JP7172262B2 - Light control film and its manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a light control film having an optical element (light control layer) that controls the state of light transmission by electrical control, and more particularly to a light control film having an improved sealing structure on the outer peripheral end surface of the light control film. Various terms such as light control body, light control device, light control sheet, light control film, etc., refer to the form of use of the light control film in the form of a flexible resin film, and the thickness and rigidity of the flexible light control film. Therefore, there are differences in nuances due to the usage pattern in which the glass is bonded to and fixed to a rigid base material (or in the form of sandwiched laminated glass). shall be handled uniformly as "film".

Light control films that switch between an opaque state (or cloudy state) and a transparent state are used in various applications.

For example, a light control film includes a liquid crystal layer held between electrodes, and a voltage applied to the electrodes changes the alignment state of liquid crystal molecules contained in the liquid crystal layer to change the orientation state of the liquid crystal molecules contained in the liquid crystal layer to an opaque state that scatters incident light, and an opaque state that scatters incident light. It is configured to be switchable between a transparent state and a transparent state in which light is transmitted (see, for example, Patent Document 1).

By fixing the light control film to a transparent substrate such as glass, it can be used for window glass, display windows, partitions, etc. For example, to separate private space from public space, it is possible to separate spaces. In addition to the equipment used for manufacturing, it has also been proposed to use it for automobile sunroofs and sunvisors.

Flexible resin film is used instead of rigid base material (glass, resin plate) for both the front and back substrates that sandwich the liquid crystal layer, and continuous manufacturing is performed using a roll-to-roll method. A light management film with a structure (and process) suitable for (See Patent Document 2)
The product (light control film) according to Patent Document 2 is lightweight and flexible as a whole, and has the advantage of maintaining the light control function without hindrance even if it is cut into an arbitrary size and shape.

In addition to the further diversification of the advantages, there is also a demand for a thinner light control film for the purpose of compactness, weight reduction, cost reduction, curved surface followability by improving flexibility, etc., mainly for the liquid crystal layer. Thinning (reducing the amount of liquid crystal material used), changing the material of the transparent base material, and design changes due to thinning have been taken, making it easier for the upper and lower transparent conductive films to come into contact, preventing the occurrence of electrical shorts. It becomes easy to invite, and it invites the risk of equipment failure of the light control film (the possibility of ignition or fire cannot be denied).

The liquid crystal layer that becomes the light control layer 13 of the light control film 10 is increasingly being manufactured with a thickness of 5 μm to 50 μm (preferably about 10 μm to 25 μm).

The transparent conductive film (transparent film with a transparent electrode) 15 is a set (two sheets) formed by forming a transparent electrode 12 made of a transparent conductive material such as ITO, IZO, or an organic conductive film on a film substrate 11. The light modulating layer 13 is sandwiched between the transparent conductive films 15 so that the transparent electrodes 12 sides of the transparent conductive films 15 face each other. A preferable thickness of the transparent electrode 12 is approximately 80 nm or more and 150 nm or less. (See Figure 2)

JP 2014-146051 A Japanese Patent No. 4387931

When the light control film is manufactured by cutting it into a predetermined size and shape, a cutter is often used to push off the edge of the light control film mounted on the support base.

As shown in FIG. 3(b), the cut surface is deformed by the pressure of the cutter blade and has a crushed shape. It is predicted that the same phenomenon will occur when cutting with scissors instead of with a cutter.

In the figure, the transparent conductive film 12 and the liquid crystal layer 13 are deformed so as to tilt downward to the left, so that the upper and lower transparent conductive films 12 easily come into contact with each other. (The liquid crystal layer 13 runs down, further increasing the risk.)
If the subsequent finishing (sealing of the edges, etc.) is carried out with the edges cut as shown in FIG. (Short circuit) occurs, which increases the possibility of not only quality defects but also accidents.

In addition to the cut ends of the light control film, the power supply part 20 is formed at the part where the light control film is half-cut (one of the transparent conductive films 15 is cut out) and the other transparent conductive film 12 is exposed. However, by wiping off the liquid crystal layer 13, the upper and lower transparent conductive films 12 that form a pair become exposed and opposed to each other, and are likely to come into contact with each other due to stress from the outside.

