Patent ID: 7141358

Claim:
A developer comprising at least one carbonate selected from the group consisting of sodium carbonate, potassium carbonate and ammonium carbonate, at least one hydrogen carbonate selected from the group consisting of sodium hydrogen carbonate, potassium hydrogen carbonate and ammonium hydrogen carbonate and at least one alkali silicate selected from the group consisting of sodium silicate, potassium silicate, lithium silicate and ammonium silicate, wherein the amount of the carbonate is from 0.06 to 0.15 mol/l, the amount of bicarbonate is from 0.02 to 0.4 mol/l, the amount of silicate is from 15 to 80 g/l, the ratio of the total molar concentration “a” of the carbonate and the hydrogen carbonate to the molar concentration “b” of the SiO 2 component present in the alkali silicate: “a/b” ranges from 1:0.3 to 1:2, the total molar concentration of “a” and “b”: “a+b” ranges from 0.1 to 2 mole/L, and the pH value thereof ranges from 9.1 to 10.9, said developer further comprising at least one surfactant selected from the group consisting of anionic surfactants and nonionic surfactants in an amount ranging from 1 to 10% by mass, said anionic surfactant being represented by the following general formula (I-B): wherein R 5 represents a linear or branched alkylene group having 1 to 5 carbon atoms; R 6 represents a linear or branched alkyl group having 1 to 20 carbon atoms; q represents 0, 1 or 2; X 2 represents a single bond or an alkylene group having 1 to 10 carbon atoms; s is an integer ranging from 1 to 100, provided that if s is not less than 2, R 5 may be selected from at least two kinds of groups, and said nonionic surfactant being selected from the group consisting of nonionic aromatic ether type surfactants represented by the following formula (1): X—Y—O-(A) n -(B) m —H (1) wherein X represents a substituted or unsubstituted aromatic group; Y represents a single bond or an alkylene group having 1 to 10 carbon atoms; A and B represent groups different from one another and each represents either —CH 2 CH 2 O— or —CH 2 CH(CH 3 )O—; m and n are 0 or integers ranging from 1 to 100, respectively, provided that n and m cannot simultaneously represent 0 and that when n or m is 0, n and m cannot represent 1, wherein the developer has an electrical conductivity of from 34 to 82 mS at 25° C. and does not exhibit condensation of silicate.