Transparent substrate for dimming sheet, and dimming sheet

Abstract

To provide: a transparent substrate for liquid crystal devices capable of suppressing physical damage in an alignment layer included in the transparent substrate for liquid crystal devices; and a dimmer sheet.SOLUTION: A first substrate 11 includes: an alignment layer 21 that regulates an alignment direction of liquid crystal molecules included in a liquid crystal layer provided in a liquid crystal device; and a ground layer 11A where the alignment layer 21 is formed. The first substrate is provided with: a first surface 11S1; and a second surface 11S2 on an opposite side to the first surface 11S1. The first surface 11S1 is included in the alignment layer 21, and the second surface 11S2 is included in the ground layer 11A. A coefficient of static friction between the first surface 11S1 and the second surface 11S2 is 1.3 or less. The first surface 11S1 or on a surface on the opposite side to the second surface 11S2 of the ground layer 11A has hardness equal to or greater than F in a pencil hardness test performed thereon.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to Dimming sheet a transparent substrate and a dimming sheet.

Background Art

[0002] A reverse-type dimming sheet includes a dimming layer containing liquid crystal molecules, a pair of conductive layers sandwiching the dimming layer in the thickness direction of the dimming layer, and alignment layers respectively positioned between the dimming layer and the conductive layers. In the reverse-type dimming sheet, in a state where no voltage is applied between the pair of conductive layers, the alignment layer vertically aligns the liquid crystal molecules. On the other hand, in a state where a voltage is applied between the pair of conductive layers, the liquid crystal molecules align perpendicular to the electric field formed between the pair of conductive layers. Thereby, the reverse-type dimming sheet has a relatively low haze in a state where no voltage is applied between the pair of conductive layers, and has a relatively high haze in a state where a voltage is applied between the pair of conductive layers (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, for a light control sheet and a transparent substrate provided with an alignment layer, from the viewpoint of enabling mass production of the light control sheet, it is required that the production can be carried out using a roll-to-roll apparatus. When the transparent substrate is produced using a roll-to-roll apparatus, during the conveyance of the transparent substrate by the roll-to-roll apparatus, during the winding of the transparent substrate using the roll-to-roll apparatus, and during the conveyance of the wound transparent substrate, etc., an external force acts on the transparent substrate, and thus, on the alignment layer provided in the transparent substrate, and as a result, physical damage may occur in the alignment layer. Thus, new problems have arisen for the transparent substrate provided with an alignment layer due to the production of the transparent substrate using a roll-to-roll apparatus.

[0005] Note that such matters are common not only to the transparent substrate for a light control sheet but also to the transparent substrates for other liquid crystal devices produced using a roll-to-roll apparatus.

Means for Solving the Problems

[0006] The transparent substrate for a liquid crystal device for solving the above problems is a transparent substrate for a liquid crystal device including an alignment layer that regulates the alignment direction of liquid crystal molecules included in a liquid crystal layer provided in the liquid crystal device, and a base layer on which the alignment layer is formed. The transparent substrate for a liquid crystal device includes a first surface and a second surface opposite to the first surface. The first surface is the surface including the alignment layer, and the second surface is the surface including the base layer. The coefficient of static friction between the first surface and the second surface is 1.3 or less, and in a pencil hardness test on the first surface or the surface of the base layer opposite to the second surface, it has a hardness of F or more. The light control sheet for solving the above problems includes the above transparent substrate for a liquid crystal device and a light control layer in contact with the first surface of the transparent substrate for a liquid crystal device and including liquid crystal molecules.

[0007] According to the transparent substrate for the liquid crystal device, since the coefficient of static friction between the first surface and the second surface is 1.3 or less, when the first surface rubs against the second surface, damage to the first surface can be suppressed. Further, since the surface on which the alignment layer is formed in the first surface itself or the underlayer has a high pencil hardness, even when an external impact is applied to the first surface, the first surface is less likely to be damaged. Thereby, it is possible to suppress physical damage to the alignment layer.

[0008] The underlayer for the liquid crystal device includes a hard coat layer, and may have a hardness of F or more in a pencil hardness test on the surface of the underlayer opposite to the second surface. According to this transparent substrate for the liquid crystal device, since the high pencil hardness in the underlayer is realized by the hard coat layer, the alignment layer does not need to have both the function of regulating the alignment of liquid crystal molecules and high hardness, so it is possible to reduce the constraints on the configuration of the alignment layer including the thickness and material.

[0009] In the transparent substrate for the liquid crystal device, the underlayer includes a conductive layer in contact with the alignment layer, and the conductive layer may be located between the hard coat layer and the alignment layer in the thickness direction of the transparent substrate for the liquid crystal device.

[0010] According to the transparent substrate for the liquid crystal device, since the conductive layer is located between the alignment layer and the hard coat layer in the thickness direction of the transparent substrate for the liquid crystal device, when a voltage is applied between the conductive layers of the liquid crystal device, an electric field having an intensity enabling the driving of liquid crystal molecules is formed between the conductive layers.

[0011] In the transparent substrate for the liquid crystal device, the underlayer includes a support substrate, an adhesive layer laminated on the support substrate, and a protective layer attached to the support substrate by the adhesive layer, and the protective layer may include the second surface.

[0012] According to the transparent substrate for a liquid crystal device, since a protective layer including a second surface is provided separately from the support substrate, it is possible to reduce the restrictions on the configuration of the support substrate including the thickness and material, etc., compared with the case where the support substrate includes the second surface.

[0013] In the transparent substrate for a liquid crystal device, the underlayer includes a support substrate and a lubricating layer laminated on the support substrate and including a plurality of fine particles. The lubricating layer includes the second surface, and the plurality of fine particles may include the fine particles partially exposed on the second surface.

