JP3844816B2 - Optical sheet and optical sheet with transparent electrode - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to a symmetrical optical sheet suitable as an electrode substrate of a liquid crystal cell of a liquid crystal display element or a transparent conductive film for a touch panel, and an optical sheet with a transparent electrode using the optical sheet.
[0002]
[Prior art]
Conventionally, polycarbonate films, polyarylate films, polyethersulfone films, polysulfone films, and the like have been used as optical base films. This is because these films have good optical isotropy and transparency, and have a certain degree of heat resistance.
[0003]
Only these base films lack properties such as air resistance, solvent resistance, and transparent electrode adhesion. Therefore, it has also been proposed to laminate and install an air-permeable resin layer or a cross-linkable resin cured material layer on one or both surfaces of these films. For example, Japanese Patent Application Laid-Open No. 63-71829, filed by the present applicant, discloses a liquid crystal display panel having a layer configuration of a light isotropic substrate film layer / anchor coat layer / air-permeable resin layer / crosslinkable resin cured material layer. JP-A-4-159518 discloses two or more unit laminated sheets having a layer configuration of an optically isotropic base film layer / an air-resistant resin layer / a cross-linkable resin cured product layer. An electrode substrate for a liquid crystal display panel having a structure in which a crosslinkable resin cured product layer is bonded via an adhesive layer so as to be both outermost layers is shown.
[0004]
Optical sheets that do not use a base film have also been proposed. For example, in Japanese Patent Publication No. 7-27134 (Japanese Patent Laid-Open No. 1-50021) according to the application of the present applicant, laminates of an air-permeable synthetic resin film layer and a crosslinkable resin cured product layer are respectively An electrode substrate for a liquid crystal display panel is shown which is laminated and integrated with an adhesive layer in a state in which the air-permeable synthetic resin film layer surfaces face each other, and Japanese Patent Publication No. 7-27135 (Japanese Patent Laid-Open No. 1-50022). (Patent Publication) discloses a method for producing an electrode substrate for a liquid crystal display panel in which a crosslinkable resin cured product layer is directly formed on both surfaces of an air-permeable synthetic resin film layer by a casting method.
[0005]
There is also known an optical sheet in which an active energy ray-curable resin cured material layer is provided on a base film through an air-resistant resin layer as necessary. For example, see JP-A-5-162228, JP-A-5-162229, JP-A-5-309794, and JP-A-5-313150 according to the application of the present applicant. JP-A-6-64103 discloses an optical sheet in which an active energy ray-curable resin cured material layer is provided on a base film via a heat-crosslinkable resin layer.
[0006]
[Problems to be solved by the invention]
When the optical sheet as described above is used for an electrode substrate of a liquid crystal cell or a transparent conductive film for a touch panel, the outermost cured product layer (thermosetting type crosslinkable resin cured product layer or active energy ray) A transparent electrode typified by ITO is formed on the curable resin layer) by sputtering. The transparent electrode at this time may be a full surface electrode or a patterned electrode. In the latter case, it is necessary to pattern the full surface electrode formed by sputtering.
[0007]
Patterning of the whole surface electrode to make a pattern electrode is performed by the procedures of resist coating, exposure, development, etching, and cured resist peeling according to a conventional method. However, the obtained pattern is not always neat and used for a display or the like. There was a tendency for the sharpness to be insufficient.
[0008]
Accordingly, the present inventors conducted detailed observation and evaluation of both the front and back surfaces of the optical sheet after pattern electrode formation using a laser displacement meter, etc., and the surface side became non-round irregularities between the pattern electrodes and also had transparency. It has been found that the back side is similarly non-round irregularities and the transparency is also reduced to a spot. This is considered to be because both the front and back surfaces of the optical sheet are affected by the chemical (particularly alkali) used in the patterning process.
[0009]
In order to overcome this problem, the present inventors tried to use a curable resin having as good alkali resistance as possible as the outermost cured product layer, but the degree of improvement was not as expected. This seems to be because if we focus only on the outermost layer, it will not reach an essential improvement.
