KR20170012753A

KR20170012753A - Transmissivity changeable film, display device including the same and method for preparing transmissivity changeable film

Info

Publication number: KR20170012753A
Application number: KR1020150104433A
Authority: KR
Inventors: 임지원; 이민희; 김지연; 김동응
Original assignee: (주)엘지하우시스
Priority date: 2015-07-23
Filing date: 2015-07-23
Publication date: 2017-02-03

Abstract

An upper electrode; A lower electrode including a conductive material layer formed in a linear pattern and spaced apart from the upper electrode; And an ink receiving layer disposed between the upper electrode and the lower electrode, the ink receiving layer containing ink containing colored charged particles in the space, And a bottom surface of the space is formed by a concave surface.

Description

TECHNICAL FIELD [0001] The present invention relates to a variable transmissivity film, and a display device including the same. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

A light transmittance variable film and a display device including the same.

BACKGROUND ART In general, a digital paper display has been spotlighted as a next generation display device following a liquid crystal display, a plasma display panel, and an organic luminescence display. Type display device.

In such a display device, an electrochromic method, a polymer dispersed LC (PDLC) method, or the like can be used as a method of controlling the light transmittance.

One embodiment of the present invention provides a light transmittance variable film that realizes excellent maximum transmittance at high speed.

Another embodiment of the present invention provides a display device including the light transmittance variable film.

In one embodiment of the present invention, an upper electrode; A lower electrode including a conductive material layer formed in a linear pattern and spaced apart from the upper electrode; And an ink receiving layer disposed between the upper electrode and the lower electrode, the ink receiving layer containing ink containing colored charged particles in the space, And a bottom surface of the space is formed by a concave surface.

In another embodiment of the present invention, the light transmittance variable film; And a voltage application means electrically connected to the light transmittance variable film.

The light transmittance variable film can change the transmittance at a high speed and can realize an excellent maximum transmittance.

1 schematically shows a cross section of a light transmittance variable film according to an embodiment of the present invention.
2 is a schematic view of a cross section of a light transmittance variable film according to another embodiment of the present invention when a voltage is applied.
Fig. 3 shows a cross section of a structure deformed so as to be contrasted with the internal structure of the light transmittance variable film.
4 shows a cross section of the light transmittance variable film according to another embodiment of the present invention.
5 shows a cross section of the light transmittance variable film according to another embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

In the drawings, the thickness is enlarged to clearly represent the layers and regions. In the drawings, for the convenience of explanation, the thicknesses of some layers and regions are exaggerated.

Hereinafter, the formation of any structure in the "upper (or lower)" or the "upper (or lower)" of the substrate means that any structure is formed in contact with the upper surface (or lower surface) of the substrate However, the present invention is not limited to not including other configurations between the substrate and any structure formed on (or under) the substrate.

In one embodiment of the present invention, an upper electrode; A lower electrode including a conductive material layer formed in a linear pattern and spaced apart from the upper electrode; And an ink receiving layer disposed between the upper electrode and the lower electrode, the ink receiving layer containing ink containing colored charged particles in the space, A skeleton forming the bottom surface of the space and the space, and the bottom surface of the space is formed as a concave surface.

FIG. 1 schematically shows a cross section of the light transmittance variable film 100. 1, the light transmittance variable film 100 includes an upper electrode 110; A lower electrode 120 including a conductive material layer 122 formed in a linear pattern and spaced apart from the upper electrode 110; And a space 132 partitioned by the barrier ribs 131. The upper electrode 110 and the lower electrode 120 receive the ink containing colored charged particles 134 in the space 132, And an ink receiving layer 130 disposed between the ink receiving layer 130 and the ink receiving layer 130.

1, the lower electrode 120 is formed in a linear pattern extending in a direction perpendicular to a cross section.

The light transmittance variable film 100 is a film whose light transmittance can be changed depending on whether a voltage is applied or not.

The ink is contained in the space 132 as described above.

The space 132 may be formed, for example, as a microcup such as a microcapsule structure as a microcup or a closed space having an open top, but is not limited thereto. In FIG. 1, the space 132 is formed in a cup shape with a bottom surface and a micro cup structure with an open top. The side surface of the individual space 132 is formed by the partition 131 of the ink receiving layer 130.

The meaning of micro in the space 132 means several to several thousand micro scale.

The ink may further include an insulating medium, and if no voltage is applied to the light transmittance varying film, the colored charged particles 134 contained in the space may be dispersed randomly in the insulating medium . When the voltage is not applied, the colored charged particles 134 are dispersed evenly in the insulating medium to block the transmission of light, The light transmittance of the variable transmissivity film 100 may be, for example, about 0% to about 10%, and thus the light transmissivity of the variable transmissivity film 100 is almost opaque.

When a voltage is applied to the variable transmissivity film 100, an electric field is generated and a conductive material layer 122 formed in a linear pattern of the lower electrode 120 is charged. The colored charged particles 134 may have a charge opposite to that of the conductive material layer 122 of the lower electrode 120 formed when the voltage is applied so that the colored charged particles 134 and the lower An electrical attraction force due to electrical interaction acts between the conductive material layers 122 included in the electrodes.

