JP2018105984A - Sealant for lighting control film and manufacturing method of lighting control film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealant for a lighting control film and a manufacturing method of a lighting control film, unlikely to generate air bubbles or retardation unevenness in a vicinity of a sealant.SOLUTION: A lighting control film 1 includes: a film-like first laminate 12 at least having a substrate 21A; a film-like second laminate 13 at least having a substrate 21B; and a liquid crystal layer 14 holding a liquid crystal 14A by the first laminate 12 and the second laminate 13 and configured to control an orientation of the liquid crystal 14A by driving electrodes 22A, 22B arranged at least one of the first laminate 12 and the second laminate 13. A sealant 25 for a lighting control film covers an outer periphery of the liquid crystal 14A arranged between the first laminate 12 and the second laminate 13. The sealant 25 is a curable resin, and has a viscosity coefficient of 50-300 Pa s before curing.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a sealing agent for a light control film and a method for producing the light control film.

Conventionally, for example, various devices relating to a light control film that is attached to a window to control the transmission of external light have been proposed (Patent Documents 1 and 2). One such light control film uses liquid crystal. The light control film using a liquid crystal is produced by sandwiching a liquid crystal with a transparent substrate on which a transparent electrode and an alignment layer are produced. And this light control film changes the orientation of a liquid crystal by changing the electric field applied to a liquid crystal, adjusts the amount of transmitted light, and controls the transmission of extraneous light.
Here, the outer periphery of the liquid crystal is surrounded by a sealing agent. In addition, a spacer is provided in the interior surrounded by the sealing agent, and the distance between the upper and lower transparent substrates is kept constant by the spacer.

JP 03-47392 A Japanese Patent Laid-Open No. 08-184273

The sealant is applied so as to be higher than the spacer in order to prevent the liquid crystal from flowing out. When the two transparent substrates are bonded and integrated, they are crushed and adhered to the transparent substrate. May be.
Here, when the light control film is sandwiched between glass plates, the transparent substrate is also flattened by the rigidity of the glass plates. That is, the sealing agent is crushed to the height of the spacer.
However, in the light control film sandwiched by a flexible resin film or the like instead of the glass plate, the sealing agent is not sufficiently crushed, and the sealing agent is higher than the spacer. If it does so, a light control film will become thick in the peripheral part by which the sealing agent is arrange | positioned, a bubble will be generated in a thick part, and phase difference nonuniformity may be visually recognized.
An object of this invention is to provide the manufacturing method of the sealing agent for light control films which does not generate | occur | produce a bubble and phase difference nonuniformity in the vicinity of a sealing agent, and a light control film.

In order to achieve the above object, the present invention provides the following.
(1) A film-like first laminate including at least a substrate, a film-like second laminate including at least a substrate, a liquid crystal sandwiched between the first laminate and the second laminate, In the light control film provided with the liquid crystal layer by which the orientation of the said liquid crystal is controlled by the drive of the electrode provided in at least one of the 1 laminated body and the said 2nd laminated body, the said 1st laminated body and the said 2nd laminated body, A dimming film sealing agent that covers the outer periphery of the liquid crystal disposed between the two, wherein the sealing agent is a curable resin, and the viscosity before curing is 50 Pa · s to 300 Pa · s. Sealant for film.

(2) In (1), the viscosity of the sealing agent is 200 Pa · s or more and 260 Pa · s or less.

(3) In (1) or (2), the sealing agent is a thermosetting resin.

(4) A second laminate manufacturing process for manufacturing a film-like second laminate including at least a substrate, a first laminate manufacturing process for manufacturing a film-like first laminate including at least a substrate, A spacer arrangement step of arranging a spacer on the second laminated body or the first laminated body, and a sealing agent having a viscosity of not less than ◯ and not more than 300 Pa · s in the thickness direction higher than the spacer in the outer peripheral portion of the second laminated body A sealant coating process for forming a frame shape, a liquid crystal inflow process for flowing liquid crystal into the frame shape, and pressing the sealant while bonding the first laminate to the second laminate side. The manufacturing method of a light control film provided with a lamination process.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the sealing agent for light control films which can hardly produce a bubble and phase difference nonuniformity in the vicinity of a sealing agent, and a light control film can be provided.

It is sectional drawing which shows the light control film 10 as one Embodiment of the laminated | multilayer film of this invention. 3 is a flowchart showing a manufacturing process of the light control film 10. It is an experimental result which shows whether the bubble generate | occur | produced in the sealing agent 25 vicinity of the outer peripheral part of the light control film 1. FIG. 5 is a graph showing the relationship between the viscosity of the sealing agent 25 and the height H of the sealing agent 25. 5 is a graph showing the relationship between the viscosity of the sealing agent 25 and the difference H−h between the height H of the sealing agent 25 and the height h of the liquid crystal layer 14 at the center of the light control film 1. 6 is a graph showing the relationship between the viscosity of the sealant 25 and the variation σ of the height H of the sealant 25.

