JP7184510B2 - Light-transmitting conductive film for light control film and light control film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a light-transmissive conductive film for a light-control film, which is used for a light-control film and has light transmission properties and electrical conductivity. The present invention also relates to a light control film using the light-transmitting conductive film for a light control film.

Light control materials and the like are used in light control films and the like. Light modulating materials are used for the purpose of adjusting transmittance or adjusting color tone by blocking light of a specific wavelength. Light control films are used in various fields such as interior materials, building materials and electronic parts.

For example, Patent Document 1 below discloses a light control film including two transparent conductive resin substrates and a light control layer sandwiched between the two transparent conductive resin substrates. The light management layer includes a resin matrix and a light control suspension dispersed in the resin matrix. The thickness of the transparent conductive resin substrate is 130 to 500 μm. In the transparent conductive resin substrate, a transparent conductive film is formed on the transparent resin substrate by coating or the like.

WO2008/075772A1

As described in Patent Document 1, a transparent conductive resin substrate (light-transmitting conductive film) having a conductive film (conductive layer) is used in a light control film.

A light-transmissive conductive film is generally required to have a high total light transmittance and a low surface resistance of the conductive layer. However, with conventional light-transmitting conductive films, it is difficult to effectively increase the total light transmittance and to effectively reduce the surface resistance of the conductive layer. Furthermore, the present inventors have found that the surface resistance varies when the surface resistance of the conductive layer of the light-transmitting conductive film is measured at a plurality of points.

An object of the present invention is to provide a light-transmitting film for a light control film that can effectively increase the total light transmittance, effectively reduce the surface resistance of the conductive layer, and further improve the uniformity of the surface resistance of the conductive layer. An object of the present invention is to provide a conductive film. Moreover, this invention is providing the light control film using the said light transmissive conductive film for light control films.

The present inventors have found a configuration that can effectively increase the total light transmittance and effectively reduce the surface resistance of the conductive layer. Furthermore, the present inventors have found a configuration that can effectively reduce variations in the surface resistance of the conductive layer.

According to a broad aspect of the present invention, a light-transmitting and electrically conductive film used for a light control film, a base film having light-transmitting properties, and a first base film of the base film and a light-transmitting conductive layer disposed on the surface side, wherein the conductive layer has an average thickness of 15 nm or more and 35 nm or less, and the standard deviation of the thickness of the conductive layer is less than 1.0 nm . A light-transmitting conductive film for a light control film (hereinafter sometimes referred to as "light-transmitting conductive film") is provided.

In a specific aspect of the light-transmitting conductive film according to the present invention, the conductive layer has a surface resistance of 180Ω/□ or less.

In a specific aspect of the light transmissive conductive film according to the present invention, the total light transmittance at a wavelength of 550 nm is 86% or more.

In a specific aspect of the light-transmissive conductive film according to the present invention, the haze value is 1.3% or less.

In a broad aspect of the present invention, it comprises two light-transmitting conductive films and a light-modulating layer, wherein the two light-transmitting conductive films are the light-transmitting conductive films for light-control films described above, and the two light-transmitting conductive films A light control film is provided in which the light control layer is arranged between the conductive layer sides of the light-transmissive conductive film.

In the light-transmissive conductive film for a light control film according to the present invention, the total light transmittance is effectively increased, the surface resistance of the conductive layer is effectively decreased, and the uniformity of the surface resistance of the conductive layer is increased. be able to.

FIG. 1 is a cross-sectional view showing a light-transmissive conductive film for a light control film according to one embodiment of the present invention. FIG. 2 is a cross-sectional view showing an example of a light control film using the light-transmitting conductive film for a light control film shown in FIG. 1. FIG.

Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

FIG. 1 is a cross-sectional view showing a light-transmissive conductive film for a light control film according to one embodiment of the present invention.

A light-transmissive conductive film 1 shown in FIG. 1 is used for a light control film.

The light-transmissive conductive film 1 includes a base film 11 and a conductive layer 12 .

The base film 11 has optical transparency. The base film 11 is made of a material with high light transmittance. The base film 11 has a first surface 11a and a second surface 11b. The first surface 11a and the second surface 11b face each other.

