Light control film, light control plate and light control device

Abstract

To provide a transparent conductive film with an alignment film capable of avoiding deterioration in visibility of a dimming film as a transparent conductive film with an alignment film which can have the alignment film and a dimming layer enhanced in adhesion force when a dimming film is manufactured, by patterning the alignment film.SOLUTION: There is provided a transparent conductive film with an alignment film which has at least a transparent conductive film 2 and an alignment film 3 laminated in this order on a transparent base material 1, the transparent conductive film 10 with the alignment film being characterized in that the alignment film enabling a liquid crystal material to be vertically aligned has a plurality of alignment film removing parts 4 of invisible size which expose the transparent conductive film as a substrate of the alignment film to bring the liquid crystal material and transparent conductive film into contact to enhance adhesion force thereof.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a transparent conductive film used for a light control film, etc. More specifically, the present invention relates to a transparent conductive film with an alignment film used for a light control film, which has enhanced adhesion between the light control layer and the alignment film, and a light control film, a light control plate, and a light control device using the same. [Background technology]

[0002] A light control film is a laminate in which a light control layer made of a liquid crystal material is laminated on a pair of transparent conductive films, each of which has a transparent conductive film such as ITO (Indium Tin Oxide) formed on a transparent resin film such as a polyethylene terephthalate (PET) film, with the transparent conductive film side facing inward.

[0003] Known light-control layers include those that use polymer dispersed liquid crystal (PDLC: Polymer Dispersed Liquid Crystal), in which liquid crystal molecules are dispersed in a polymer, and polymer network liquid crystal (PNLC: Polymer Network Liquid Crystal), in which liquid crystal molecules are arranged in voids formed inside a polymer network made of resin formed into a three-dimensional mesh pattern.

[0004] There are two types of light-control films: normal mode light-control films that become opaque when no voltage is applied, and reverse mode light-control films that become transparent when no voltage is applied.

[0005] In normal mode light-control films, a pair of transparent conductive films and PDLC or PNLC are used as the light-control layer. On the other hand, in reverse mode light control films, the liquid crystal material needs to be vertically oriented, so the light control film is produced by using a transparent conductive film with an alignment film, in which an alignment film is formed on the transparent conductive film of a transparent conductive film.

[0006] Since the alignment film is highly hydrophobic, there is a problem of poor adhesion between the alignment film and the light control layer made of liquid crystal material. For this reason, measures have been taken to introduce a large amount of hardener (polymerizable compound) into the light control layer used in reverse mode light control films to improve adhesion between the light control layer and the alignment film. However, introducing a large amount of hardener inhibits the vertical alignment of the liquid crystal, resulting in a problem of a significant decrease in transparency when no voltage is applied and a significant decrease in scattering characteristics when voltage is applied.

[0007] As a prior art that solves the problem of low adhesion between the light-controlling layer and the alignment film, Patent Document 1 discloses a light-controlling film that uses a transparent conductive film with an alignment film, in which the alignment film is patterned to form areas where the alignment film has been removed, and the exposed transparent conductive film and the light-controlling layer are polymerized and bonded in those areas, thereby enhancing the adhesion between the alignment film and the light-controlling layer.

[0008] However, this technology does not take into consideration the deterioration of visibility caused by patterning the alignment film, and the formation of liquid crystal domains only in the areas where the alignment film is present. In other words, if the size of the area where the alignment film is removed to strengthen the adhesion between the alignment film and the light control layer is large enough to be visible, the area of ​​the light control layer that is not oriented, i.e., the area where the vertical alignment of the liquid crystal is inhibited, will become large, which may cause problems such as a significant decrease in transparency when no voltage is applied and a significant decrease in scattering characteristics when voltage is applied. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2019-020433 A Summary of the Invention [Problem to be solved by the invention]

[0010] In view of the above circumstances, the present invention aims to provide a transparent conductive film with an alignment film that can prevent deterioration of the visibility of the light-controlling film, in which the adhesion between the alignment film and the light-controlling layer can be increased by patterning the alignment film when the light-controlling film is produced. [Means for solving the problem]

[0011] As a means for solving the above problems, a first aspect of the present invention provides a transparent conductive film with an alignment film, in which at least a transparent conductive film and an alignment film are laminated in this order on a transparent substrate, This is a transparent conductive film with an alignment film, which is characterized in that the alignment film, which enables the liquid crystal material to be vertically aligned, has multiple alignment film removal portions of a size that is not visible to the naked eye, which expose the transparent conductive film underlying the alignment film and thereby bring the liquid crystal material into contact with the transparent conductive film, thereby enhancing the adhesion between them.

