Unite, which represents around 100 of the plant’s workers, warned that workers would down tools on 20, 22, 24, 26 and 28 September for 12 hours at a time.

Workers have enforced an overtime ban since July.

DTF, which turns over around £100m, is a major supplier of PET films to the packaging, labelling, digital printing and medical industries.

Products include Melinex film used for applications including durable labels, roll-up displays and banners; and the Mylar range of packaging films used for printing, converting and metallising.

The strikes represent an escalation of a pay dispute that has been running at the plant since the company bypassed the union to offer workers a 3.1% pay rise in April 2023.

Andy Macfarlane, Unite industrial officer, said: “DuPont imposed a brutal wage cut on our members in April without any negotiation. Our members have no option but to take strike action, and we don’t rule out more days.

“Management have not addressed longstanding issues over different rates of pay, shift allowances, and holiday entitlements among workers. 

“Unite is clear that workers in the same area who are carrying out exactly the same duties must be paid the same rate, and they must enjoy the same terms and conditions. 

“This dispute is entirely of DuPont’s making, for management to resolve it they need to quickly get back round the table before this dispute escalates.”

Printweek has contacted DTF for comment.