. Printing in a specific pattern or the like, and firing to remove the binder and organic matter in the printed paste.

(1) Preparation of inorganic particle filler that satisfies predetermined conditions

The inorganic particle filler is an ultrafine ceramic in which a refractive index is matched with a resin 120 constituting the flexible substrate 100 so that the flexible substrate 100 of the present invention can secure a transmittance of 85% or more. Use powder.

Specifically, it is preferable to use a ceramic powder having a difference in refractive index within ± 0.01 from the resin 120 constituting the flexible substrate 100 and having a particle size of 200 nm or less, preferably 100 nm or less.

That is, the substrate applied to the liquid crystal display panel is a light emitted from the liquid crystal to pass through the substrate to reach the user, the flexible substrate 100 of the present invention has a predetermined pattern inside the resin 120 constituting the substrate Because of the structural characteristics impregnated with the inorganic particle filler, it is necessary to minimize the difference in refractive index between the inorganic particle filler pattern 110 and the resin 120 to display a clear image.

In addition, when the particle size of the inorganic particle filler used is larger than 200 nm, since light is scattered at the interface with the resin due to the particle size and haze increases, an inorganic particle filler having a particle size of at least 200 nm or less is used. It is preferable.

In addition, the inorganic particle filler according to the present invention uses an inorganic particle filler having a low coefficient of thermal expansion so as to lower the coefficient of thermal expansion of the flexible substrate 100 of the present invention, and specifically, an ultra fine ceramic having a coefficient of thermal expansion (CTE) of 8 ppm or less Use powder.

(2) Paste the prepared inorganic particle filler

In order to print the inorganic particle filler satisfying the above conditions in a specific pattern shape, a process of pasting the inorganic particle filler in powder form is required.

Looking at the preparation method of the inorganic particle filler paste, a binder containing at least one selected from nitro cellulose (NC: Nitro Cellulose), butyl carbitol acetate (BCA: Butyl Carbital Acetate) and terpineol (terpineol) Binder) can be achieved by stirring with an inorganic particle filler.

Specifically, the inorganic particle filler paste according to a preferred embodiment of the present invention was prepared using a binder consisting of 3% NC and 97% BCA as a main component. The compounding ratio of the inorganic particle filler paste was 60 wt% of the inorganic particle filler and 40wt% of the binder, and the compounding ratio need not be limited to a specific compounding ratio within the range in which the inorganic particle filler can be printed in a specific pattern shape.

(3) Printing Pasted Inorganic Particle Filler in a Specific Pattern

When the pasting of the inorganic particle filler is completed, a job of printing a predetermined pattern shape using the paste is necessary. Hereinafter, a pattern of a specific shape printed using the inorganic particle filler paste will be referred to as "inorganic particle filler pattern 110".

The inorganic particle filler pattern 110 is formed by printing the prepared inorganic particle filler paste on the flat plate member 10 using a mesh screen. Inorganic particle filler pattern 110 according to a preferred embodiment of the present invention, the rectangular opening surface is configured to have a plaid pattern that is formed repeatedly repeatedly over the entire surface of the inorganic particle filler pattern 110, The shape of the opening surface is not limited to a quadrangular shape, and various grid patterns including an opening surface such as a hexagonal shape or a circular shape may be adopted.

In addition, the inorganic particle filler pattern 110 is preferably formed to have an opening ratio of at least 50%. The aperture ratio means that the inorganic particle filler is expressed in% of the unprinted area in a constant area. For example, if the area occupied by the filler in an area within 1 cm 2 is 0.4 cm 2, the opening ratio may be defined as 60%. This is because when the inorganic particle filler pattern 110 existing in the resin 120 in the impregnated state is formed to have an opening ratio of less than 50%, the transmittance of the substrate decreases, which is not suitable for the liquid crystal display panel.

Therefore, when the flexible substrate 100 of the present invention is applied to a display panel that does not require a transparent substrate, the inorganic particle filler pattern 110 is configured to have an opening ratio of less than 50%, thereby greatly improving the thermal characteristics of the substrate. Of course you can.