[0012] A second aspect is the alignment-film-attached transparent conductive film according to the first aspect, characterized in that the alignment-film-removed portions having a plurality of invisible sizes are periodically formed.

[0013] A third aspect is the alignment-film-attached transparent conductive film according to the first or second aspect, characterized in that the alignment-film-removed portion has a maximum dimension of 400 nm or less in a plan view.

[0014] A fourth aspect is a light control film obtained by laminating a liquid crystal light control layer on a pair of alignment-film-attached transparent conductive films according to any one of the first to third aspects, with the transparent conductive films facing inward, This light control film is characterized in that liquid crystal domains, which are regions having a uniform liquid crystal structure inside, are formed only on the alignment film.

[0015] A fifth aspect is a light control film obtained by laminating a liquid crystal light control layer on a pair of alignment-film-attached transparent conductive films according to any one of the first to third aspects, with the transparent conductive films facing inward, The light control film according to the fourth aspect is characterized in that the peel strength in the 180° direction of one of the alignment film-attached transparent conductive films measured against the other alignment film-attached transparent conductive film is 0.1 to 10.0 N / 25 mm in accordance with JIS Z 0237:2009.

[0016] In addition, the sixth aspect is a light-control film according to the fourth or fifth aspect, characterized in that the haze value in the transparent state is 10% or less, the haze value in the opaque state is 85% to 100%, and the light transmittance in the visible light range in the opaque state is 30% to 80%.

[0017] Further, the seventh aspect is a light control panel characterized in that a support plate made of colorless, transparent or colored, transparent glass or resin is provided on one or both sides of the light control film described in any of the fourth to sixth aspects.

[0018] In addition, an eighth aspect is a dimming panel described in the seventh aspect, characterized in that an intermediate film is provided between the dimming film and the support plate provided on either one or both sides of the dimming film.

[0019] In addition, the ninth aspect is a light control film according to any one of the first to sixth aspects or a light control plate according to the seventh or eighth aspect, an AC power source that supplies a driving voltage to the light control film or the light control plate, and a driving voltage supplied from the AC power source that is applied to the light control film or the light control plate. The dimming device is characterized by having a switch for changing the light intensity. Effect of the Invention

[0020] In the transparent conductive film with an alignment film of the present invention, the alignment film formed on the transparent conductive film has a plurality of alignment film removal parts of an invisible size that expose the transparent conductive film under the alignment film. Therefore, in a light control film obtained by using two transparent conductive films with an alignment film of the present invention and laminating a liquid crystal light control layer with the transparent conductive film sides facing inward, the adhesion between one transparent conductive film with an alignment film and the liquid crystal light control layer is strengthened. Similarly, the adhesion between the other transparent conductive film with an alignment film and the liquid crystal light control layer is strengthened. Therefore, the problem of weak adhesion between the alignment film and the liquid crystal light control layer can be avoided without introducing a curing agent into the light control layer to such an extent that the vertical alignment of the liquid crystal is hindered.

[0021] In addition, according to the light-controlling film of the present invention, the problem of weak adhesion between the alignment film and the liquid crystal light-controlling layer can be avoided without introducing a curing agent into the light-controlling layer to such an extent that the vertical alignment of the liquid crystal is inhibited.

[0022] In addition, according to the dimming plate of the present invention, since the dimming film of the present invention is used, it is possible to avoid the problem of weak adhesion between the alignment film and the liquid crystal dimming layer without introducing a hardener into the dimming layer to the extent that the vertical alignment of the liquid crystal is hindered.