[0014] According to the transparent substrate for a liquid crystal device, since a lubricating layer including a second surface is provided separately from the support substrate, it is possible to reduce the restrictions on the configuration of the support substrate including the thickness and material, etc., compared with the case where the support substrate includes the second surface. [Advantages of the Invention]

[0015] The present invention can suppress physical damage in the alignment layer provided in the transparent substrate for a liquid crystal device. [Brief Description of the Drawings]

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

[0017] [First Embodiment] With reference to FIGS. 1 to 3, a first embodiment of a transparent substrate for a liquid crystal device and a light control sheet will be described.

[0018] [Dimming Sheet] The dimming sheet will be described with reference to FIG. 1. As shown in FIG. 1, the dimming sheet 10 includes a first base material 11, a second base material 12, and a dimming layer 13. The dimming layer 13 contains liquid crystal molecules. The dimming layer 13 is an example of a liquid crystal layer. In the dimming layer 13, the holding form of the liquid crystal molecules may be a polymer network type (PNLC: Polymer Network Liquid Crystal) or a polymer dispersed type (PDLC: Polymer Dispersed Liquid Crystal). The liquid crystal molecules have negative dielectric anisotropy. In other words, the liquid crystal molecules are of the n-type. The type of the dimming sheet 10 is a reverse type.

[0019] Each of the first base material 11 and the second base material 12 is an example of a transparent base material for a liquid crystal device. Each base material 11, 12 has transparency to visible light. Each base material 11, 12 includes an alignment layer. The alignment layer regulates the alignment direction of the liquid crystal molecules included in the dimming layer 13. The alignment layer is a vertical alignment film. Each base material 11, 12 is in contact with the dimming layer 13. In each of the base materials 11, 12, the surface in contact with the dimming layer 13 is the first surface. Hereinafter, with reference to FIG. 2, the structure of each of the base materials 11, 12 will be described in more detail.

[0020] [Transparent Base Material for Liquid Crystal Device] The transparent base material for a liquid crystal device will be described with reference to FIG. 2. FIG. 2 shows a cross-sectional structure of a first base material 11 which is an example of a transparent base material for a liquid crystal device. Note that, while the position of the second base material 12 in the thickness direction of the dimming sheet 10 is different from that of the first base material 11, the layers included in the second base material 12 are common to the layers included in the first base material 11. Therefore, hereinafter, while the structure of the first base material 11 will be described in detail, a detailed description of the structure of the second base material 12 will be omitted.

[0021] As shown in FIG. 2, the first substrate 11 includes an alignment layer 21 and a base layer 11A on which the alignment layer 21 is formed. The alignment layer 21 is in contact with the base layer 11A. The first substrate 11 includes a first surface 11S1 and a second surface 11S2 on the side opposite to the first surface 11S1. The first surface 11S1 is the surface including the alignment layer 21. The second surface 11S2 is the surface including the base layer 11A. The coefficient of static friction between the first surface 11S1 and the second surface 11S2 is 1.3 or less. The first substrate 11 has a hardness of F or more in a pencil hardness test with respect to the surface on the side opposite to the first surface 11S1 or the second surface 11S2 of the base layer 11A.

[0022] The pencil hardness test is performed by a method compliant with JIS K 5600-5-4:1999 "General Test Methods for Paints - Part 5: Mechanical Properties of Coating Films - Section 4: Scratch Hardness (Pencil Method)".

[0023] The base layer 11A includes a hard coat layer 23. The first substrate 11 has a hardness of F or more in a pencil hardness test with respect to the surface on the side opposite to the second surface 11S2 of the base layer 11A. According to the first substrate 11, since the high pencil hardness in the base layer 11A is realized by the hard coat layer 23, the alignment layer 21 does not need to have both the function of regulating the alignment of liquid crystal molecules and high hardness. Therefore, it is possible to reduce the constraints on the configuration of the alignment layer 21 including the thickness and material compared to the case where the alignment layer 21 itself has high pencil hardness.

[0024] The base layer 11A includes a conductive layer 22 in contact with the alignment layer 21. The conductive layer 22 is located between the hard coat layer 23 and the alignment layer 21 in the thickness direction of the first substrate 11. Since the conductive layer 22 is located between the alignment layer 21 and the hard coat layer 23 in the thickness direction of the first substrate 11, when a voltage is applied to the conductive layer 22, an electric field having an intensity enabling the driving of liquid crystal molecules is easily formed between the conductive layer 22 of the first substrate 11 and the conductive layer of the second substrate 12.

[0025] The underlayer 11A includes a support substrate 24, an adhesive layer 25, and a protective layer 26. The adhesive layer 25 is laminated on the support substrate 24. The protective layer 26 is attached to the support substrate 24 by the adhesive layer 25. The protective layer 26 includes the second surface 11S2. According to the first substrate 11, since the protective layer 26 including the second surface 11S2 is provided separately from the support substrate 24, compared with the case where the support substrate 24 includes the second surface 11S2, it is possible to reduce the constraints on the configuration of the support substrate 24 including the thickness and material.

[0026] The strength of the hard coat layer 23 is higher than the strength of the support substrate 24. Therefore, compared with the case where the underlayer 11A does not include the hard coat layer 23, the hardness on the surface of the alignment layer 21 formed on the underlayer 11A also increases.

[0027] The support substrate 24 has a pair of opposing surfaces in the thickness direction of the first substrate 11. The surface roughness of the second surface 11S2 included in the protective layer 26 is greater than the surface roughness of at least the surface in contact with the adhesive layer 25 among the pair of surfaces of the first substrate 11. The surface roughness is the arithmetic mean roughness Ra defined in JIS B 0601:2013 "Geometrical Product Specifications (GPS) - Surface texture: Profile method - Terms, definitions and surface texture parameters".

