KR101301540B1 - Optical film for display device and manufacturing method of the same - Google Patents

Abstract

The present invention relates to a microcapsule-type display device and a manufacturing method thereof, and an object of the present invention is to propose a method for rearranging a plurality of microcapsules contained in a microcapsule layer into a monolayer structure, thereby providing optical characteristics of the display device. It is to provide a microcapsule-type display device and a method of manufacturing the same that can improve the.
In the microcapsule-type display device according to the present invention, after forming a microcapsule layer stacked between an upper substrate on which an upper electrode is formed and a lower organ on which a lower electrode is formed, the microcapsule display device forms a monolayer microcapsule layer by applying a thermal shock. Is achievable by

Description

Optical film for display display device and manufacturing method thereof {OPTICAL FILM FOR DISPLAY DEVICE AND MANUFACTURING METHOD OF THE SAME}

The present invention relates to an optical film for a display display device and a manufacturing method thereof, and more particularly, to an optical film for a display display device having a microcapsule layer of a mono-layer structure and a manufacturing method thereof.

The use of large amounts of paper has various problems that destroy forests and generate garbage. With the spread of personal computers and the development of the Internet-based information society, the consumption of paper as so-called short-lived documents for the purpose of temporary reading of electronic information tends to increase, and research on display media instead of paper is actively conducted. It's going on.

Among them, the microcapsule type (particularly, cholesteric liquid crystal capsule type) display device has a memory property capable of maintaining display with no power supply, and the liquidity of liquid crystal is suppressed, resulting in less confusion of image due to warpage and pressure. In particular, it is suitable for implementing a flexible display, and due to the fact that it does not use a polarizer and does not require a color filter, it has recently attracted attention.

1 is a cross-sectional view schematically showing a conventional cholesteric liquid crystal capsule-type flexible display display optical film. The microcapsule type display device includes a display device including an optical film interposed between an upper substrate and a lower substrate by forming a liquid crystal into a capsule form 13 by forming a liquid crystal droplet and then mixing it with a polymer binder. As shown in FIG. 1, a microcapsule layer 15 is interposed between an upper substrate 10 having an upper electrode 11 and a lower substrate (not shown) having a lower electrode (not shown).

However, such a conventional microcapsule type display device has the following problems. That is, when looking at the detailed configuration and structure of the conventional microcapsule type display device, since a plurality of microcapsules contained in the microcapsule layer is randomly arranged in a multi-layer inside the binder has a structure overlapping or stacked between the capsules As shown in FIG. 1, light scattering occurs through the microcapsule layer, resulting in a decrease in light transmittance, thereby lowering optical characteristics of the display device.

The present invention has been made to solve the above problems, an object of the present invention is to propose a method for rearranging a plurality of microcapsules contained in the microcapsule layer in a monolayer structure, thereby improving the optical characteristics of the display device The present invention provides an optical film for a display display device and a method of manufacturing the same.

Method for manufacturing an optical film for a flexible display display device according to the present invention for achieving the above object is a method for manufacturing an optical film for a flexible display display device comprising a microcapsule layer between the upper substrate and the lower substrate on which the upper electrode is formed. In the first method, the microcapsule layer structure includes a first step of preparing a microcapsule, a second step of laminating at 50 ° C. on the upper electrode of the upper substrate by mixing the microcapsules with a binder. After the microcapsule layer is rapidly dried at room temperature by rapidly cooling the upper substrate on which the microcapsule layer is laminated to 0 ° C., after drying of the microcapsule layer is completed, at least 50% or more of the total area of the microcapsule layer is micro And a third step of allowing the capsule to be rearranged in a monolayer structure on the upper pole. .

In the microcapsule-type display device according to the present invention, in contrast to the case where a light source is incident on a conventional microcapsule-type display device (see FIG. 1), light scattering phenomenon is greatly increased by the microcapsule layer 155 having a monolayer structure. There is an advantage that can be reduced to improve the light transmittance.

In addition, as each of the plurality of microcapsules 130 is disposed in close contact with each other on a single layer, voids between the particles of the capsules 130 are minimized, which may reduce the thickness of the microcapsule layer 155 (ie, the thickness of the display device). It can act as a factor.

