A thermoplastic layer material has at least one odor reducing surface which is treated with a carboxylic acid-based odor control agent, and which is able to withstand insults with an aqueous liquid. The acid-based odor control agent is bound to the layer material by an organosilicone polymer binder. The binder is water-insoluble, and can form a highly gas-permeable coating. The binder is also highly porous, so as to expose the odor control agent to ammonia and other odoriferous gases which it is intended to control.