[0028] The alignment layer 21 is a vertical alignment film. The alignment layer 21 aligns the liquid crystal molecules so that the long axis of the liquid crystal molecules is perpendicular to the plane in which the alignment layer 21 spreads. Note that the angle formed by the alignment layer 21 and the long axis of the liquid crystal molecules may have a deviation from a right angle within a range that can be regarded as substantially a right angle. The alignment layer 21 is formed of, for example, polyamic acid, polyimide, and polyvinyl alcohol (PVA). A rubbing treatment may be performed on the surface of the alignment layer 21. The thickness of the alignment layer 21 may be, for example, 20 nm or more and 500 nm or less. The alignment layer 21 has transparency to visible light.

[0029] The conductive layer 22 is formed of, for example, a transparent conductive oxide (TCO). The TCO may be, for example, indium tin oxide (ITO), zinc oxide (ZnO), tin oxide (SnO2), indium zinc oxide (IZO), indium - gallium - zinc oxide (IGZO), or the like. The conductive layer 22 can have a thickness of, for example, 5 nm or more and 100 nm or less. The conductive layer 22 has permeability to visible light.

[0030] The hard coat layer 23 may be formed of, for example, any of an organic - based material, a silicon - based material, and an inorganic - based material. The organic - based material is a synthetic resin and may be, for example, any of a melamine - based resin, a urethane - based resin, and an acrylic - based resin. The silicon - based material may be a silane compound. The inorganic - based material may be a metal oxide. The hard coat layer 23 can have a thickness of, for example, 1 μm or more and 10 μm or less. The hard coat layer 23 has permeability to visible light. The hard coat layer 23 is not limited to a single - layer structure and may have a multilayer structure. When the hard coat layer 23 has a multilayer structure, the hard coat layer 23 may include a first layer formed of a first material and a second layer formed of a second material different from the first material.

[0031] The support substrate 24 is formed of, for example, a synthetic resin. The synthetic resin may be, for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or the like. The support substrate 24 can have a thickness of, for example, 16 μm or more and 250 μm or less. The support substrate 24 has permeability to visible light. Note that the support substrate 24 is not limited to a single - layer structure and may have a multilayer structure. When the support substrate 24 has a multilayer structure, the support substrate 24 may include a first layer formed of a first material and a second layer formed of a second material different from the first material.

[0032] The adhesive layer 25 is formed from various adhesives. The adhesive may be, for example, a rubber-based adhesive, an acrylic-based adhesive, or a silicone-based adhesive. The adhesive layer 25 can have a thickness of, for example, 2 μm or more and 100 μm or less. The adhesive layer 25 has permeability to visible light.

[0033] The protective layer 26 is formed from a synthetic resin. The synthetic resin may be, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), or polyolefin (PO). The protective layer 26 can have a thickness of, for example, 25 μm or more and 188 μm or less. The protective layer 26 has permeability to visible light.

[0034] [Function] With reference to FIG. 3, the function of the first substrate 11 will be described. When the dimming sheet 10 is manufactured using the first substrate 11, the first substrate 11 is conveyed by a roll-to-roll device along the longitudinal direction of the first substrate 11. At this time, a tension is applied to the first substrate 11 along the longitudinal direction, and the first substrate 11 is conveyed along the longitudinal direction while being in contact with a guide roll provided in the roll-to-roll device. Therefore, when the first surface 11S1 of the first substrate 11 contacts the guide roll, friction occurs between the first surface 11S1 included in the alignment layer 21 and the guide roll. When the frictional force acting on the first surface 11S1 exceeds the strength of the first surface 11S1, a defect, which is a physical damage, occurs in the portion of the alignment layer 21 where the frictional force acts. The defect is a portion where a part of the alignment layer 21 is missing.

[0035] As shown in FIG. 3, since the first substrate 11 has a strip shape, when the first substrate 11 is transported from the roll-to-roll device to another device, or when the first substrate 11 is stored, the first substrate 11 has a roll shape wound around a core C. When the first substrate 11 is wound around the core C, friction occurs between the first surface 11S1 and the second surface 11S2 of the first substrate 11. When the frictional force acting on the first surface 11S1 exceeds the strength of the first surface 11S1, a defect occurs in the portion of the alignment layer 21 where the frictional force acts.

[0036] Further, when the first substrate 11 is transported, vibration is applied to the first substrate 11, so that friction occurs between a part of the first surface 11S1 of the first substrate 11 and a part of the second surface 11S2 in contact with the part. Also in this case, if the frictional force acting on the first surface 11S1 exceeds the strength of the first surface 11S1, defects will occur in the portion of the alignment layer 21 where the frictional force acts.

[0037] In this regard, according to the first substrate 11, since the coefficient of static friction between the first surface 11S1 and the second surface 11S2 is 1.3 or less, when the first surface 11S1 rubs against the second surface 11S2, damage to the first surface 11S1 can be suppressed. Further, since the lower layer of the first surface 11S1 has a high pencil hardness, even when an external impact is applied to the first surface 11S1, the first surface 11S1 is less likely to be damaged. Thereby, physical damage to the alignment layer 21 can be suppressed.

[0038] As described above, the alignment layer 21 is a very thin layer and has a thickness of at most about several hundred nm. Therefore, it is considered that the alignment layer 21 maintains the strength to exist as a thin film by following the underlayer 11A of the alignment layer 21. In this regard, since the first substrate 11 has a hard coat layer 23 with higher strength than the support substrate 24, it is considered that the strength of the underlayer 11A is increased, and the strength of the alignment layer 21 following the underlayer 11A, and thus the hardness on the first surface 11S1 is also increased.

[0039] Further, since the surface roughness of the second surface 11S2 included in the protective layer 26 is larger than the surface roughness of the support substrate 24, an increase in the coefficient of static friction between the first surface 11S1 and the second surface 11S2 can be suppressed, and an increase in the frictional force acting on the first surface 11S1 can also be suppressed.

