Light control film and transparent conductive film

Abstract

To provide a light control film and transparent conductive film, which offer suppressed cratering and foreign matter defects and superior appearance quality.SOLUTION: A light control film according to an embodiment comprises a pair of transparent conductive films and a light control layer provided between the pair of transparent conductive films, where surfaces of the transparent conductive films in contact with the light control layer have a surface tension of 51 to 70 dyn / cm, inclusive.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a light control film and a transparent conductive film. [Background technology]

[0002] Patent Document 1 discloses that the surface tension of the transparent conductive layer of the transparent conductive film used in the light control film is 28 dyn / cm or more and 50 dyn / cm or less. Patent Document 1 states that this can prevent uneven bonding between the transparent conductive film and the light control layer, and can also improve adhesion between the transparent conductive layer and the light control layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 180172 Summary of the Invention [Problem to be solved by the invention]

[0004] Since the light-controlling layer is formed directly on the surface of the transparent conductive film, it is strongly influenced by the surface of the transparent conductive film. It has been found that, depending on the magnitude of the surface tension, cissing defects and foreign matter defects are observed in the light-controlling layer, resulting in problems such as poor appearance and deterioration of characteristics.

[0005] The present invention has been made in view of the above points, and has an object to provide a light control film and a transparent conductive film that suppress cissing defects and foreign matter defects and have excellent appearance quality. [Means for solving the problem]

[0006] The light-controlling film of this embodiment has a pair of transparent conductive films and a light-controlling layer located between the transparent conductive films, and is characterized in that the surface tension of the transparent conductive film surface in contact with the light-controlling layer is 51 dyn / cm or more and 70 dyn / cm or less.

[0007] The transparent conductive film of this embodiment is a transparent conductive film that is applied to a light-control film, and is characterized in that the surface tension of the surface that contacts the light-control layer of the light-control film is 51 dyn / cm or more and 70 dyn / cm or less. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a light control film that can reduce the occurrence of cissing defects and foreign matter defects and has good appearance quality, and a transparent conductive film used therefor. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional schematic diagram of a light control film according to a first embodiment. [Figure 2] FIG. 10 is an enlarged schematic view showing a state in which a cissing defect occurs in the light-control layer. [Figure 3] (a) is a photograph of a cissing defect, and (b) is a schematic diagram thereof. [Figure 4] FIG. 10 is an enlarged schematic view showing a state in which a foreign matter defect occurs in the photochromic layer. [Figure 5] (a) is a photograph of a foreign matter defect, and (b) is a schematic diagram thereof. [Figure 6] FIG. 10 is an explanatory diagram showing a method for measuring a defect size. [Figure 7] FIG. 10 is a cross-sectional schematic view of a light control film according to a second embodiment. [Figure 8] FIG. 10 is a cross-sectional schematic view of a light control film according to a third embodiment. [Figure 9] FIG. 10 is a cross-sectional schematic view of a light control film according to a fourth embodiment. [Figure 10] 1 is a graph showing the relationship between the surface tension of a transparent conductive film and the number of cissing defects and the number of foreign matter defects. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes in detail an embodiment of the present invention, but the following description is an example (representative example) of the embodiment of the present description, and the present invention is not limited to these contents as long as it does not go beyond the gist of the present invention.

[0011] <Configuration of the light control film 10 in the first embodiment> Fig. 1 is a cross-sectional schematic diagram of a light control film 10 according to a first embodiment. As shown in Fig. 1, the light control film 10 comprises a pair of transparent conductive films 1, 1 and a light control layer 2 located between the transparent conductive films 1, 1. The light control layer 2 is in direct contact with the transparent conductive film surfaces 1a, 1a.

[0012] (Transparent conductive film 1) The transparent conductive film 1 is composed of a transparent substrate 3 and a transparent conductive layer 4 formed on the surface of the transparent substrate 3. Here, the term "film" refers to a planar shape whose planar width and length are much greater than its thickness, but it can also be read as "sheet." Note that in this embodiment, the terms "film" and "sheet" are not distinguished by the thickness defined in the JIS standard. The surface of the transparent conductive layer 4 facing the light-controlling layer 2 constitutes the transparent conductive film surface 1 a that is in direct contact with the light-controlling layer 2 .