A conductive layer 12 is arranged on the first surface 11a side of the base film 11 . The conductive layer 12 has optical transparency. The conductive layer 12 is made of a material having high light transmittance and high conductivity. The conductive layer 12 is laminated directly on the first surface 11 a of the base film 11 . The conductive layer does not have to be laminated directly on the first surface of the base film. For example, an undercoat layer may be placed between the conductive layer and the base film.

The average thickness of the conductive layer 12 is 15 nm or more and 35 nm or less. The standard deviation of the thickness of the conductive layer 12 is less than 1.0 nm .

Like the light-transmitting conductive film 1, the light-transmitting conductive film for a light control film according to the present invention includes a light-transmitting base film and a first surface side of the base film. and a light-transmitting conductive layer, the average thickness of the conductive layer is 15 nm or more and 35 nm or less, and the standard deviation of the thickness of the conductive layer is less than 1.0 nm .

Since the light-transmitting conductive film according to the present invention has the above configuration, the average thickness of the conductive layer is 15 nm or more and 35 nm or less, and the standard deviation of the thickness of the conductive layer is 1.0. Since the thickness is less than nm , the total light transmittance can be effectively increased, the surface resistance of the conductive layer can be effectively decreased, and the uniformity of the surface resistance of the conductive layer can be increased. Furthermore, the present invention can effectively lower the haze value of the light control film when transparent.

From the viewpoint of further effectively increasing the total light transmittance, further effectively lowering the surface resistance of the conductive layer, and further improving the uniformity of the surface resistance, the average thickness of the conductive layer is preferably is 17 nm or more, preferably 30 nm or less. Moreover, electroconductivity becomes it still higher that the average thickness of the said conductive layer is more than the said minimum.

The average thickness of the conductive layer is preferably the average value of the measurement results at 10 points, and is preferably the average thickness at 10 points.

When the thickness of the conductive layer and the surface resistance of the conductive layer are measured at 10 points, it is preferable that the 10 measurement points are separated from each other by 10 mm or more.

From the viewpoint of further effectively increasing the total light transmittance, further effectively lowering the surface resistance of the conductive layer, and further improving the uniformity of the surface resistance, the standard deviation of the thickness of the conductive layer is , preferably 0.8 nm or less.

The standard deviation of the thickness of the conductive layer is preferably the standard deviation at 10 points. When the thickness of the conductive layer is measured at 10 points, the standard deviation of the thickness of the conductive layer is preferably the standard deviation of the results of measuring the thickness of the conductive layer at 10 points.

From the viewpoint of lowering the haze value of the light control film when transparent, the surface resistance of the conductive layer is preferably 180 Ω/□ or less, more preferably 170 Ω/□ or less, even more preferably 150 Ω/□ or less, and particularly preferably It is 100Ω/□ or less. The surface resistance of the conductive layer is usually 0Ω/□ or more.

The surface resistance of the conductive layer is measured on the surface side of the conductive layer opposite to the substrate film side.

The surface resistance of the conductive layer is preferably the average value of the measurement results at 10 points, and is preferably the average surface resistance at 10 points.

When the surface resistance of the conductive layer is measured at 10 points, the absolute value of the difference between the maximum value and the minimum value of the surface resistance measured at 10 points is preferably 15 Ω/□ or less, more preferably 9 Ω/□. It is below. When the absolute value of the difference between the maximum value and the minimum value of the surface resistance measurement results at 10 points is equal to or less than the above upper limit, the transmittance of the light control film is lowered and the color variation of the light control film is reduced. be able to.

The surface resistance is measured by a four-probe method using a surface resistance meter ("Loresta-EP" manufactured by MITSUBISHI CHEMICAL ANALYTECH, or equivalent).

From the viewpoint of further increasing light transmittance, the total light transmittance of the light-transmitting conductive film at a wavelength of 550 nm is preferably 86% or more, more preferably 88% or more, and still more preferably 89% or more. In addition, the total light transmittance of the light-transmitting conductive film at a wavelength of 550 nm is usually 100% or less.

The total light transmittance is measured according to JIS K7105 using a haze meter (“NDH 2000” manufactured by Nippon Denshoku Industries Co., Ltd., or equivalent).

From the viewpoint of further increasing light transmittance, the haze value of the light-transmitting conductive film is preferably 1.3% or less, more preferably 0.8% or less, and even more preferably 0.7% or less. In addition, the haze value of the said light transmissive conductive film is 0 % or more normally.