The colored electrostatic particles 134 are electrophoretically moved by the electrical interaction generated when the voltage is applied to the variable transmissivity film 100 so that the upper portion of the conductive material layer 122 of the linear pattern of the lower electrode 120 The colored charged particles 134 are arranged to correspond to the linear pattern.

2 is a schematic view of a cross section of the light transmittance variable film 200 when a voltage is applied.

When the colored charged particles 134 are arranged in this manner, the distance between the colored charged particles 134 becomes narrow, and accordingly, the colored charged particles 134 having the same polarity as the charged charged particles 134, The gap between the colored charged particles 134 is not infinitely narrowed and the electrophoretic force due to the applied voltage and the electrical repulsive force acting between the colored charged particles 134 balance the forces The gap is not narrowed any more, and a specific distance between particles can be maintained.

When the voltage is applied, the colored charged particles 134 gather on the conductive material layer 122 of the linear pattern of the lower electrode 120 by the electrical attraction, The area occupied by the colored charged particles 134 gradually decreases and the area in which the colored charged particles 134 do not exist can be gradually increased. As a result, light blocking is not caused by the colored charged particles 134 in the cross section perpendicular to the direction in which the light of the variable transmissivity film 200 is incident, and the area through which the light is transmitted gradually increases. The light transmittance of the colored particles 200 gradually increases and the maximum transmittance can be realized when the electrophoretic force and the electrical repulsive force between the colored charged particles 134 are balanced.

That is, the light transmittance of the light transmittance variable films 100 and 200 is determined by the electrical property between the colored charged particles 134, which are generated in accordance with the presence or absence of an electric field, and the conductive material layer 122 of the linear pattern of the lower electrode 120, The light transmissivity of the variable transmissivity films 100 and 200 can be easily changed at a high speed and thus the transmissivity can be controlled.

The thickness of the skeleton below the concave surface of the bottom surface of the space 132 may be between about 0.001 탆 and about 1 탆. By making the bottom surface of the space 132 and the conductive material layer 122 close to each other as in the above range, the electrical interaction between the colored charged particles 134 and the conductive material layer 122 can be further enhanced So that the colored charged particles 134 can be more densely packed so that blocking of the light by the colored charged particles 134 in the cross section perpendicular to the direction in which the light of the variable transmissivity film 200 is incident The area through which the light is transmitted without waking up can be further widened.

The variable light transmittance films 100 and 200 may be formed by recessing the bottom surface of the space 132 to prevent the colored electrified particles 134 from being electrically repelled when the voltage is applied, The area where the light is transmitted without interrupting the light by the colored charged particles 134 at a cross section perpendicular to the direction in which the light of the variable transmissivity film 200 is incident is further widened . This is because the colored charged particles 134 can be collected by the concave portion formed on the bottom surface of the space 132.

Specifically, the concave portion formed by the concave surface may be formed at a depth of about 0.2 탆 to about 1 탆. By forming the concave portion having the depth in the above range, the skeletal material thickness under the bottom surface of the space 132 can be appropriately secured to maintain the mechanical stability, and at the same time, the area through which the light is transmitted when the voltage is applied can be further widened.

3 shows a cross section of a structure formed by a flat bottom surface so as to be in contrast to the bottom surface of the space 132 formed by the concave surface of the light transmittance variable film.

3 is a sectional view assuming that the bottom surface of the space 132 is flat without being recessed. As shown in FIG. 2, since the bottom surface of the space 132 is formed as a flat bottom without a concave portion, Even when the colored charged particles 134 are densely packed, they spread more widely than when they are gathered in the concave portion of Fig.

The maximum transmittance of the light transmittance variable film 200 can be, for example, about 40% or more, and specifically about 49% to about 70%, thereby achieving excellent maximum transmittance. The light transmittance variable film 200 at this time can be realized as a transparent film having a high transmittance.

The light transmittance variable film (100, 200) can be changed into a transparent film state having a high light transmittance of about 40% to about 70% when a voltage is applied in a substantially opaque state with a light transmittance of about 0 to about 10% Is a variable film.

The space 132 is divided by the barrier ribs 131 so that the transmittance can be more effectively controlled by applying the voltage.

The lower electrode 120 includes a transparent substrate 121; And a conductive material layer 122 formed in a linear pattern on the transparent substrate 121.

The transparent substrate 121 may be, for example, a transparent film.

The transparent film may be a film having excellent transparency and strength. Examples of the transparent film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polycarbonate selected from the group comprising poly carbonate (PC), polypropylene (PP), polyimide (PI), cyclo-olefin copolymer, norbornene resin and combinations thereof But is not limited to, a transparent film of a resin containing at least one of them.

The transparent film may be, for example, about 50 탆 to about 500 탆 in thickness. By including the transparent film having the above-mentioned thickness range, it is possible to effectively realize necessary mechanical properties by appropriately adjusting the durability and flexibility without excessively increasing the total thickness of the light transmittance variable films 100 and 200

The conductive material layer 122 of the lower electrode 120 may be formed, for example, by laminating or coating a conductive material on one side of the transparent film. For example, the conductive material layer 122 may be formed by any one of sputtering, CVD, PECVD, spray coating, air jet coating, gravure offset coating, rotary screen coating, and silk screen coating , And may be appropriately selected depending on the kind of the conductive material used as the material of the conductive material layer 122 among the above methods, but is not limited thereto

The conductive material may be, for example, indium tin oxide (ITO), zinc oxide (ZnO), zinc tin oxide (ZTO), graphene, carbon nanotube (CNT) But is not limited to, at least one selected from the group consisting of fluorine-doped tin oxide (FTO), silver nanowire, metal, conductive polymer, and combinations thereof.