[0040] [Examples] With reference to Table 1, examples and comparative examples will be described. [Example 1-1] A PET film (Cosmoshine A4300, manufactured by Toyobo Co., Ltd.) (Cosmoshine is a registered trademark) having a thickness of 125 μm was prepared. An acrylic paint (Lucifrail NAB-016, manufactured by Nippon Paint Industrial Coatings Co., Ltd.) (Lucifrail is a registered trademark) was adjusted using methyl ethyl ketone (MEK) so that the solid content became 40% by weight, thereby obtaining a coating liquid for forming a back coat layer. A coating film was formed by applying the coating liquid to the second surface of the PET film using a gravure coater. After drying the coating film at 80°C for 1 minute, the coating film was exposed using a high-pressure mercury lamp under the condition of 300 mJ / cm 2 to form a back coat layer having a thickness of 2 μm.

[0041] A paint for a hard coat layer (Rioduras LCH6701, manufactured by Toyochem Co., Ltd.) (Rioduras is a registered trademark), which is the base of the conductive layer, was adjusted using MEK so that the solid content became 50% by weight, thereby obtaining a coating liquid for forming a hard coat layer. A coating film was obtained by applying the coating liquid to the first surface of the PET film using a gravure coater. After drying the coating film at 60°C for 1 minute, the coating film was exposed using a high-pressure mercury lamp under the condition of 300 mJ / cm 2 to form a hard coat layer having a thickness of 2 μm.

[0042] The PET film having the hard coat layer formed thereon was installed in a roll-to-roll sputtering apparatus. Next, after evacuating the processing chamber of the sputtering apparatus to 0.4 Pa, argon gas and oxygen gas were introduced into the processing chamber. The target was sputtered by supplying power to a mixed sintered target of 90% by weight indium oxide and 10% by weight tin oxide. At this time, the temperature of the PET film was set to 40°C. Thereby, an ITO layer having a thickness of 50 nm was formed on the hard coat layer. Then, the ITO was crystallized by heating the ITO layer at 140°C for 90 minutes. The PET film having the ITO layer formed thereon was wound up.

[0043] A protective film with an adhesive layer (Suntect SAT-TM40125TG, manufactured by Sun Ace Chemical Co., Ltd.) (Suntect is a registered trademark) was prepared, and the protective film was attached to the backcoat layer using a laminator. As a result, a base layer on which an alignment layer is formed was obtained from among the transparent substrates for liquid crystal devices.

[0044] A coating liquid for forming an alignment layer was obtained by adjusting a paint for an alignment layer mainly composed of polyamic acid (Sunever SE-H682, manufactured by Nissan Chemical Industries, Ltd.) (Sunever is a registered trademark) using a solvent so that the solid content became 5% by weight. In addition, in the solvent, the weight ratio of propylene glycol monomethyl ether to γ-butyrolactone was set as follows.

[0045] Propylene glycol monomethyl ether:γ-butyrolactone = 8:2 A coating film was formed by applying the coating liquid onto the ITO layer of the base layer using a roll coater. By drying the coating film at 150°C for 5 minutes, an alignment layer having a thickness of 100 nm was formed. As a result, a transparent substrate for a liquid crystal device was obtained. Then, the transparent substrate for a liquid crystal device was wound up. The transparent substrate for a liquid crystal device was stored in a clean room maintained at 23°C and a relative humidity of 50%RH for 7 days. Thereafter, the transparent substrate for a liquid crystal device was used for the production of a light control sheet.

[0046] A pair of transparent substrates for liquid crystal devices was prepared. Bead spacers dispersed in isopropyl alcohol (IPA) were applied onto the alignment layer of one of the transparent substrates for liquid crystal devices. At this time, bead spacers having a diameter of 6 μm and mainly composed of divinylbenzene were used. In addition, the bead spacers were applied so that the occupied area of the bead spacers on the first surface became 1.5%. After drying the IPA at 100°C, the base layer having the bead spacers was wound up.

[0047] In order to form a light control layer, first, the following materials were mixed to prepare a mixed solution. Loctite 3736 (registered trademark, manufactured by Henkel) 17.5 parts by weight 17.5 parts by weight of 1,9 - nonanediol methacrylate Next, 65 parts by weight of an n - type liquid crystal (MLC - 6608, manufactured by Merck & Co., Inc.) was mixed into the mixed solution to obtain a coating liquid for forming a light - modulating layer.

[0048] A light - modulating sheet was manufactured using a coating apparatus equipped with a first unwinding device, a second unwinding device, a die - head coater, an irradiation device equipped with a high - pressure mercury lamp, and a roll - to - roll device equipped with one winding device. The irradiation device was set so as not to irradiate light having a wavelength of 350 nm or less. A transparent substrate for a liquid crystal device having bead spacers was drawn out from the first unwinding device, and a coating film was formed by applying a coating liquid for forming a light - modulating layer onto the alignment layer having bead spacers using a die - head coater. Next, in a nitrogen atmosphere, ultraviolet rays were irradiated on the coating liquid for 30 seconds under the condition of 20 mW / cm 2 2 At this time, the temperature inside the irradiation device was set to 25°C. Thereby, the coating film was cured to obtain a polymer network - type light - modulating layer. The transparent substrate for a liquid crystal device drawn out from the second unwinding device was bonded to the light - modulating layer such that the alignment layer of the transparent substrate for a liquid crystal device was in contact with the light - modulating layer, thereby obtaining the light - modulating sheet of Example 1. After bonding the transparent substrates for liquid crystal devices, the light - modulating sheet was wound up using a winding device to obtain a roll - shaped light - modulating sheet.

