Patent ID: 7411092

Claim:
A quaternary ammonium salt of the following formula (3): (R 6 R 7 R 8 R 9 N) + .A − (3) wherein, R 6 , R 7 , R 8 and R 9 may be mutually the same or different and represent an alkyl group having 1 to 4 carbon atoms or an alkyloxyethoxyethyl group of the formula (4): R 4 OCH 2 CH 2 OCH 2 CH 2 — (4) (wherein, R 4 represents a methyl group or ethyl group), and at least one of R 6 , R 7 , R 8 and R 9 represents an alkyloxyethoxyethyl group of the formula (4), and A − represents a bis(trifluoromethylsulfonyl)imidate ion [N(SO 2 CF 3 ) 2 − ], tetrafluoroborate ion (BF 4 − ) or hexafluorophosphate ion (PF 6 − ) and wherein any two of R 6 , R 7 , R 8 and R 9 represent a methyl group.