The thickness of the conductive material layer 122 included in the lower electrode 120 may be, for example, about 0.01 μm to about 2.0 μm. By including the conductive material layer 122 in the thickness range, it is possible to reduce the cost while forming a sufficient electric field at the time of voltage application.

As described above, since the conductive material layer 122 is formed in a linear pattern, it is possible to adjust the light transmittance by adjusting the arrangement of the colored charged particles 134 by an electric field.

The intensity of the voltage applied to form this electric field may be, for example, from about 5 V to about 50 V. [ By applying a voltage in the intensity range, all of the colored charged particles 134 can be sufficiently densely gathered over the conductive material layer 122 of the linear pattern, thereby realizing excellent transmittance.

The upper electrode 110 includes a transparent substrate 111; And a conductive material layer 112 formed under the transparent substrate 111.

The conductive material layer 112 may be formed on the entire surface of the transparent substrate 111 or may be formed in a linear pattern as in the conductive material layer 122 of the lower electrode 120 described above.

1, the upper electrode 110 includes a planar conductive material layer 112 formed on a lower surface of the transparent substrate 111.

When the conductive material layer 112 is formed on the surface, the electric field can be strongly formed when a voltage is applied. The conductive material layer 122 having a linear pattern included in the colored charged particles 134 and the lower electrode 120, The electric attraction force generated between the electrodes can be further increased.

When the electrical attraction generated between the colored charged particles 134 and the linear conductive material layer 122 included in the lower electrode 120 is increased, the colored charged particles 134 are attracted to the lower electrode 120 Can be gathered more densely on the conductive material layer 122 of the linear pattern so that the colored charged particles 134 do not exist in a cross section perpendicular to the direction in which the light of the light transmittance variable films 100 and 200 is incident The area can be further widened and the light transmittance can be further increased.

The transparent substrate 111 may be a transparent film, as in the lower electrode 120. Specific examples of the transparent film are as described above.

The conductive material layer 112 of the upper electrode 110 may be formed, for example, by laminating or coating a conductive material on one side of the transparent film. The specific manufacturing process is the same as that in the conductive material layer 122 of the lower electrode 120, and may be formed in a planar or linear pattern according to the known method.

An example of a conductive material that can be used as the material of the conductive material layer 112 of the upper electrode 110 is the same as the description of the conductive material that can be used as the material of the conductive material layer 122 of the lower electrode 120 .

The thickness of the conductive material layer 112 of the upper electrode 110 may be, for example, from about 0.01 탆 to about 2.0 탆. By including the conductive material layer 112 in the thickness range, it is possible to reduce the cost while forming a sufficient electric field at the time of voltage application.

The upper electrode 110 may further include a protective layer formed on the conductive material layer 112.

FIG. 4 shows a cross section of the light transmittance variable film 300 according to another embodiment of the present invention. In FIG. 3, a protective layer 113 is formed under the conductive material layer 112 of the upper electrode 110 Respectively.

The protective layer 113 may be formed of the same material as the skeleton material constituting the side surface and the bottom surface of the space 132 in the ink receiving layer 130. For example, the skeleton may be formed of a transparent photo- A thermosetting resin, and a combination thereof.

The colored charged particles 134 can move freely within the space 132 and physical contact or the like caused by repetitive collision with the conductive material layer 112 included in the upper electrode 110 occurs during the process, Since the conductive material layer 112 may be gradually damaged, a direct physical contact between the conductive material layer 112 and the colored electrified particles 134 is blocked by including a protective layer 113 under the conductive material layer 112 Thereby preventing the conductive material layer 112 from being damaged and improving the durability of the light transmittance variable film 300.

In addition, the lower electrode 110 may further include a protective layer 123 formed on the conductive material layer 122.

In FIG. 4, a protective layer 123 is further formed on the conductive material layer 122 of the lower electrode 120.

Similarly, the protective layer 123 may be formed of the same material as the skeletal material constituting the side surface and the bottom surface of the space 132 in the ink receiving layer 130. For example, At least one selected from the group consisting of a photo-curing resin, a transparent thermosetting resin, and a combination thereof.

The colored charged particles 134 are separated from the bottom surface side skeleton of the space 132. The protective layer 123 may be further formed on the lower electrode 120 so that the conductive material of the lower electrode 120 The direct physical contact between the layer 122 and the colored charged particles 134 is more stably shielded to prevent the conductive material layer 122 from being damaged and the durability of the light transmittance variable film 300 can be improved.

The ink receiving layer 130 is located between the upper electrode 110 and the lower electrode 120.

The ink receiving layer 130 includes a space 132 horizontally divided by the barrier ribs 131. The ink receiving layer 130 includes a skeleton forming the space 132, And may be divided into the ink accommodated in the space 132. The skeletal material forms the partition wall 131 and the bottom surface of the space 132.

