JP2021173898A - Dimming unit - Google Patents

Abstract

To provide a dimming unit capable of visually recognizing and identifying a state of a joint part of an ACF by a simple method without requiring the magnified visual inspection work with an optical microscope.SOLUTION: A dimming unit includes: a dimming sheet formed by sandwiching a dimming layer including a liquid crystal composition between a first transparent conductive film having a first transparent electrode layer and a second transparent conductive film having a second transparent electrode layer; and first and second power feeding parts having an FPC for supplying driving power from an external power source to the dimming layer and an ACF for electrically connecting the FPC to the first and second transparent electrode layers. The ACF has a coloring material having heat sensitivity in a binder consisting of a thermosetting resin layer and is provided with a heat-discoloring layer which is discolored by heating.SELECTED DRAWING: Figure 2

Description

The present invention relates to a dimming unit including a liquid crystal type dimming sheet and a connecting portion for connecting the dimming sheet to a power source.

The light control sheet includes a light control layer containing a liquid crystal composition and a pair of transparent electrode layers sandwiching the light control layer. When a driving voltage is applied to the pair of transparent electrode layers, the orientation state of the liquid crystal molecules contained in the light control layer changes, so that the light transmittance of the light control sheet changes (see Patent Document 1). The dimming unit is composed of such a dimming sheet and a connecting portion for connecting the transparent electrode layer to the power source.

When connecting the dimming sheet to an external power source, conventionally, a structure has been adopted in which at least a conductive tape is attached to the exposed surface of the transparent conductive layer and connected to the lead wire via solder formed on the conductive tape. rice field. Nowadays, as a low-cost and simple structure, a structure that draws out wiring by mechanically adhering while electrically connecting using FPC (flexible printed wiring board) and ACF (anisotropic conductive film) is adopted. (See Patent Document 2). In the connection using FPC and ACF, the point-like joining structure by solder on the conductive tape is changed to a planar joining structure, and the durability of the joining is durable against shaking and impact during transportation and installation work of the dimming unit. The sex is improving.

The FPC is provided with a wiring layer formed by patterning a metal thin film such as copper on the surface of an insulating resin layer which is a flexible base material made of an insulating resin such as polyimide, and is provided with an external power source. Responsible for supplying power to the dimming sheet from.

ACF is a thermosetting or thermoplastic resin sheet material containing surface conductive beads (hereinafter collectively referred to as conductive particles) of a fine resin coated with gold or nickel or an inorganic material. This resin sheet material, which may have adhesiveness by itself, is installed between the terminal portion of the FPC and the surface of the transparent electrode layer in the power feeding region, and the resin is cured or molded while being heat-bonded. As a result, conductive particles can be brought into contact with each other in the thickness direction of the pattern to be the heat-bonded portion, so that conduction can be achieved. On the other hand, in the in-plane direction of the ACF without heat crimping (the direction perpendicular to the thickness direction), the conduction due to the contact of the conductive particles does not occur, and the ACF becomes conductive in the thickness direction and the in-plane direction. Has anisotropy.

In joining by heat crimping of FPC via ACF, defects such as insufficient heating and insufficient pressurization may cause uncertain electrical continuity, so it is necessary to ensure non-defective products in the manufacturing process. In addition, there is also a demand for observing the presence of conductive particles contained in ACF on the connection terminals. Conventionally, in order to confirm the connection state between the connection terminal and the FPC, a method of visually recognizing traces of conductive particles left on the connection terminal (see Patent Document 3), or a method of simulating the connection terminal and at least partially transparent. A method of observing the existence state of conductive particles that are supposed to be present in the dummy terminal with an optical microscope by further providing a certain dummy terminal (see Patent Document 4) has been proposed.

JP-A-2017-187775 Japanese Patent No. 6439029 Japanese Unexamined Patent Publication No. 2001-109010 Japanese Patent No. 4992774

The inspection work of magnifying and visually observing the joint ACF with an optical microscope not only has a large process load, but also has a new defective accident depending on the handling when the flexible dimming sheet, which is an inspection sample, is transported to the inspection process in a single sheet. There is a concern that this will lead to a further decrease in yield. An object of the present invention is to provide a dimming unit capable of visually recognizing and identifying the state of a joint ACF by a simple method without requiring an inspection work of magnified visual inspection by an optical microscope.