The purpose of the present invention is to propose an effective structure for avoiding unnecessary contact between the upper and lower transparent conductive films at the edge of a light control film having a cutting portion with a cutter or scissors, and an improved cutting method. do.

The light control film according to the present invention is
A liquid crystal layer is sandwiched between first and second laminates each having a structure in which at least a transparent electrode is formed on a transparent film. In the light control film that controls
At the outer peripheral end face of the light control film having the cut edge, the upper transparent film with the transparent electrode is removed, and the lower transparent film with the transparent electrode protrudes like a tongue. A cross section including the cut surface of the transparent film and the liquid crystal layer is sealed with a sealing material.

The method for producing a light control film according to the present invention comprises:
When correcting the outer peripheral end face of the light control film, which is cut by pressing the light control film on the support base with a knife, half cut and remove the upper transparent film with the transparent electrode at the edge of the light control film. It is characterized by having a step.

As a means for cutting the light control film, it is effective to have a step of cutting the light control film from above with a knife in a state in which the film is stretched in the air while holding the ends without being mounted on a support.

As the half-cutting means, burning-cutting by a laser beam may be adopted.

Short circuits due to unnecessary contact between the upper and lower transparent conductive films at the edges of the light control film are avoided, ensuring the safety of the light control body and preventing equipment failure of the light control film (which may lead to ignition or fire). undeniable) risk is reduced.

Explanatory drawing which shows the structure example of the light control film by this invention. FIG. 4 is an explanatory diagram showing a structural example of a power supply electrode portion in a light control film; (conventional technology) Explanatory drawing showing the cutting method of the light control film and the cutting section. (conventional technology)

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited by the following drawings and descriptions.

In the present invention, the liquid crystal layer is a type of PNLC (polymer network liquid crystal) in which liquid crystal molecules are arranged in the voids formed inside a polymer network made of a resin formed in a three-dimensional mesh shape, or Assuming that any type of PDLC (Polymer Dispersed Liquid Crystal) having dispersedly arranged liquid crystal molecules is adopted, the PNLC type will be mainly described in the following description. may have other configurations.

<Transparent conductive film 15>
As the film substrate 11 constituting the transparent conductive film 15, any substantially transparent flexible film substrate suitable for roll-to-roll production can be used. Specifically, for example, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polycarbonate resins, acrylic resins, cellulose derivatives such as triacetyl cellulose (TAC), and polyether sulfone (PES). Films made of resins, polyimide resins, and polyolefin resins such as polyethylene and polypropylene can be exemplified, but are not necessarily limited to these.

Such a transparent film may contain an ultraviolet absorber, a stabilizer, etc., and an ultraviolet absorbing layer, a heat ray reflecting layer, a barrier layer, etc. may be provided on either side of the transparent film. There is no problem even if
In addition, the transparent film may be appropriately subjected to an easy-adhesion treatment, an antistatic treatment, or the like, and may be further provided with a reinforcing substrate or the like without any problem.

For the transparent electrode 12, any known transparent electrode material can be used. For example, indium tin oxide (ITO) conductive film, tin oxide conductive film, zinc oxide conductive film, polymer conductive film and the like can be exemplified, but are not necessarily limited to these.

Such a transparent electrode 12 can be formed by using a physical vapor deposition method (PVD method) such as a vacuum deposition method or a sputtering method, various chemical vapor deposition methods (CVD method), various coating methods, and the like. can be done.

Moreover, if patterning of the transparent electrode 12 is required, it can be carried out by an arbitrary method such as an etching method, a lift-off method, a laser trimming method, or a method using various masks.

An alignment film or the like may be appropriately provided on the transparent electrode 12 as necessary.

In the present invention, any type of liquid crystal composition such as PDLC and PNLC can be used as the light control layer 13 .

There are known two types of the light modulating layer 13 made of liquid crystal elements depending on the mode of use: normal mode and reverse mode. The normal mode is a mode in which a transmission state is obtained by voltage application (ON) and a scattering state is obtained by voltage removal (OFF). In addition, the reverse mode is a mode in which a transmission state is obtained by voltage removal (OFF) and a scattering state is obtained by voltage application (ON). In the case of the reverse mode, a transparent conductive film 15 having an orientation film formed on the transparent electrode 12 is required.