(Light control film)
FIG. 1 is a cross-sectional view showing a light control film 10 as an embodiment of the laminated film of the present invention. For example, the light control film 10 is attached to a sunroof or the like of a vehicle, and can be switched between transmission and opaqueness.

The light control film 10 is a light control film 1 that controls transmitted light using the liquid crystal 14 </ b> A, and is configured such that the liquid crystal layer 14 is sandwiched between the first stacked body 12 and the second stacked body 13. A spacer 24 for keeping the thickness of the liquid crystal layer 14 constant is provided between the first stacked body 12 and the second stacked body 13. The first laminated body 12 and the second laminated body 13 sequentially form the first electrode 22A, the second electrode 22B, the first alignment layer 23A, and the second alignment layer 23B on the first base material 21A and the second base material 21B, respectively. Formed.
In the case of using the IPS method described later, the first electrode 22A and the second electrode 22B are manufactured together on one side of the first alignment layer 23A or 23B.
And the light control film 10 controls permeation | transmission of external light by changing the electric potential difference between 22 A of 1st electrodes, and the 2nd electrode 22B, and switches a state between a transparent state and a non-transparent state.

(Base material)
The first base material 21A and the second base material 21B are made of various laminates such as flexible TAC, polycarbonate, COP (cycloolefin polymer), acrylic, and PET (polyethylene terephthalate) applicable to the light control film 1. In this embodiment, a film material made of polycarbonate in which a hard coat layer is produced on both sides is applied.
The thickness of the first base material 21A and the second base material 21B is about 50 μm to 500 μm.

(Orientation layer)
The first alignment layer 23A and the second alignment layer 23B are formed of a photo-alignment layer. As the photo-alignment material applicable to the photo-alignment layer, various materials to which the photo-alignment technique can be applied can be widely applied. In this embodiment, for example, a photodimerization type material is used. Regarding this photodimerization type material, “M. Schadt, K. Schmitt, V. Kozinkov and V. Chigrinov: Jpn. J. Appl. Phys., 31, 2155 (1992)”, “M. Schadt, H. Seiberle and A. Schuster: Nature, 381, 212 (1996).

Further, the first alignment layer 23A and the second alignment layer 23B may be manufactured by rubbing treatment instead of the photo-alignment layer. In this case, after the first alignment layer 23A and the second alignment layer 23B are manufactured by manufacturing various material layers applicable to the alignment layer such as polyimide, fine lines are formed by rubbing treatment using a rubbing roll on the surface of the material layer. It is formed by manufacturing a concavo-convex shape.
Instead of the alignment layer and the photo-alignment layer by such a rubbing treatment, a fine line-shaped uneven shape produced by the rubbing treatment may be produced by a shaping treatment to produce the orientation layer.

(Spacer)
In the present embodiment, a spherical bead spacer 24 is used as the spacer 24. The bead spacer 24 is provided to define the thickness of the portion of the liquid crystal layer 14 excluding the outer peripheral portion. The bead spacer 24 can be widely applied to a configuration of an inorganic material such as silica, a configuration of an organic material, a configuration of a core-shell structure combining these, and the like. Moreover, you may comprise by the rod shape by cylindrical shape, prismatic shape, etc. other than the structure by spherical shape.
However, the member that defines the thickness of the liquid crystal layer 14 is not limited to the bead spacer 24. For example, the liquid crystal layer 14 may be formed into a cylindrical shape by applying a photoresist to the first base 21A side, exposing, and developing. .

(Liquid crystal layer)
Various liquid crystal materials applicable to this type of light control film can be widely applied to the liquid crystal layer 14.
In the present embodiment, the liquid crystal layer 14 is a guest-host type liquid crystal 14a mixed with a dichroic dye. By moving the dichroic dye as the liquid crystal molecules move, light transmission and light shielding can be controlled.
When a TN liquid crystal (twisted liquid crystal) is used as a host and a dichroic dye is used as a guest, the light control film aligns liquid crystal molecules and dichroic dyes horizontally when no voltage is applied. It is a so-called normally black type that blocks the screen and becomes “black”. When a voltage is gradually applied, the liquid crystal molecules rise vertically and the dichroic dye rises, and light is transmitted.

  However, the present invention is not limited to this, and as the liquid crystal 14A and the dye used for the guest-host method, a mixture of the liquid crystal 14A and the dye proposed for the guest-host method can be widely applied.