The dimming unit according to the present invention
A light control sheet in which a light control layer containing a liquid crystal composition is sandwiched between a first transparent conductive film having a first transparent electrode layer and a second transparent conductive film having a second transparent electrode layer.
An FPC for supplying drive power from an external power source to the dimming layer, and a first and second feeding unit having an ACF for electrically connecting the FPC to the first and second transparent electrode layers. Have,
The ACF is characterized by having a heat-sensitive coloring material in a binder made of a thermosetting resin layer, and including a heat-discoloring layer that changes color by heating.

It is desirable that the melting point of the base film on which the first and second transparent conductive layers are formed is equal to or higher than the thermosetting temperature of the thermosetting layer.

The temperature at which the thermal discoloration layer is heat-sensitive and discolors is preferably 30 ° C. or higher.

The ACF may have a laminated structure of a heat-discoloring layer containing a heat-sensitive coloring material and a thermosetting resin layer not containing the heat-sensitive coloring material.

The discoloration of ACF may be either decolorization or color development due to heating.
Further, the discoloration of ACF may be irreversible or reversible.

Considering the design and decorativeness of the dimming unit, it is transparent (non-transparent) for the purpose of minimizing the area of the light-shielded part and forming a structure with many transparent or highly translucent areas including the power supply part. The adoption of FPC using a light-shielding material is also promising, and it is desirable that the suitable discoloration of ACF is irreversible decolorization.

The thermal discoloration layer is
It is a configuration in which either a dye or a pigment is added to a binder component containing 5 or more and 30 or less (unit: weight%) of a mixture of (A) fatty acid glycol ester and (B) fatty acid alkylolamide.
It is preferable that the mixing ratio of (A): (B) is in the range of 1: 3 or more and 1:30 or less.

The thermal discoloration layer is
A reversible heat-sensitive decolorizing layer containing a leuco compound, a color reducing agent that develops or reduces color by thermally reacting with the leuco compound, and a binder as main components may be used.

The ends of the first and second transparent conductive films on which the FPCs of the first and second feeding portions are formed are on the same side of the rectangular film, and the FPCs are arranged apart from each other within the same side without facing each other. The configuration is preferred. In this case, the regions where the first and second power feeding portions are formed (hereinafter referred to as power feeding regions) are concentrated on one side of the rectangular dimming sheet, and the effective region of the dimming sheet can be widely and effectively used.

According to the present invention, by visually recognizing the discoloration of the ACF at the FPC joint, it is possible to easily identify whether the heat crimping is performed and whether the heating / pressurizing degree is sufficient, and the process load is reduced. At the same time, a dimming unit that can contribute to the improvement of decorativeness is provided.

Explanatory drawing which shows the structural outline of the dimming unit. FIG. 5 is an enlarged cross-sectional view showing a configuration example of ACF. The explanatory view which shows the process of joining ACF to FPC to a power feeding part.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, the drawings are schematic, and for convenience of explanation, the relationship with the plane dimensions, the ratio of the thickness of each layer, and the like may be exaggerated to a size different from the actual scale. Further, the embodiments shown below exemplify a configuration for embodying the technical idea of the present invention, and the technical idea of the present invention describes the materials, shapes, structures, etc. of the constituent parts as follows. It is not specific to anything. The technical idea of the present invention may be modified in various ways within the technical scope specified by the claims stated in the claims.

[Dimming unit]
FIG. 1 is an explanatory diagram showing an outline of the configuration of a dimming unit.
Each component of the dimming unit 100 including the dimming sheet 10 will be described in detail with reference to FIG. In FIG. 1, when it is necessary to distinguish the power feeding unit 20 and the transparent conductive film 15 from each other, one is defined as the first and the other is defined as the second for convenience, and the reference numerals a and b are assigned to each. Display with it.

As shown in FIG. 1A, the dimming unit 100 includes a dimming sheet 10 and a power feeding unit 20 (a, b). The dimming sheet 10 is mainly made of a flexible and thin material, and is rich in flexibility. For example, in a large area usage pattern, the dimming unit 100 is used by being sandwiched between two transparent plates such as glass or mounted on the transparent plate. The transparent plate serving as the supporting base material is a transparent plate-shaped member made of glass, resin, or the like, and may be flat or curved. The transparent plate may be, for example, a building material such as a window glass, a partition or a glass wall, or a vehicle member such as an automobile window glass.

In the dimming region (effective region), the dimming layer 13 is sandwiched between the first transparent conductive film 15a having the first transparent electrode layer 12 and the second transparent conductive film 15b having the second transparent electrode layer 12. It has been.

