Patent ID: 7220879

Claim:
A method for inhibiting polymerization of (meth)acrylic acid and its esters, comprising the steps of: (A) providing a product comprising at least one compound selected from the group consisting of (meth)acrylic acid and its esters; and (B) adding an amount of a polymerization inhibitor to said product, said amount being sufficient to inhibit polymerization of said product and said polymerization inhibitor comprising at least one reduced halide-content azine dye-based compound having a cationic component and an anionic component wherein said at least one reduced halide-content azine dye-based compound has the general formula: wherein Y is selected from the group consisting of S, O, or NR*, where R* is selected from the group consisting of hydrogen, and saturated, unsaturated and substituted hydrocarbons; R 1 -R 4 are the same or different from one another; R 5 -R 10 are the same or different from one another; and each of R 1 -R 10 is selected from the group consisting of hydrogen, and saturated, unsaturated and substituted hydrocarbons; and X comprises at least one mono-, di- or tri-anion in a 1, 1/2, or 1/3 ratio respectively to the cationic component.