The space 132 may have a substantially cuboid shape, and the partition 131 forming the space 132 may be formed in a grid shape in a horizontal section.

A skeleton exists under the bottom surface of the space 132 so that the ink in the space 132 and the conductive material layer 122 of the lower electrode 120 do not physically contact each other.

The thickness of the skeleton below the bottom surface of the space 132, that is, the thickness from the upper surface of the conductive material layer 122 to the bottom surface of the space 132, if the protective layer 123 exists, The thinner the thickness from the upper surface to the bottom surface of the space 132, the faster the reaction speed at which the colored charged particles 134 are aligned when the voltage is applied, thereby effectively controlling the light transmittance.

On the other hand, when the thickness is too thin, there is a fear that the ink and the conductive material layer 122 of the lower electrode 120 directly come into contact with each other when the bottom surface is corroded by the ink.

The bottom surface of the space 132 is formed as a concave surface as described above. The concave portion formed by the concave surface is formed to have a depth of about 0.2 탆 to about 1 탆, and the thickness of the skeleton below the concave surface is set to about In the case of 0.001 m to about 1 m, it is possible to stably isolate the conductive material layer 122 of the ink and the lower electrode 120 with a fast reaction speed of the colored charged particles upon voltage application.

Specifically, the light transmittance variable film has a transmittance change (DELTA T) of about 50% (about 10%) at a voltage of about 20 V, and more specifically, % To about 60%) can be realized at a level lower than about 1 second, and the response to the change in the transmittance of about 75% (from about 5% to about 80%) It can be implemented with a speed of about 10 seconds or less.

The spaces 132 may be horizontally arranged in the ink receiving layer 130 by the barrier ribs 131 and the barrier ribs 131 may be disposed between the upper electrodes 110 and the lower electrodes 120. It is possible to improve the durability of the light transmittance variable films 100, 200,

The ink containing the colored charged particles 134 can be accommodated in the space 132 and the ink can further include an insulating medium and the colored charged particles 134 Is present in a state dispersed in the insulating medium to block transmission of light, and rearranges it when a voltage is applied to increase light transmittance. Therefore, the light transmittance of the variable film 100, 200, 300 can be changed freely, for example, the light transmittance may be 0% to about 70%, and the maximum transmittance may be 40% The point is meaningful.

The ink receiving layer 130 may be manufactured by forming the barrier ribs 131 and the spaces 132 by, for example, a screen printing method or an imprinting method, but is not limited thereto. Specifically, a coating composition for forming an ink receptive layer containing a resin containing at least one selected from the group consisting of a photo-curing resin, a transparent thermosetting resin, and a combination thereof is prepared, and then the coating composition is applied to form a layer The shape of the partition wall 131, the space 132, and the like may be formed by a method such as back-imprinting, and then, the skeleton may be integrated by photo-curing or thermosetting.

In order to form the bottom surface of the space 132 as a concave surface, for example, the shape of the imprinting forming mold itself may be formed and used. In another example, the skeleton may be formed by photocuring or thermosetting The central portion of the bottom surface is relatively less cured so that the uncured resin is released when the imprinting mold is removed, so that the recessed portion can be formed so that the uncured resin is separated from the resin.

The specific size of the ink receiving layer 130 may be designed as follows.

The spacing of the barrier ribs 131, that is, the spacing between the two spaced spaces 132, may be between about 5 microns and about 20 microns.

The width of the space 132, that is, the distance between the two spaced apart partition walls 131 may be about 100 μm to about 2000 μm.

The overall height of the ink receiving layer 130 may be about 5 占 퐉 to about 50 占 퐉, specifically about 10 占 퐉 to about 40 占 퐉, more specifically about 20 占 퐉 to about 30 占 퐉. The entire height of the ink receiving layer 130 includes a portion buried in the conductive material layer 122 of the lower electrode 120 as shown in FIGS. 1 to 4 (indicated by A in FIGS. 1 and 3). The height of the conductive material layer 122 of the lower electrode 120 may be about 0.01 탆 to about 2.0 탆 as described above.

The total thickness of the light transmittance variable films 100, 200, and 300 may not be excessively increased by forming the overall height of the ink receiving layer 130 within the above-described size range. In addition, High light transmittance can be exhibited.

If the height of the space 132 in the ink receiving layer 130 is too large, the operating voltage can be increased accordingly. For example, at about 40 [mu] m, an operating voltage of about 40 V may be required. On the other hand, if the height of the space 132 is too low, the ink filling amount is not enough, and the lowest transmittance may be increased when the voltage is not applied.

By forming the size of the space 132 within the size range, the ratio of the colored charged particles 134 in the cross-sectional area of the variable transmissivity films 100, 200, and 300 perpendicular to the incident direction of light can be kept large The space in which the barrier ribs 131 horizontally separating the spaces 132 are formed in the variable light transmittance films 100, 200, and 300 of a predetermined size is suitably secured So that excellent durability can be realized.

