# US 10,369,768 B2 · Cover element provided with transparent pressure-sensitive adhesive layer

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- Number: US 10,369,768 B2
- Document ID: US10369768B2
- Status: Granted
- Kind: B2
- Application number: 15/552,706
- Filed: 2016-07-11
- Published: 2018-02-22
- Granted: 2019-08-06
- Earliest claimed: 2015-07-22
- Assignees: Nitto Denko Corporation
- Applicants: Nitto Denko Corporation
- Inventors: Hirofumi Katami; Atsushi Yasui
- Web page: https://patentgrep.com/patent/US10369768B2

## CPC

- B32B 5/16: characterised by features of a layer formed of particles, e.g. chips, powder {or granules (layer formed of natural mineral particles B32B19/00; layer being formed of wood fibres, chips or particles B32B21/02)}
- B32B 5/26: another layer {next to it} also being fibrous or filamentary {(relative arrangement of fibres or filaments of different layers B32B5/12)}
- B32B 5/30: one layer {being formed of particles, e.g. chips,} granules, powder
- B32B 7/12: using interposed adhesives or interposed materials with bonding properties
- B32B 17/06: comprising glass as the main or only constituent of a layer, next to another layer of a specific {material}
- B32B 23/04: comprising such {cellulosic plastic} substance as the main or only constituent of a layer, {which is} next to another layer of {the same or of} a {different material (next to a glass layer B32B17/08)}
- B32B 23/08: of synthetic resin
- B32B 27/00: Layered products comprising {a layer of} synthetic resin {(fibrous or filamentary layer made of a synthetic resin B32B5/02; particulate layer made of a synthetic resin B32B5/16; foamed layer made of a synthetic resin B32B5/18)}
- B32B 27/06: as the main or only constituent of a layer, {which is} next to another layer of {the same or of} a {different material (next to a layer of a particular substance B32B9/045; next to a bituminous or tarry layer B32B11/046; next to a water setting substance layer B32B13/12; next to a metal layer B32B15/08; next to a glass layer B32B17/10; next to a layer formed of natural mineral fibres or particles B32B19/045; next to a wood layer B32B21/08; next to a cellulosic plastic layer B32B23/08; next to a natural or synthetic rubber layer B32B25/08)}
- B32B 27/08: of synthetic resin
- B32B 27/12: next to a fibrous or filamentary layer
- B32B 27/14: next to a particulate layer
- B32B 27/28: comprising synthetic resins not wholly covered by any one of the sub-groups {B32B27/30 - B32B27/42}
- B32B 27/281: {comprising polyimides}
- B32B 27/283: {comprising polysiloxanes}
- B32B 27/286: {comprising polysulphones; polysulfides}
- B32B 27/30: comprising vinyl {(co)polymers; comprising acrylic (co)polymers}
- B32B 27/302: {comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers}
- B32B 27/306: {comprising vinyl acetate or vinyl alcohol (co)polymers}
- B32B 27/308: {comprising acrylic (co)polymers}
- B32B 27/32: comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)}
- B32B 27/325: {comprising polycycloolefins}
- B32B 27/34: comprising polyamides
- B32B 27/36: comprising polyesters
- B32B 27/365: {comprising polycarbonates}
- B32B 27/40: comprising polyurethanes
- C03C 27/10: with the aid of adhesive specially adapted for that purpose
- C08K 3/22: of metals
- C09J 7/10: without carriers
- C09J 201/00: Adhesives based on unspecified macromolecular compounds
- G06F 3/041: Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
- B32B 2255/10: on synthetic resin layer or on natural or synthetic rubber layer
- B32B 2255/20: Inorganic coating
- B32B 2255/205: Metallic coating
- B32B 2255/26: Polymeric coating
- B32B 2255/28: Multiple coating on one surface
- B32B 2260/021: Fibrous or filamentary layer
- B32B 2260/025: Particulate layer
- B32B 2260/046: Synthetic resin
- B32B 2262/0261: Polyamide fibres
- B32B 2262/04: Cellulosic plastic fibres, e.g. rayon
- B32B 2262/101: Glass fibres
- B32B 2264/102: Oxide or hydroxide
- B32B 2307/202: Conductive
- B32B 2307/21: Anti-static
- B32B 2307/4026: within the layer by addition of a colorant, e.g. pigments, dyes
- B32B 2307/412: Transparent
- B32B 2307/418: Refractive
- B32B 2307/51: Elastic
- B32B 2307/54: Yield strength; Tensile strength
- B32B 2307/708: Isotropic
- B32B 2307/732: Dimensional properties
- B32B 2405/00: Adhesive articles, e.g. adhesive tapes
- B32B 2457/00: Electrical equipment
- B32B 2457/204: Plasma displays
- B32B 2457/206: Organic displays, e.g. OLED
- C08K 2201/002: Physical properties
- C09J 2203/318: for the production of liquid crystal displays
- C09J 2301/1242: the opposite adhesive layers being different
- C09J 2301/302: the adhesive being pressure-sensitive, i.e. tacky at temperatures inferior to 30°C
- C09J 2301/408: additives as essential feature of the adhesive layer
- G02F 2202/28: Adhesive materials or arrangements
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- C09J: ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES (preparation of glue or gelatine C09H)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS

## Abstract

The present invention provides a cover element having a pressure-sensitive adhesive sheet preliminarily laminated thereto, wherein the pressure-sensitive adhesive sheet comprises a pressure-sensitive adhesive layer in which a refractive index adjustment zone having a refractive index greater than that of a base pressure-sensitive adhesive material thereof is formed over a given range from a surface of the pressure-sensitive adhesive layer in a thickness direction thereof, whereby: in a lamination process of a customer which is a supply destination of the cover element, it becomes possible to eliminate a need to distinguish between obverse and reverse sides of the pressure-sensitive adhesive sheet itself; and, when the cover element is bonded to an optical element through the pressure-sensitive adhesive layer, it becomes possible to suppress internal reflection in a laminate formed of these optical elements.

## Claims

### Claim 1

A cover element provided with a transparent pressure-sensitive adhesive layer, wherein:
the pressure-sensitive adhesive layer is made of a transparent base pressure-sensitive adhesive material and is a single-layer having two principal surfaces opposite to each other,
the pressure-sensitive adhesive layer comprises:
a base adhesive zone made essentially of the transparent base pressure-sensitive adhesive material and formed over a given range from a first one of the two principal surfaces of the pressure-sensitive adhesive layer in a thickness direction of the pressure-sensitive adhesive layer; and
a transparent, adherent, refractive index adjustment zone formed over a given range from a second one of the two principal surfaces of the single-layered pressure-sensitive adhesive layer in the thickness direction,
the base adhesive zone is in contact with the cover element,
the refractive index adjustment zone includes a material having a refractive index greater than a refractive index of the base pressure-sensitive adhesive material in the single-layered pressure-sensitive adhesive layer,
the base adhesive zone is free of the material having the refractive index greater than refractive index of the base pressure-sensitive material, and
a boundary between the refractive index adjustment zone and the base adhesive zone in the pressure-sensitive adhesive layer is formed as an irregular undulating curve.

### Claim 2 (depends on 1)

The cover element as recited in claim 1, which is a glass substrate or a transparent resin substrate.

### Claim 3 (depends on 1)

The cover element as recited in claim 1, wherein the refractive index adjustment zone has a thickness of 20 nm to 600 nm.

### Claim 4 (depends on 1)

The cover element as recited in claim 1, wherein the refractive index adjustment zone is formed by dispersing, in a pressure-sensitive adhesive material identical to the base pressure-sensitive adhesive material, particles of a high refractive index material having a refractive index greater than that of the pressure-sensitive adhesive material, to thereby increase an average refractive index of the refractive index adjustment zone.

### Claim 5 (depends on 4)

The cover element as recited in claim 4, wherein the refractive index of the high refractive index material particles is in the range of 1.60 to 2.74.

### Claim 6 (depends on 4)

The cover element as recited in claim 4, wherein the high refractive index material particles have an average primary particle size of 3 nm to 100 nm as measured by TEM observation.

### Claim 7 (depends on 4)

The cover element as recited in claim 4, wherein a difference between the refractive index of the high refractive index material particles and the refractive index of the base pressure-sensitive adhesive material is in the range of 0.15 to 1.34.

### Claim 8 (depends on 4)

The cover element as recited in claim 4, wherein the high refractive index material is one or more compounds selected from the group consisting of TiO2, ZrO2, CeO2, Al2O3, BaTiO3, Nb2O5 and SnO2.

### Claim 9 (depends on 1)

The cover element as recited in claim 1, wherein the refractive index adjustment zone is formed by adding, to a pressure-sensitive adhesive material identical to the base pressure-sensitive adhesive material, an organic material having a refractive index greater than that of the pressure-sensitive adhesive material, in the form of particle, polymer or oligomer, to thereby increase an average refractive index of the refractive index adjustment zone.

### Claim 10 (depends on 9)

The cover element as recited in claim 9, wherein the refractive index of the base pressure-sensitive adhesive material is in the range of 1.40 to 1.55, and the refractive index of the organic material is in the range of 1.59 to 2.04.

### Claim 11 (depends on 1)

The cover element as recited in claim 1, wherein the pressure-sensitive adhesive layer has a total light transmittance of 80% or more.

### Claim 12 (depends on 4)

The cover element as recited in claim 4, wherein the high refractive index material particles partially exist in the form of an aggregate arising from aggregation of two or more thereof.