[0023] In addition, according to the dimming device of the present invention, since the dimming film or the dimming plate of the present invention is used, it is possible to avoid the problem of weak adhesion between the alignment film and the liquid crystal dimming layer without introducing a hardener into the dimming layer to the extent that the vertical alignment of the liquid crystal is hindered. [Brief description of the drawings]

[0024] [Figure 1] FIG. 2 is a cross-sectional view illustrating an example of the alignment film-attached transparent conductive film of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view illustrating an example of the light control film of the present invention. [Diagram 3] FIG. 2 is a cross-sectional view illustrating an example of a light control plate of the present invention. [Figure 4] FIG. 2 is an explanatory diagram showing an example of a light control device of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] <Transparent conductive film with alignment layer> The transparent conductive film with an alignment film of the present invention will be described with reference to FIGS. The transparent conductive film 10 with an alignment film of the present invention is a transparent conductive film with an alignment film in which at least a transparent conductive film 2 and an alignment film 3 are laminated in this order on a transparent substrate 1, and the alignment film 3 has a plurality of alignment film removal portions 4 of an invisible size formed therein, which expose the transparent conductive film 2 underlying the alignment film 3.

[0026] By forming the alignment film removal portion 4, the alignment film-attached transparent conductive film 10 is formed in which the transparent conductive film 2 underlying the alignment film 3 is exposed. By forming the alignment film-attached transparent conductive film 10 in which a part of the transparent conductive film 2 is exposed, when a light control film 20 is produced as a laminate in which a pair of alignment film-attached transparent conductive films 10 are arranged with the alignment film 3 side on the inside and a light control layer 6 is sandwiched (see FIG. 2), the light control layer 6 and the transparent conductive film 2 come into direct contact at the alignment film removal portion 4. Since the adhesion between the light control layer 6 and the transparent conductive film 2 is strong, when the light control film 20 is produced using the alignment film-attached transparent conductive film 10 in which multiple alignment film removal portions 4 are formed, it is possible to enhance the adhesion between the light control layer 6 and the alignment film-attached transparent conductive film 10.

[0027] In addition, in the alignment film-attached transparent conductive film 10 of the present invention, a plurality of alignment film-removed portions 4 having a size that is not visible to the naked eye may be formed periodically. For example, they may be arranged in an XY matrix or a houndstooth check pattern in a plan view. They may also be arranged periodically on a plurality of straight lines. The straight lines may be arranged in any manner, and may be arranged in any periodic pattern as long as they are not visible.

[0028] Furthermore, in the alignment film-attached transparent conductive film 10 of the present invention, the size of the alignment film-removed portions 4 may be an invisible size. An invisible size may be, for example, a maximum dimension of 400 nm or less in a plan view. If the alignment film-removed portions 4 are circular in a plan view, the diameter may be 400 nm or less. If they are rectangular in a plan view, the length of the longer side may be 400 nm or less. If they are irregular in a plan view, the diameter of the circle or the length of the major axis of the ellipse that contains the figure may be 400 nm or less.

[0029] By adopting the above-mentioned configuration, it is possible to enhance the adhesion between the light control layer 6 and the alignment-film-attached transparent conductive film 10 while avoiding deterioration of the visibility of the light control film 20.

[0030] (Alignment film) A polyimide film can be suitably used as the material of the alignment film 3 in the alignment film-attached transparent conductive film 10 of the present invention. Known polyimides include thermosetting polyimides and solvent-soluble polyimides.

[0031] Thermosetting polyimide can be made by applying polyamic acid to a substrate using a coating method such as offset printing, and then heating the substrate at approximately 250°C to volatilize the solvent and simultaneously harden the substrate through a dehydration condensation reaction, thereby forming a polyimide film.

[0032] Solvent-soluble polyimide can be applied to a substrate by printing or the like, and then a polyimide film can be formed by volatilizing the solvent, so that a polyimide film can be formed at a lower temperature. In order to obtain good alignment, it is preferable to use a polyimide film having a small number of cross-linked structures and a high imidization rate.

[0033] (Method of forming alignment film removal portion) The thickness of the alignment film 3 is, for example, between 0.004 μm (4 nm) and 0.6 μm (600 nm) inclusive, so that the liquid crystal material can be aligned. The alignment film removed portion 4 having a diameter of, for example, 0.4 μm can be formed in the alignment film 3 having such a thickness by the following method.

