Transmittance variable film, manufacturing method and use thereof

Abstract

The present application relates to a transmittance variable film, a method for producing the same, and a use thereof. The transmittance variable film of the present application can solve the drive unevenness phenomenon by adjusting the pre-tilt of the opposite alignment film of the alignment film to which the ball spacer is fixed to minimize the reverse tilt occurring upon on-off driving. The transmittance variable film of the present application can be used as sunroofs.

Claims

1. A transmittance variable film comprising a first substrate member comprising a first electrode film, a first alignment film formed on the first electrode film, and ball spacers fixed to the first alignment film, a second substrate member comprising a second electrode film and a second alignment film formed on the second electrode film, wherein the second alignment film has a pre-tilt angle of 0.2 to 89 degrees, and a liquid crystal layer formed between the first alignment film and the second alignment film, wherein the first alignment film has a surface roughness of 3 nm to 100 nm, wherein the first alignment film comprises an alignment film material and nanoparticles, wherein the nanoparticles have an average particle diameter from 1 nm to less than 1000 nm.

2. The transmittance variable film according to claim 1, wherein a lower part of each of the ball spacers is fixed to the first alignment film via a cured product formed on an upper part of the first alignment film.

3. The transmittance variable film according to claim 1, wherein an upper part of each of the ball spacers is in contact with the second alignment film to maintain a gap, so that the liquid crystal layer can be formed between the first alignment film and the second alignment film.

4. The transmittance variable film according to claim 1, wherein each of the ball spacers has a diameter of 2 m to 100 m and comprises at least one selected from the group consisting of a carbon-based material, a metal-based material, an oxide-based material, and a composite material thereof.

5. The transmittance variable film according to claim 1, wherein the first alignment film has a random pre-tilt.

6. The transmittance variable film according to claim 1, wherein the liquid crystal layer comprises a smectic liquid crystal compound, a nematic liquid crystal compound, or a cholesteric liquid crystal compound.

7. The transmittance variable film according to claim 1, wherein the liquid crystal layer further comprises an anisotropic dye.

8. The transmittance variable film according to claim 1, wherein the first alignment film and the second alignment film are a photo-alignment film.

9. The transmittance variable film according to claim 1, wherein the first alignment film and the second alignment film are a horizontal alignment film, and the liquid crystal layer is in a horizontally aligned state under a state of no voltage application and is converted into a vertically aligned state under a state of voltage application.

10. A sunroof comprising the transmittance variable film of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the transmittance variable film of Example 1 of the present application.

(2) FIG. 2 shows the transmittance variable film of Comparative Example 1.

(3) FIGS. 3 to 5 are drive images of Examples 1 to 3, respectively.

(4) FIG. 6 is a drive image of Comparative Example 1.

(5) FIG. 7 shows haze values of Example 1 and Comparative Example 1 according to the angles.

DETAILED DESCRIPTION OF THE INVENTION

(6) Hereinafter, the present application will be described in detail with reference to the following examples, but the scope of the present application is not limited by the following examples.

Example 1

(7) Preparation of First Alignment Film Composition

(8) 9.675 g of a solvent (cyclohexanone), 0.325 g of a photo-alignment material (5-norbornene-2-methyl-4-methoxycinnamate) and 0.01 g of nanoparticles (PMMA, SEKISUI Co., average particle diameter: 370 nm) were added to a vial of 20 ml and mixed.

(9) Preparation of Ball Spacer Composition

(10) 9.675 g of a solvent (cyclohexanone), 0.065 g of a photo-alignment material (5-norbornene-2-methyl-4-methoxycinnamate) and 0.1 g of ball spacers (KBN-510, SEKISUI Co., particle diameter: 10 m) were added to a vial of 20 ml and mixed.

(11) Preparation of Second Alignment Film Composition

(12) 9.675 g of a solvent (cyclohexanone) and 0.325 g of a photo-alignment material (5-norbornene-2-methyl-4-methoxycinnamate) were added to a vial of 20 ml and mixed.

(13) Manufacture of First Substrate Member

(14) A nanoparticle composition was coated on the ITO layer of the first electrode film (PC/ITO film, widthlength=100 mm100 mm) using a #4 Meyer bar to a thickness of about 300 nm. The coated composition was dried at about 80 C. for about 2 minutes. The dried composition was vertically (0 degrees) irradiated with a polarized ultraviolet ray having an intensity of 200 mW/cm.sup.2 for 10 seconds and cured to form a first alignment film. The ball spacer composition was coated on the first alignment film to a thickness of about 60 nm using a #10 Meyer bar. The coated composition was dried at about 100 C. for about 2 minutes. The dried composition was vertically (0 degrees) irradiated with the polarized ultraviolet ray having an intensity of about 200 mW/cm.sup.2 for 10 seconds to fix the ball spacer to the first alignment film, thereby manufacturing a first substrate member.