When viewed from the direction facing the surface of the dimming sheet 10, the dimming sheet 10 has a substantially rectangular shape, and a dimming region (effective region) occupying most of the dimming sheet 10 and an end portion of the dimming sheet. Includes the power supply area (invalid area) of. The feeding portions 20 (a, b) are formed in the feeding region, and the FPC 25 is connected to the joints 21 provided on the feeding portions 20 (a, b) via the ACF 22. The power feeding region is located at the end of the dimming sheet 10 along one side of the dimming sheet 10. The one side on which the power feeding region is arranged may be any side of a rectangle, and may be set according to the arrangement of the transparent plate and the drive circuit. Further, the power feeding unit 20 (a, b) may be arranged at a position including the central portion of the one side, or as shown in FIG. 1 (a), is arranged at a position including the end portion of the one side. May be good. In the configuration in which the forming portions of the feeding portions 20 (a, b) including the FPC 25 are arranged apart from each other within the same side of the rectangular dimming sheet 10, the feeding regions are concentrated on one side of the dimming sheet 10 and adjusted. The effective area of the optical sheet 10 can be widely and effectively used.

1 (b) and 1 (c) are cross-sectional views taken along the lines AA and BB in FIG. 1 (a), respectively. As shown in FIGS. 1B and 1C, the light control sheet includes a light control layer 13, a first transparent conductive film 15a, and a second transparent conductive film 15b. The first transparent conductive film 15a is composed of a first transparent electrode layer 12 and a first transparent film 11 that supports the first transparent electrode layer 12. The second transparent conductive film 15b is composed of a second transparent electrode layer 12 and a second transparent film 11 that supports the second transparent electrode layer 12.

The materials of the first and second transparent films 11 are not particularly limited as long as they are transparent and heat-resistant plastic films. A polymer film having a thickness of 16 μm or more and 1000 μm or less made of polyethylene, polystyrene, polyethylene terephthalate, polyvinyl alcohol, polycarbonate, polyvinyl chloride, polyimide, polysulfone, cycloolefin polymer, triacetyl cellulose and the like is used. If the thickness is less than 16 μm, handling as a film base material becomes difficult, and thereafter, following the film formation of the first and second transparent electrode layers 12, the dimming layer 13 is applied and sandwiched by a roll-to-roll method. , It becomes difficult to maintain quality in processes such as exposure processing. Further, if the thickness exceeds 1000 μm, the flexibility is lacking, it becomes difficult to handle by the roll-to-roll method, and the transparency and translucency are likely to be deteriorated. As the heat resistance, it is sufficient that it has a temperature characteristic (behavior of ACF = melting point equal to or higher than the solidification temperature) that can withstand the heating temperature at the time of joining FPC and ACF by heat crimping.

Each of the first transparent electrode layer 12 and the second transparent electrode layer 12 is a transparent layer having conductivity. Examples of the material constituting the transparent electrode layer 12 include indium tin oxide (ITO), fluorine-doped tin oxide (FTO), tin oxide, zinc oxide, carbon nanotubes (CNT), and poly (3,4-ethylenedioxythiophene). ) (PEDOT)-containing polymer and the like. The transparency required for the first and second transparent electrode layers is preferably 70% or more for the total light transmittance, and the surface resistivity is preferably 2000 Ω / □ or less for the conductivity. When the total light transmittance is less than 70%, cloudiness is felt when the dimming unit is used in the transparent state (low haze), and it is difficult to distinguish the haze difference from the case where the dimming unit is modulated in the scattered state (high haze). If the surface resistivity is more than 2000Ω / □, it is necessary to apply a high voltage to supply power to the dimming unit, which not only hinders driving but also tends to cause excessive heat generation in the circuit. The thickness of the first and second transparent electrode layers is determined in consideration of followability to the first and second transparent films 11, poor conductivity due to breakage (cracking during handling), reduction of the amount of expensive rare metals used, and the like. It is preferably 1 μm or less.