Further, not only the guest-host method but also a VA (Virtual Alignment) method may be used for driving the liquid crystal layer 14. The VA method is a method of controlling the transmitted light by changing the alignment of the liquid crystal 14A between vertical alignment and horizontal alignment. The liquid crystal layer 14 is sandwiched between the vertical alignment layers by vertically aligning the liquid crystal 14A when no electric field is applied. Thus, the light control film 1 is configured, and the liquid crystal 14A is horizontally aligned by applying an electric field. The VA system is a so-called normally black type in which the screen is generally “black” when no voltage is applied.
In the case of a TN system that is not a guest-host type liquid crystal, the light control film is a so-called normally white, in which liquid crystal molecules are aligned horizontally when no voltage is applied, and the screen is “white” through light. The type is common. In this case, as the voltage is gradually applied, the liquid crystal molecules rise vertically, blocking the light and blacking the screen.

  Further, an IPS (In-Place-Switching) method may be used. In the IPS system, a driving electrode is collectively formed on one of a pair of substrates sandwiching the liquid crystal layer 14, and a so-called lateral electric field that is an in-plane electric field on the substrate surface is formed by the electrodes. In this driving method, an electric field is formed to control the alignment of the liquid crystal 14A.

  A sealing agent 25 is formed in a frame shape so as to surround the liquid crystal layer 14. The sealing agent 25 is fixed to the first laminated body 12 and the second laminated body 13, and the leakage of the liquid crystal 14A is prevented by the sealing agent 25.

(Manufacturing process)
FIG. 2 is a flowchart showing the manufacturing process of the light control film 10.
First, in the second stacked body manufacturing step SP2, the second stacked body 13 is manufactured. The second laminate manufacturing process SP2 includes a second electrode manufacturing process SP2-1, a second spacer arrangement process SP2-2, and a second alignment layer manufacturing process SP2-3.
In the second electrode manufacturing step SP2-1, the second transparent electrode 22B made of ITO is manufactured on the second base material 21B by a vacuum film forming method such as sputtering.

  In the spacer arrangement step SP2-2, the coating liquid in which the bead spacers 24 are dispersed is applied by a spin coating method or the like, and thereafter, drying and baking processes are sequentially performed. The bead spacers 24 are randomly arranged.

  In the second alignment layer manufacturing step SP2-3, the coating liquid related to the second alignment layer 23B is applied and dried, and then cured by irradiation with ultraviolet rays, whereby the second alignment layer 23B is manufactured. Thus, in this embodiment, the second laminate 13 is manufactured.

  The subsequent first laminate manufacturing process SP3 is the same as the second laminate manufacturing process SP2 except that the spacer arranging process is not included. That is, the first laminate manufacturing process SP3 includes a first electrode manufacturing process SP3-1 and a first alignment layer manufacturing process SP3-2. In the first electrode manufacturing step SP3-1, the first transparent electrode 22A made of ITO is manufactured on the first base material 21A. Next, in the first alignment layer manufacturing step SP3-2, the first alignment layer 23A is disposed. Thus, the first laminated body 12 is manufactured.

  In the sealant application process SP4 following the first laminate manufacturing process SP3, the sealant 25 is applied to the second laminate 13 in a frame shape using a dispenser. Here, the sealing agent 25 is applied slightly higher than the spacer 24. In this embodiment, the sealing agent 25 is a UV (ultraviolet) thermosetting resin.

  Next, in the liquid crystal inflow step SP5, the liquid crystal 14A flows into the frame shape.

  In the laminating step SP6, the first laminated body 12 and the second laminated body 13 are bonded to each other while being pressed with a roller, for example, so that the liquid crystal 14A disposed in the second laminated body 13 is spread. Under the present circumstances, the distance between the 1st laminated body 12 and the 2nd laminated body 13 in the center part of the light control film 1 is hold | maintained at the height (diameter) of the spacer 24. FIG. Then, the sealing agent 25 is crushed by the roller.

Thereafter, in the sealing agent curing step SP7, the sealing agent 25 is cured by ultraviolet irradiation and heating, whereby the light control film 1 is manufactured.
As for the arrangement of the liquid crystal 14A, various methods, for example, the case where the liquid crystal 14A is arranged in the gap formed in the portion related to the liquid crystal layer 14 after the first laminated body 12 and the second laminated body 13 are laminated. Various methods can be widely applied.

