Polyester film for metal sheet laminating, metal sheet laminated with this film, and metal vessel formed from this metal sheet

• US 20030069387A1
• Filed: 06/26/2002
• Published: 04/10/2003
• Est. Priority Date: 05/30/2000
• Status: Active Grant

• Current Assignee: Daiwa Can Company, Unitika Limited
• Original Assignee: Unitika Limited
• Inventors: Kusunoki, Mikio, Majima, Shigemi, Menju, Akira
• Granted Patent: US 6,780,482 B2
• Time in Patent Office: Days
• US Class Current: 528/271
• CPC Class Codes: B32B 15/08 of synthetic resin
• CPC Class Codes: B32B 15/09 comprising polyesters
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: C08L 2666/18 Polyesters or polycarbonates according to C08L67/00 - C08L69/00; Derivatives thereof
• CPC Class Codes: C08L 67/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds C08L67/06 takes precedence
• CPC Class Codes: Y10T 428/1355 Elemental metal containing [e.g., substrate, foil, film, coating, etc.]
• CPC Class Codes: Y10T 428/31681 Next to polyester, polyamide or polyimide [e.g., alkyd, glue, or nylon, etc.]

Abstract

A polyester film for metal sheet laminating. The film comprises a blend of (I) polybutylene terephthalate or a polyester comprising it as the main ingredient with (II) polyethylene terephthalte or a polyester comprising it as the main ingredient, the contents of the polyester (I) and the polyester (II) being 80 to 40 wt % and 20 to 60 wt %, respectively. This film has a melting point of 200 to 223° C. attributable to the polyester (I) and a melting point of 230 to 256° C. attributable to the polyester (II). The film as a whole has an intrinsic viscosity of 0.75 or higher.

Claims

1. A polyester film for metal sheet laminating, the polyester film comprising a blend of a polyester (I) consisting of polybutylene terephthalate or consisting essentially of polybutylene terephthalate and a polyester (II) consisting of polyethylene terephthalate or consisting essentially of polyethylene terephthalate, the polyester (I) being present in the film in a proportion of 80 to 40 wt %, the polyester (II) being present in the film in a proportion of 20 to 60 wt %, the polyester (I) having a melting point of 200 to 223°

C., the polyester (II) having a melting point of 230 to 256°

C., the film entirely having an intrinsic viscosity of not lower than 0.75.

2. A polyester film for metal sheet laminating, as set forth in claim 1, wherein an index of ester exchange between the polyester (I) and the polyester (II) is 1 to 10 %.

3. A polyester film for metal sheet laminating, as set forth in claim 2, wherein the index of the ester exchange between the polyester (I) and the polyester (II) is 2 to 7% .

4. A polyester film for metal sheet laminating, as set forth in any one of claims 1 to 3, wherein terminal carboxyl groups are present in a proportion of not greater than 30 equivalents/ton.

5. A polyester film for metal sheet laminating, as set forth in any one of claims 1 to 4, which has a polybutylene terephthalate residue index of 40 to 75%.

6. A polyester film for metal sheet laminating, as set forth in any one of claims 1 to 5, which has a heat-up crystallization peak temperature of 60 to 100°

C. at which a transition from an amorphous phase occurs.

7. A polyester film for metal sheet laminating, as set forth in any one of claims 1 to 6, which has a heat-up crystallization index of not smaller than 0 J/g•

°

C. in a temperature range of 60 to 100°

C.

8. A polyester film for metal sheet laminating, as set forth in any one of claims 1 to 7, which has an elongation of not smaller than 100% at rupture at a heat-up crystallization peak temperature.

9. A film-laminated metal sheet, where in a polyester film as recited in any one of claims 1 to 8 is laminated on a metal sheet directly or with the intervention of an adhesive.

10. A metal container produced by working a film-laminated metal sheet as recited in claim 9.