The dimming layer 13 includes a dimming body made of a liquid crystal composition, an electromic, an SPD, or the like. The dimming layer 13 includes, for example, a polymer network type liquid crystal (PNLC: Polymer Network Liquid Crystal), a polymer dispersed liquid crystal (PDLC: Polymer Dispersed Liquid Crystal), a capsule type nematic liquid crystal (NCAP: Nematic Curve Phase), and the like. It is composed. For example, a polymer network type liquid crystal has a polymer network having a three-dimensional network shape, and holds liquid crystal molecules in the voids of the polymer network. The liquid crystal molecules contained in the dimming layer 13 have, for example, positive dielectric anisotropy, and the dielectric constant of the liquid crystal molecules in the long axis direction is larger than the dielectric constant of the liquid crystal molecules in the minor axis direction. The liquid crystal molecules are, for example, Schiff base-based, azo-based, azoxy-based, biphenyl-based, terphenyl-based, benzoic acid ester-based, trans, pyrimidine-based, cyclohexanecarboxylic acid ester-based, phenylcyclohexane-based, and dioxane-based liquid crystal molecules. be.

In the light control sheet in the normal mode, when the driving voltage is not applied to the transparent electrode layer 12, the orientation of the liquid crystal molecules in the long axis direction is irregular. Therefore, the light incident on the dimming layer 13 is scattered, and the dimming region appears cloudy. That is, when the driving voltage is not applied to the dimming layer 13, the dimming region is opaque. On the other hand, when a driving voltage is applied between the first transparent electrode layer 12 and the second transparent electrode layer 12 through the FPC 25, the liquid crystal molecules are oriented, and the long axis direction of the liquid crystal molecules is between the transparent electrode layers 12 and 12. The orientation is along the direction of the electric field. As a result, light is easily transmitted through the dimming layer 13, and the dimming region becomes transparent.

In the light feeding portion 20a (20b), the second transparent conductive film 15b (first transparent conductive film 15a) at the corresponding portion is cut and removed from the light control sheet, and the light control layer 13 is removed by wiping. Area. In the power feeding region, a joint portion 21 serving as an electrical connection terminal is formed on the surface of the first transparent electrode layer 15a (second transparent conductive film 15b) exposed due to the absence of the dimming layer 13, and the FPC 25 is formed on the surface. The ends of the conductor pattern that will be the connection terminals (pads) formed in the above are joined, and the drive power from the external power supply is supplied. ACF22 is arranged at the joining portion of the FPC 25, and is joined to the surface of the first transparent electrode layer 15a (second transparent electrode layer 15b) by heat pressure bonding.

In the FPC 25 arranged in the power feeding region, the conductor pattern serving as the connection terminal (pad portion) is joined to the joining portion (conductive tape) 21 formed on the transparent electrode layer 12 on the feeding region via the ACF 22. A drawer wiring portion that is pulled out of the frame of the dimming sheet 10 is provided, extends from the power feeding region to the outside of the dimming sheet 10, and is connected to a drive circuit (not shown).

[ACF]
FIG. 2 is an enlarged cross-sectional view showing a configuration example of the ACF 22.
The ACF 22 contains a heat-sensitive coloring material 32 and conductive particles 33 in a binder 31 made of a thermosetting resin, and is provided with a heat-discoloring layer that changes color when heated by heat-bonding. In the figure, for convenience, the coloring material 32 is shown in a circular shape, and the conductive particles 33 are shown in an elliptical shape.

FIG. 2A is a schematic configuration diagram in the case of a single-layer structure in which the entire ACF 22 is a thermosetting layer, and FIG. 2B shows a thermosetting layer 22a containing a heat-sensitive coloring material and a heat-sensitive layer. It is a schematic block diagram which shows the ACF 22 in the case of the laminated structure of the thermosetting resin layer 22b which does not contain a coloring material having property.

In both FIGS. 2A and 2B, the upper part shows before joining by heat crimping of FPC25, and the lower part shows after joining. In the figure, the illustrated FPC 25 is intended as a conductive connection terminal portion. With the heat crimping, the thickness of the ACF 22 decreases, and the conductive particles 33 dispersed inside come into close contact with each other. The conductive particles 33 are arranged in contact with each other in the thickness direction corresponding to the heat-bonded portion, so that the transparent electrode layer 12 and the ACF 22 are electrically conductive. In the application of the present invention, it is not essential that the ACF has anisotropy in conductivity in the thickness direction and the in-plane direction, and it is required that the conductivity in the thickness direction is generated by heat crimping. Therefore, there is no problem even if conductivity is generated in the in-plane direction.