Although the light control film 1 is manufactured as mentioned above, when the sealing agent 25 used in sealing agent coating process SP4 is too hard, when laminating | stacking the 1st laminated body 12 and the 2nd laminated body 13 in a lamination process. Moreover, the sealing agent 25 is not sufficiently crushed, and the thickness of the outer peripheral portion of the light control film 1 becomes thicker than the central portion. If it does so, bubbles may mix in this thick outer peripheral part, or a rainbow nonuniformity may be made.
On the other hand, if the sealing agent 25 is too soft, it does not function as the sealing agent 25, and the liquid crystal 14 </ b> A leaks out from the sealing agent 25. Therefore, the viscosity of the sealing agent 25 has a suitable range.

(Experimental result)
Hereinafter, the conditions other than the viscosity of the sealant 25 are the same, and six light control films 1 (samples A to F) that differ only in the viscosity of the sealant 25 are prepared, and after pressing on the outer peripheral portion of the light control film 1 The height H of the sealant 25, the height difference Hh between the H and the thickness 13 of the liquid crystal layer at the center of the light control film 1, the variation in the height H of the sealant 25, and the bubble The experimental results of measuring the presence or absence of occurrence will be described.

As a sample of the sealant 25, World Rock 700 series manufactured by Kyoritsu Chemical Industry Co., Ltd. was used. The viscosities of Samples A to F are as follows: Sample A has a viscosity of 210 Pa · s, B has a viscosity of 230 Pa · s, C has a viscosity of 260 Pa · s, D has a viscosity of 310 Pa · s, E has a viscosity of 330 Pa · s, and F has a viscosity of 350 Pa · s. It is.
Further, the types of the sealing agent 25 of the sample A-F are all UV thermosetting resins. However, the present invention is not limited to this, and a UV curable resin sealing agent 25 may be used.

  The sealant 25 of sample A-F is four levels of the same system in UV thermosetting resin. Then, fillers were added to 2 levels among them, and 6 types of different viscosities were used. The kind of filler is silica, and is added between 0% and 10%. Note that the viscosity of the sealant 25 can be adjusted to some extent by the amount of filler.

The first stacked body 12 and the second stacked body 13 are 10 cm square rectangular base materials. On the second base material 21B of the second laminate 13, the sealing agent 25 was drawn in a rectangular frame shape having a width of about 500 μm and a height of about 100 μm and a 7 cm square.
A spacer 24 was disposed in a frame formed of the sealing agent 25. The height (diameter) of the spacer 24 is 16 μm.
Then, the 1st laminated body 12 and the 2nd laminated body 13 side were bonded using the roller. The pressing force of the roller is 0.1 MPa. The material of the roller is rubber having a hardness of 70 degrees. Moreover, the temperature at the time of bonding is 25 degreeC.
Then, the sealing agent 25 was hardened by ultraviolet irradiation and heating, and the light control film 1 of sample AF was completed.

In the light control film 1 of sample A-F manufactured as mentioned above, the height H of the sealing agent 25 after bonding the 1st laminated body 12 and the 2nd laminated body 13 was measured. The height H of the sealant 25 is an average measured at 8 points. Further, the height h of the liquid crystal layer 14 in the central portion of the light control film 1 was also measured. And the height difference Hh of both was calculated | required. The variation in the seal height H is the standard deviation σ when eight points are measured. The measurement is four points on a square and four points on each of the four sides. The measurement of the seal height H was performed using a model number TH-104 manufactured by Tester Sangyo Co., Ltd., a thickness measuring device for paper and film.
The height H of the sealant 25 is measured with the first laminated body 12 and the second laminated body 13 bonded together, and the thicknesses of the first laminated body 12 and the second laminated body 13 are measured and subtracted. And calculated.
For the height h of the liquid crystal layer 14 in the central portion of the light control film 1, the diameter of the bead spacer 24 was measured by microscopic observation. It is assumed that the height h of the liquid crystal layer 14 at the center of the light control film 1 is the same height as the diameter of the bead spacer 24.

  FIG. 4 is a graph showing the relationship between the viscosity of the sealing agent 25 and the height H of the sealing agent 25. As shown in the graph, the height H of the sealing agent 25 increases as the viscosity of the sealing agent 25 increases. It is considered that when the viscosity of the sealing agent 25 increases when the first laminated body 12 and the second laminated body 13 are bonded using a roller, the sealing agent 25 is not easily crushed.

  FIG. 5 is a graph showing the relationship between the viscosity of the sealing agent 25 and the difference H−h between the height H of the sealing agent 25 and the height h of the liquid crystal layer 14 in the central portion of the light control film 1. As shown in the figure, the difference H-h increases as the viscosity of the sealant 25 increases.