[0013] The material of the transparent substrate 3 is not limited, but for example, a PET (Polyethylene Terephthalate) film is preferably used.

[0014] The transparent conductive layer 4 is a transparent layer having conductivity, and the material is not limited, but examples thereof include indium tin oxide (ITO), fluorine-doped tin oxide (FTO), tin oxide, zinc oxide, carbon nanotubes (CNT), polymers containing poly(3,4-ethylenedioxythiophene) (PEDOT), and multilayer films containing Ag alloy thin films. Of these, it is preferable to use ITO or Ag alloy for the transparent conductive layer 4.

[0015] Although there are no limitations on the film thickness, the transparent substrate 3 has a thickness of about 50 μm to 200 μm, and the transparent conductive layer 4 has a thickness of about 10 μm to 100 μm.

[0016] (Photochromic layer 2) The light-controlling layer 2 is made of, for example, a polymer network liquid crystal (PNLC), a polymer dispersed liquid crystal (PDLC), or a nematic curvilinear aligned phase (NCAP). For example, a polymer network liquid crystal has a three-dimensional mesh-like polymer network, and liquid crystal molecules are held in the voids of the polymer network. The liquid crystal molecules contained in the light-controlling layer 2 have, for example, a positive dielectric anisotropy, and the dielectric constant in the long axis direction of the liquid crystal molecules is larger than the dielectric constant in the short axis direction of the liquid crystal molecules. The liquid crystal molecules are, for example, Schiff base-based, azo-based, azoxy-based, biphenyl-based, terphenyl-based, benzoate-based, tolan-based, pyrimidine-based, cyclohexanecarboxylic acid ester-based, phenylcyclohexane-based, or dioxane-based liquid crystal molecules.

[0017] The light-controlling layer 2 in this embodiment preferably contains liquid crystal molecules, a photocurable resin, and spacers.

[0018] <Background to the development of the light control film 10 of this embodiment> Fig. 2 is an enlarged schematic diagram showing a state in which a cissing defect 13 has occurred in a conventional photochromic layer 12. As shown in Fig. 2, a cissing defect 13 was observed near the boundary between a pair of transparent conductive films 11 and the photochromic layer 12 located between the transparent conductive films 11, resulting in poor appearance. Fig. 3(a) is a photograph of the cissing defect, and Fig. 3(b) is a schematic diagram thereof.

[0019] FIG. 4 is an enlarged schematic diagram showing a state in which a foreign matter defect 14 has occurred in a conventional photochromic layer 12. As shown in FIG. 4, a foreign matter 14a has been mixed into the photochromic layer 12 located between a pair of transparent conductive films 11, and a foreign matter defect 14 including the foreign matter 14a and its surroundings has been observed, resulting in a poor appearance. Defects such as the formation of voids and irregular alignment of liquid crystal molecules have occurred around the foreign matter 14a. FIG. 5(a) is a photograph of the foreign matter defect, and FIG. 5(b) is a schematic diagram thereof.

[0020] In this way, the light-controlling layer 12 is formed in direct contact with the transparent conductive film 11. For this reason, it has been found that the appearance and characteristics are affected by the transparent conductive film surface 11a, and the above-mentioned cissing defects 13 and foreign matter defects 14 occur.

[0021] Therefore, the inventors have conducted extensive research and have invented a light control film 10 that has good appearance quality and can reduce the occurrence of cissing defects and foreign matter defects by adjusting the surface tension of the transparent conductive film surface 1a.

[0022] <Features of the light control film 10 of this embodiment> This embodiment is characterized in that the surface tension of the transparent conductive film surface 1a in contact with the light-switching layer 2 is 51 dyn / cm or more and 70 dyn / cm or less. The surface tension is evaluated according to JIS K 6768.

