# US 12,181,630 B2 · Low-refractive-index film, laminate, optical element, windbreak material, and display device

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 12,181,630 B2
- Document ID: US12181630B2
- Status: Granted
- Kind: B2
- Application number: 17/904,905
- Filed: 2021-02-01
- Published: 2023-04-13
- Granted: 2024-12-31
- Earliest claimed: 2020-02-28
- Assignees: Nippon Sheet Glass Co., Ltd.
- Applicants: Nippon Sheet Glass Company, Limited
- Inventors: Satoru Kusaka; Koichiro Nakamura; Hisao Imai; Hiroyuki Tanaka
- Web page: https://patentgrep.com/patent/US12181630B2

## CPC

- G02B 1/111: using layers comprising organic materials
- G02B 1/118: having sub-optical wavelength surface structures designed to provide an enhanced transmittance, e.g. moth-eye structures
- B32B 17/06: comprising glass as the main or only constituent of a layer, next to another layer of a specific {material}
- B32B 2255/20: Inorganic coating
- B32B 2255/28: Multiple coating on one surface
- B32B 2457/20: Displays, e.g. liquid crystal displays, plasma displays
- B32B 2551/00: Optical elements
- G02B 1/14: Protective coatings, e.g. hard coatings
- G02B 2207/107: Porous materials, e.g. for reducing the refractive index
- G02B 2207/109: Sols, gels, sol-gel materials
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM

## Abstract

A low-refractive-index film 10 includes a first layer 11 and a second layer 12. The first layer 11 is adjacent to a substrate 20. The low-refractive-index film 10 has a refractive index of greater than or equal to 1.01 and less than or equal to 1.30. The first layer 11 and the second layer 12 each include hollow particles 13 and a binder 14. The first layer 11 satisfies, for example, at least one selected from a group of conditions (I) and (II) described below. (I) A number density ρv1 of voids 15 each having a cross-sectional area of greater than or equal to 1000 nm2 is greater than or equal to 5/μm2 and less than or equal to 100/μm2 on a cross-section of the first layer 11. (II) A ratio of a cross-sectional area of the voids 15 on the cross-section to a total area of the cross-section of the first layer 11 is greater than or equal to 5% and less than or equal to 70%.

## Claims

### Claim 1

A low-refractive-index film comprising a first layer and a second layer,
the low-refractive-index film being configured to be provided on or above a substrate with the first layer between the second layer and the substrate,
the low-refractive-index film having a refractive index greater than or equal to 1.01 and less than or equal to 1.25,
the first layer and the second layer each including:
hollow particles
a binder, and
a plurality of voids each with cross-sectional area of 1000 nm2 or more in a cross-sectional view,
the first layer having a thickness less than or equal to half a thickness of the low-refractive-index film and less than or equal to 200 nm,
the first layer having a first number density of the voids in a cross section view of the first layer,
the second layer having a second number density of the voids in a cross section view of the second layer,
the first number density being 13/μm2 or more and 100/μm2 or less, and
the first number density being greater than the second number density.

### Claim 2 (depends on 1)

The low-refractive-index film according to claim 1,
the first layer further having a first ratio of the total cross-sectional area of voids with each cross-sectional area of 1000 nm2 or more to the cross-sectional area of the first layer,
the second layer further having a second ratio of the total cross-sectional area of voids with each cross-sectional area of 1000 nm2 or more to the cross-sectional area of the second layer,
the first ratio being 26% or more and 70% or less, and
the first ratio being greater than the second ratio.

### Claim 3 (depends on 1)

The low-refractive-index film according to claim 1,
the low-refractive-index film having a thickness dt of greater than or equal to 70 nm, wherein
a thickness d1 of the first layer equals dt/2 in a first case of 70 nm≤dt≤400 nm or 200 nm in a second case of 400 nm<dt.

### Claim 4 (depends on 1)

The low-refractive-index film according to claim 1, wherein an average particle diameter of the hollow particles is greater than or equal to 20 nm and less than or equal to 100 nm.

### Claim 5 (depends on 1)

The low-refractive-index film according to claim 1, wherein a ratio of a content of the binder to a content of the hollow particles is greater than or equal to 0.2 and less than or equal to 20 on a mass basis.

### Claim 6 (depends on 1)

A laminate sequentially comprising
a substrate, and
the low-refractive-index film according to claim 1.

### Claim 7 (depends on 6)

The laminate according to claim 6, wherein an arithmetic average roughness, of a surface of the substrate, determined in accordance with Japanese Industrial Standards (JIS) B 0601-1994 is greater than or equal to 0.3 nm and less than or equal to 140 nm.

### Claim 8 (depends on 6)

The laminate according to claim 6, wherein a contact angle of a water droplet on a surface of the substrate is greater than or equal to 5° and less than or equal to 140°.

### Claim 9 (depends on 6)

The laminate according to claim 6, the laminate further comprising an underlayer forming a surface of the substrate.

### Claim 10 (depends on 9)

The laminate according to claim 9, wherein the underlayer contains at least one selected from a group of silica and silsesquioxane.

### Claim 11 (depends on 9)

The laminate according to claim 9, wherein the underlayer has a thickness of 5 to 50 nm.

### Claim 12 (depends on 1)

A laminate comprising:
a substrate;
at least one selected from a group of an anti-fogging film, a water-repellent film, an oil-repellent film, and a hydrophilic film formed on the substrate; and
the low-refractive-index film according to claim 1.

### Claim 13 (depends on 1)

An optical element comprising a surface formed by the low-refractive-index film according to claim 1.

### Claim 14 (depends on 1)

A windshield comprising the low-refractive-index film according to claim 1.

### Claim 15 (depends on 1)

A display device comprising the low-refractive-index film according to claim 1.