Patent ID: 8029609

Claim:
A method of using a compound having a guanidine group to produce an ejection liquid to be ejected by a thermal inkjet method, the ejection liquid comprising (a) the compound having a guanidine group and (b) at least one selected from proteins and peptides, wherein the method comprises a production method of producing the ejection liquid, the production method comprising the steps of: dissolving at least one selected from proteins and peptides into a liquid medium to form a solution; adding the compound having a guanidine group to the solution; and co-adding at least one surfactant selected from the group consisting of N-lauroyl sarcosine and arginine coconut oil fatty acid salt, wherein the compound having a guanidine group is a compound selected from the group consisting of: (a) a compound represented by the general formula (1): wherein R 1 , R 2 and R 3 is independently a hydrogen atom, and R 4 is a hydrogen atom, or a straight or branched alkyl group having 1-6 carbon atoms; (b) a compound represented by the general formula (2): wherein R 5 is a straight alkyl group having 1-6 carbon atoms, R 6 is a hydrogen atom, R 7 is a hydrogen atom, or a straight or branched alkyl group having 1-6 carbon atoms, R 8 is a hydrogen atom, and R 9 is a hydrogen atom, or a straight or branched acyl group having 1-6 carbon atoms; (c) N,N′-dimethyl biguanide; and (d) salts thereof.