Polarizing plate laminated with an improved glue composition and a method of manufacturing the same

• US 7,399,376 B2
• Filed: 01/03/2005
• Issued: 07/15/2008
• Est. Priority Date: 05/04/2004
• Status: Expired due to Fees

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Wang, Yongcai, McCovick, Robert E., Linehan, Daniel T.
• Primary Examiner(s): GOFF II, JOHN L
• Application Number:
  US11/028,036
• Publication Number:
  US 20050249932A1
• Time in Patent Office: 1,289 Days
• Field of Search: 156/307.3, 156/308.6, 156/324.4, 359/483, 359/485
• US Class Current: 156/307.3
• CPC Class Codes: B29K 2029/04 PVOH, i.e. polyvinyl alcohol B29K2031/04 takes precedence
• CPC Class Codes: B32B 2037/243 Coating
• CPC Class Codes: B32B 2307/42 Polarizing, birefringent, filtering
• CPC Class Codes: B32B 2329/04 Polyvinylalcohol
• CPC Class Codes: B32B 2331/04 Polymers of vinyl acetate, e.g. PVA
• CPC Class Codes: B32B 2367/00 Polyesters, e.g. PET, i.e. polyethylene terephthalate
• CPC Class Codes: B32B 2457/20 Displays, e.g. liquid crystal displays, plasma displays
• CPC Class Codes: B32B 2551/00 Optical elements
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/26 using curing agents
• CPC Class Codes: B32B 27/30 comprising vinyl (co)polymers; comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/306 comprising vinyl acetate or vinyl alcohol (co)polymers
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 37/206 Laminating a continuous layer between two continuous plastic layers
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings
• CPC Class Codes: G02B 1/16 having an anti-static effect, e.g. electrically conducting coatings
• CPC Class Codes: G02B 5/305 including organic materials, e.g. polymeric layers
• CPC Class Codes: Y10T 428/31938 Polymer of monoethylenically unsaturated hydrocarbon

Abstract

The present invention generally relates a method of forming a polarizing plate comprising providing two protective cover sheets, each protective cover sheet for polarizers comprising a low birefringence protective polymer film and a layer promoting adhesion to poly(vinyl alcohol)-containing films comprising a hydrophilic polymer. The cover sheets are brought into contact with a PVA dichroic polarizing film such that said layer promoting adhesion to poly(vinyl alcohol)-containing films in each of said two cover sheets is in contact with said PVA dichroic polarizing film. A glue composition is applied just before contacting said PVA dichroic polarizing film and said cover sheets, said glue composition being substantially free of dissolved polymer and comprising a crosslinking agent that crosslinks PVA.

Claims

1. A method of forming a polarizing plate comprising:

(a) providing two cover sheets, each cover sheet comprising a low birefringence protective polymer films, comprising cellulose ester and having an in-plane birefringence Δ

n_in of less than about 1×

10<sup>−

4</sup> and an out-of-lane birefringence Δ

n_in of from 0.005 to −

0.005, and a layer promoting adhesion to poly(vinyl alcohol)-containing films that comprises a hydrophilic polymer;

(b) providing a PVA dichroic polarizing film; and

(c) simultaneously or sequentially bringing said two cover sheets into contact with said PVA dichroic polarizing film such that said layer promoting adhesion to poly(vinyl alcohol)-containing films in each of said two cover sheets is in contact with said PVA dicliroic polarizing film, wherein prior to contact a glue composition is applied to said PVA dichroic polarizing film supplied from a supply reel or said two cover sheets entering a nip between pinch rollers, and wherein said glue composition is substantially free of dissolved polymer and comprises, for crosslinking PVA, a first crosslinking agent that comprises boron and a second crosslinking agent that comprises multivalent ion.

2. The method of claim 1 wherein said glue composition is free of dissolved polymer and comprises a crosslinking agent that crosslinks PVA.

3. The method of claim 1 wherein said glue composition is applied to both sides of the PVA dichroic polarizing film or to a lowermost layer of said two cover sheets prior to said two cover sheets and said PVA dichroic polarizing film entering a nip between pinch rollers wherein said two cover sheets are laminated to either side of said PVA dichroic polarizing film, with application of pressure and optional heat, between opposing pinch rollers, resulting in said polarizer plate in sheet form.

4. The method of claim 1 wherein said glue composition further comprises an organic crosslinking agent.

5. The method of claim 1 wherein said second crosslinking agent comprises a coordination compound comprising titanium or zirconium.

6. A method of forming a polarizing plate comprising:

(a) providing two guarded cover sheet composites each comprising a carrier substrate and a protective cover sheet that comprises a low birefringence protective polymer film, comprising cellulose ester and having an in-plane birefringence Δ

n_in of less than about 1×

10<sup>−

4</sup> and an out-of-plane birefringence Δ

n_th of from 0.005 to −

0.005, and a layer promoting adhesion to poly(vinyl alcohol)-containing films that comprises a hydrophilic polymer;

(b) optionally removing said carrier substrates from said protective cover sheet to provide two unguarded cover sheets;

(c) providing a PVA dichroic film; and

(d) simultaneously or sequentially bringing said unguarded or guarded cover sheets into contact with said PVA dichroic film such that said layer promoting adhesion to poly(vinyl alcohol)-containing films in each of said two cover sheets is in contact with said PVA dichroic film, wherein a glue composition is applied to said PVA dichroic film supplied from a supply reel or said cover sheets entering a nip between pinch rollers, and wherein prior to contact said glue composition is substantially free of dissolved polymer and comprises, for crosslinking poly(vinyl alcohol), a first crosslinking agent that comprises boron and a second crosslinking agent that comprises multivalent ion.

7. The method of claim 6 wherein said glue composition further comprises an organic crosslinking agent.