Based on the difference in the design of the heat-discoloring layer containing the heat-sensitive coloring material, ACF22 is discolored from "colorless to colored" in response to heat pressure bonding in FIG. The discoloration layer 22a is discolored from "coloring to decolorization". In the present invention, the discoloration may be any of "colorless → color development" and "coloring → decolorization". Further, it does not matter whether the discoloration is maintained or restored as the temperature rises and falls, that is, whether it is reversible or irreversible. However, as an application in the present technical field, it is preferable that the ACF is irreversible and has a reactivity from a colored state to a decolored state because of its decorativeness and ease of discrimination in a post-process.

ACF22 is preferably liquid or viscous at room temperature and has the property of losing fluidity, viscosity and tackiness and solidifying when heated at 250 ° C. or lower. When heating exceeding 250 ° C. is required for solidification, the melting points of the first and second transparent films 11 may be exceeded, which may cause damage to the light control sheet during joining (heat crimping) of FPC and ACF. become.

Hereinafter, the formulation of ACF22 (heat discoloration layer) will be described.
Epoxy-based resins and acrylic-based resins are preferable as the thermosetting resin constituting the binder 31. Further, it is preferable that it contains a curing agent for causing thermosetting, but a material that cures by having self-reactivity and self-crosslinking property may also be used. The thickness of ACF22 (layer 22b) is preferably 1 to 50 μm. If the thickness is less than 1 μm, the surface unevenness of the FPC 25 cannot be followed, which may lead to poor energization. If the thickness exceeds 50 μm, there is a possibility that the heating is not sufficiently transmitted during heat crimping, and the amount of expensive conductive particles described below increases, which also leads to an increase in cost. ..

The conductive particles 33 are generally organic resin particles coated with metals such as gold, tin, copper, palladium, and nickel and their alloys, but if the surface layer is a conductive material, the material is used. ， The shape is not limited. When the particle size of the conductive particles 33 is equal to or larger than the thickness of the ACF 22 (layer 22b), the conductive particles 33 are exposed due to the decrease in the thickness of the ACF 22 (layer 22b) due to heat bonding, and the bonding force between the ACF 22 and the FPC 25 There is also a concern due to the decline in the number of particles.

The coloring material 32 contained in the thermal discoloration layer 22a of FIGS. 2 (a) and 2 (b) in which the entire ACF 22 is a thermal discoloration layer is
It is a composition obtained by adding a dye and / or a pigment to a mixture of (A) fatty acid glycol ester (B) fatty acid alkyrrole amide.

A dye and / or a dye and / Alternatively, by adding a pigment, the coloring material 32 is formulated.

The fatty acid glycol ester (A) has, for example, monovalent or divalent fatty acid groups such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, and behenic acid, and is referred to as C14-C18. As the glycol group, ethylene glycol or propylene glycol can be applied.

(B) Fatty acid alkylolamide is a compound obtained by alkylating a saturated or unsaturated fatty acid with an amine, and as the amine, monoethanolamine or diethanolamine is preferably used.

For either the dye or the pigment, a dye or pigment which is a non-thermally decolorizing coloring component can be added in a dispersed state. Examples of dyes include Spiron Pink BH (CI Solvent Red 82) OIL PINK 312 and the like.

As another example of the heat-discoloring layer 22a, it is possible to apply a material in which a change from reversible color development to decolorization occurs in various ways depending on the heating temperature, instead of irreversible color development, as a characteristic of color development or decolorization by heating. be. Such a material is mainly composed of a leuco compound, a color reducing agent that develops or reduces color by thermally reacting with the leuco compound, and a binder.

Leuco compounds include fluorin compounds such as 3-pyrodinillo-anilinofluorane and 3-diethylamino-7- (m-trifluoromethylanilino) fluorane, triaryl compounds, diphenylmethane compounds, thiazine compounds, and spiro. It is selected from system compounds, lactam compounds, etc. The color developer is selected from, for example, 4,4'-dihydroxydiphenylmethane, 4,4'-isopropyridene diphenol and the like.

Such a decolorizing ink containing a leuco compound develops a color with a thermal energy h1 (about 50 ° C. to about 80 ° C.), while it decolorizes with a higher thermal energy h2 (about 120 ° C. to about 150 ° C.). It has the property of making it transparent. Therefore, it is considered that the operator who heat-bonds the FPC can grasp the heating temperature during the work according to the change in the state (hue) of the heat-discoloring layer 22a. However, as described above, for the worker in the post-process (or the user of the manufactured product), it is irreversible that the colored state before joining → the decolorized state after heat joining and the decolorized state is maintained even after cooling. The thermal discoloration layer 22a having the decolorizing property of is preferable.