The haze value is measured based on JIS K7136 using a haze meter (“NDH 2000” manufactured by Nippon Denshoku Industries Co., Ltd., or equivalent).

The light-transmissive conductive film according to the present invention is used as a light control film.

FIG. 2 is a cross-sectional view showing an example of a light control film using the light-transmitting conductive film for a light control film shown in FIG. 1. FIG.

The light control film 21 shown in FIG. 2 includes two light-transmissive conductive films 1 and a light control layer 31 . A light modulating layer 31 is arranged between two light transmissive conductive films 1 . Specifically, the light control layer 31 is arranged between the two conductive layers 12 . The two light-transmitting conductive films 1 are first and second light-transmitting conductive films.

Like the light control film 21, the light control film according to the present invention includes two light-transmissive conductive films according to the present invention (a first light-transmissive conductive film and a second light-transmissive conductive film) and a light-transmissive conductive film. and a light layer, and the light control layer is arranged between the first light-transmitting conductive film and the second light-transmitting conductive film.

Other details of the light-transmissive conductive film according to the present invention will be described below.

(Base film)
The base film preferably has high light transmittance. Materials for the base film are not particularly limited, but examples include polyolefin, polyether sulfone, polysulfone, polycarbonate, cycloolefin polymer, cycloolefin copolymer, polyarylate, polyamide, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, Examples include polyethylene naphthalate, triacetyl cellulose, and cellulose nanofiber. The material of the base film is preferably resin. The material of the base film is preferably polyethylene terephthalate because it can effectively increase the light transmittance. The materials for the base film may be used alone or in combination.

From the viewpoint of further increasing light transmittance, the total light transmittance of the substrate film at a wavelength of 550 nm is preferably 88% or higher, more preferably 90% or higher, and even more preferably 91% or higher. The total light transmittance of the substrate film at a wavelength of 550 nm is usually 100% or less.

The base film may contain various stabilizers, UV absorbers, plasticizers, lubricants or colorants.

(Conductive layer)
The conductive layer is made of a conductive material having optical transparency. Examples of the conductive material include, but are not limited to, In-based oxides such as IZO (indium zinc oxide ₎ and ITO (indium tin oxide); Zn-based oxides such as AZO (aluminum zinc oxide) and GZO (gallium zinc oxide), sodium, sodium-potassium alloy, lithium, magnesium, aluminum, magnesium-silver mixture, magnesium-indium mixture, aluminum - Lithium alloys, Al/Al ₂ O ₃ mixtures, Al/LiF mixtures, metals such as gold, CuI, Ag nanowires (AgNW), carbon nanotubes (CNT) and conductive transparent polymers. The above conductive materials may be used alone or in combination.

From the viewpoint of further increasing conductivity and further increasing light transmittance, the above-described conductive materials include In-based oxides such as IZO (indium zinc oxide) and ITO (indium tin oxide), SnO ₂ , and FTO. Sn-based oxides such as (fluorine-doped tin oxide) and Zn-based oxides such as AZO (aluminum zinc oxide) and GZO (gallium zinc oxide) are preferred. From the viewpoint of further increasing conductivity and further increasing light transmittance, the conductive material is more preferably AZO (aluminum zinc oxide) or ITO (indium tin oxide). It is more preferable that it is a product).

A method for forming the conductive layer is not particularly limited. For example, a method of etching a metal film formed by vapor deposition or sputtering, various printing methods such as screen printing or inkjet printing, and known patterning methods such as photolithography using a resist can be used. The formed conductive layer is preferably used after being subjected to an annealing treatment to increase the crystallinity.

Hereinafter, the present invention will be described in more detail based on specific examples. In addition, the present invention is not limited to the following examples.

( Reference example 1)
A conductive layer was formed on one surface of a polyethylene terephthalate (PET) film having a thickness of 125 μm as follows to obtain a light-transmissive conductive film.