For example, when the ratio of the area occupied by the barrier ribs 131 in the horizontal cross section of the ink receiving layer 130 is increased, the minimum value of the visible light transmittance is increased. Specifically, the area ratio of the barrier ribs 131 in the horizontal cross section of the ink receiving layer 130 may be 0.9 to 5%. For example, when the square barrier rib has a width of 10 mu m and a space between the barrier ribs is 2000 mu m, the area ratio can be 0.9%, the width of the barrier rib is 50 mu m, The area ratio may be formed to be 5% when forming a regular square grid pattern. If the area ratio of the barrier ribs 131 in the horizontal cross section of the ink receiving layer 130 exceeds the above range, the minimum value of the visible light transmittance may become higher than a predetermined numerical value and may not be suitable for use.

The specific standard design of the ink receiving layer 130 is not limited thereto, and may be variously changed according to the object and function of the invention.

The skeleton may include, for example, a transparent photocurable resin, a transparent thermosetting resin, or both, and a photocurable or thermosetting resin capable of realizing transparency may be used without limitation. For example, a resin having a light transmittance of 90% or more, specifically, about 90 to about 100% after curing can be used.

The transparent photocurable resin may be, for example, a transparent acrylic resin such as urethane acrylate or epoxy acrylate, but is not limited thereto.

The transparent thermosetting resin included in the resin composition may be, for example, a polyamide resin, a polyimide resin, a silicone resin, an epoxy resin, an acrylic resin, a polyester resin, or the like, but is not limited thereto.

The photocurable or thermosetting resin for forming the skeleton should have excellent adhesion with the lower electrode 120 and excellent releasability from the mold during imprinting or the like. For example, the degree of curing of the skeleton formed after curing can be increased to increase the releasability.

On the other hand, the photocurable or thermosetting resin forming the skeleton has excellent adhesion to the transparent substrate 121. For example, a cross-cut knife is used to make 10 square and 10 square squares on a resin-coated surface to make a total of 100 square squares. Then, the cross-cut tape is attached to the surface without bubbles, Adhesion can be tested with the detachment method (ASTM D3359). According to the result, the level of 5B to 0B is determined according to the number of squares that are separated among 100 squares. 5B for 0, 4B for 1 ~ 5, 3B for 5 ~ 15, 15 ~ 35 If it is 2B in the individual case, 1B in the case of 35 to 65, and 0B in the case of more than 35, the adhesion of the photocurable or thermosetting resin forming the skeleton to the transparent substrate 121 may be 2B or more.

In addition, the photocurable or thermosetting resin forming the skeleton forms a partition wall 131 and directly comes into contact with the ink in the space 132. Therefore, the photocurable or thermosetting resin forming the skeleton should be selected as a material having chemical resistance to ink. The chemical resistance tends to be better as the molecular structure of the resin is dense and the degree of curing is high. The chemical resistance can be evaluated by measuring the weight loss before and after immersion in the ink after curing the resin. Specifically, a material which can attain a weight loss of 1 wt% or less when immersed at 80 DEG C for 2 hours or at room temperature for 24 hours is suitable.

In addition, the photocurable or thermosetting resin forming the skeletal material must have stain resistance to colored particles such as carbon black which may be contained in the ink. For example, in order to increase the stain resistance to the colored particles, an additive for lowering the surface tension inside the resin may be added to the resin composition for skeletal reformation. The surface tension inside the resin forming the skeleton may be equal to or higher than the surface tension of the ink.

The skeleton of the ink receiving layer 130 formed from the coating composition for forming an ink receiving layer requires a certain level of strength or more. This is because laminating to form a bulkhead and space must withstand the compression process and no curling should occur. The desired level of hardness may vary depending on the process being performed and may be such that the degree of curling measured by the height of the skeleton formed after the compression of the ink receptive layer 130 from the ground is less than about 1 mm. Examples of a method of realizing such strength include a method of selecting a specific resin type such as using an aromatic acrylate rather than an aliphatic acrylate and appropriately using the content thereof, a method of using a monomer having a large number of functional groups, A method of increasing the cross-linking density by using a photoinitiator that is increased or reacted with a high degree, or a method of using an oligomer having a high Tg.

The coating composition for forming an ink receiving layer may further include, for example, a photocuring agent, a heat curing agent, or both. The photocuring agent and the thermosetting agent may be variously used in accordance with the object and nature of the invention without any particular limitation.

The colored charged particles 134 refer to charged particles showing color, and the color may be chromatic or achromatic, and may be black, but it is not limited thereto and may be variously changed according to the purpose and properties of the invention .

The colored charged particles 134 may include at least one selected from the group consisting of, for example, metal particles, polymer particles, inorganic particles, semiconductor particles, and combinations thereof. The colored charged particles 134 may be a metal particle including an element such as aluminum, copper, silver, silicon, carbon, iron, nickel, gold, titanium, zinc, zirconium, tungsten and the like and a combination thereof, polystyrene, polypropylene, polyvinyl Polymer particles such as chloride, polyethylene, and polypropylene, inorganic particles such as carbon black, and the like, but are not limited thereto.

In addition, for example, the colored charged particles 134 may include a shell formed by adsorbing a substance partially charged in a core having no charge, with the above-described particles as a core. The core may be formed as a cluster or a cluster of particles. The core may refer to a material in which the particles or clusters are gathered to form a lump and the whole behaves like a particle.

