# US 9,519,090 B2 · Uniaxially stretched multi-layer laminate film, polarizing plate comprising same, optical member for liquid crystal display device, and liquid crystal display device

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- Number: US 9,519,090 B2
- Document ID: US9519090B2
- Status: Granted
- Kind: B2
- Application number: 14/407,324
- Filed: 2013-09-20
- Published: 2015-05-07
- Granted: 2016-12-13
- Earliest claimed: 2012-09-24
- Assignees: Teijin Limited
- Applicants: Teijin Limited
- Inventors: Taro Oya; Kana Tanabu; Takashi Nakahiro; Tetsuo Yoshida; Hiromi Shiroma; Tomoko Shimizu
- Web page: https://patentgrep.com/patent/US9519090B2

## CPC

- G02B 5/3025: {Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state (G02B5/3008, G02B5/3016 take precedence)}
- B32B 27/08: of synthetic resin
- B32B 27/20: using fillers, pigments, thixotroping agents
- B32B 27/36: comprising polyesters
- C08G 63/187: containing condensed aromatic rings
- C08G 63/189: containing a naphthalene ring
- C08G 63/199: Acids or hydroxy compounds containing cycloaliphatic rings
- G02B 1/04: made of organic materials, e.g. plastics (G02B1/08 takes precedence)
- G02B 5/208: {for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation}
- G02B 5/305: {including organic materials, e.g. polymeric layers}
- G02B 5/3083: {Birefringent or phase retarding elements (G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001)}
- G02F 1/133536: {Reflective polarizers (G02F1/13362 takes precedence)}
- G02F 1/1336: {Illuminating devices}
- B32B 2250/05: 5 or more layers
- B32B 2264/108: Carbon, e.g. graphite particles
- B32B 2307/42: Polarizing, birefringent, filtering
- B32B 2307/516: mono-axially
- B32B 2367/00: Polyesters, e.g. PET, i.e. polyethylene terephthalate
- B32B 2457/202: LCD, i.e. liquid crystal displays
- C09K 2323/03: Viewing layer characterised by chemical composition
- C09K 2323/031: Polarizer or dye
- G02F 2201/086: UV absorbing
- 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
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- 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
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE

## Abstract

A uniaxially stretched multi-layer laminate film that exhibits a high polarization performance of 99.5% or more in a simpler configuration than before, a polarizing plate that is composed of the same, an optical member for a liquid crystal display device, and a liquid crystal display device are provided. Namely, in the uniaxially stretched multi-layer laminate film in which a first layer and a second layer are alternately laminated, the uniaxially stretched multi-layer laminate film includes an intermediate layer that has a thickness of 2 μm or more and 30 μm or less; the first layer is composed of a polyester containing a naphthalene dicarboxylic acid ester; the second layer is composed of a copolymer polyester and is an optically isotropic layer that has an average refractive index of 1.50 or more and 1.60 or less; the first layer, the second layer, both first and second layers, or the intermediate layer contains a visible light absorbent, which has a weight loss of less than 10% when it is kept at 300° C. for 1 hour, in an amount of 200 ppm or more and 2500 ppm or less on the basis of the weight of the layer; the uniaxially stretched multi-layer laminate film has a polarization degree of 99.5 or more; and the average transmittance Ts for S-polarized light in a wavelength range of 400 nm to 800 nm is 60% or more.

## Claims

### Claim 1

A uniaxially stretched multi-layer laminate film, in which a first layer and a second layer are alternately laminated, comprising an intermediate layer which is inside of the alternately laminated configuration of the first and second layers and which has a thickness of 2 μm or more and 30 μm or less, wherein
(1) the first layer is composed of a polyester containing a naphthalene dicarboxylic acid ester,
(2) the second layer is composed of a copolymer polyester and is an optically isotropic layer having an average refractive index of 1.50 or more and 1.60 or less,
(3) the first layer, the second layer, both first and second layers, or the intermediate layer contains a visible light absorbent that exhibits a weight loss of less than 10% when the visible light absorbent is kept at 300° C. for 1 hour, in an amount of 200 ppm or more and 2500 ppm or less on the basis of the weight of each layer, and
(4) the uniaxially stretched multi-layer laminate film has a polarization degree (P %) represented by the following equation (1) of 99.5 or more and an average transmission Ts of 60% or more for S-polarized light in a wavelength range of 400 nm to 800 nm,
Polarization degree(P)={(Ts−Tp)/(Tp+Ts)}×100 (1)
wherein Tp represents an average transmission for P-polarized light in a wavelength range of 400 nm to 800 nm and Ts represents an average transmission for S-polarized light in a wavelength range of 400 nm to 800 nm.

