Lubricants for magnetic recording media
The invention relates to lubricants for magnetic recording media, and in particular, to such lubricants containing cyclotriphosphazene. Methods for preparing the lubricants are also disclosed.
1. A compound of formula (I)
wherein
n is 1 to 6;
R f is selected from the group consisting of CF 2 CF 2 O(CF 2 CF 2 CF 2 O) m CF 2 CF 2 wherein m is 2 to 30 and CF 2 (OCF 2 CF 2 ) r O(CF 2 ) s wherein r is 2 to 30 and s is 0, 1, 2, or 3.
2. The compound of claim 1 , wherein n is 3.
3. The compound of claim 1 or 2 , wherein R f is CF 2 CF 2 O(CF 2 CF 2 CF 2 O) m CF 2 CF 2 , and wherein m is 21.
4. The compound of claim 1 or 2 , wherein R f is CF 2 (OCF 2 CF 2 ) r O(CF 2 ) s , and wherein r is 2 and s is 3.
5. A compound of formula (IDL1)
6. A method for forming the compound of formula (I)
wherein
n is 1 to 6;
R f is selected from the group consisting of CF 2 CF 2 O(CF 2 CF 2 CF 2 O) m CF 2 CF 2 wherein m is 2 to 30 and CF 2 (OCF 2 CF 2 ) r O(CF 2 ) s wherein r is 2 to 30 and s is 0, 1, 2, or 3, the method comprising:
reacting hexakis(pentafluorophenoxy)cyclotriphosphazene with a perfluoropolyether in a mixture of an organic solvent and a perfluorinated solvent in the presence of cesium carbonate at a temperature range of about 50 to 250° C.,
wherein the perfluoropolyether is a hydroxyl-terminated perfluoropolyether comprising HOCH 2 —R f —CF 3 ,
wherein R f is defined above.
7. The method of claim 6 , wherein the hydroxyl-terminated perfluoropolyether is HOCH 2 CF 2 (OCF 2 CF 2 ) 3 OCF 2 CF 2 CF 3 or HOCH 2 CF 2 (OCF 2 CF 2 ) 3 O(CF 2 ) 3 CF 3 .
8. The method of claim 7 , wherein the organic solvent is selected from the group consisting of tetrahydrofuran, benzene, and methylbenzene.
9. The method of claim 6 , wherein the hexakis(pentafluorophenoxy)cyclotriphosphazene is prepared by mixing hexachlorocyclotriphosphazene and a pentafluorophenoxide in a tetrahydrofuran solvent.
10. A method for lubricating a magnetic recording medium, comprising applying a lubricant comprising a compound of formula (I) to the magnetic recording medium,
wherein
n is 1 to 6;
R f is selected from the group consisting of CF 2 CF 2 O(CF 2 CF 2 CF 2 O) m CF 2 CF 2 wherein m is 2 to 30 and CF 2 (OCF 2 CF 2 ) r O(CF 2 ) s wherein r is 2 to 30 and s is 0, 1, 2, or 3.