The invention relates to thermoplastic polyurethane elastomers obtainable by inaction of a) unmodified and/or modified organic polyisocyanates, preferably 4,4'diisocyanatodiphenylmethane, with b) polyoxybutylene glycols and/or polyoxybutylene/polyoxyalkylene glycols with a molecular weight of from 150 to 1800 and a content of crown ethers, preferably those of the formula (-CH2CH2CH2CH2O-)m, where m is from 3 to 6, not exceeding 0.06% of the total weight and c) chain extenders with a molecular weight of from 60 to 400, preferably 1,4-butanediol, to a process for the preparation thereof and to the use thereof for producing molded articles and sheets for use in the medical or hygiene sector and in the foodstuffs sector.