# US 9,751,999 B2 · Polarizing plate protective film, dope composition, method for manufacturing polarizing plate protective film, polarizing plate, and liquid crystal display device

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- Number: US 9,751,999 B2
- Document ID: US9751999B2
- Status: Granted
- Kind: B2
- Application number: 15/138,754
- Filed: 2016-04-26
- Published: 2016-08-18
- Granted: 2017-09-05
- Earliest claimed: 2013-11-01
- Assignees: FUJIFILM Corporation
- Applicants: FUJIFILM Corporation
- Inventors: Katsumi Sasata; Hajime Nakayama; Shusuke Arita; Yutaka Nozoe
- Web page: https://patentgrep.com/patent/US9751999B2

## CPC

- C08J 5/18: Manufacture of films or sheets
- B29C 41/003: {characterised by the choice of material}
- B29C 41/02: for making articles of definite length, i.e. discrete articles
- B29C 55/005: {characterised by the choice of materials}
- B29C 55/143: {firstly parallel to the direction of feed and then transversely thereto}
- B29C 69/00: Combinations of shaping techniques not provided for in a single one of main groups B29C39/00 - B29C67/00, e.g. associations of moulding and joining techniques; Apparatus therefore {(B29C48/001 takes precedence)}
- B29D 7/01: Films or sheets
- C08F 220/14: Methyl esters {, e.g. methyl (meth)acrylate}
- C08L 33/12: Homopolymers or copolymers of methyl methacrylate
- G02B 1/14: Protective coatings, e.g. hard coatings
- G02B 5/3033: {in the form of a thin sheet or foil, e.g. Polaroid}
- B29K 2033/12: {Polymers of methacrylic acid esters, e.g. PMMA, i.e. polymethylmethacrylate}
- B29K 2105/0058: {Liquid or visquous}
- B29K 2105/16: Fillers
- B29K 2105/256: {Sheets, plates, blanks or films}
- B29K 2995/0017: Heat stable
- C08J 2333/12: Homopolymers or copolymers of methyl methacrylate
- G02F 1/133528: {Polarisers}
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00)
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- 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

A polarizing plate protective film containing an acrylic resin, in which the acrylic resin includes a methyl methacrylate unit a, a mass fraction of an alkyl (meth)acrylate unit b other than methyl methacrylate is less than 5 mass %, a weight average molecular weight is 250,000 to 4,000,000, and a weight decreasing amount at the time of being heated at 140° C. for 1 hour is less than or equal to 0.5%, has excellent heat resistance and an excellent surface shape; a dope composition; a method for manufacturing a polarizing plate protective film; a polarizing plate; and a liquid crystal display device.

## Claims

### Claim 1

A polarizing plate protective film, containing:
an acrylic resin,
wherein the acrylic resin includes a methyl methacrylate unit a,
a mass fraction of an alkyl (meth)acrylate unit b other than methyl methacrylate is less than 5 mass %,
a weight average molecular weight is 250,000 to 4,000,000, and
a weight decreasing amount at the time of being heated at 140° C. for 1 hour is less than or equal to 0.5%.

### Claim 2 (depends on 1)

The polarizing plate protective film according to claim 1,
wherein the acrylic resin is formed of an alkyl (meth)acrylate unit, and
a mass fraction of the methyl methacrylate unit a is greater than or equal to 95 mass %.

### Claim 3 (depends on 1)

The polarizing plate protective film according to claim 1,
wherein the number of times of folding endurance which is measured on the basis of JIS P8115 in conditions of a load of 100 g is greater than or equal to 30 times in both of a longitudinal direction and a width direction of a film.

### Claim 4 (depends on 1)

The polarizing plate protective film according to claim 1,
wherein the weight average molecular weight of the acrylic resin is 600,000 to 4,000,000.

### Claim 5 (depends on 1)

The polarizing plate protective film according to claim 1,
wherein the weight decreasing amount at the time of being heated at 140° C. for 1 hour is less than or equal to 0.2%.

### Claim 6

A dope composition, containing:
an acrylic resin,
wherein the acrylic resin includes a methyl methacrylate unit a,
a mass fraction of an alkyl (meth)acrylate unit b other than methyl methacrylate is less than 5 mass %,
a weight average molecular weight is 250,000 to 4,000,000, and
a weight decreasing amount at the time of being heated at 140° C. for 1 hour is less than or equal to 0.5%.

### Claim 7 (depends on 6)

The dope composition according to claim 6,
wherein the acrylic resin is formed of an alkyl (meth)acrylate unit, and
a mass fraction of the methyl methacrylate unit a is greater than or equal to 95 mass %.

### Claim 8 (depends on 7)

The dope composition according to claim 7,
wherein the weight average molecular weight of the acrylic resin is 600,000 to 4,000,000.

### Claim 9

A method for manufacturing a polarizing plate protective film, comprising:
a film forming step of forming a film by casting a solution in which an acrylic resin is dissolved in a solvent onto a support and by drying the solution, and of peeling off the film;
a first stretching step of stretching the film in a longitudinal direction; and
a second stretching step of stretching the film in a width direction,
wherein the acrylic resin includes a methyl methacrylate unit a,
a mass fraction of an alkyl (meth)acrylate unit b other than methyl methacrylate is less than 5 mass %,
a weight average molecular weight is 250,000 to 4,000,000,
a weight decreasing amount at the time of being heated at 140° C. for 1 hour is less than or equal to 0.5%002C
when a residual volatile content of the film is set to A1 and a surface temperature of the film is set to T1 in the first stretching step, and a residual volatile content of the film is set to A2 and a surface temperature of the film is set to T2 in the second stretching step, conditions of Expressions (1) and (2) described below are satisfied, and
unit of A1 and A2 is %, and unit of T1 and T2 is ° C.
T1≦170−2.8A1 Expression (1)
T2≦170−2.8A2. Expression (2)

### Claim 10 (depends on 9)

The method for manufacturing a polarizing plate protective film according to claim 9,
wherein the residual volatile content A1 of the film and the surface temperature T1 of the film in the first stretching step satisfy conditions of Expression (3) described below,
the residual volatile content A2 of the film and the surface temperature T2 of the film in the second stretching step satisfy conditions of Expression (4) described below, and
the unit of A1 and A2 is %, and the unit of T1 and T2 is ° C.
100−3.2A1≦T1 Expression (3)
100−3.2A2≦T2. Expression (4)

### Claim 11 (depends on 9)

The method for manufacturing a polarizing plate protective film according to claim 9,
wherein both of a stretching ratio in the first stretching step and a stretching ratio in the second stretching step are 130% to 180%.

### Claim 12 (depends on 9)

The method for manufacturing a polarizing plate protective film according to claim 9,
wherein the residual volatile content of the film in the first stretching step is 10% to 30%, and
the residual volatile content of the film in the second stretching step is less than or equal to 10%.

### Claim 13 (depends on 1)

A polarizing plate, comprising:
the polarizing plate protective film according to claim 1.

### Claim 14 (depends on 13)

A liquid crystal display device, comprising:
the polarizing plate according to claim 13.