In addition, when the film substrate having the microcapsule layer 155 thinned as described above is applied to the device, the driving voltage of the device can be lowered.

Finally, the microcapsule-type display device according to the present invention may be formed as a flexible display device when applied to a flexible substrate, and may occur in a display device having a liquid crystal material injected between the substrates in any direction. There is an advantage that the image can be maintained as it is without the liquid crystal shift phenomenon.

1 is a cross-sectional view schematically showing a conventional liquid crystal microcapsule type flexible display display optical film.
2 is a process flow diagram illustrating a manufacturing process of the optical film for a flexible display display device according to the present invention.
3 is a cross-sectional view of an optical film for a flexible display display device illustrating a microcapsule rearrangement process for rearranging a microcapsule layer having a multilayer structure manufactured according to each step of FIG. 2 according to a first method of the present invention.
4 is a cross-sectional view schematically showing an example in which a light source is incident on the optical film for a flexible display display device according to the present invention.

An optical film for a flexible display display device and a method of manufacturing the same according to the present invention are characterized in that the microcapsule layer structure in which a plurality of microcapsules are arranged in a mono-layer structure and an effective method of manufacturing a microcapsule layer having such a mono-layer structure are provided. It presents technical features that can improve the optical and electrical properties.

Hereinafter, exemplary embodiments, features, and advantages of the present invention will be described in detail with reference to the accompanying drawings.

2 is a process flowchart illustrating a manufacturing process of an optical film for a flexible display display device according to the present invention.

An optical film for a flexible display display device according to the present invention includes a microcapsule layer between an upper substrate 100 having an upper electrode 110 and a lower substrate (not shown) having a lower electrode (not shown), and the micro The plurality of microcapsules 130 contained in the capsule layer is characterized in that they are arranged in a single layer (monolayer).

The optical film for a flexible display display device of the present invention is manufactured through a microcapsule 130 manufacturing step, a microcapsule layer forming step, and a microcapsule 130 rearrangement step.

First, the microcapsule 130 manufacturing steps will be described. Microcapsules having a diameter of 5 to 50 μm using a complex phase separation method, an interfacial polymerization method, an in-situ polymerization method, and the like. 130 is a step of manufacturing.

The microcapsules 130 may be applied to liquid crystal microcapsules or electrophoretic microcapsules. Hereinafter, the liquid crystal microcapsules will be described with reference to specific manufacturing methods.

When the liquid crystal microcapsules are applied, a nematic liquid crystal, a smectic liquid crystal, a cholesteric liquid crystal 131, and the like are used as the liquid crystal 131 used in capsule manufacturing. In addition, the manufactured microcapsules may further include a dichroic dye and a chiral dopant in addition to the liquid crystal described above.

Specifically, the microcapsules 130 printed on the upper substrate 100 of the present invention may be emulsified to form droplets of a liquid crystal, which is a core material, encapsulation by coservation, gelation of capsule outer walls, Manufactured through capsule outer wall curing process and aging process.

The emulsifying process of the present invention is a step of forming a droplet of a liquid crystal as a core material using a high speed homogenizer in an aqueous solution containing an emulsifier. The emulsifiers include gelatin, gum arabic, albumin, alginate, It is preferred to use at least one selected from natural emulsifiers such as casein to synthetic emulsifiers such as polyurethane, polyacrylic acid, polyethylene, and amines, but is not necessarily limited thereto.

The emulsifiers used in the present invention used gelatin (Type-A, Sigma-Aldrich) and Arabian gum (Arabia Gum, Fluka), specifically, a liquid crystal (600g) in which dichroic dye was dissolved in 360g of 10% aqueous arabic gum solution drop by drop. Using a high speed homogenizer, the speed was increased to 6,500 / 7,500 / 8,500 and emulsified for 10 minutes. In addition, S-428, M-483, M-412 (Mitsui Fine Chemical) were used as the dichroic dyes doped in the liquid crystal, and the liquid crystals were ZLI-1840, ZLI-1565, ZLI-2806 (Merck), and the like. It was.

