Tupperware Brands Corp., whose plastic containers became synonymous with food storage, has filed for bankruptcy following a years-long struggle with sales declines and growing competition.

The 80-year-old company filed for Chapter 11 protection in Delaware, where it said it will seek court approval to facilitate a sale process of the business as it keeps operating. The filing follows protracted negotiations between the company and its lenders over how to manage more than $700 million in loans.