Linear perfluoropolyethers having an improved thermooxidative stability

摘要

Linear perfluoropolyethers of formula:
T-O (CF2O)n (CF2CF2O)m (CF2CF2CF2O)r (CF2CF2CF2CF2O)s-T1  (I)
wherein n, m, r, s are integers such that the polymer number average molecular weight is comprised between 700 and 100,000 and the n/(n+m+r+s) ratio ranges from 0.05 to 0.40, and respective preparation process by addition of a peroxidic perfluoropolyether of formula (III):
T4-O(CF2O)n, (CF2CF2O)m, (O)h-T5  (III)
having a PO from 1.8 to 4, to a perfluoropolyether oil preheated at a temperature comprised between 150° C. and 250° C. and subsequent exhaustive fluorination of the obtained compound.

主权项

1. Linear perfluoropolyethers having the following structure formula:
T-O(CF2O)n(CF2CF2O)m(CF2CF2CF2O)r(CF2CF2CF2CF2O)s-T1  (I) wherein:
T and T1, equal to or different from each other are selected from the group consisting of CF3—, CF3CF2—, C3F7—, C4F9—, CICF2— and —(CF2)COF wherein z=0, 1, 2, 3;n, m, r, s are integers such that the number average molecular weight is comprised between 700 and 100,000;the m/n ratio is comprised between 2 and 20;the (r+s)/(n+m+r+s) ratio is comprised between 0.05 and 0.2;the n/(n+m+r+s) ratio ranges from 0.05 to 0.40; wherein the perfluorooxyalkylene units are statistically distributed along the polymeric chain, and wherein the total moles of the end groups comprise from 0.5% by moles to 50% by moles of “—(CF2)zCOF groups”.