Copolyester resin and polyester film for covering metal plates and laminated polyester film comprising same made into film

• US 11,046,864 B2
• Filed: 07/05/2013
• Issued: 06/29/2021
• Est. Priority Date: 07/05/2013
• Status: Active Grant

• Current Assignee: Bell Polyester Products, Inc., Daiwa Can Company
• Original Assignee: Daiwa Can Company
• Inventors: Kimiduka, Takashi, Takeuchi, Yuji, Matsumura, Junji, Okimoto, Masaya, Katsuma, Keita, Tomura, Hideaki, Nakatsuka, Sadamu
• Primary Examiner(s): Sanderson, Lee E
• Assistant Examiner(s): Romanowski, Michael C
• Application Number:
  US14/902,609
• Publication Number:
  US 20160186005A1
• Time in Patent Office: 2,916 Days
• Field of Search: 525167, 525168, 525444, 524167, 5241675, 524168, 5282953
• CPC Class Codes: B32B 15/09 comprising polyesters
• CPC Class Codes: B32B 2307/558 Impact strength, toughness
• CPC Class Codes: B32B 2439/66 Cans, tins
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B65D 1/12 Cans, casks, barrels, or drums
• CPC Class Codes: B65D 25/14 Linings or internal coatings of containers made by folding or erecting blanks made of paper B65D5/56 ; linings for domestic water storage heaters F24H1/183
• CPC Class Codes: B65D 25/34 Coverings or external coatings of containers made by folding or erecting blanks made of paper B65D5/62; for bottles or jars B65D23/08; wrappers B65D65/00
• CPC Class Codes: C08G 63/183 Terephthalic acids
• CPC Class Codes: C08G 63/199 Acids or hydroxy compounds containing cycloaliphatic rings
• CPC Class Codes: C08G 63/78 Preparation processes
• CPC Class Codes: C09D 167/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds C09D167/06 takes precedence
• CPC Class Codes: C09D 167/08 Polyesters modified with higher fatty oils or their acids, or with natural resins or resin acids

Abstract

The problem to be solved by the present invention is to provide a polyester resin excellent in various properties wherein the film formability is good, film fracture (hairs) and scraping (galling) are not easily generated in the drawing/ironing process when applied to a metal-sheet-coating polyester film, the film surface is not damaged when used as the inner-surface film for a metallic can, and the metallic can is hardly corroded (dent resistance), by dropping or external impact (denting), after a product is made by enclosing contents into the can.

The copolyester resin of the present invention is characterized by comprising, as the constituent units, 50 to 93 mass % of (A) ester oligomer with the number-average molecular weight of 700 or lower and consisting of a dicarboxylic acid unit (a1) containing 70 mole % or more of the terephthalic acid component and a diol unit (a2) containing 70 mole % or more of the ethylene glycol component; and 7 to 50 mass % of (B) polyester polyol with the number-average molecular weight of 1500 to 3000 and consisting of a hydrogenated dimer acid unit (b1) and a 1,4-butanediol unit (b2).

Claims

1. A method of producing a copolyester resin comprising:

obtaining an ester oligomer (A) having a number-average molecular weight of 700 or lower by esterifying or transesterifying a dicarboxylic acid unit (a1) containing 70 mole % or more of terephthalic acid and a diol unit (a2) containing 70 mole % or more of ethylene glycol and then subsequently depolymerizing the reaction product of said esterification or transesterification reaction to form said ester oligomer (A) having the number-average molecular weight of 700 or lower;

and then, copolymerizing 50 to 93 mass % of the ester oligomer (A) and 7 to 50 mass % of a polyester polyol (B) by a polycondensation reaction to form the copolyester resin, where polyester polyol (B) has a number-average molecular weight of 1,500 to 3,000 and is formed from a hydrogenated dimer acid (b1) and 1,4-butanediol (b2).