As shown in FIG. 2B, the ACF 22 has a laminated structure of a heat-discoloring layer 22a containing a heat-sensitive coloring material and a thermosetting resin layer 22b not containing the heat-sensitive coloring material. The stacking order of 22a and 22b is not limited to the illustration, and may be reversed, or 22a may be arranged in two layers on the front and back surfaces of 22b. The characteristic required for the heat discoloration layer 22a is preferably a thickness of half or less of the layer 22b so as not to interfere with the electrical conduction between the transparent electrode layer 12 and the FPC 25. Further, it is preferable to have a thickness of 1 μm or more in order to reliably visually recognize the discoloration of the layer 22a.

Hereinafter, examples will be described.
An example in which a PNLC (polymer network liquid crystal display) is used as the dimming layer 13 will be described.

<Example 1>
(1) Light control sheet In manufacturing a light control sheet having a light control layer made of PNLC, a mixture of a liquid crystal and a photopolymerizable compound (monomer) is sandwiched between a pair of transparent electrode substrates, and under certain conditions. The photopolymerizable compound is transformed into a polymer by photopolymerization, and a polymer network having innumerable fine domains (polymer voids) is formed in the liquid crystal by photopolymerization and cross-linking.

The drive voltage of the PNLC generally depends on the structural characteristics of the polymer network (domain size and shape, film thickness of the polymer network, etc.), and the structure of the polymer network and the obtained light transmittance or scattering degree. In relation, the drive voltage is determined.

In order to construct a PNLC that can obtain sufficient light transmittance or scattering degree in a voltage region of 100 V or less, each domain must have an appropriate size and be uniform, and the shape must be uniform. It is necessary to form a polymer network so as to. In this example, the domain size depending on the polymer network structure is controlled to be 3 μm or less, preferably 2 μm or less, and more preferably about 1 μm.

As the first and second transparent conductive films (15a, 15b), PET films (11) having ITO (12) deposited on one surface were prepared, and two transparent conductive films (15a, 15b) were prepared by a roll-to-roll method. The ITO film-forming surfaces of 15a and 15b) were opposed to each other, and the dimming layer 13 was coated and formed with a film thickness of 20 μm so as to be sandwiched, and then the dimming sheet 10 was produced based on the above process.

(2) Formation of power feeding unit The dimming sheet 10 is cut into A4 size, and as shown in FIG. 3A, the long side is 10 mm in the short side direction from the lower left corner where the power feeding unit 20a is planned to be formed. The transparent conductive film 15b in a region of 7 mm in the direction was half-cut, removed, and peeled off. The dimming layer 13 (PNLC) remaining in the exposed portion (shown exaggerated from the actual size) was wiped off with a non-woven fabric impregnated with a solvent to expose the ITO film-forming (12a) surface. On the back surface of the dimming sheet 10 inverted, the same treatment was performed on the planned portion where the power feeding portion 20b is to be formed.

(2-1) ACF (heat discoloration layer) formation Rikemar PS-100 (manufactured by RIKEN Vitamin) 15 parts by weight, Amizole CME (manufactured by Kawasaki Fine Chemicals) 5 parts by weight, NIKKOL AM-103EX (Nikko Chemicals), Triethanolamine 0. 5 parts by weight, 10 parts by weight of glycerin, and 58.5 parts by weight of water were stirred, heated to 70 ° C. to dissolve them, and then cooled to room temperature. By adding 1 part by weight of OIL PINK 312 (manufactured by Orient Chemical Industry Co., Ltd.) to this and stirring the mixture, a heat-coloring material constituting the heat-coloring layer 22a was obtained.

(2-2) ACF22b
Phenoxy resin (Nippon Steel & Sumikin Chemical Co., Ltd., YP-50) 60 parts by weight, microcapsule type latent curing agent (Asahi Kasei Co., Ltd., Novacure HX394HP) 40 parts by weight, silica particles (Nihon Aerosil Co., Ltd., AEROSILR200) 20 An anionic epoxy resin composition was prepared from parts by weight.

(2-3)
90 parts by weight of the binder prepared in (2-2) above and 10 parts by weight of conductive particles (micropearl manufactured by Sekisui Chemical Co., Ltd.) having a particle size of 5 μm were added and dissolved in MEK so that these had a solid content of 30%. This solution was applied to a PET film having a thickness of 50 μm and dried in an oven at 80 ° C. for 5 minutes to obtain an ACF layer 22b having a thickness of 10 μm.