[0010]
Under such a background, the present invention provides an optical sheet in which the base sheet surface is not affected by the patterning of the transparent electrode, and an optical sheet with a transparent electrode provided with the transparent electrode on the optical sheet. It is for the purpose.
[0011]
[Means for Solving the Problems]
The optical sheet of the present invention comprises a moisture-proof and alkali-resistant layer (4) / inorganic thin layer (3) / cured resin cured layer (2) / core resin layer (1) / cured resin cured layer (2) It is a symmetrical optical sheet having a layer structure of: / inorganic thin layer (3) / moisture-proof and alkali-resistant layer (4) .
[0012]
Transparent electrode optical sheet of the present invention, on at least one side of moisture-proof alkali resistance layer (4) side of the optical sheet, those formed by providing a transparent electrode (5).
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below. In this specification, terms such as a sheet, a film, a layer, and a thin layer are used, but all mean thin layers, and there is no particular difference between them.
[0014]
Each layer constituting the optical sheet of the present invention will be described. First, as the core resin layer (1), a base film layer, a base film layer / a base film layer, a gas-resistant resin layer / a base film layer / a gas-resistant resin layer, a cured resin cured material layer / Base film layer / cured resin cured material layer, curable resin cured material layer / air-permeable resin layer / base film layer / air-resistant resin layer / cured resin cured material layer, air-resistant resin layer / cured Hardened resin layer / base film layer / hardened resin hard layer / air-permeable resin layer and other layers including base film layers, air-resistant resin layer / air-resistant resin layer, curability Cured resin layer / breathable resin layer / breathable resin layer / cured resin cured layer, breathable resin layer / cured resin cured layer / breathable resin layer, breathable resin layer / cured Examples include layers that do not contain a base film layer, such as hardened resin layer / cured resin layer / breathable resin layer. Can show. An anchor coating layer or an adhesive layer may be present between the layers or on the layers.
[0015]
Here, examples of the base film layer include a polycarbonate film, a polyarylate film, a polyethersulfone film, a polysulfone film, and an amorphous polyolefin film. The thickness of the base film layer is arbitrary, and can be several μm to several hundred μm or more.
[0016]
Examples of the air-resistant resin layer include polyvinyl alcohol or a copolymerized modified product / graft thereof / polymer alloy, a vinyl alcohol resin layer such as an ethylene-vinyl alcohol copolymer having an ethylene content of 15 to 50 mol%, and a vinylidene chloride resin. Examples thereof include a layer, a high acrylonitrile resin layer, and the layer formed by blending a cross-linking agent with the vinyl alcohol resin layer described above, especially a graft copolymer modified product of polyvinyl alcohol, is particularly important. The thickness of the air-permeable resin layer is often about 2 to 30 μm (preferably about 3 to 20 μm, especially about 5 to 15 μm). This gas-permeable resin layer is usually formed by a casting method.
[0017]
The cured resin layer includes various active energy ray-curable resin cured layers such as ester acrylate, epoxy acrylate, urethane acrylate, silicone acrylate, polyimide acrylate and polyamideimide acrylate, and phenoxy ether type thermosetting. Examples include a cured resin layer. The thickness of the curable resin cured product layer is not particularly limited, but it is often 2 to 300 μm or more, particularly 2 to 100 μm, more preferably 2 to 50 μm.
[0018]
Among the core resin layers (1) described above, those that are particularly practical are those having a layer structure of an air-resistant resin layer (1b) / a base film layer (1a) / an air-resistant resin layer (1b). is there.
[0019]
The curable resin cured product layer (2) is the same as the active energy ray curable resin layer or the thermosetting resin cured product layer mentioned in the description of the core resin layer (1). The active energy ray-curable resin cured product layer used is particularly important.