The material capable of having such charge includes, for example, an organic compound containing a hydrocarbon group; A complex compound containing a halogen element; A coordination compound comprising at least one member selected from the group consisting of an amine group, a thiol group, a phosphine group, or a combination thereof; And a combination thereof. The charge-imparting substance may be a compound having a charge imparted thereto by forming a radical in a substance including at least one selected from the group consisting of:

The hydrocarbon group may include at least one functional group selected from the group consisting of, for example, carboxylic acid, ester, acyl, and combinations thereof.

The ink contained in the ink receiving layer 130 may further include an insulating medium and the insulating medium may have a specific gravity equal to or similar to that of the colored charged particles 134 so that the colored charged particles 134 can be mixed well. And a material suitable for ensuring electrophoretic stability, bistability of the colored charged particles 134, and combinations thereof.

For example, the insulating medium may be a material having a low dielectric constant, and specifically may include an alkyl silicone oil such as a hydrocarbon solvent such as dodecane, a halocarbon oil, a dimethyl silicone oil, and the like.

Also, for example, the insulating medium may be a material having a polarity index of higher than about 1, and specifically, it may be formed of at least one material selected from the group consisting of dodecane, trichlorethylene, carbon tetrachloride, Di-iso-propyl ether, toluene, methyl-t-butyl ether, xylene, benzene, diethyl ether, Dichloromethane, 1,2-Dichloroethane, Butyl Acetate, Iso-Propanol, n-Butanol, tetrahydrofuran, But are not limited to, tetrahydrofuran, n-propanol, chloroform, ethylacetate, 2-butanone, dioxane, acetone, ), Ethanol, acetonitrile, acetic acid, dimethylformamide, dimethylsulfoxide (Dimeth (such as N, N-dimethyl sulfoxide, N, N-dimethyl sulfoxide, N, N-dimethylformamide, N-methylpyrrolodone) 1 < / RTI >

The insulating medium may be, for example, a transparent material, but is not limited thereto, and the colored charged particles 134 may be included to reflect light of a specific wavelength to realize a specific color.

The light transmittance variable film may be formed by attaching the upper electrode 110 and the ink receiving layer 130 via a sealing film.

5 shows a cross section of the light transmittance variable film 400 according to another embodiment of the present invention. In FIG. 5, the light transmittance varying film 400 further includes a sealing film 135.

4, the sealing film 135 may be interposed either on the upper surface of the barrier rib 131 or only on the upper surface of the barrier rib 131a located at the outermost side of the side surface of the ink receiving layer 130 .

The sealing film 135 may prevent the ink contained in the ink receiving layer 130 from leaking to the outside of the lateral side of the light transmittance variable film 400.

5, a sealing film 135 is interposed between the outermost barrier rib 131a of the ink receiving layer 130 and the conductive material layer 112 of the upper electrode 110. By forming the sealing film 135 only partially on the outermost partition wall 131a of the light transmittance varying film 400, the ink contained in the space 132 is reduced in thickness, It is possible to effectively prevent leakage to the outside of the side surface of the casing 400.

For example, the sealing film 135 may be formed on the uppermost surface of the outermost barrier rib 131a only along the four corners of the light transmissivity variable film 400 as the outermost barrier rib 131a.

The sealing film 135 may include, for example, a photo-curable resin, a thermosetting resin, and both, and a known adhesive substance may be used without limitation.

The thickness of the sealing film 150 may be, for example, from about 1 [mu] m to about 20 [mu] m.

The display device may be, for example, a display device of an electronic device such as a TV, a smart phone, a computer, a notebook computer, or the like, but the present invention is not limited thereto. .

The light transmittance variable film may be formed by applying a resin composition for forming a skeleton of an ink receiving layer so that the conductive material layer is embedded on an upper portion of a lower electrode on which a linear conductive material layer is formed on a transparent substrate, To form the ink receiving layer on which the space is formed.

The ink receiving layer may be formed such that the partition and the space are formed by imprinting using a mold or a roll having a pattern formed thereon. In this case, the ink and the lower electrode may not be in direct contact with each other only when the lower surface of the space is formed to have a thickness.

As described above, the concave portion of the bottom surface of the space may be formed by forming the shape of the portion corresponding to the bottom surface of the space of the forming mold or the roll for imprinting to be a convex portion, By controlling the degree of curing of the center of the bottom surface of the space during photocuring or thermosetting of the composition, uncalcified cargo is allowed to exist so that uncured cargo is adhered to the imprinting mold when the imprinting mold is removed.

The resin composition for skeletal reformation of the ink receiving layer includes at least one selected from the group consisting of a transparent photocurable resin, a transparent thermosetting resin, and a combination thereof, and the detailed description thereof is as described above.

The imprinting process will be described in more detail. A resin composition for skeletal reformation of the ink receiving layer is applied on top of the lower electrode between two rolls, The pattern of the roll is transferred to the side where the ink receiving layer is to be formed, thereby forming the ink receiving layer in which the pattern of the partition and the space is formed.

The imprinting is performed so that the ink receiving layer is laminated on the lower electrode while the pattern is formed.