(2-4) Formation of Thermal Discoloration Layer The thermal discoloration layer 22a prepared in (2-1) was laminated on the ACF layer 22b so as to have a thickness of 5 μm. In this way, the ACF layer 22 with a thermal discoloration function was obtained.

(3) FPC junction (dimming unit)
A power feeding portion 25a was formed on the light control sheet whose ITO film formation (12a) surface was exposed in (2) by the following procedure.

(3-1)
As shown in FIG. 3 (b), the thermal discoloration ACF22 (22a + 22b) obtained in (2-4) was laminated on ITO (12a) exposed in a region of 10 mm × 7 mm.
In this embodiment, a procedure may be used in which the ACF layer 22b is formed on the ITO (12a) and then the heat discoloration layer 22a is sequentially laminated on the ACF layer 22b (not shown).

(3-2)
As shown in FIG. 3C, an FPC 25 (manufactured by Oki Electric Industry Co., Ltd.) in which Cu foil is laminated on a polyimide base material and the Cu foil is wiring-patterned is arranged on the laminated ACF22 surface. The wiring pattern (not shown) on the FPC 25 faces the ITO (12a) side. For convenience, the FPC 25 is shown in a dark color, but the case where the polyimide base material of the FPC 25 is transparent colored in light brown will be described below.

(3-3)
The ACF 22 is pink and can pass through the FPC 25 to identify the hue.

(3-4)
The thermal head of the thermal transfer device was heat-bonded from above the FPC 25 at 180 ° C. and 0.5 MPa.

(3-5)
It was confirmed through the FPC25 that the ACF22 changed to colorless and transparent by heat crimping. It became colorless and transparent as a whole, it became difficult to distinguish the boundary between the ACF 22 and the FPC 25, and it was visually confirmed that the FPC 25 was reliably joined via the ACF 22 by heat crimping.

<Example 2>
In the thermal discoloration layer formation in step (2-1), ACF22 by heat crimping was applied in exactly the same manner as in Example 1 except that OIL PINK 312 (manufactured by Orient Chemical Industry Co., Ltd.) was replaced with OIL BLUE 312 (manufactured by Orient Chemical Industry Co., Ltd.). Joining of FPC25 through was carried out.

<Example 3>
(2-4) The film formation of the heat discoloration layer 22a was carried out in exactly the same manner as in Example 1 except that the film thickness was set to 2 μm.

<Example 4>
(2-4) In the film formation of the heat discoloration layer 22a, the film thickness was exactly the same as in Example 1 except that the film thickness was set to 8 μm.

<Comparative example 1>
Step (2-4) In the film formation of the thermal discoloration layer, the FPC25 via the ACF22 by heat crimping is exactly the same as in Example 1 except that the thermal discoloration layer 22a is laminated instead so as to have a thickness of 0.5 μm. Was joined.

<Comparative example 2>
Step (2-4) In the film formation of the thermal discoloration layer, the FPC25 is joined via ACF22 by heat crimping in exactly the same manner as in Example 1 except that the thermal discoloration layer 22a is laminated instead so as to have a thickness of 10 μm. Was carried out.

<Comparative example 3>
In the step (3-1), an anisotropic conductive film (CP923CM-25AC: manufactured by Sony Chemical Co., Ltd.) was laminated on the ITO (12a) exposed in the region of 10 mm × 7 mm in place of the heat-discoloring ACF22 (22a + 22b). ..

In the step (3-2), FPC25 (manufactured by Oki Electric Industry Co., Ltd.) was placed on the surface of the laminated anisotropic conductive film, in which Cu foil was laminated on a polyimide base material and the Cu foil was wiring-patterned. The polyimide base material of FPC25 is colorless and transparent.

In the step (3-4), the thermal head of the thermal transfer device was used to heat-press the FPC 25 at 180 ° C. and 0.5 MPa.

There was no visual change in hue from step (3-2) to step (3-4). Therefore, it was necessary to confirm the bonding state between the FPC 25 and the ACF (22a) with an optical microscope.

The following were evaluated for each of the dimming units of Examples 1 to 4 and Comparative Examples 1 to 3.