[0020]
It is particularly desirable to place the curable resin cured product layer (2) on the core resin layer (1) industrially by the following mold film method. That is, the core resin layer (1) (the core resin layer (1) with a support film required for the production) was placed on one of a pair of rolls arranged in parallel with a slight gap. And a mold film (M) is supplied to the other roll, and a non-solvent active energy ray-curable or thermosetting resin liquid is discharged toward the gap between the two rolls. Then, both rolls are rotated in a direction to bite each other so that the resin liquid is sandwiched between the core resin layer (1) and the mold film (M), and then the active energy ray is sandwiched between the rolls. It is cured by irradiation or heating to form a curable resin cured product layer (2). Subsequently, if the same operation is repeated using the thus obtained laminated film and the mold film (M), the cured resin cured material layer (2) / core material resin layer (1) / cured resin cured A laminated film of the physical layer (2) can be obtained.
[0021]
Here, as the mold film (M), a film such as a biaxially stretched polyester (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate) film or a biaxially stretched polypropylene film is preferably used. The smoothness of the surface of this mold film (M) can be selected arbitrarily, so that the surface roughness is not more than ± 0.1μm and the surface is very smooth. The thing with arbitrary smoothness thru | or roughness can be used to the thing provided with the unevenness | corrugation. The surface state of the mold film (M) is transferred to the curable resin cured product layer (2).
[0022]
Examples of the inorganic thin layer (3) include thin layers such as oxides or nitrides of metals such as silicon, tin, indium, vanadium, tungsten, nickel, niobium, aluminum, magnesium, and molybdenum. It may be a mixture of This inorganic thin layer (3) is formed by a sputtering method, an ion plating method, a vacuum deposition method, a photo CVD method, or the like, and the sputtering method is particularly preferable. The thickness of the inorganic thin layer (3) is 10 to 1000 angstroms, preferably 20 to 300 angstroms. However, the thickness is such that transparency is not impaired.
[0023]
Examples of the moisture-proof and alkali-resistant layer (4) include those similar to the active energy ray curable resin layer or the thermosetting resin cured layer mentioned in the description of the core resin layer (1) above. Those having good alkali resistance are used.
[0024]
In the optical sheet of the present invention, each of the above-described layers is composed of “ moisture-proof and alkali-resistant layer (4) / inorganic thin layer (3) / cured resin cured product layer (2) / core resin layer (1) / cured. Hardened resin layer (2) / inorganic thin layer (3) / moisture-proof and alkali-resistant layer (4) ”are arranged in a symmetrical structure .
[0025]
An optical sheet with a transparent electrode is obtained by providing the transparent electrode (5) on at least one side of the moisture-proof and alkali-resistant layer (4) side of the optical sheet having the symmetrical layer structure.
[0026]
The transparent electrode (5) is practically limited to ITO (indium-tin composite oxide) in consideration of operability, cost, etching properties and the like. The thickness of the transparent electrode (5) is about 100 to 1500 angstroms, preferably 150 to 1000 angstroms, more preferably 200 to 800 angstroms.
[0027]
When patterning the transparent electrode (5), resist coating, exposure, development, etching, and removal of the cured resist are carried out in this order according to a conventional method. As the processing solution at this time, for example, a dilute aqueous solution of alkali such as sodium carbonate or potassium carbonate as a developing solution, an aqueous solution of ferric chloride or cupric chloride or an aqueous solution of an acid such as hydrochloric acid as an etching solution, or curing. An alkaline stripping solution made of an aqueous solution having a concentration of 1 to 5% by weight, such as sodium hydroxide or potassium hydroxide, is used as the edist stripping solution.
[0028]
This optical sheet with a transparent electrode is particularly useful as an electrode substrate of a liquid crystal cell constituting a liquid crystal display element. It is also useful as a film with a transparent electrode for a touch panel (including not only a polarizing plate but also an inner touch panel laminated and used under the polarizing plate). Moreover, it can use as an optical sheet for various uses which have not only these but a transparent electrode.