The alignment film may be either a horizontal alignment film or a vertical alignment film, as long as it is a conventionally known alignment film, and can be appropriately selected according to the application.

A light control film having a reverse type PNLC light control layer is generally manufactured as follows. First, a mixture of a liquid crystal and a photopolymerizable compound (monomer) is sandwiched between a pair of transparent conductive films 15 (laminated transparent electrodes and alignment layers). Then, by irradiating ultraviolet rays under certain conditions, the photopolymerizable compound in the liquid crystal is changed into a polymer by photopolymerization. Photopolymerization and cross-linking form a polymer network with countless fine domains (macromolecular voids) in the liquid crystal.

The liquid crystal layer 13 shows a behavior in which there is almost no unreacted component in the phase separation, and the polymer network and the liquid crystal region are clearly separated with high purity. In addition, it is possible to realize an ideal alignment state without pretilt alignment treatment by rubbing the substrate (conductive film), and the liquid crystal molecules are aligned almost uniformly in each domain divided by the polymer network. It will be.

The size of the domain of PNLC is as fine as about 1 μm compared to the fine particles (approximately 2 to 10 μm diameter) in the light diffusion sheet and dispersed nematic liquid crystal droplets (generally several μm diameter) in PDLC, and Rayleigh scattering (Wavelength-selective scattering) is not caused, and scattering in a wide wavelength range including at least visible light region wavelengths (400 to 780 nm) is efficiently generated.

The driving voltage of a PNLC generally depends on the structural properties of the polymer network (size and shape of domains, film thickness of the polymer network, etc.), and the structure of the polymer network and the resulting degree of light transmission and scattering. In relation, the drive voltage is determined. In the voltage range of 100 V or less, in order to construct a PNLC that can obtain a sufficient degree of light transmission and scattering, each domain must have an appropriate size and a uniform shape. It is necessary to form a polymer network as follows. In the present invention, the domain size, which depends on the polymer network structure, is controlled to be 3 μm or less, preferably 2 μm or less, more preferably about 1 μm.

<Cutting>
After trimming the light control film 10 to a predetermined size and shape, the following finishing processing is performed.
For cutting, as shown in FIG. 3(a), conventionally, the end portion of the light control film 10 mounted on a support base is cut off by a cutter.

When the light control film 10 mounted on the support stand is cut by a cutter or cut by scissors, pressure is applied to both sides of the light control film 10, and pressure is also applied around the cutting line by the blade on the support stand. The phenomenon of collapsing at the surface is not completely avoided.

In order to eliminate the collapse phenomenon, if the light control film 10 is stretched in the air and suspended in the air, and then cut by dropping the blade of the cutter from above, the load applied only to the cutting line increases, and the cut surface increases. It was confirmed that there was little collapse of
Also, burning off with a laser beam is an effective method for cutting the light control film 10 while it is mounted on a support because it does not apply a load to anything other than the cutting line.

<Half cut>
As shown in FIG. 1( a ), the upper transparent conductive film 15 is removed from the outer peripheral end face (left side of the figure) of the light control film 10 having the cut end, and the lower transparent conductive film 15 is removed. It is finished to form a protruding piece.

In correcting the outer peripheral end face, the upper transparent conductive film 15 (the portion indicated by the dotted line in the figure) at the end of the light control film 10 is half-cut and removed.

By half-cutting and removing the upper transparent conductive film 15 (dotted line), the end of the upper transparent electrode 12 that was deformed during cutting and hung down to the lower left is removed, and the distance from the lower transparent electrode 12 (liquid crystal layer 13 thickness) is ensured.

In the half-cutting, it is effective to employ burning-cutting by a laser beam so as not to cause deformation (collapse). After the end of the transparent electrode 12 is removed, the liquid crystal remaining on the lower transparent electrode 12 is not completely wiped off, and the upper and lower transparent electrodes are separated by the interposition of the liquid crystal layer by leaving the liquid crystal slightly protruding from the half-cut surface. 12 contacts are avoided and the electrical insulation is more reliable.

<Peripheral seal>
Next, a seal portion 16 is formed as shown in FIG. 1(b).
The liquid crystal layer is prone to deterioration due to acid, moisture, ultraviolet rays, etc. In particular, the sheet edge (periphery) where the liquid crystal layer is sandwiched is likely to come into contact with moisture, acid, ultraviolet rays, etc., and the deterioration of the liquid crystal layer is likely to occur. easily occur.