[0023] By adjusting the surface tension within the above range, it is possible to suppress the occurrence of cissing defects 13 shown in FIG. 2 and foreign matter defects 14 shown in FIG. 4. In this embodiment, the defect sizes of cissing defects and foreign matter defects are set to a diameter of 2.0 mm or more. The diameter φ can be calculated by measuring the width dimension a and length dimension b in the case of circular or elliptical shapes as shown in FIG. 6(a) or irregular shapes as shown in FIG. 6(b) and then calculating the diameter φ as (width dimension a + length dimension b) / 2. The width dimension a and length dimension b are orthogonal to each other. Here, examples are given of circular, elliptical, and irregular shapes of defects, but the diameter φ can be calculated in the same way even for shapes other than these.

[0024] As shown in Fig. 2, repelling defects 13 occur near the interface between the photochromic layer 12 and the transparent conductive film 11, but by setting the surface tension of the transparent conductive film surface to 51 dyn / cm or more, wettability at the interface is improved, making it possible to prevent repelling when the photochromic material is applied. On the other hand, if the surface tension of the transparent conductive film surface is too high, foreign matter 14a is likely to become mixed into the photochromic layer 12 during the coating process of the photochromic material, as shown in Fig. 4. Therefore, by setting the surface tension to 70 dyn / cm or less, it is possible to prevent foreign matter 14a from becoming trapped during the coating of the photochromic layer.

[0025] In this embodiment, the surface tension is preferably 54 dyn / cm or more, more preferably 56 dyn / cm or more, and preferably 66 dyn / cm or less, more preferably 64 dyn / cm or less, and even more preferably 62 dyn / cm or less.

[0026] In this embodiment, the total number of defects including cissing defects is set to 0.69 / m 2 It can be suppressed to 0.5 pieces / m or less, preferably 0.5 pieces / m 2 It can be made to be less than 0.45 pieces / m, and more preferably, it can be made to be less than 0.45 pieces / m 2 You can do the following:

[0027] As the surface modification treatment for adjusting the surface tension, corona treatment or atmospheric pressure plasma treatment can be carried out, but the treatment is not limited to these.

[0028] <Configuration of light control film in other embodiments> In FIG. 7, the transparent conductive film 5 is a laminated film of a transparent substrate 3 / a transparent conductive layer 4 / a protective layer 6 , and the transparent conductive film surface 5 a in contact with the light-controlling layer 2 is the protective layer 6 .

[0029] In FIG. 8, the transparent conductive film 7 is a laminated film of the transparent substrate 3 / the transparent conductive layer 4 / the alignment layer 8 , and the transparent conductive film surface 7 a in contact with the light-controlling layer 2 is the alignment layer 8 .

[0030] In FIG. 9, the transparent conductive film 9 is a laminated film of the transparent substrate 3 / transparent conductive layer 4 / protective layer 6 / alignment layer 8, and the transparent conductive film surface 9a in contact with the light-controlling layer 2 is the alignment layer 8.

[0031] As described above, the surface of the transparent conductive film in contact with the light-controlling layer 2 is not limited to the transparent conductive layer 4 as shown in Fig. 1, but may be a protective layer 6 as shown in Fig. 7 or an alignment layer 8 as shown in Figs. 8 and 9. In either case, the surface tension of the transparent conductive film surfaces 6a, 7a, and 8a is adjusted to 51 dyn / cm or more and 70 dyn / cm or less.

[0032] The configuration in which an alignment layer 8 is provided in the layer structure of the light control film as shown in FIGS. 8 and 9 is applied to a reverse-type light control film.

[0033] (Alignment layer 8) The alignment layer 8 is a layer that controls the alignment of the liquid crystal molecules contained in the light control layer 2. The light control film 10 of this embodiment shown in Figures 8 and 9 is a reverse-type light control film, which is transparent when no driving voltage is applied, with the liquid crystal molecules oriented along the normal direction of the alignment layer 8 (vertical alignment), and becomes opaque when a driving voltage is applied.

[0034] There is no limitation on the material that constitutes the alignment layer 8, but examples thereof include polyamide, polyimide, polycarbonate, polystyrene, polysiloxane, polyesters such as polyethylene terephthalate and polyethylene naphthalate, and polyacrylates such as polymethyl methacrylate. Among these, it is preferable to use a polyimide-based resin.