When the above-mentioned emulsification step is completed, the process proceeds to encapsulation by co-servation. The encapsulation process by the co-servation is a process of forming a coarse hydrate of a water-soluble polymer (gelatin, gum arabic) through the pH control of the aqueous solution, and forming the capsule outer wall through a combination of gelatin and gum arabic.

The embodiment of the present invention was adjusted pH using citric acid or glacial acetic acid. Specifically, 240 g of 10% gelatin aqueous solution and 600 g of pure water are added, and after adding a primary gelatin aqueous solution to adjust the pH to 4.5 using citric acid, the mixture is moved to a general stirrer, and 120 g of the 10% gelatin aqueous solution and 240 g of pure water are further added. The co-servation is complete by slowly adding the solution and adjusting the pH to 4.4 using citric acid.

Co-ablation is a phase separation phenomenon in a colloidal system, and refers to a phenomenon in which two types of colloidal rich layers and colloidal pore layers are separated by precipitation or aggregation of colloidal materials. In the present invention, gelatin and gum agglomerates agglomerated with opposite charges at a pH of about 4.4, which is a co-servation phenomenon. In this case, the coagulation phenomenon causes gelatin to have a positive charge (+), and arabic gum has a negative charge (-), so that hydrophilic colloids having opposite charges are entangled with each other to form the outer wall of the microcapsule.

When the above-mentioned liquid crystal encapsulation process by the coagulation is completed, it will transfer to a gelation process. The gelation process is a process of gelling the outer wall of the capsule through the temperature change, the embodiment of the present invention after cooling the temperature at a cooling rate of about 0.2 ℃ / min from 40 ℃ to 20 ℃, when reaching 20 ℃ Up to 10 ° C. was quenched at a cooling rate of about 0.5 ° C./min. In addition, the liquid crystal capsule is agitated by increasing the rotation speed of the stirrer so that the liquid crystal capsule does not clump at a low temperature due to quenching.

Once the gelling process is complete, the capsule outer wall hardening process is entered. The outer wall curing process is a step of curing the capsule outer wall by adding a curing agent, the curing agent cross-reacts the amino group of gelatin with glutaraldehyde or formaldehyde to cure the capsule to produce a complete microcapsules. In the embodiment of the present invention, the capsule outer wall hardening process was performed by slowly administering 4 g of glutaraldehyde.

After completing the capsule outer wall hardening process, the complete microcapsules were completed. After stirring for about 1 hour, the mixture was left at room temperature and gradually raised to room temperature, then moved to a ball mill and aged for about 24 hours to obtain stable microcapsules. do.

Microcapsules obtained through the above-described manufacturing process require washing and filtration, and in the case of washing, pure water, isopropyl alcohol, ethylene glycol, and the like are performed. The microcapsule 130 filtration process may be achieved through a filter paper or a membrane as a process for obtaining only microcapsules 130 having a desired size and removing impurities involved in the microcapsule 130 manufacturing process.

The microcapsules 130 having been cleaned and filtered should be stacked and fixed on one surface of the upper substrate 100, which can be achieved through the binder 140. That is, after mixing the microcapsules 130 in a predetermined ratio to the binder 140 of the transparent material is printed and fixed on one surface of the upper substrate 100.

Specifically, the mixing ratio of the microcapsules 130 and the binder 140 is preferably configured to be mixed in a 1: 1 ratio, and the binder 140 used may be polyvinyl alcohol, gelatin, formalin resolcinone resin, poly At least one transparent polymer material selected from urethane resin, acrylic acid resin, melamine, methacrylic acid resin, formaldehyde resin, fluorine resin and polyvinylpyrrolidone is used.

In addition, before printing the paste mixed with the microcapsules 130 and the binder 140 on the upper substrate 100, a degassing process is performed to remove bubbles contained in the binder 140 in the mixing process.

When all of the above processes are completed, the microcapsules 130 mixed with the binder 140 are printed on the substrate to form the microcapsule layer 150.

On one side of the upper substrate 100 according to the present invention, the upper electrode 110 thin film is formed by a deposition method or the like. The upper electrode 110 is formed using indium tin oxide (ITO), indium zinc oxide (IZO), or a transparent conductive polymer.

The upper substrate 100 may be formed of a glass substrate made of glass material, as well as a thin plastic substrate having elastic flexibility.