[0029]
<Action>
The optical sheet of the present invention comprises: “moisture-proof and alkali-resistant layer (4) / inorganic thin layer (3) / cured resin cured layer (2) / core resin layer (1) / cured resin cured layer (2 ) / Inorganic thin layer (3) / Moisture-proof and alkali-resistant layer (4) ”. In the optical sheet of the present invention, there is an inorganic thin layer (3) inside the outermost moisture-proof and alkali-resistant layer (4), and further a curable resin cured product layer (2) is located inside thereof. Yes. Therefore, after the transparent electrode (5) is provided on the outermost moisture-proof and alkali-resistant layer (4), the pattern that forms the base of the transparent electrode (5) is the moisture-proof and alkali-resistant layer (4). Since it is / inorganic thin layer (3) / cured resin cured product layer (2), the surface of the optical sheet is not affected even after a harsh patterning process or water washing process. And since it is symmetrical , the back surface of the optical sheet is not affected. The installation of the inorganic thin layer (3) is also preferable from the viewpoint of improving moisture resistance and air resistance.
[0030]
When the core resin layer (1) has a layer structure of an air-permeable resin layer (1b) / base film layer (1a) / air-proof resin layer (1b), the air-proof property is also good. Therefore, it is preferable as an electrode substrate for a liquid crystal cell.
[0031]
When the curable resin cured product layer (2) is placed on the core resin layer (1) by the above-described mold film method, it is preferable in terms of industrial productivity, thickness accuracy is good, and further, it is formed. Since the surface of the cured curable resin layer (2) can be freely set from one having high smoothness to one having round fine irregularities, it can be adapted to the application.
[0032]
【Example】
The following examples further illustrate the invention. The surface roughness is measured with a non-contact surface roughness meter using light interference.
[0033]
Example 1
FIG. 1 is an explanatory view schematically showing an example of a manufacturing process of an optical sheet and an optical sheet with a transparent electrode according to the present invention.
[0034]
By casting and drying and curing a water-soluble polyester urethane anchor coating agent having a solid content of 5% by weight on one side of a polycarbonate film having a thickness of 105 μm as an example of the base film layer (1a) and a retardation value of 6 nm. An anchor coating layer (ac) having a thickness of about 1 μm was formed. Subsequently, from the anchor coating layer (ac), a methylol melamine-based cross-linking agent (“Sumitec” manufactured by Sumitomo Chemical Co., Ltd.) was added to an aqueous solution of 12% by weight of N-methylolacrylamide-acrylic acid graft copolymer of polyvinyl alcohol. M-3 ”) was cast at a solid weight ratio of 100: 3 and dried at 70 to 90 ° C. to form an air-permeable resin layer (1b) having a thickness of 8 μm. It was. Similarly, an anchor coating layer (ac) having a thickness of about 1 μm and a gas-resistant resin layer (1b) having a thickness of 8 μm were formed on the other surface of the optically isotropic base film (1a).
[0035]
Thus, a layer structure of 123 μm having an air-permeable resin layer (1b) / anchor coating layer (ac) / base film layer (1a) / anchor coating layer (ac) / air-permeable resin layer (1b) A core resin layer (1) was obtained.
[0036]
As the mold film (M), a biaxially stretched polyethylene terephthalate film having a thickness of 100 μm and having a high smooth surface (average surface roughness of 0.006 μm and a maximum of 0.04 μm) not subjected to corona discharge treatment was prepared.
[0037]
The core resin layer (1) is supplied to one roll of a pair of rolls arranged in parallel with a slight gap, and the mold film (M) is supplied to the other roll as a smooth surface. Was fed so that the upper surface became the upper surface.
[0038]
Subsequently, toward the gap between these two rolls, non-solvent type aliphatic made by Nippon Polyurethane Industry Co., Ltd. is added to 100 parts by weight of epoxy acrylate high viscosity UV curable resin liquid which is a non-solvent type curable resin liquid. While discharging 5 parts by weight of the polyisocyanate “Coronate HK”, both rolls are rotated in the direction to bite each other, and the above-mentioned between the two films (core resin layer (1) and mold film (M)) The curable resin liquid is sandwiched, and in the sandwiched state, UV irradiation is performed under the conditions of an output of 120 W / cm, one lamp, a lamp distance of 150 mm, and an integrated light quantity of 1000 mJ / cm ² to obtain a curable resin liquid. By curing, a cured curable resin layer (2) having a thickness of 8 μm was formed, and heat treatment was further performed at a temperature of 130 ° C. for 10 minutes.