[0035] Although there are no limitations on the film thickness of the alignment layer 8, it is about 50 μm to 250 μm, and preferably about 100 μm to 200 μm, which allows for excellent alignment regulation power for liquid crystal molecules.

[0036] In the reverse type, the appearance quality in the transparent state with the power off is important. Therefore, it is desirable to adjust the surface tension of the surface of the alignment layer 8 to minimize the occurrence of cissing defects and foreign matter defects between the alignment layer 8 and the light-controlling layer 2, thereby obtaining excellent appearance quality.

[0037] 7 and 9 is not particularly limited and may be, for example, a primer layer. In addition, the transparent conductive film may include at least one functional layer such as a hard coat layer, an antiblocking layer, a primer layer, or an index matching layer. When the functional layer corresponds to the transparent conductive film surface in contact with the switchable layer 2, the surface tension of the functional layer surface is adjusted to 51 dyn / cm or more and 70 dyn / cm or less. [Example]

[0038] The present invention will be described in detail below with reference to examples carried out to clarify the effects of the present invention, but the present invention is not limited to the following examples.

[0039] <Surface modification method> The surface of the transparent conductive layer of the transparent conductive film was subjected to a modification treatment. Although the modification treatment method is not limited, in this experiment, atmospheric pressure plasma treatment was performed. In the experiment, the electrode output was controlled at 0% to 90% of 30 kV.

[0040] <Surface tension evaluation method> The surface tension of the transparent conductive layer surface was determined in accordance with JIS K 6768 (Plastics - Films and sheets - Wetting tension test method).

[0041] <Production of light-control film> Using the above-mentioned surface modification treatment, a plurality of transparent conductive films with different surface tensions were used to produce the light control films shown in Figure 1.

[0042] <Defect evaluation method> The defects were evaluated using an optical inspection machine. A high-brightness LED was used for illumination, and the detection method was a scattering transmission type.

[0043] In determining the cissing defects and foreign matter defects shown in Figures 3 and 5, defects with a diameter of 2 mm or more were considered to be defects. The defect size was calculated using Figure 6. The experimental results are shown in Table 1 and FIG.

[0044] [Table 1]

[0045] The total number of defects, including cissing and foreign matter, is 0.69 / m 2 If it is more than this, mark it as × and the number of particles is 0.69 / m 2 If the result was below the above, the result was judged as ◯.

[0046] According to the experiment, when the surface tension is 50 dyn / cm or less, many cissing defects occur, and the total number of defects is 0.69 / m. 2 Furthermore, when the surface tension is 71 dyn / cm or more, many foreign matter defects occur, and the total number of defects reaches 0.69 / m 2 That's all.

[0047] Therefore, the surface tension is set to 51 dyn / cm or more and 70 dyn / cm or less, and preferably 54 dyn / cm or more, or 56 dyn / cm or more and 66 dyn / cm or less, or 64 dyn / cm or less. [Explanation of symbols]

[0048] 1, 11: Transparent conductive film 1a, 5a, 6a, 7a, 8a, 9a, 11a: Transparent conductive film surface 2, 12: Light-controlling layer 3: Transparent base material 4: Transparent conductive layer 5, 7, 9: Transparent conductive film 6:Protective layer 8: Orientation layer 10: Light control film 13: Crack defect 14: Foreign matter defect 14a: Foreign body a: Width dimension b: Length dimension

Claims

1. A pair of transparent conductive films; a light-control layer located between the transparent conductive films, the surface tension of the transparent conductive film surface in contact with the light-controlling layer is 51 dyn / cm or more and 70 dyn / cm or less; A light control film characterized by:

2. The light-controlling layer contains liquid crystal molecules, a photocurable resin, and spacers. The light control film according to claim 1 .

3. A transparent conductive film to be applied to a light control film, The surface tension of the surface of the light control film in contact with the light control layer is 51 dyn / cm or more and 70 dyn / cm or less; A transparent conductive film characterized by:

4. The surface tension is 56 dyn / cm or more. The light control film or transparent conductive film according to claim 1 or 3.

5. the outermost layer in contact with the light-controlling layer is any one of a transparent conductive layer, a protective layer, and an alignment layer; The light control film or transparent conductive film according to claim 1 or 3.

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