It is preferable to use any one selected from polyethylene naphthalate (PEN), polyether sulfone (PES), polyarylate (PAR), polycarbonate (PC), polyethylene terephthalate (PET) as a material of the plastic substrate. , But not necessarily limited thereto.

The method of printing the paste in which the microcapsules 130 and the binder 140 are mixed on the upper substrate 100 on which the upper electrode 110 is stacked is performed by any one method selected from screen printing, stencil printing, and offset printing. It is achievable and can be achieved by any one method selected from gravure coating, knife coating, roll coating, die coating, reverse coating.

As described above, when the process of printing the paste mixed with the microcapsules 130 and the binder 140 on the upper electrode 110 of the upper substrate 100 is completed, the microcapsule layer as shown in FIG. 150). 3 is a cross-sectional view of an optical film for a flexible display display device illustrating a microcapsule rearrangement process of rearranging a microcapsule layer having a multilayer structure manufactured according to each step of FIG. 2 to a monolayer microcapsule layer.

As can be seen in Figure 3 (a), the microcapsule layer 150 has been advanced to the above-described process is a plurality of microcapsules 130 contained therein are randomly arranged in a multilayer in the binder 140 overlapping each other capsules Or stacked microcapsule layer 150.

Optical film manufacturing method for a flexible display display device of the present invention rearranges the microcapsule 130 to make a microcapsule layer 150 having a multi-layered random arrangement structure as a mono-layer structure as described above It further includes.

For reference, the term "monolayer structure" used in the present invention will be defined. The monolayer structure of the present invention does not mean that each one of the liquid crystal molecules are arranged in a single molecule layer, but means a structure in which one microcapsules formed by collecting a plurality of liquid crystals are arranged in close contact with each other in the same form as a single molecule layer.

That is, when the microcapsules are arranged in a single layer between the upper substrate and the lower substrate when the upper substrate and the lower substrate interposing the microcapsule layer are cut in the vertical direction, this corresponds to a monolayer structure. However, when the microcapsule layer is actually made to have a monolayer structure, it is impossible or extremely difficult to fabricate all microcapsules to form a 100% monolayer over the entire area of the microcapsule layer. Therefore, in the present invention, the monolayer structure means a state in which the microcapsules are arranged in a single layer structure in an area of at least 50% or more and preferably in an area of 70% or more with respect to the total area of the microcapsule layer stacked on the upper substrate. It will be defined as.

The monolayer structure of the microcapsule layer 155 is achieved through the following manufacturing method. After the microcapsule layer 150 is printed / coated on one surface of the upper substrate 100 through the aforementioned microcapsule layer forming step, the upper substrate 100 on which the microcapsule layer 150 is stacked is thermally shocked. It is using temperature change.

Positioning the upper substrate 100 in which the upper electrode 110 is formed in the chamber having the first temperature, and forming the microcapsules 130 mixed with the binder 140 on the upper electrode 110 by printing or coating method. (FIG. 3 (a)). At this time, the first temperature is preferably maintained at 40 ℃ and 60 ℃. If the inside of the chamber is maintained higher than 60 ℃ because the solvent contained in the binder 140 is evaporated for a short time there is a problem that the microcapsules 130 are hardened before being relocated to a monolayer.

Subsequently, when the internal temperature of the chamber is changed to a second temperature that is approximately 40 ° C. to 60 ° C. lower than the first temperature within 5 minutes, the microcapsules (c) mixed with the binder 140 and positioned on the upper part as shown in FIG. 130) The particles fall in the direction of gravity. At this time, it is preferable that the 2nd temperature has a temperature of 0 degreeC or more. This is because when the second temperature is maintained at a temperature lower than 0 ° C., the water-soluble binder may freeze. The microcapsule layer 150 has a rapid rise in viscosity due to a rapid temperature change due to thermal shock, and thus, a drying speed is slowed down. As a result, the descending speed of the microcapsules slows down, as shown in 3 (c). The arrangement is arranged in a monolayer arrangement. When the temperature inside the chamber is maintained at the first temperature and then lowered to the second temperature within a few minutes, the microcapsule layer 150 does not drop to the second temperature, and the curing of the binder is substantially performed between room temperature and the second temperature. It was confirmed to be complete. It can be seen from this experiment that the temperature difference applied to the microcapsule layer 130 is substantially the first temperature and the second temperature even if the temperature of the chamber is maintained at the first temperature but lowered to the second temperature lower than 40 ° C. to 60 ° C. It can be seen that less than the difference in temperature is added.