[0049] [Example 1 - 2] In Example 1 - 1, a light - modulating sheet of Example 1 - 2 was obtained by the same method as in Example 1 - 1, except that the protective film was changed to another protective film (SAT4538T - JSL, manufactured by Sun Ace Chemical Research Co., Ltd.).

[0050] [Example 1 - 3] In Example 1-1, the paint for forming the hard coat layer was changed to another paint (TP-203X coating agent, manufactured by Toyo Ink Co., Ltd.), and the solid content was adjusted to 50% by weight using MEK to obtain a coating liquid for forming the hard coat layer. A coating film was obtained by applying the coating liquid to a PET film using a gravure coater. The coating film was dried at 60°C for 1 minute, and then irradiated with 250 mJ / cm 2 A hard coat layer having a thickness of 2 μm was formed by exposing the coating film using a high-pressure mercury lamp under the conditions of

[0049] Otherwise, a light control sheet of Example 1-3 was obtained in the same manner as in Example 1-1.

[0051] [Examples 1-4] A light control sheet of Example 1-4 was obtained in the same manner as in Example 1-1, except that the thickness of the hard coat layer in Example 1-1 was changed to 5 μm.

[0052] [Comparative Example 1-1] A light-control sheet of Comparative Example 1-1 was obtained in the same manner as in Example 1-1, except that the protective film in Example 1-1 was changed to another protective film (PT820, manufactured by Tamapoly Co., Ltd.).

[0053] [Comparative Example 1-2] A light-control sheet of Comparative Example 1-2 was obtained in the same manner as in Example 1-1, except that the hard coat layer was not formed.

[0054] [Evaluation method] [Static friction coefficient] For the undercoat layer of each example and comparative example, before the light-controlling layer was applied, the static friction coefficient between the surface of the ITO film and the surface of the protective film was measured using a portable friction meter (Tribogear Muse Type: 94i, manufactured by Shinto Scientific Co., Ltd.) (Tribogear is a registered trademark).

[0055] [Pencil hardness] For the base layers of each example and each comparative example, before forming the light control layer, a pencil hardness test was conducted on the surface of the ITO layer. At this time, a method compliant with JIS K 5600-5-4:1999 "General Test Methods for Coating Films - Part 5: Mechanical Properties of Coating Films - Section 4: Scratch Hardness (Pencil Method)" was used.

[0056] [Count of Defects] From each light control sheet of each example and each comparative example, a test piece having a square shape and a side length of 1 m was cut out. The test piece without voltage applied was irradiated with light using a three-wavelength light source with an illuminance of 1000 lux or more, and the light control sheet was visually observed from the side opposite to the three-wavelength light source with respect to the test piece. Then, the white cloudy portions having a length of 2 mm or more were regarded as defects, and the defects of each test piece were counted. Note that the white cloudy portions are caused by insufficient alignment control force of the alignment layer, and thus the liquid crystal molecules do not align. Therefore, the white cloudy portions can be regarded as the portions where defects have occurred in the alignment layer.

[0057] [Haze] From each light control sheet of each example and each comparative example, an A3-sized test piece was cut out. In each test piece, a part of each ITO layer was exposed to the outside, thereby forming terminals for applying a voltage to the light control sheet. After connecting conducting wires to each terminal, an AC power supply device was connected to the conducting wires. Then, for each test piece, the haze in the state where no voltage was applied and the haze in the state where a voltage of 60 Hz and 40 V was applied were measured. When measuring the haze, a method compliant with JIS K 7136:2000 "Plastics - Method for Determining Haze of Transparent Materials" was used.

[0058] [Evaluation Results] The static friction coefficient and pencil hardness of each base layer, and the number of defects and haze of each light control sheet were as shown in Table 1 below.

[0059]

Table 1

[0060] As shown in Table 1, it was confirmed that the coefficient of static friction of the base layer in Example 1-1, Example 1-3, and Example 1-4 was 0.4, and the coefficient of static friction of the base layer in Example 1-2 was 1.3. In contrast, it was confirmed that the coefficient of static friction of the base layer in Comparative Example 1-1 was 1.5, and the coefficient of static friction of the base layer in Comparative Example 1-2 was 0.6.

[0061] Also, it was confirmed that the pencil hardness of the base layer in Example 1-1 and Example 1-2 was H, the pencil hardness of the base layer in Example 1-3 was F, and the pencil hardness of the base layer in Example 1-4 was 2H. In contrast, it was confirmed that the pencil hardness of the base layer in Comparative Example 1-1 was H, and the pencil hardness of the base layer in Comparative Example 1-2 was 2B.

[0062] Also, the number of defects in the dimming sheet of Example 1-1 and Example 1-3 was 5 defects / m 2 and the number of defects in the dimming sheet of Example 1-2 was 10 defects / m 2 and the number of defects in the dimming sheet of Example 1-4 was 7 defects / m 2 It was confirmed that. In contrast, the number of defects in the dimming sheets of Comparative Example 1-1 and Comparative Example 1-2 was 50 defects / m 2 or more.

[0063] Thus, in the transparent base material for liquid crystal devices, in the base layer on which the alignment layer is formed, when the coefficient of static friction between the first surface and the second surface is 1.3 or less, and the pencil hardness on the surface opposite to the second surface is F or more, it was confirmed that physical damage to the alignment layer can be suppressed.

[0064] As described above, according to the first embodiment of the transparent base material for liquid crystal devices and the dimming sheet, the following effects can be obtained. (1) According to the first substrate 11, since the coefficient of static friction between the first surface 11S1 and the second surface 11S2 is 1.3 or less, when the first surface 11S1 rubs against the second surface 11S2, damage to the first surface 11S1 can be suppressed. Also, since the first surface itself or the lower layer of the first surface has a high pencil hardness, even when an external impact is applied to the first surface, the first surface is less likely to be damaged. Thereby, physical damage to the alignment layer 21 can be suppressed.