FIG. 6 is a graph showing the relationship between the viscosity σ of the sealant 25 and the variation σ between the height H of the sealant 25. As shown in the figure, as the viscosity of the sealant 25 increases, the variation σ increases. This is because the discharge amount of the dispenser that discharges the sealing agent 25 becomes unstable and tends to be non-uniform near the corner. Specifically, the corner portion has a large amount of sealing material (thicker), and the sealing material is small (thinner) before and after the corner.
In addition, regarding the variation σ of the height H of the sealant 25, it is preferable that there is no (zero) or even a small variation exists. However, when the variation σ is large, there is also an advantage that when the light control film 1 is tensioned at the time of pasting to glass or the like, if the height of the sealant 25 is uneven, it may be slightly extended like a bellows. Have. Therefore, it is preferably 3.0 or less from the viewpoint of uniform thickness, and 0.01 or more from the viewpoint of easy extension. The range satisfying both is preferably 0.01 or more and 3.0 or less.

  And it was confirmed visually whether the bubble generate | occur | produced in the sealant 25 vicinity of the outer peripheral part of the light control film 1. FIG. The experimental results are shown in FIG.

  “Determination” in FIG. 3 is indicated by “X” when bubbles are confirmed, and by “◯” when bubbles are not confirmed. In Samples A, B, and C, bubbles were not confirmed. However, bubbles were confirmed in Samples D, F, and F. From the above, the sealing agent 25 preferably has a viscosity of 300 Pa · s or less so as not to generate bubbles. More preferably, it is 260 Pa · s or less.

On the other hand, if the viscosity is too low, the linearity of the sealing agent 25 cannot be maintained. Therefore, the viscosity needs to be 50 Pa · s or more. When the viscosity of the sealant 25 is lower than 50 Pa · s, the line width is increased because the sealant 25 immediately spreads by capillary action after the first laminate 12 and the second laminate 13 are bonded together. Was not suitable because it became jagged instead of straight.
From the experimental results, when the viscosity is high, the seal height varies. However, when the sealant 25 is drawn, if the viscosity is high, the discharge amount from the dispenser becomes unstable and becomes uneven near the corner. This is because it tends to be easy. Specifically, the corner portion has a large amount of the sealing agent 25 (thicker), and the front and rear thereof have a small amount of the sealing agent 25 (thinner).

  From the above, the viscosity is preferably 50 Pa · s or more and 300 Pa · s or less. More preferably, it is 200 Pa · s or more and 260 Pa · s or less. If it is this range, when laminating | stacking the 1st laminated body 12 and the 2nd laminated body 13, the sealing compound 25 is fully pressed and the thickness of the outer peripheral part of the light control film 1 is substantially the same as a center part. Also, even if there is a difference, it becomes slight. If it does so, possibility that a bubble will mix in this outer peripheral part which became thick, or a phase difference nonuniformity will be reduced is reduced.

DESCRIPTION OF SYMBOLS 10 Light control film 12 1st laminated body 13 2nd laminated body 14 Liquid crystal layer 14A Liquid crystal 14a Liquid crystal 21A 1st base material 21B 2nd base material 22A 1st transparent electrode 22B 2nd transparent electrode 23A 1st orientation layer 23B 2nd orientation layer Layer 24 Bead spacer 25 Sealant

Claims (4)

A film-like first laminate including at least a substrate;
A film-like second laminate including at least a substrate;
A liquid crystal layer in which liquid crystal is sandwiched between the first stacked body and the second stacked body, and the orientation of the liquid crystal is controlled by driving an electrode provided in at least one of the first stacked body and the second stacked body; In a light control film comprising: a sealing agent for a light control film covering an outer periphery of the liquid crystal disposed between the first laminate and the second laminate,
The sealing agent for light control films whose said sealing agent is curable resin and whose viscosity before hardening is 50 Pa.s or more and 300 Pa.s or less. The viscosity of the sealing agent is 200 Pa · s or more and 260 Pa · s or less,
The sealing agent for light control films of Claim 1. The sealing agent is a thermosetting resin;
The sealing agent for light control films of Claim 1 or 2. A second laminate production process for producing a film-like second laminate comprising at least a substrate;
A first laminate production process for producing a film-like first laminate comprising at least a substrate;
A spacer arranging step of arranging a spacer in the second laminated body or the first laminated body;
On the outer periphery of the second laminate, a sealant coating step for forming a sealant having a viscosity of 50 Pa · s or more and 300 Pa · s or less in a frame shape higher in the thickness direction than the spacer;
A liquid crystal inflow process for injecting liquid crystal into the frame shape;
A laminating step of pressing the sealing agent while bonding the first laminate to the second laminate side;
The manufacturing method of the light control film provided.

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