When the imprinting is performed, a recess formed by the concave surface is formed at a depth of about 0.2 탆 to about 1 탆 on the bottom surface of the space while laminating the lower electrode, and the thickness of the skeleton below the concave surface is about 0.001 Mu] m to about 1 [mu] m, the viscosity of the resin composition for skeletal reformation of the ink receiving layer should be controlled and the temperature condition at the time of imprinting be adjusted.

The resin composition for skeletal reformation of the ink receiving layer may be a solvent type containing a solvent or a solventless type which does not contain a solvent.

When the resin composition for skeletal reformation of the ink receptive layer contains a solvent, the viscosity at about 25 ° C should be about 10 cP to about 50 cP. In case of the solvent type, the solvent is volatilized by drying after the film formation, and imprinting is performed. Therefore, the viscosity is further increased during imprinting. In the case of the solvent type, drying after film formation can be carried out specifically at about 80 to 130 DEG C for 1 to 5 minutes.

When the resin composition for skeletal reformation of the ink receiving layer does not contain a solvent, the viscosity at about 25 ° C should be about 150 cP to about 500 cP.

When the resin composition for skeletal reformation of the ink receiving layer contains a solvent, the imprinting is performed at about 80 to about 130 캜. When the resin composition for skeletal reformation of the ink receiving layer does not contain a solvent, 30 to about 70 < 0 > C.

The resin composition for skeletal reformation of the ink receptive layer having the viscosity in the above range is applied to the upper surface of the lower electrode to perform imprinting in the temperature range to form the concave surface on the bottom surface of the space Is formed at a depth of about 0.2 탆 to about 1 탆 while the skeletal material below the lowest point of the concave name is formed to have a thickness of about 0.001 탆 to about 1 탆.

When the imprinting is performed, the concave portion formed by the concave surface on the bottom surface of the space is laminated at a depth of about 0.2 탆 to about 1 탆 while laminating the lower electrode, and the thickness of the skeleton below the concave surface Appropriate pressure must be applied in order to achieve a thickness of about 0.001 탆 to about 1 탆. One example of an approach for adjusting such a suitable pressure to be applied is to adjust the spacing between the rolls.

For example, the layer formed by applying the resin composition for skeletal reformation of the ink receiving layer may be passed between imprinting rolls having an interval of about 1 m to about 50 m. The interval between the imprinting rolls can be controlled to be thin when the layer formed by the resin composition for skeletal reformation is passed through and the layer can be appropriately expanded to about 50 탆 in consideration of the transparent base layer. By performing imprinting using the roll of the interval, it is possible to produce a predetermined ink receiving layer shape while laminating by applying appropriate pressure.

The ink receiving layer may be manufactured by imprinting as described above or after forming or forming a skeletal shape of the ink receiving layer having a space and a space and then curing the skeletal material by photo-curing or thermosetting. For example, a mold with a pattern formed thereon during imprinting is thermally cured by applying heat in a pressed state, or light cured by light irradiation to cure the resin, followed by release from the mold.

The method of manufacturing the light transmittance variable film according to the present invention includes the steps of forming the ink receiving layer by imprinting on the lower electrode as described above and then injecting ink into the space of the ink receiving layer, And the light transmittance variable film can be manufactured.

Hereinafter, examples and comparative examples of the present invention will be described. The following embodiments are only examples of the present invention, and the present invention is not limited to the following embodiments.

( Example )

Example One

A lower electrode was fabricated by forming a metal in a grid pattern on the PET transparent substrate to form a conductive material layer. The thickness of the metal grid pattern was 12 mu m and the interval was 300 mu m.

A mixed solvent such as urethane acrylate resin (Ebecryl® 220, Ebecryl® 600, etc.), acrylate monomer (DPHA, PETA and the like), MEK, IPA and ethyl cellosolve as solvents, Irg 184 , 907, etc. were mixed to prepare a resin composition for skeletal reformation of the ink receiving layer so that the viscosity became 10 cP at 25 ° C.

The resin composition for forming a skeleton of the ink receiving layer was coated on the upper electrode by using a coating bar having a thickness of 3 μm to 4 μm and then dried at 110 ° C. for 1.5 minutes to volatilize the solvent. Imprinting was performed at a temperature of 100 占 폚 at an interval of 30 占 퐉. The imprinting rolls were irradiated with UV to cure them, and then they were released from the rolls to form an ink receiving layer laminated on the lower electrode.

A corresponding surface of the imprinting roll is formed as a convex portion so that the bottom surface of the space of the ink receiving layer formed by the imprinting roll forms a concave surface.

Subsequently, ink containing a mixture of carbon black and a dodecane solvent was injected into the space of the ink receiving layer, and an upper electrode was adhered to the upper portion of the ink receiving layer to prepare a light transmittance variable film.

Example 2

The imprinting roll having the convex height of the imprinting roll lower than that of the imprinting roll of Example 1 was used so that the depth of the concave surface of the space of the ink receiving layer was changed. In manufacturing the lower electrode, the thickness of the metal grid pattern Was 5 mu m and the interval was 100 mu m, a light transmittance variable film was prepared in the same manner as in Example 1. [

Comparative Example One

The light-transmittable variable film was prepared in the same manner as in Example 1, except that an imprinting roll having no convex portions was formed so that the bottom surface of the ink-receptive layer formed by the imprinting roll was formed as a flat surface. .