[0065] (2) Since the high pencil hardness in the underlayer 11A is realized by the hard coat layer 23, it is possible to reduce the constraints on the configuration of the alignment layer 21 including thickness and material, compared with the case where the alignment layer 21 itself has a high pencil hardness.

[0066] (3) Since the conductive layer 22 is located between the alignment layer 21 and the hard coat layer 23, when a voltage is applied to the conductive layer 22, an electric field having an intensity that enables driving of liquid crystal molecules is likely to be formed between the conductive layer 22 of the first substrate 11 and the conductive layer of the second substrate 12.

[0067] [[ID=ii]] (4) Since the protective layer 26 including the second surface 11S2 is provided separately from the support substrate 24, it is possible to reduce the constraints on the configuration of the support substrate 24 including thickness and material, compared with the case where the support substrate 24 includes the second surface 11S2.

[0068] [Second Embodiment] Referring to FIG. 4, a second embodiment of the transparent substrate for liquid crystal devices and the light control sheet will be described. In the second embodiment, the transparent substrate for liquid crystal devices includes a slippery layer, which is different from the transparent substrate for liquid crystal devices of the first embodiment. Therefore, hereinafter, while the configuration different from that of the first embodiment in the second embodiment will be described in detail, the same reference numerals as those in the first embodiment will be given to the configurations common to the first embodiment in the second embodiment, and the detailed description of the configurations will be omitted.

[0069] [Transparent Substrate for Liquid Crystal Devices] The transparent substrate for liquid crystal devices will be described with reference to FIG. 4. FIG. 4 shows a cross-sectional structure of a first substrate 11, which is an example of a transparent substrate for a liquid crystal device. Note that, while the position of the second substrate 12 in the thickness direction of the light control sheet 10 is different from that of the first substrate 11, the layers included in the second substrate 12 are common to the layers included in the first substrate 11. Therefore, hereinafter, while the structure of the first substrate 11 will be described in detail, a detailed description of the structure of the second substrate 12 will be omitted.

[0070] As shown in FIG. 4, the first substrate 11 includes an alignment layer 21 and an underlayer 11A, similarly to the first substrate 11 of the first embodiment. The underlayer 11A includes a conductive layer 22, a hard coat layer 23, and a support substrate 24, similarly to the first substrate 11 of the first embodiment. The first substrate 11 further includes a lubricating layer 31. The lubricating layer 31 contains a plurality of fine particles 31P. The lubricating layer 31 includes a second surface 11S2. The plurality of fine particles 31P include fine particles 31P partially exposed on the second surface 11S2. In other words, the fine particles 31P partially exposed are located at a plurality of positions on the second surface 11S2.

[0071] According to the first substrate 11, since the lubricating layer 31 including the second surface 11S2 is provided separately from the support substrate 24, it is possible to reduce the constraints on the configuration of the support substrate 24 including the thickness and material, compared with the case where the support substrate 24 includes the second surface 11S2.

[0072] The arithmetic mean roughness Ra of the second surface 11S2 included in the lubricating layer 31 may be, for example, 5 nm or more and 94 nm or less. By the arithmetic mean roughness Ra being 5 nm or more, it is possible to reduce the coefficient of static friction between the first surface 11S1 and the second surface 11S2. Further, by the arithmetic mean roughness Ra being 94 nm or less, it is possible to suppress the lubricating layer 31 from including fine particles 31P to such an extent that the haze of the underlayer 11A increases, and thereby suppress an increase in the haze during transparency in the liquid crystal device including the first substrate 11.

[0073] The slippery layer 31 may be formed of, for example, a synthetic resin. The synthetic resin may be, for example, any one of a melamine resin, a urethane resin, and an acrylic resin. The slippery layer 31 can have a thickness of, for example, 1 μm or more and 10 μm or less. Note that the thickness of the slippery layer 31 is the thickness at a portion where the fine particles 31P are not located. The slippery layer 31 has permeability to visible light.

[0074] The fine particles 31P may be formed of, for example, a synthetic resin. When the fine particles 31P are used as primary particles, the diameter of the fine particles 31P is preferably larger than the thickness of the slippery layer 31. In this case, the diameter of the fine particles 31P may be, for example, 1.5 μm or more and 15 μm or less. Further, it is also possible to use the fine particles 31P as secondary particles obtained by secondary aggregation, and thereby reduce the coefficient of static friction by exposing the fine particles 31P from the slippery layer 31. In this case, the diameter of the fine particles 31P may be smaller than the thickness of the slippery layer 31. Note that it is also possible to use the fine particles 31P as higher-order particles.

[0075] [Operation] Also in the first base material 11 of the second embodiment, similar to the first base material 11 of the first embodiment, when the first base material 11 is conveyed by a roll-to-roll apparatus, when the first base material 11 is wound up by the roll-to-roll apparatus, and when the wound-up first base material 11 is transported, physical damage to the alignment layer 21 can be suppressed.

[0076] [Examples] Examples and comparative examples will be described with reference to Table 2. [Example 2-1] In Example 1-1, instead of adhering a protective film to the PET film with an adhesive layer, a light-dimming sheet of Example 2-1 was obtained by the same method as in Example 1-1, except that a lubricious layer was formed by the method described below. That is, 0.2% by weight of acrylic particles (Tech Polymer SSX-102, manufactured by Sekisui Chemical Co., Ltd.) (Tech Polymer is a registered trademark) with an average particle size of 2 μm was added to a paint for the lubricious layer (Rioduras LCH6701, manufactured by Toyochem Co., Ltd.) (Rioduras is a registered trademark). Then, the paint to which the acrylic particles were added was adjusted using MEK so that the solid content was 40% by weight, thereby obtaining a coating liquid for forming a lubricious layer. A coating film was formed by applying the coating liquid to the first surface of the PET film using a gravure coater. After drying the coating film at 80°C for 1 minute, the coating film was exposed using a high-pressure mercury lamp under the conditions of 300 mJ / cm 2 to form a lubricious layer having a thickness of 1 μm in the portion where no acrylic particles were located.