### Claim 2 (depends on 1)

The uniaxially stretched multi-layer laminate film according to claim 1, wherein the second layer and/or the intermediate layer further contains a UV light absorbent that exhibits a weight loss of less than 3% when the UV light absorbent is kept at 300° C. for 1 hour, in an amount of 0.2 wt % to 5 wt %, and the uniaxially stretched multi-layer laminate film has a transmission of less than 5% for S-polarized light at 380 nm.

### Claim 3 (depends on 2)

The uniaxially stretched multi-layer laminate film according to claim 2, wherein the transmission of the uniaxially stretched multi-layer laminate film for S-polarized light at 400 nm is 10% or more and less than 80%.

### Claim 4 (depends on 1)

The uniaxially stretched multi-layer laminate film according to claim 1, wherein the polyester that composes the first layer and contains a naphthalene dicarboxylic acid ester is a copolymer polyester that contains a naphthalene dicarboxylic acid ester.

### Claim 5 (depends on 4)

The uniaxially stretched multi-layer laminate film according to claim 4, wherein the copolymer polyester that composes the first layer and contains the naphthalene dicarboxylic acid ester contains
(i) a component represented by the following Formula (A) as a dicarboxylic acid component in an amount of 5 mol % or more and 50 mol % or less and a naphthalene dicarboxylic acid component in an amount of 50 mol % or more and 95 mol % or less,
wherein RA represents an alkylene group having 2 to 10 atoms, and
(ii) a diol component that has an alkylene group having 2 to 10 carbon atoms in an amount of 90 mol % or more and 100 mol % or less as a diol component.

### Claim 6 (depends on 1)

The uniaxially stretched multi-layer laminate film according to claim 1, wherein the copolymer polyester that composes the second layer is a copolymer polyester that has a glass transition temperature of 90° C. or higher.

### Claim 7 (depends on 1)

The uniaxially stretched multi-layer laminate film according to claim 1, wherein the copolymer polyester that composes the second layer contains an alicyclic diol as a copolymer component.

### Claim 8 (depends on 7)

The uniaxially stretched multi-layer laminate film according to claim 7, wherein the alicyclic diol is at least one kind selected from the group consisting of spiroglycol, tricyclodecane dimethanol, and cyclohexane dimethanol.

### Claim 9 (depends on 1)

The uniaxially stretched multi-layer laminate film according to claim 1, wherein the visible light absorbent is at least one kind selected from the group consisting of inorganic pigment, organic dye, and organic pigment, and is black or gray.

### Claim 10 (depends on 9)

The uniaxially stretched multi-layer laminate film according to claim 9, wherein the inorganic pigment is carbon black.

### Claim 11 (depends on 2)

The uniaxially stretched multi-layer laminate film according to claim 2, wherein the UV light absorbent is a compound represented by the following Formula (B):
wherein each of n1, n2, and n3 represents respectively any integer of 4 to 10,
or Formula (C):
wherein each of X and Y represents a hydrogen or an alkyl group having 1 to 4 carbon atoms.

### Claim 12 (depends on 1)

The uniaxially stretched multi-layer laminate film according to claim 1,
wherein it is used in a manner adjacent to a liquid crystal cell.

### Claim 13 (depends on 1)

The uniaxially stretched multi-layer laminate film according to claim 1,
wherein, it is obtained by a coextrusion method.

### Claim 14 (depends on 1)

A polarizing plate, comprising the uniaxially stretched multi-layer laminate film according to claim 1.

### Claim 15 (depends on 14)

An optical member for a liquid crystal display device, comprising:
a first polarizing plate composed of the polarizing plate according to claim 14, a liquid crystal cell, and a second polarizing plate, laminated in this order.

### Claim 16 (depends on 15)

The optical member for a liquid crystal display device according to claim 15, wherein a configuration in which the first polarizing plate is laminated with an absorption type polarizing plate is excluded.

### Claim 17 (depends on 15)

The optical member according to claim 15,
wherein the second polarizing plate is an absorption type polarizing plate.

### Claim 18 (depends on 14)

An optical member, comprising a first polarizing plate, a liquid crystal cell, and a second polarizing plate laminated in this order,
wherein the first polarizing plate and the second polarizing plate are composed of the polarizing plate according to claim 14.

### Claim 19 (depends on 15)

A liquid crystal display device, comprising a light source and the optical member for a liquid crystal display device according to claim 15,
wherein the first polarizing plate is disposed on the side of the light source.

### Claim 20 (depends on 19)

The liquid crystal display device according to claim 19,
wherein a reflective polarizing plate is not additionally disposed between the light source and the first polarizing plate.