<Initial characteristics of dimming unit>
(1) Resistance value The electrical resistance value of the exposed surface of ITO12 and the wiring portion (metal) of FPC25 was measured with a digital multimeter via ACF22.

(2) Adhesion of FPC25-ACF22-dimming sheet 10 A clip (about 10 g) with a weight of 200 g was sandwiched between the ends of the FPC 25. Next, the light control sheet 10 was lifted by grasping the opposite side of the power feeding unit 20 (the FPC25-ACF22 was joined) so that the weight was hung on the FPC25. After leaving it in this state for 10 minutes or more, the joining state of FPC25 was confirmed.

(3) Operating state of the dimming unit The optical characteristics (haze) at the center of the A4 size dimming sheet bonded to the glass plate were measured. In order to confirm the operation of the dimming unit, the haze was measured in a non-energized state, and the haze was measured in a state where AC-40V (50 Hz) was applied.

(4) Visibility The color change of ACF22 before and after heat crimping of FPC25 was visually confirmed.

The evaluation results are shown in Table 1.

From the results shown in Table 1, in the dimming units of Examples 1 to 4, it was easy to identify the color change of ACF22 before and after heat crimping of FPC25, and it was not necessary to inspect and confirm the electrical continuity. The process load has been reduced.

On the other hand, in the dimming units of Comparative Examples 1 and 3, no visual change was observed in the ACF 22 before and after the heat crimping of the FPC 25, and the sample was moved out of the manufacturing process to inspect and confirm the electrical continuity. It was necessary to inspect the magnified visual perception of ACF22 with an optical microscope.
In the dimming unit of Comparative Example 2, it was easy to identify the color change of ACF22, but it did not conduct in the inspection of <Initial characteristics of the dimming unit> (1), and <Initial characteristics of the dimming unit. > In the inspection of (2), peeling and dropping of FPC25 occurred.

100 ... Dimming unit 10 ... Dimming sheet 15 (a, b) ... Transparent conductive film (1st and 2nd)
11 ... Transparent film (1st and 2nd)
12 ... Transparent electrode layer (first and second)
13 ... Dimming layer 20 (a, b) ... Power feeding unit (first, second)
22, 22b ... ACF
31 ... Binder 22a ... Thermal discoloration layer 32 ... Coloring material 33 ... Conductive particles 25 ... FPC

Claims (8)

A light control sheet in which a light control layer containing a liquid crystal composition is sandwiched between a first transparent conductive film having a first transparent electrode layer and a second transparent conductive film having a second transparent electrode layer.
A first and second power supply having an FPC for supplying drive power from an external power source to the dimming layer and an ACF for electrically connecting the FPC to the first and second transparent electrode layers. With a part,
The ACF is a dimming unit characterized in that it has a heat-sensitive coloring material in a binder made of a thermosetting resin layer, and includes a heat-discoloring layer that changes color by heating. The dimming unit according to claim 1, wherein the melting point of the base film on which the first and second transparent conductive layers are formed is equal to or higher than the thermosetting temperature of the thermosetting layer. The dimming unit according to claim 1 or 2, wherein the temperature at which the thermal discoloration layer is heat-sensitive and discolors is 30 ° C. or higher. The ACF according to claims 1 to 3, wherein the ACF has a laminated structure of a thermosetting layer containing a heat-sensitive coloring material and a thermosetting resin layer containing no heat-sensitive coloring material. The dimming unit described in any of them. The dimming unit according to any one of claims 1 to 4, wherein the discoloration of the ACF is either decolorization or color development due to heating. The thermal discoloration layer is
(A) Fatty acid glycol ester,
(B) Fatty acid alkylolamide,
It is a composition in which either a dye or a pigment is added to a binder component containing 5 or more and 30 or less (unit: weight%) of the mixture of the above.
The dimming unit according to any one of claims 1 to 5, wherein the mixing ratio of (A): (B) is in the range of 1: 3 or more and 1:30 or less. The thermal discoloration layer is
Claims 1 to 6, wherein the leuco compound is a reversible heat-sensitive color-dissipating layer containing a leuco compound, a color-reducing agent that develops or reduces color by thermally reacting with the leuco compound, and a binder as main components. The dimming unit described in any of them. The ends of the first and second transparent conductive films on which the FPCs of the first and second feeding portions are formed are on the same side of the rectangular film, and the FPCs are separated from each other within the same side without facing each other. The dimming unit according to any one of claims 1 to 7, wherein the dimming unit has an arranged configuration.

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