Liquid developer for use in development of an electrostatic latent image comprising a copolymer containing an amino group converted into a quaternary ammonium salt or hydroxide

Claim 1

A liquid developer for use in development of an electrostatic latent image comprising an electrically insulating carrier liquid and a toner dispersed therein, the liquid developer comprising a copolymer wherein the amino group thereof is converted into a quaternary ammonium salt or a quaternary ammonium hydroxide, the copolymer being composed of at least one member selected from the monomers of the following formula (1), at least one member selected from the monomers of the following formula (2) and at least one member selected from the monomers of the following formula (3), Formula (1): ##EQU1## wherein X is selected from the class of --H and --CH 3 and Y 1 is selected from the class of --C n H 2n +1 , --OC n H 2n +1 and --COOC n H 2n +1 in which n is from 8 to 20, wherein the monomer of formula (1) is present in a mole ratio sufficient to prevent a decrease in the solubility of the copolymer in said carrier liquid; Formula (2): ##EQU2## wherein X 1 is selected from the class of --H, --CH 3 and --COOM and M is selected from the class of an alkali metal and alkaline earth metal. Formula (3): ##EQU3## wherein X is selected from the class of --H and --CH 3 and Y 2 is selected from the class of the following substituents: ##SPC2## wherein 1 ≦ n ≦ 4; R 1 and R 2 are similar or dissimilar, selected from the class of --H and --C m H 2m +1 ; and 1 ≦ m ≦ 4.