The plate member 10 used for printing the inorganic particle filler pattern 110 may use a plate member or a release film of glass or SUS material, but is not necessarily limited thereto.

Figure 4 is an embodiment photograph showing the inorganic particle filler pattern actually produced through the above-described process. Inorganic particle filler pattern 110 according to the present invention is a feature produced by pasting ceramic powder, and a predetermined lattice pattern is repeatedly formed uniformly over the entire surface to ensure the following advantages through structural features: do.

That is, as shown in Figure 4, the inorganic particle filler pattern 110 according to the present invention has no variation in height, unlike the glass cloth composed of a conventional glass fiber in the form of a fabric, in particular when the grid pattern is configured in a square As the opening surfaces having the same length ratio (horizontal: vertical) are arranged at the same interval, thermal expansion can be induced to occur uniformly, thereby ensuring uniformity for thermal expansion. In addition, there is an advantage that it is possible to minimize the occurrence of roughness (Roughness) on the substrate by the impregnated material as the height is constant over the entire surface of the pattern.

(4) Firing of Printed Inorganic Particle Filler Paste

In the inorganic particle filler paste printed with a specific pattern, the above-described binder, organic substance, and the like are introduced. Therefore, in order to remove the binder contained in the inorganic particle filler pattern 110 and various organic matters, it is necessary to fire the work.

The firing operation may completely remove the binder and various organic substances present in the inorganic particle filler paste by performing burnout on the paste at a temperature of 300 ° C. or higher.

Next, the steps of completing the flexible substrate 100 of the present invention by transferring the inorganic particle filler pattern 110 printed on the plate member 10 into the resin 120 will be described.

As described above, when the printing and firing operations of the inorganic particle filler having a predetermined pattern shape are completed, a process of curing the resin 120 by pouring the liquid resin 120 on the inorganic particle filler pattern 110 is required. Do.

The resin 120 is preferably a heat-resistant UV curable resin or thermosetting resin in order to minimize the thermal deformation of the substrate in the liquid crystal display process of 180 ℃ temperature, specific examples, polysulfone (polysulfone), polyether (at least one heat resistant resin selected from polyether, polyether lmide, and polyarylate (PAR), preferably having a glass transition point of 200 ° C. or higher and a refractive index of 1.6 or more, but not necessarily limited thereto. It is not.

In addition, the coating and coating operations of the liquid resin 120 may be achieved by using a slit die coater, etc., which is a well-known technique and will not be described in detail.

When the heat resistant resin sheet coated and cured on the inorganic particle filler pattern 110 is removed from the plate member 10, the inorganic particle filler pattern 110 printed on the plate member 10 is impregnated in the resin 120. The flexible substrate 100 of the present invention is included in the resin 120.

Table 1 is actual measurement data which measured the thermal characteristic and the optical characteristic by actual operation of the board | substrate according to the manufacturing method of the above-mentioned flexible substrate.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Film thickness (㎛) 70 70 70 100 100 100 Inorganic particle filler pattern shape (A: B, mm) 0.5: 0.5 1: 1 1.5: 1 2: 1 3: 1 3: 0.5 Thermal expansion coefficient ppm / ℃ 19 15 18 20 24 27 Transmittance 550nm (%) 80 82 83 85 87 89

Each Example of Table 1 is demonstrated. Inorganic particle filler paste is obtained by mixing 60 wt% of glass powder having a refractive index of 1.63, a particle size of less than 100 nm, and a thermal expansion coefficient of 5.3 ppm with 40 wt% of a binder composed of 3% of NC and 97% of BCA. To prepare a pattern on a glass substrate. The inorganic particle filler paste was burned out at a temperature of 200 ° C. to form an inorganic particle filler pattern. The polyarylate was poured onto the resulting inorganic particle filler pattern in a liquid resin 120 and immersed using the slit die coater method, and then cured after UV curing to produce a flexible substrate.

FIG. 5 is an enlarged view for explaining the print shape of the filler pattern shown in Table 1. FIG. The inorganic particle filler pattern 110 used in the embodiment of the present invention was configured in a grid shape having a square opening surface, and the opening ratio was designed to be at least 50% or more, respectively. The symbol "A" of the inorganic particle filler pattern item of FIG. 5 corresponds to the width of the opening surface, and the symbol "B" corresponds to the line width of the pattern.