A transparent conductive layer was formed on the PET film by a DC magnetron sputtering method using a sintered material containing 93% by weight of indium oxide and 7% by weight of tin oxide as a target material. Specifically, after evacuating the chamber to 5×10 ⁻⁴ Pa or less, a mixed gas of Ar gas: 95% and oxygen gas: 5% was introduced into the chamber so that the chamber pressure was 0.67 Pa. to form an ITO layer (transparent conductive layer) having an average thickness shown in Table 1. The PET film deposited with the ITO layer was heated in an oven at 150° C. for 60 minutes to obtain a light-transmissive conductive film.

( Reference example 2)
A light-transmissive conductive film was obtained in the same manner as in Reference Example 1, except that the film formation time was lengthened and the average thickness of the ITO layer was changed as shown in Table 1.

( Reference example 3)
Reference example except that the flow rate of the mixed gas was changed so that the chamber pressure during film formation was 0.33 Pa, and the average thickness of the ITO layer was changed as shown in Table 1 along with this change in flow rate. A light-transmissive conductive film was obtained in the same manner as in 1.

( Reference example 4)
Reference example except that the flow rate of the mixed gas was changed so that the chamber pressure during film formation was 0.33 Pa, and the average thickness of the ITO layer was changed as shown in Table 1 along with this change in flow rate. A light-transmissive conductive film was obtained in the same manner as in Example 2.

( Reference example 5)
Same as Reference Example ₁ except that a SiO film was formed on a PET film with a thickness of 125 μm by AC magnetron sputtering using a sintered material of polycrystalline Si with a Si purity of 99.9% as a target material. Then, a light-transmitting conductive film was obtained. Specifically, after evacuating the chamber to 5×10 ⁻⁴ Pa or less, a mixed gas of Ar gas: 95% and oxygen gas: 5% was introduced into the chamber, and SiO ₂ with a thickness of 23 nm was introduced. A film was deposited and an ITO layer with an average thickness shown in Table 1 was deposited on this SiO ₂ layer.

(Example 6)
A light-transmissive conductive film was obtained in the same manner as in Reference Example 5, except that the film formation time was lengthened and the average thickness of the ITO layer was changed as shown in Table 1.

( Reference example 7)
A light-transmitting conductive film was obtained in the same manner as in Reference Example 1, except that the base film was changed to a cycloolefin copolymer (COP) film having a thickness of 50 µm. In Reference Example 7, an ITO layer with an average thickness of 15.5 nm was formed.

( Reference example 8)
In the same manner as in Reference Example 5, except that a sintered material of zinc oxide: 97% by weight and alumina: 3% by weight was used as a target material, and an AZO layer was formed on the _SiO2 layer. A conductive film was obtained. In Reference Example 8, an AZO layer having an average thickness of 30.1 nm was formed.

( Reference example 9)
A light-transmitting conductive film was obtained in the same manner as in Reference Example 8, except that the film formation time was lengthened and the average thickness of the AZO layer was changed as shown in Table 1.

(Comparative example 1)
A light-transmitting conductive film was obtained in the same manner as in Reference Example 1, except that the film formation time was shortened and the average thickness of the ITO layer was changed as shown in Table 1.

(Comparative example 2)
A light-transmissive conductive film was obtained in the same manner as in Reference Example 1, except that the film formation time was lengthened and the average thickness of the ITO layer was changed as shown in Table 1.

(Comparative Example 3)
A SiO ₂ film was formed on a 125 μm-thick PET film by AC magnetron sputtering using a sintered material of polycrystalline Si with a Si purity of 99.9% as a target material. Specifically, after the inside of the chamber was evacuated to 5×10 ⁻⁴ Pa or less, Ar gas was introduced into the chamber to deposit a SiO ₂ film equivalent to a thickness of 1 nm. A light-transmitting conductive film was obtained in the same manner as in Reference Example 1, except that an ITO layer having an average thickness shown in Table 1 was formed on this SiO ₂ film.

(evaluation)
(1) Average Thickness of Conductive Layer and Standard Deviation of Conductive Layer Thickness The thickness (optical film thickness) of the conductive layer was calculated by measuring the specular reflectance and performing an optical simulation based on the measured value. Specifically, for reflectance measurement, a 5° regular reflection unit attached to a spectrophotometer ("U4100" manufactured by Hitachi, Ltd., or equivalent) is attached, and the incident angle is set to 5° using the regular reflection mode. As a wavelength: 200 ~ 800nm (measurement range) reflection spectrum was measured.