[0039]
As a result, a laminated film having a layer structure of (1) / (2) / (M) was obtained, and this operation was repeated using this laminated film and the mold film (M). . As a result, a symmetric mold film (M) having a layer structure of (M) / (2) / (1) / (2) / (M) was obtained. (M) and (M) were peeled off.
[0040]
SiOx (x = 0.9) was sputtered on one side of the laminated film having the layer structure of (2) / (1) / (2) thus obtained to form an inorganic thin layer (3) having a thickness of 100 Å. . Similarly, SiOx (x = 0.9) was sputtered on the other surface of the laminated film to form an inorganic thin layer (3) having a thickness of 100 angstroms. As a result, a laminated film having a layer structure of (3) / (2) / (1) / (2) / (3) was obtained.
[0041]
The laminated film obtained above is supplied to one roll of a pair of rolls arranged in parallel with a slight gap, and the same mold film (M) as above is supplied to the other roll. It was supplied to become.
[0042]
Subsequently, toward the gap between these two rolls, non-solvent type aliphatic made by Nippon Polyurethane Industry Co., Ltd. is added to 100 parts by weight of epoxy acrylate high viscosity UV curable resin liquid which is a non-solvent type curable resin liquid. While discharging 5 parts by weight of the polyisocyanate “Coronate HK”, both rolls are rotated in the direction to bite each other, and the above-mentioned between the two films (core resin layer (1) and mold film (M)) The curable resin liquid is sandwiched, and in the sandwiched state, UV irradiation is performed under the conditions of an output of 120 W / cm, one lamp, a lamp distance of 150 mm, and an integrated light quantity of 1000 mJ / cm ² to obtain a curable resin liquid. By curing, a moisture-proof and alkali-resistant layer (4) having a thickness of 8 μm was formed, and further heat treatment was performed at a temperature of 130 ° C. for 10 minutes.
[0043]
As a result, a laminated film having a layer structure of (3) / (2) / (1) / (2) / (3) / (4) / (M) was obtained. The above operation was repeated using the mold film (M). Thus, the mold films (M), (M), (M), (4) / (3) / (2) / (1) / (2) / (3) / (4) / (M) Since a laminated film with M) was obtained, the mold films (M) and (M) were peeled and removed at an appropriate stage after dripping, and (4) / (3) / (2) / (1) / (2) A symmetrical optical sheet having a layer structure of / (3) / (4) was obtained.
[0044]
Further, an ITO layer was formed on one side of the optical sheet by sputtering to form a transparent electrode (5) having a thickness of 600 angstroms. As a result, an optical sheet with a transparent electrode having a layer structure of (5) / (4) / (3) / (2) / (1) / (2) / (3) / (4) was obtained.
[0045]
Next, resist coating, exposure, development, etching, and removal of the cured resist were performed in this order on the surface on the transparent electrode (5) side of the optical sheet with a transparent electrode in accordance with a conventional method. When the obtained pattern electrode surface was observed in detail using a laser displacement meter `` Trin '' manufactured by Doi Seimitsu Co., Ltd., the surface of the moisture-proof and alkali-resistant layer (4) exposed between the pattern electrodes was completely smooth and uneven. Even the symptoms were not observed. The surface of the moisture-proof and alkali-resistant layer (4) on the back side was also completely smooth, and even the phenomenon affected by the unevenness was not observed.