[0034] (1) Photolithography Using a photomask, a 1:1 projection electron beam exposure device or a deep ultraviolet light exposure device, and (2) a reticle, a 10:1 reduction exposure device or a 10:1 reduction electron beam exposure device are used to expose the photosensitive resin layer formed on the alignment film 3 to a pattern, and then development is performed to form a resist pattern corresponding to the alignment film removal portion 4. Next, the resist pattern and the alignment film 3 exposed from the resist pattern are ashed by irradiating the entire surface with ultraviolet light, and then the substrate is washed with an alkaline resist stripping solution or the like to remove the ashed alignment film and resist pattern, and the alignment film 3 is patterned to form the alignment film removal portion 4.

[0035] (2) Nanoimprint Lithography A convex micro mold is fabricated, a resin layer that will become the alignment film is formed, and then the mold is pressed against the alignment film before hardening to form the alignment film removal portion 4. It is preferable to remove the alignment film (polyimide film) remaining at the bottom of the alignment film removal portion 4 by ashing treatment using oxygen gas plasma or the like.

[0036] <Light control film> Next, the light control film of the present invention will be described with reference to FIG. The light control film 20 of the present invention is a light control film obtained by laminating a light control layer 6 on the transparent conductive film 10 with an alignment film of the present invention, with the transparent conductive film 2 (or alignment film) facing inward. In the light control film 20 of the present invention, liquid crystal domains, which are regions having a uniform liquid crystal structure inside, are formed only on the alignment film.

[0037] 1, the alignment film 3 of the transparent conductive film 10 with an alignment film of the present invention has a plurality of alignment film removal parts 4 formed by removing a part of the alignment film 3 to expose the transparent conductive film 2 underlying the alignment film 3. Since the adhesion between the transparent conductive film 2 exposed at the bottom of the alignment film removal parts 4 and the light control layer 6 is high, in the light control film 20 of the present invention, the peel strength in the 180° direction measured between one transparent conductive film 10 with an alignment film and the other transparent conductive film 10 with an alignment film is 0.1 to 10.0 N / 25 mm in accordance with JIS Z 0237:2009, and it is possible to provide a sufficiently high peel strength.

[0038] As shown in Figure 2, the light-controlling film 20 of the present invention is a laminate in which two transparent conductive films 10 with an alignment film of the present invention are sandwiched with a light-controlling layer 6 between them, with the alignment film 3 side (or the transparent conductive film 2 side) facing inward.

[0039] A plurality of alignment film-removed portions 4 of a size that is not visible to the naked eye are formed in the alignment film 3, but the transparent conductive film 2 is exposed at the bottom of the alignment film-removed portions 4, and the liquid crystal material constituting the light-controlling layer 6 is not oriented and does not form a liquid crystal domain even if the light-controlling layer 6 is in contact with the transparent conductive film 2. Therefore, that portion does not function as the light-controlling layer 6.

[0040] On the other hand, in the light control layer 6 on the alignment film 3, the liquid crystal is vertically aligned by the alignment film 3, and liquid crystal domains are formed. Therefore, the light control layer 6 functions normally.

[0041] Therefore, in the light control film 20 of the present invention, the haze value in the transparent state is 10% or less, and the haze value in the opaque state is 85% to 100%, and the light transmittance in the visible light range in the opaque state is 30% to 80%. The reason why the haze value in the transparent state is 10% or less is that liquid crystal domains are formed on the alignment film and the liquid crystal is aligned vertically. The reason why the haze value in the opaque state is 85% to 100% and the light transmittance in the visible light region in the opaque state is 30% to 80% is because the liquid crystal and the resin are phase-separated and the liquid crystal is not solidified in a vertically aligned state.

[0042] <Light control panel> The light control plate of the present invention will be described with reference to FIG. The dimming plate 30 (see Figure 3(a)) and 30-1 (see Figure 3(b)) of the present invention are provided with a support plate 7 made of colorless, transparent or colored, transparent glass or resin on one side (see Figure 3(a)) or both sides (see Figure 3(b)) of the dimming film 20 of the present invention.

[0043] In addition, the light control plate 30, 30-1 of the present invention may have an intermediate film (not shown) between the light control film 20 and the support plate 7 provided on either one or both sides of the light control film 20.

[0044] (Support plate) The support plate 7 has a weak mechanical strength and does not have the strength to stand on its own because the light control film 20 is in the form of a film. The support plate 7 may be any plate-shaped article made of colorless transparent or colored transparent glass or resin that has the mechanical strength to stand on its own.