[0077] [Example 2-2] In Example 2-1, a light-dimming sheet of Example 2-2 was obtained by the same method as in Example 2-1, except that the addition amount of the acrylic particles was changed to 1.5% by weight.

[0078] [Example 2-3] In Example 2-1, a light-dimming sheet of Example 2-3 was obtained by the same method as in Example 2-1, except that the addition amount of the acrylic particles was changed to 3.0% by weight.

[0079] [Example 2-4] In Example 2-1, a light-dimming sheet of Example 2-4 was obtained by the same method as in Example 2-1, except that the addition amount of the acrylic particles was changed to 0.1% by weight.

[0080] [Example 2-5] In Example 1-3, instead of adhering a protective film to the PET film with an adhesive layer, a light-dimming sheet of Example 2-5 was obtained by the same method as in Example 1-3, except that a lubricious layer was formed by the same method as in Example 2-1.

[0081] [Example 2-6] In Example 2-1, a dimming sheet of Example 2-6 was obtained by the same method as in Example 2-1, except that the thickness of the hard coat layer was changed to 5 μm.

[0082] [Example 2-7] In Example 2-1, a dimming sheet of Example 2-7 was obtained by the same method as in Example 2-1, except that the addition amount of acrylic particles was changed to 4.0% by weight.

[0083] [Comparative Example 2-1] In Example 2-1, a dimming sheet of Comparative Example 2-1 was obtained by the same method as in Example 2-1, except that acrylic particles were not added to the slip layer.

[0084] [Comparative Example 2-2] In Example 2-1, a dimming sheet of Comparative Example 2-2 was obtained by the same method as in Example 2-1, except that the hard coat layer was not formed.

[0085] [Evaluation Method] [Surface Roughness] Using a white interferometer (VertScan, manufactured by Ryoka Systems, Ltd.), the arithmetic mean roughness Ra of the second surface including the slip layer was measured. At this time, the arithmetic mean roughness Ra was measured in a rectangular field of view with a width of 1.408 mm and a length of 1.885 mm. Also, the arithmetic mean roughness Ra was measured by a method according to JIS B 0601:2013.

[0086] In addition, the measurement of the static friction coefficient, the measurement of the pencil hardness, the counting of defects, and the measurement of haze were performed in the same manner as in the examples of the first embodiment. However, in this example, the haze of the base layer was also measured by the same method as the method for measuring the haze of the dimming sheet.

[0087] [Evaluation Results] The coefficient of static friction, pencil hardness of each base layer, and the number of defects and haze of each dimming sheet were as shown in Table 2 below.

[0088]

Table 2

[0089] As shown in Table 2, it was confirmed that in the base layers of Examples 2-1 to 2-7, the coefficient of static friction was included in the range of 0.1 or more and 1.3 or less. In contrast, the coefficient of static friction of the base layer of Comparative Example 2-1 was 1.5, and the coefficient of static friction of the base layer of Comparative Example 2-2 was 0.6. Also, in the base layers of Examples 2-1 to 2-7, it was confirmed that the arithmetic mean roughness Ra of the second surface was included in the range of 5 or more and 122 or less. In contrast, in the base layer of Comparative Example 2-1, the arithmetic mean roughness Ra of the second surface was 3 nm, and in the base layer of Comparative Example 2-2, the arithmetic mean roughness Ra of the second surface was 8 nm.

[0090] Also, in the base layers of Examples 2-1 to 2-7, it was confirmed that the pencil hardness was included in the range of F or more and 2H or less. In contrast, the pencil hardness of the base layer of Comparative Example 2-1 was H, and the pencil hardness of the base layer of Comparative Example 2-2 was 2B.

[0091] Also, in the dimming sheets of Examples 2-1 to 2-7, the number of defects was 0 pieces / m 2 or more and 10 pieces / m 2 and was included in the range. In contrast, in the dimming sheets of Comparative Example 2-1 and Comparative Example 2, the number of defects was 50 pieces / m 2 or more.

[0092] Thus, in the transparent substrate for a liquid crystal device, in the base layer on which the alignment layer is formed, when the coefficient of static friction between the first surface and the second surface is 1.3 or less and the pencil hardness on the surface of the base layer opposite to the second surface is F or more, it has been confirmed that physical damage to the alignment layer can be suppressed. Further, from the viewpoint of suppressing an increase in haze of the base layer, it has been confirmed that it is preferable that the arithmetic mean roughness Ra of the second surface is included in the range of 5 nm or more and 94 nm or less.

[0093] As described above, according to the second embodiment of the transparent substrate for a liquid crystal device and the light control sheet, in addition to (1) to (3) described above, the following effects can be obtained. (5) According to the first base material 11, since the slippery layer 31 including the second surface 11S2 is provided separately from the support base material 24, compared with the case where the support base material 24 includes the second surface 11S2, it is possible to reduce the restrictions on the configuration of the support base material 24 including the thickness and material.

[0094] [Modification example] Each of the above-described embodiments can be implemented with the following modifications. [Base layer] · The base layer 11A of each embodiment includes the hard coat layer 23, but if a pencil hardness of F or more is realized on the surface of the base layer 11A opposite to the second surface 11S2, the base layer 11A may not include the hard coat layer 23. In this case, for example, it is sufficient if the support base material 24 has a high strength to realize a pencil hardness of F or more.