Comparative Example 2

The light-transmittance variable film was prepared in the same manner as in Example 2, except that the imprinting roll formed by the imprinting roll was not provided with a convex portion so that the bottom surface of the space was formed as a flat surface. .

evaluation

Experimental Example One

In the light transmittance variable film produced in Example 1-2 and Comparative Example 1-2, the depth of the concave portion formed by the concave surface on the bottom surface of the space was measured and described in Table 1 below.

Experimental Example 2

Light transmittance The aperture ratio of the variable film is a theoretical value excluding the metal mesh portion in the entire area. However, due to the loss of transmittance due to the PET film and the ink, the maximum transmittance value is actually less than theoretically calculated aperture ratio.

The light transmittance variable films prepared in Example 1-2 and Comparative Example 1-2 were repeatedly subjected to + 20V / 30 seconds and -20V / 10 seconds using a bipolar power supply (PBZ40-10) manufactured by KIKUSUI Co., And the real time transmittance was measured, and the maximum transmittance according to the measured transmittance was shown in Table 1 below.

Depth of recess (㎛) Aperture ratio (%) Maximum transmittance (%) Example 1 1.7 92.2 62 Example 2 0.8 92.2 60 Comparative Example 1 0 92.2 57 Comparative Example 2 0 92.2 55

From the results shown in Table 1, it was confirmed that the maximum transmittance of Example 1-2 was higher than that of Comparative Example 1-2.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

100, 200, 300, 400: light transmittance variable film
110: upper electrode
120: Lower electrode
111, 121: Transparent film
112: conductive material layer of the upper electrode
122: conductive material layer of the lower electrode
113, 123: protective layer
130:
131:
131a:
132: Space
134: colored charged particles
135: sealing film
X: Thickness of the skeleton below the space bottom
A: Overall thickness of the ink receiving layer

Claims

An upper electrode;
A lower electrode including a conductive material layer formed in a linear pattern and spaced apart from the upper electrode; And
An ink receiving layer which contains a space partitioned by the barrier and accommodates ink containing colored charged particles in the space, the ink receiving layer being located between the upper electrode and the lower electrode;
/ RTI >
Wherein the ink receiving layer is composed of a skeleton forming the partition and a bottom surface of the space and the space,
The bottom surface of the space is formed with a concave surface
Light transmittance variable film.

The method according to claim 1,
The ink contained in the space is separated from the lower electrode by the skeleton material formed below the bottom surface of the space,
Light transmittance variable film.

The method according to claim 1,
Wherein the thickness of the skeleton below the concave surface is from 0.001 mu m to 1 mu m
Light transmittance variable film.

The method according to claim 1,
The concave portion formed by the concave surface is formed at a depth of 0.2 mu m to 1 mu m
Light transmittance variable film.

The method according to claim 1,
Wherein the distance between the two spaced apart spaces is 5 占 퐉 to 20 占 퐉 and the distance between the two spaced apart walls is 100 占 퐉 to 2000 占 퐉 as the width of the space, 5 mu m to 50 mu m, and the height of the conductive material layer of the lower electrode is 0.01 mu m to 2.0 mu m
Light transmittance variable film.

The method according to claim 1,
Wherein the lower electrode comprises a transparent material; And a layer of a conductive material formed in a linear pattern on the transparent substrate
Light transmittance variable film.

The method according to claim 1,
Wherein the upper electrode comprises a transparent material; And a conductive material layer formed below the transparent substrate
Light transmittance variable film.

8. The method of claim 7,
The conductive material layer may be formed on the surface of the transparent substrate, or may be formed in a linear pattern
Light transmittance variable film.

The method according to claim 1,
The conductive material layer may include at least one of indium tin oxide (ITO), zinc oxide (ZnO), zinc tin oxide (ZTO), graphene, carbon nanotube (CNT), fluorine- doped Tin Oxide (FTO), silver nanowire, metal, conductive polymer, and combinations thereof.
Light transmittance variable film.

The method according to claim 1,
Wherein the skeleton material comprises at least one selected from the group consisting of a transparent photocurable resin, a transparent thermosetting resin, and combinations thereof
Light transmittance variable film.

The method according to claim 1,
Wherein the upper electrode, the lower electrode or both all further comprise a protective layer on the conductive material layer
Light transmittance variable film.

12. The method of claim 11,
The protective layer may be made of the same material as the skeleton
Light transmittance variable film.

The method according to claim 1,
When the voltage is applied, the conductive material layer of the lower electrode is charged, and the colored charged particles have a charge opposite to the charge of the conductive material layer
Light transmittance variable film.

The method according to claim 1,
Wherein the ink further comprises an insulating medium
Light transmittance variable film.

The method according to claim 1,
The ink-receiving layer may further include a sealing film formed on an upper portion of the barrier rib. The barrier ribs of the ink-receiving layer and the upper electrode,
Light transmittance variable film.

16. The method of claim 15,
The sealing film is formed only on the uppermost outermost barrier ribs outside the side surface of the ink receiving layer
Light transmittance variable film.

A light transmittance variable film according to any one of claims 1 to 16; And
And a voltage application means electrically connected to the light transmittance variable film.