In the above description, it is preferable to use a chamber to apply a temperature shock. However, when it is difficult to use the chamber, the upper substrate 100 is placed on a hot plate substrate (not shown), and the temperature applied to the hot plate substrate is measured. It is also possible to sharply fall from the temperature to the second temperature. In particular, in this case, dew condensation may occur due to moisture in the microcapsule layer due to a sudden temperature change. To prevent this phenomenon, the relative humidity is kept below 50%, more preferably below 30%. It is important to do.

4 is a cross-sectional view schematically illustrating an example in which a light source is incident on the optical film for a flexible display display device according to the present invention.

As can be seen in FIG. 4, the microcapsule-type display device according to the present invention is prepared by the microcapsule layer 155 having a monolayer structure in contrast to the case where a light source is incident on a conventional microcapsule-type display device (see FIG. 1). The light scattering phenomenon is greatly reduced, there is an advantage that can improve the light transmittance.

In addition, as each of the plurality of microcapsules 130 is disposed in close contact with each other on a single layer, voids between the particles of the capsules 130 are minimized, which may reduce the thickness of the microcapsule layer 155 (ie, the thickness of the display device). It can act as a factor.

In addition, if the film substrate having the thin microcapsule layer 155 as described above is applied to the device, the driving voltage of the device can be lowered, and the liquid crystal does not move even when the substrate is bent. .

While specific embodiments of the invention have been illustrated and described, it will be obvious that the same may be varied in many ways by those skilled in the art without departing from the spirit of the invention. Such modified embodiments are not to be understood individually from the spirit and scope of the present invention, but are to be regarded as falling within the scope of the appended claims.

100: upper substrate 110: upper electrode
130: microcapsules 131: liquid crystal
140: binder 150: microcapsule layer
155: microcapsule layer of monolayer structure

Claims (10)

An optical film manufacturing method for a display display device including a microcapsule layer between an upper substrate on which an upper electrode is formed and a lower substrate on which a lower electrode is formed.
A first step of preparing microcapsules;
Stacking the microcapsules by mixing the microcapsules with a binder to form the upper electrodes; And
At least 50% or more of the microcapsule layer with respect to the total area of the microcapsule layer by thermally impacting the upper substrate on which the microcapsule layer is stacked comprises a third step of rearranging the microcapsules in a monolayer structure on the upper electrode. An optical film manufacturing method for a display display device.
The method of claim 1,
The third step of thermal shock is characterized in that the upper substrate is located inside the chamber or on the hot plate substrate, and the temperature inside the chamber or the temperature of the hot plate substrate is changed from the first temperature to the second temperature. And wherein the second temperature is lower than 40 ° C. to 60 ° C. than the first temperature.
The method of claim 2,
The microcapsules are liquid crystal microcapsules or electrophoretic microcapsules characterized in that the optical film manufacturing method for a display display device.
The method of claim 3, wherein
The liquid crystal microcapsules include nematic liquid crystal, smectic liquid crystal, Cholesteric liquid crystal and a dichroic dye.
5. The method of claim 4,
The upper substrate or the lower substrate is an optical film manufacturing method for a display display device, characterized in that the plastic substrate.
6. The method of claim 5,
The plastic substrate is at least one selected from polyethylene naphthalate (PEN), polyether sulfone (PES), polyarylate (PAR), polycarbonate (PC) and polyethylene terephthalate (PET). Method for producing optical film for use.
The method of claim 2,
The first temperature is a method of manufacturing an optical film for a display display device, characterized in that less than 60 ℃.
The method of claim 2,
The second temperature is 0 ℃ or more method for manufacturing an optical film for a display display device.
The method of claim 1,
The thermal shock is applied to the optical film manufacturing method for a display display device, characterized in that applied within 5 minutes.
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