As shown in the examples of Table 1, the flexible substrate 100 of the present invention, in which the faced inorganic particle filler pattern is impregnated into the heat resistant resin 120, has a transmittance of not less than 85% and a coefficient of thermal expansion of not more than 20 ppm that can be used as a liquid crystal panel. Also, the surface roughness of the substrate is improved through the structural feature that the inorganic particle pattern having no height deviation is included in the resin 120, thereby preventing a problem of lowering contrast due to surface roughness. There is this. In addition, the flexible substrate of the present invention has an advantage of being able to improve the productivity by enabling a continuous manufacturing process of a roll type.

In the above, although the preferred embodiment of the present invention has been described and illustrated, it is obvious that various changes and changes can be made without departing from the spirit and scope of the following claims. Such modified embodiments should not be understood individually from the spirit and scope of the present invention, but should fall within the claims appended to the present invention.

1 (a) to (d) is a view showing a manufacturing process of a flexible substrate for a display panel according to the present invention.

2 (a) and (b) are a plan view and a cross-sectional view of the final flexible substrate through the manufacturing process of FIG.

3 is a block flow diagram showing a workflow of a method for manufacturing a flexible substrate for a display panel according to the present invention.

Figure 4 is an embodiment photograph showing an inorganic particle filler pattern actually produced through the above-described process.

5 is an enlarged view for explaining the print shape of the filler pattern shown in Table 1. FIG.

** Description of symbols for the main parts of the drawing **

100: flexible substrate 110: inorganic particle filler pattern

120: heat resistant resin 10: plate member

Claims (10)

Including an inorganic particle filler pattern impregnated in the cured heat-resistant resin, the inorganic particle filler pattern is formed by forming a paste-formed inorganic particle filler in a predetermined pattern and then fired to form a flexible substrate for a display panel . The method of claim 1, The inorganic particle filler pattern is a flexible panel for a display panel, characterized in that the opening surface of a particular shape is a lattice pattern that is formed repeatedly repeatedly over the entire surface of the inorganic particle filler pattern. The method of claim 2, And the inorganic particle filler pattern has an opening ratio of at least 50%. The method of claim 1, The inorganic particle filler is an ultra fine ceramic powder having a particle size of 200 nm or less and a thermal expansion coefficient of 8 ppm or less. The method of claim 1, The heat resistant resin is at least one selected from polysulfone, polyether, polyether lmide, and polyarylate (PAR: polyarylate) having a glass transition point of 200 ° C. or more. Flexible substrate for panels. The method of claim 1, The heat resistant resin has a refractive index of 1.6 or more, and the difference in refractive index between the heat resistant resin and the inorganic particle filler is within ± 0.01. As a method of manufacturing a flexible substrate for a display panel, A first step of preparing an inorganic particle filler having a thermal expansion coefficient of 8 ppm or less; A second step of pasting the prepared inorganic particle filler; A third step of printing the paste-formed inorganic particle filler in a plaid pattern on the plate member; A fourth step of firing to remove binder and organics in the printed paste; A fifth step of transferring the inorganic particle filler pattern printed on the plate-like member to the inside of the heat resistant resin by pouring and immersing the liquid heat resistant resin into the inorganic particle filler pattern after the baking is completed; And And a sixth step of removing the heat-resistant resin from which the transfer of the inorganic particle filler pattern is completed from the plate member. The method of claim 7, wherein The inorganic particle filler has a difference in refractive index within ± 0.01 from the heat-resistant resin constituting the flexible substrate, and ultrafine ceramic powder having a particle size of 200 nm or less is used. The method of claim 7, wherein The inorganic particle filler paste is prepared by stirring a binder containing at least one selected from nitro cellulose, NC, butyl carbital acetate, and terpineol. Flexible substrate manufacturing method for a display panel, characterized in that provided. The method of claim 7, wherein The firing of the fourth step is carried out by performing burnout on the inorganic particle filler paste at a temperature of 200 ° C.

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