[0046]
Comparative Example 1
A transparent electrode (5) is formed on one side of a laminated film having a layer structure of (2) / (1) / (2) obtained in the intermediate step in Example 1, and (5) / (2) / (1) / The laminated film having the layer structure (2) was formed, and then the surface on the transparent electrode (5) side was subjected to resist coating, exposure, development, etching, and removal of the cured resist in this order. When the obtained pattern electrode surface was observed in detail using a laser displacement meter, the exposed surface of the cured curable resin layer (2) between the pattern electrodes became uneven from the order of 1/10 μm to several μm. Turned out to be. The same was true for the back side.
[0047]
Comparative Example 2
A transparent electrode (5) is formed on one side of the laminated film having the layer structure of (3) / (2) / (1) / (2) / (3) obtained in the intermediate step in Example 1, and (5) / (3) / (2) / (1) / (2) / (3) layered film, and then the transparent electrode (5) side surface was coated with resist, exposed, Development, etching, and removal of the cured resist were performed in this order. The surface of the exposed inorganic thin layer (3) between the pattern electrodes was improved as compared with Comparative Example 1, but was inferior as compared with Example 1. The same was true for the back side.
[0048]
Comparative Example 3
A symmetrical laminated film having a layer structure of (4) / (2) / (1) / (2) / (4) is obtained according to Example 1 except that the formation of the inorganic thin layer (3) is omitted. Then, a transparent electrode (5) is formed on one side to form a laminated film having a layer structure of (5) / (4) / (2) / (1) / (2) / (4), and then the transparent electrode ( 5) Resist coating, exposure, development, etching, and removal of the cured resist were performed in this order on the side surface according to a conventional method. The exposed surface of the cured alkali-resistant curable resin layer (4) between the pattern electrodes was improved as compared with Comparative Example 1, but clearly inferior to that of Example 1, and Comparative Example. It was slightly inferior to 2. The same was true for the back side.
[0049]
Example 2
As the inorganic thin layer (3), instead of _{SiOx, SiO 2, SnO 2,} In 2 O 3, VO 2, WO 3, NiO, Nb 2 O 5, Al 2 O 3, MgO, MoO 3, Si 3 N _4. Example 1 was repeated except that InN was formed by sputtering or photo-CVD, and the same preferable results as in Example 1 were obtained.
[0050]
【The invention's effect】
In the case where the transparent sheet is provided on the optical sheet having a specific symmetrical structure of the present invention, the surface of the optical sheet is not affected even through a severe patterning process or a water washing process. Similarly, the back surface of the optical sheet is not affected. The inorganic thin layer (3) provided between the curable resin cured product layer (2) and the moisture-proof and alkali-resistant layer (4) gives favorable results also in terms of improvement in moisture-proof and air-proof properties.
[Brief description of the drawings]
FIG. 1 is an explanatory view schematically showing an example of a production process of an optical sheet and an optical sheet with a transparent electrode according to the present invention.
[Explanation of symbols]
(1) ... core resin layer,
(1a) ... base film layer,
(1b) ... Air-permeable resin layer,
(ac)… Anchor coating layer,
(2) ... curable resin cured product layer,
(3)… inorganic thin layer,
(4)… moisture and alkali resistant layer,
(5)… transparent electrode,
(M) ... Mold film

Claims (4)

Moisture-proof and alkali-resistant layer (4) / Inorganic thin layer (3) / Curable resin cured material layer (2) / Core resin layer (1) / Curable resin cured material layer (2) / Inorganic thin layer (3) / An optical sheet, which is a symmetrical optical sheet having a layer structure of a moisture-proof and alkali-resistant layer (4). The optical sheet according to claim 1 , wherein the core resin layer (1) is a layer having a layer structure of an air-permeable resin layer (1b) / a base film layer (1a) / an air-resistant resin layer (1b). . The optical sheet according to claim 1, wherein the inorganic thin layer (3) is a thin layer of oxide or nitride of silicon, tin, indium, vanadium, tungsten, nickel, niobium, aluminum, magnesium or molybdenum. An optical sheet with a transparent electrode , wherein a transparent electrode (5) is provided on at least one side of the moisture-proof and alkali-resistant layer (4) side of the optical sheet according to claim 1 .

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