In addition, in order to eliminate the reflection from the back side of the light-transmitting conductive film (sample) and the reflection from the back side at the time of measurement, a black tape ("NO200-50-21" manufactured by Yamato Co., Ltd.) was attached to the back side of the sample. attached. The back surface of the sample is the surface opposite to the conductive layer side of the light-transmitting conductive film. Optical simulation software ("WVASE32" manufactured by JA Woollam) was used to fit the shape of the specular reflection spectrum and the positions of peaks and valleys, and the thickness of the conductive layer was calculated.

The thickness of the conductive layer was measured at 10 points. The average value of the ten measurement results was taken as the average thickness of the conductive layer. In addition, the standard deviation of the thickness of the conductive layer at 10 points was obtained from the measurement results of the thickness of the conductive layer at 10 points.

(2) Surface resistance of the conductive layer (sheet resistance) and the absolute value of the difference between the maximum value and the minimum value of the measurement results of the surface resistance of the conductive layer at 10 points ("Loresta-EP" manufactured by Sanyo Denki Co., Ltd.) was measured by the four-probe method. The surface resistance of the surface opposite to the base film side of the conductive layer was measured at 10 points. The average value of the ten measurement results was taken as the surface resistance of the conductive layer. In addition, the absolute value of the difference between the maximum value and the minimum value of the ten measurement results of the surface resistance of the conductive layer was obtained.

(3) Total light transmittance of light-transmitting conductive film The total light transmittance was measured based on JIS K7105 using a haze meter (“NDH 2000” manufactured by Nippon Denshoku Industries Co., Ltd.). The total light transmittance at a wavelength of 550 nm of the light-transmitting conductive film was obtained.

(4) Haze value of light-transmitting conductive film The haze value was measured according to JIS K7136 using a haze meter (“NDH 2000” manufactured by Nippon Denshoku Industries Co., Ltd.).

The results are shown in Table 1 below.

DESCRIPTION OF SYMBOLS 1... Light transmissive conductive film 11... Base film 11a... 1st surface 11b... 2nd surface 12... Conductive layer 21... Light control film 31... Light control layer

Claims (9)

A light-transmissive and conductive film used for a light control film,
a base film having optical transparency;
a conductive layer disposed on the first surface side of the base film and having optical transparency;
An undercoat layer disposed between the base film and the conductive layer,
When the thickness of the conductive layer is measured at 10 points separated by 10 mm or more , and the surface resistance of the conductive layer is measured at 10 points separated by 10 mm or more,
The average thickness of the conductive layer at 10 locations is 30.3 nm or more and 35 nm or less,
The standard deviation of the thickness at 10 locations of the conductive layer is less than 1.0 nm,
A light-transmitting conductive film for a light control film, wherein the absolute value of the difference between the maximum value and the minimum value of surface resistance at 10 locations of the conductive layer is 3Ω/□ or less. 2. The light-transmissive conductive film for a light control film according to claim 1, wherein the standard deviation of the thickness of said conductive layer at 10 locations is 0.42 nm or less. The light-transmissive conductive film for a light control film according to claim 1 or 2, wherein the conductive layer is a single-layer conductive layer. 4. The light-transmitting conductive film according to any one of claims 1 to 3, except for a light-transmitting conductive film for a light control film, in which the surface of the conductive layer opposite to the base film side has a surface roughness of 7 nm or more and 20 nm or less. Light transmissive conductive film for light control film. 5. The light-transmitting conductive film for a light control film according to claim 1, wherein the average value of surface resistance at 10 locations of said conductive layer is 180Ω/□ or less. 6. The light-transmitting conductive film for a light control film according to claim 1, which has a total light transmittance of 86% or more at a wavelength of 550 nm. 7. The light-transmitting conductive film for a light control film according to claim 1, which has a haze value of 1.3% or less. The light-transmitting conductive film for a light control film according to any one of claims 1 to 7, wherein the undercoat layer is a SiO ₂ layer. Equipped with two light-transmitting conductive films and a light control layer,
The two light-transmitting conductive films are the light-transmitting conductive film for a light control film according to any one of claims 1 to 8 ,
A light control film, wherein the light control layer is arranged between the conductive layer sides of the two light transmissive conductive films.

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