[0095] · The base layer 11A of the first embodiment includes the protective layer 26, but if the coefficient of static friction between the first surface 11S1 and the second surface 11S2 is 1.3 or less, the base layer 11A may not include the protective layer 26. In addition, when the base layer 11A does not include the protective layer 26, the adhesive layer 25 for adhering the protective layer 26 to the support base material 24 is also unnecessary. In this case, for example, it is sufficient if the support base material 24 includes the second surface 11S2 and the second surface 11S2 has an arithmetic mean roughness Ra high enough to have a coefficient of static friction of 1.3 or less between the first surface 11S1.

[0096] · Although the base layer 11A of the second embodiment includes the low-friction layer 31, the base layer 11A may not include the low-friction layer 31 if the coefficient of static friction between the first surface 11S1 and the second surface 11S2 is 1.3 or less. In this case, for example, the support substrate 24 may include the second surface 11S2, and the second surface 11S2 may have an arithmetic mean roughness Ra that is high enough so that the coefficient of static friction between the second surface 11S2 and the first surface 11S1 is 1.3 or less.

[0097] · The conductive layer 22 may be located between the support substrate 24 and the hard coat layer 23 in the thickness direction of the base layer 11A. Even in this case, since the base layer 11A has the hard coat layer 23, the effects according to (1) described above can be obtained. Note that, in this case, since the distance between the conductive layer 22 and the first surface 11S1 is increased in the thickness direction of the base layer 11A, there may be a case where a high voltage is applied due to the driving of the liquid crystal molecules.

[0098] [Alignment layer] · On the first surface 11S1 included in the alignment layer 21, the pencil hardness may be F or more. Even in this case, physical damage to the alignment layer 21 can be suppressed. Note that if it is possible to achieve a pencil hardness of F or more due to the strength of the alignment layer 21 even when the base layer 11A does not have the hard coat layer 23, the base layer 11A may not have the hard coat layer 23.

[0099] [Light control sheet] · The type of the light control sheet is not limited to the reverse type and may be the normal type. In this case, the alignment layers provided in the first substrate 11 and the second substrate 12 may be horizontal alignment films, and the liquid crystal molecules included in the light control layer 13 may be p-type liquid crystal molecules. Alternatively, the alignment layers provided in the first substrate 11 and the second substrate 12 may be vertical alignment films, the liquid crystal molecules included in the light control layer 13 may be n-type liquid crystal molecules, and the light control sheet 10 may include a pair of polarizing plates that sandwich the pair of substrates 11 and 12 in the thickness direction of the light control sheet 10.

[0100] [Liquid crystal device] · The liquid crystal device to which the transparent substrate for a liquid crystal device of the present disclosure is applied is not limited to the above-described light control sheet, and may be, for example, a liquid crystal display device.

Explanation of Signs

[0101] 10…Light control sheet 11…First substrate 11A…Base layer 12…Second substrate 13…Light control layer 21…Alignment layer 22…Conductive layer 23…Hard coat layer 24…Support substrate 25…Adhesive layer 26…Protection layer 31…Slip layer

Claims

1. A transparent substrate for a dimming sheet, which is used for a dimming sheet that does not include a black matrix and includes an alignment layer that regulates the alignment direction of liquid crystal molecules included in a liquid crystal layer included in the dimming sheet and a base layer on which the alignment layer is formed, and includes: a first surface and a second surface opposite to the first surface; the first surface is the surface including the alignment layer; the second surface is the surface including the base layer; the coefficient of static friction between the first surface and the second surface is 1.3 or less; in a pencil hardness test on the first surface or the surface of the base layer opposite to the second surface, it has a hardness of F or more; the base layer includes: a support substrate; an adhesive layer laminated on the support substrate; and a protective layer attached to the support substrate by the adhesive layer, and includes: the protective layer includes the second surface; the protective layer is formed of any one selected from polyethylene terephthalate, polyethylene, polypropylene, and polyolefin; the surface roughness on the second surface is larger than the surface roughness of the surface of the support substrate in contact with the adhesive layer; A transparent substrate for a dimming sheet.

2. the base layer includes a hard coat layer; in a pencil hardness test on the surface of the base layer opposite to the second surface, it has a hardness of F or more; The transparent substrate for a dimming sheet according to Claim 1.

3. the base layer includes a conductive layer in contact with the alignment layer; the conductive layer is located between the hard coat layer and the alignment layer in the thickness direction of the transparent substrate for a dimming sheet; The transparent substrate for a dimming sheet according to Claim 2.

4. A transparent substrate for a dimming sheet, which is used for a dimming sheet that does not include a black matrix and includes an alignment layer that regulates the alignment direction of liquid crystal molecules included in a liquid crystal layer included in the dimming sheet and a base layer on which the alignment layer is formed, and includes: a first surface and a second surface opposite to the first surface; the first surface is the surface including the alignment layer; the second surface is the surface including the base layer; the coefficient of static friction between the first surface and the second surface is 1.3 or less; in a pencil hardness test on the first surface or the surface of the base layer opposite to the second surface, it has a hardness of F or more; the base layer includes: a support substrate; a lubricating layer laminated on the support substrate and including a plurality of fine particles; the lubricating layer includes the second surface; the plurality of fine particles include the fine particles partially exposed on the second surface; Among the slip layers, the portion other than the fine particles is formed from any one selected from melamine resins, urethane resins, and acrylic resins. The fine particles are formed from a synthetic resin. The surface roughness on the second surface is greater than the surface roughness of the surface of the support substrate that contacts the slip layer. A transparent substrate for a dimming sheet.

5. A transparent substrate for a dimming sheet according to any one of claims 1 to 4, and A dimming layer that contacts the first surface of the transparent substrate for a dimming sheet and contains liquid crystal molecules. A dimming sheet.

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