The company employs people in the Midlands.
SIPTU will ballot its members employed by Bord na Mona recycling for strike action.
The union is saying no assurances have been provided about workers' terms and conditions of employment, if the sale to Kerry-based KWD Recycling goes through.
That's despite Bord na Mona publically saying all employees will have those terms protected on handover.
A secret ballot will now take place in two weeks, with a result expected within five to ten days.
Several meetings have been carried out between Bord Na Mona and SIPTU, with the most recent meeting taking place on Tuesday.
SIPTU Organiser Adrian Kane says the welfare of their members needs to be considered:
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