Conventionally, there have been proposals related to a sealing structure for the periphery of a PDLC panel in which a front substrate is coated with PDLC and a rear substrate is laminated thereon. A seal structure for applying an agent is disclosed. For example, the characteristics required for the sealant are that it is a non-solvent silicone adhesive with a viscosity of 100,000 to 500,000 CP, and that the color of the sealant is similar to that of the PDLC panel. It is mentioned to be inconspicuous.

It can be said that it is desirable that the sealing portion 16 for obtaining such characteristics is substantially transparent, but pigments, fillers, and the like may be appropriately added depending on the situation. When a dye is added, it is desirable to use a pigment-based dye in consideration of weather resistance and the like.

Examples of the sealing material used for the sealing portion 16 include various resins such as epoxy resin, urethane resin, acrylic resin, vinyl acetate resin, en-thiol resin, silicone resin, and modified polymer. Various resin materials such as thermosetting, photo-curing, moisture-curing, and anaerobic-curing types can be used.

In the present embodiment, a photocurable resin liquid containing a polythiol compound, a polyene compound having two or more carbon-carbon double bonds in one molecule, and a photopolymerization initiator is used. Examples of polyene compounds include allyl compounds, propenyl compounds, (meth)acrylate compounds, etc. Polyene-polythiol resins and (meth)acrylate compounds were used.

Peripheral seal processing may be performed not only on the outer peripheral portion cut into a predetermined shape to define the outer shape of the light control film 10, but also on the power supply electrode portion to the light control film 10 shown in FIG. 2(b).

The power supply electrode 20 to the light control film 10 is connected by a silver paste applied on the transparent electrode 12 exposed by half-cutting or removing one of the transparent conductive films 15 and a copper tape stuck on the upper side of the silver paste. A lead wire (wiring) for supplying power from an external power source (not shown) is fixed by solder formed on the connecting portion. (Silver paste and copper tape are shown in simplified form in the figure.)
By sealing the wall surface where the half-cut cross section is exposed at the portion where the power supply electrode 20 is provided, it is possible to reliably prevent a short circuit at the portion to which electric power is supplied, which is preferable.

Although not shown, the sealing portion 16 is formed not only by forming a coating film on the wall surface but also by forming a thick film so as to completely cover the power supply electrode 20, thereby preventing mechanical damage to the power supply electrode 20 (tape, solder peeling, lead, etc.). Wire breakage, peeling from solder) or electrical protection (avoiding contact with the upper power supply electrode 20 in FIG. 2(b)) can be achieved.

By performing the sealing (sealing) process according to the present invention in advance, in the case of adopting the light control film for construction purposes, conventionally, at the construction site, the part including the cut surface that has been cut is waterproofed. , Putty processing was performed mainly for the purpose of fixing, and electrical insulation was not necessarily perfect, but after construction, unnecessary contact between the upper and lower transparent conductive films was revealed. will be eliminated.

REFERENCE SIGNS LIST 10 light control film 15 transparent conductive film 11 film substrate 12 transparent conductive film 13 liquid crystal layer 20 feeding electrode

Claims (2)

A liquid crystal layer is sandwiched between a first laminated body and a second laminated body having a structure in which at least a transparent electrode is formed on a transparent film. In a light control film that controls and controls transmitted light,
The outer peripheral end surface of the light control film having a cut edge ,
Consisting of a feeding portion forming end face which is an end face provided with a feeding portion and a non-feeding portion forming end face which is an end face not provided with the feeding portion,
On the non-feeding portion forming end face,
a configuration in which the second laminate has a tongue-like protruding region, and the liquid crystal layer is present on a part of the tongue-like protruding region;
A light control film, wherein a cross section including the cut surface of the first laminate and the liquid crystal layer is sealed with a sealing material. A partial region on the tongue-like protruding region, a cross section including the cut surface of the first laminate and the liquid crystal layer, and a surface of the first laminate opposite to the surface in contact with the liquid crystal layer 2 . The light control film according to claim 1 , wherein a part of the area on the cut surface side is sealed with the sealing member.

Images