[0045] (Interlayer) The interlayer film has thermoplastic properties, is sufficiently transparent, and has the function of improving adhesion to glass. Materials that can be used as the interlayer film include polyvinyl butyral (PVB) and ethylene-vinyl acetate copolymer (EVA).

[0046] (Light control device) The light control device of the present invention will be described with reference to FIG. The dimming device 40 of the present invention comprises the dimming film 20 of the present invention or the dimming plate 30, 30-1 of the present invention (see Figure 3), an AC power source 8 that supplies a driving voltage to the dimming film 20 or the dimming plate 30, 30-1, and a switch 9 that switches the driving voltage supplied from the AC power source 8 to be applied to the dimming film 20 or the dimming plate 30, 30-1.

[0047] The light control device 40 of the present invention may include other components than those described above.

[0048] (AC power supply) The AC power source 8 used in the light control device 40 of the present invention does not need to be particularly limited as long as it is an AC power source with a voltage, power, and frequency that can drive the light control film 20 of the present invention. For example, an AC power source of 50 Hz, 20 V to 80 V, and on the order of several watts (depending on the area of ​​the light control film) can be suitably used.

[0049] (Switch) The switch 9 used in the light control device 40 of the present invention does not need to be particularly limited as long as it is a changeover switch that can switch the voltage supplied from the multiple terminals to which the AC power source 8 can output to the two-terminal light control film 20 of the present invention. For example, if there are six voltages that can be output from the AC power source 8, 5V, 10V, 20V, 30V, 40V, and 50V, and there are six output terminals corresponding to these voltages and one common terminal, the common terminal of the AC power source 8 is connected to one terminal of the light control film 20 as the common terminal. Then, any switch that can switch between the other terminal of the light control film 20 and the six terminals of the AC power source 8 will suffice. The switchable switch may be a mechanical switch or an electronic switch, either of which may be used. [Explanation of symbols]

[0050] 1...Transparent base material 2. Transparent conductive film 3. Alignment film 4. Alignment film removal section 5. Transparent conductive film 6. Photochromic layer 7...Support plate 8...AC power supply 9. Switch 10. Transparent conductive film with alignment layer 20. Light control film 30, 30-1....Light control panel 40... Light control device

Claims

1. A light control film comprising a pair of transparent conductive films with alignment layers, the transparent conductive films of which are disposed on the inner side, and a liquid crystal light control layer laminated thereon, In the transparent conductive film having an alignment film, at least the transparent conductive film and an alignment film are laminated in this order on a transparent substrate, The alignment film is capable of vertically aligning a liquid crystal material, The alignment film is provided with a plurality of alignment film removal portions each having a size that is not visible to the naked eye, the alignment film exposing the transparent conductive film underlying the alignment film to bring the liquid crystal material into contact with the transparent conductive film and thereby enhancing adhesion therebetween; The maximum dimension of the alignment film removal portion in a plan view is 400 nm or less, A light control film characterized in that a liquid crystal domain, which is an area having a uniform liquid crystal structure inside, is formed only on the alignment film.

2. The light control film according to claim 1 , wherein the alignment film removed portions each having a size that is not visible to the naked eye are formed periodically.

3. A light control film as described in claim 1 or 2, characterized in that the peel strength in the 180° direction of one of the transparent conductive films with an alignment film measured against the other transparent conductive film with an alignment film is 0.1 to 10.0 N / 25 mm in accordance with JIS Z 0237:2009.

4. The light control film according to any one of claims 1 to 3, characterized in that the haze value in the transparent state is 10% or less, the haze value in the opaque state is 85% to 100%, and the light transmittance in the visible light region in the opaque state is 30% to 80%.

5. A light control plate comprising a support plate made of colorless transparent or colored transparent glass or resin on one or both sides of the light control film according to any one of claims 1 to 4.

6. The light control panel according to claim 5, characterized in that an intermediate film is provided between the light control film and the support plate provided on either one or both surfaces of the light control film.

7. A dimming device comprising: a dimming film according to any one of claims 1 to 4 or a dimming plate according to claim 5 or 6; an AC power source that supplies a driving voltage to the dimming film or the dimming plate; and a switch that switches the driving voltage supplied from the AC power source to be applied to the dimming film or the dimming plate.

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