摘要:
Use of solvents capable of removing oily substances without solubilizing them, consisting of hydrofluoropolyethers having the general formula HF 2 CO(CF 2 O) n (CF 2 CF 2 O) m CF 2 H wherein n and m are integers comprised between 0 and 20, excluding when m and n are contemporaneously 0, and having boiling point from 30° to 200°C and having a molar ratio 0/C comprised between 0.5-1.
摘要:
The invention relates to a process for reducing the back migration of the most volatile fractions of perfluoropolyethers during the operation of mechanical vacuum-generating pumps which utilize perfluoropolyethers: use is made of perfluoropolyethers containing not more than 0.1% by weight of fractions having a molecular weight lower than or equal to 1,500 and not more than 1.3% by weight of fractions having a molecular weight lower than or equal to 1,800.
摘要:
Method for the water removal from a surface, which comprises covering the surface with a composition having specific weight higher than that of the water, and subsequently removing water from the composition by skimming, such composition comprising a (per)fluoropolyether having molecular weight comprised between 300 and 1500 and a non ionic additive having a (perfluoropolyethereal structure similar to that of the solvent, linked to an hydrogenated part of hydrophilic type, the molecular weight of the (per)fluorinated part is comprised between 400 and 1200 and the ratio by weight between (per)fluorinated part and hydrogenated part is comprised between 1.5 and 3.5.
摘要:
Method for the water removal from a surface, which comprises covering the surface with a composition having specific weight higher than that of the water, and subsequently removing water from the composition by skimming, such composition comprising a (per)fluoropolyether having molecular weight comprised between 300 and 1500 and a non ionic additive having a (perfluoropolyethereal structure similar to that of the solvent, linked to an hydrogenated part of hydrophilic type, the molecular weight of the (per)fluorinated part is comprised between 400 and 1200 and the ratio by weight between (per)fluorinated part and hydrogenated part is comprised between 1.5 and 3.5.
摘要:
The invention relates to a process for reducing the back migration of the most volatile fractions of perfluoropolyethers during the operation of mechanical vacuum-generating pumps which utilize perfluoropolyethers: use is made of perfluoropolyethers containing not more than 0.1% by weight of fractions having a molecular weight lower than or equal to 1,500 and not more than 1.3% by weight of fractions having a molecular weight lower than or equal to 1,800.
摘要:
Use of solvents capable of removing oily substances without solubilizing them, consisting of hydrofluoropolyethers having the general formula
HF 2 CO(CF 2 O) n (CF 2 CF 2 O) m CF 2 H
wherein n and m are integers comprised between 0 and 20, excluding when m and n are contemporaneously 0, and having boiling point from 30° to 200°C and having a molar ratio 0/C comprised between 0.5-1.