(15) Manufacture of Second Substrate Member

(16) The second alignment film composition was coated on the ITO layer of the second electrode film (PC/ITO film, widthlength=100 mm100 mm) to a thickness of about 300 nm using a #4 Meyer bar. The coated composition was dried at about 80 C. for about 2 minutes. The dried composition was irradiated with the polarized ultraviolet ray having an intensity of about 200 mW/cm.sup.2 at a tilt angle of about 70 degrees for about 10 seconds to manufacture a second substrate member.

(17) Cell Lamination

(18) 1 g of liquid crystal composition (Merck, MDA-14-4145) comprising liquid crystals and an azo-based dye was applied on the first alignment film of the first substrate member, and then the second substrate member was laminated so that the second alignment film was in contact with the ball spacer, thereby manufacturing a cell.

Example 2

(19) A liquid crystal cell was produced in the same manner as in Example 1, except that upon manufacturing the second substrate member the polarized ultraviolet ray irradiation condition was changed to a tilt angle of about 45 degrees to manufacture an alignment film.

Example 3

(20) A liquid crystal cell was produced in the same manner as in Example 1, except that upon manufacturing the second substrate member the polarized ultraviolet ray irradiation condition was changed to a tilt angle of about 20 degrees to manufacture an alignment film.

Comparative Example 1

(21) A cell was produced in the same manner as in Example 1, except that upon manufacturing the second substrate member the irradiation angle of the polarized ultraviolet ray for forming the second alignment film was changed to the vertical (0 degrees).

Measurement Example 1Pre-Tilt Angle Measurement

(22) The pre-tilt angles of the second alignment films of the upper plates of Examples 1 to 3 and Comparative Example 1 were measured and the results were shown in Table 1 below. FIGS. 1 and 2 illustratively show the alignment states of liquid crystal compounds adjacent to the second alignment films of Examples 1 to 3 and Comparative Example 1, respectively. The pre-tilt angles were measured by measuring and simulating phase difference values by angle using an Axoscan (Axometics, Inc.) equipment. Specifically, isotropic base materials coated with the second alignment films were formed into an anti-parallel orientation structure to manufacture a device having a cell gap of 3 m, and then the pre-tilt angles were measured by measuring phase differences at intervals of 0.1 degrees from 70 degrees to 70 degrees and then simulating from the molecular arrangement of the liquid crystal layer using 22 Jones matrix through differences in the phase differences at the same angles.

(23) TABLE-US-00001 TABLE 1 Pre-tilt angle () Example 1 12.5 Example 2 5.5 Example 3 0.45 Comparative Example 1 0.06

Evaluation Example 1Domain Size Evaluation (Microscopic Observation)

(24) For Examples 1 to 3 and Comparative Example 1, it was evaluated whether the uniform driving was performed. Specifically, it was evaluated by a method of measuring the reverse tilt domain sizes expressed by the liquid crystal at low voltage drive (3V) with a microscope.

(25) FIGS. 3 to 5 and FIG. 6 are drive images of Examples 1 to 3 and Comparative Example 1, respectively. The left images in FIGS. 3 to 5 and FIG. 6 are cell photographs at 3V (AC), and the right images in FIGS. 3 to 5 and 6 are microscopic photographs (4 magnification) at 3V (AC). From FIGS. 3 to 5, Examples 1 to 3 are observed as reverse tilt domains having a size of about 10 m to 30 m, and from FIG. 6, Comparative Example 1 is observed as a reverse tilt domain having a size of about 200 m to 500 m, whereby it can be seen that Example 1 is driven uniformly over Comparative Example 1.

Evaluation Example 2Evaluation of Electrooptical Characteristics (Hazemeter Measurement)

(26) For Example 1 and Comparative Example 1, it was evaluated whether the uniform driving was performed. Specifically, it was evaluated for elements of Example 1 and Comparative Example 1 by a method of measuring haze values according to angles (viewing angles) using a hazemeter (NDH-5000SP) equipment, while applying a voltage.

(27) FIG. 7 shows the results of measurement of haze values of Example 1 and Comparative Example 1 according to angles. As shown in FIG. 7, Example 1 exhibits 5.71% at 0 degrees, 4.50% at 10 degrees, 4.04% at 20 degrees and 3.38% at 30 degrees, and Comparative Example 1 exhibits 9.48% at 0 degrees, 9.38% at 10 degrees, 8.40% at 20 degrees and 6.79% at 30 degrees, whereby it can be confirmed that the haze values of Comparative Example 1 according to the angles are larger than those of Example 1. The results are caused by the fact that the reverse tilt domain size of Comparative Example 1 is larger than that of Example 1, from which it can be seen that Example 1 is driven more uniformly than Comparative Example 1.

EXPLANATION OF REFERENCE NUMERALS

(28) 11: first electrode film 12: first alignment film 13: ball spacer 14: cured product 21: second electrode film 22: second alignment film 30: liquid crystal layer 31: liquid crystal compound