Applied Research Of Environment-friendly Insoluble Azo Dyes On Anti-counterfeiting Paper

In recent years, high intelligence crimes have became more and more rampant along with the popularization of science and technology, such as fake ID cards, counterfeited passports and so on. It caused a bad influence on politics and brought great economic loss for the country, individual and collectivity. In order to prevent the forgery from spreading, developing different kinds of safety papers which could improve the ability of anti-counterfeiting becomes necessary. Anti-counterfeiting paper has advantages of easy to identify, cost effective, difficulty in imitation and widespread application. The new method is to use non-EU-banned insoluble azo dyes to prepare a new-type of colour-display anti-counterfeiting paper. The paper can display colors after it is wiped with alcohol, which is very simple and convenient to test.How to use non-EU-banned insoluble azo dyes for preparing a new-type colour-display anti-counterfeiting paper (ACP) is investigated in this paper. The ACP will display colour spots when it is wiped with alcohol, showing fine anti-conterfeiting effect. Through studying its main affecting facts, including the dosage of Naphthol AS-BO, dosage of Chromophore Red-B, the Chromophore's pH value and the drying temperature etc., the best optimize technological conditions are obtained from insoluble azo dyes' color-displaying on the paper for the purpose of anti-counterfeiting. In this paper, the basis weight of a hand sheet is 70g/m2, the amount of Naphthol is 1.6%, the best charge of wet-end agent is: AKD 0.15%, oxidizing starch 2.0%. The amount of Chromophore is 0.5%. The pH values` appropriate range of Chromophore diazonium salt solution is 1.5 to 2.0.Treating the paper sheet in these conditions, and properties were determined after 24h. After the red spot is displayed on the paper, the chromatic aberration and physical properties of the paper are detected. The results showed that the paper made by adding Chromophore Red-B and Naphthol AS-BO had a very good anti-counterfeiting effect, while its physical properties had only changed a little. When the pulp with Naphthol solid powder compared with blank pulp, the Zeta potential did not show obvious change. It has little effect on the pulp system. The anti-counterfeiting paper which added the insoluble azo dyes can show clear red spots when it was wiped with organic solvents such as alcohol, ketone, benzene, alkanes, and ethers. The figures reflects significant effect of different alcohol volume fraction on anti-counterfeiting paper's colour-display time and chromatism. Alcohol is more pure, paper's colour-display time is shorter, and chromatism is bigger. From the scanning electron microscope, we can see Naphthol solid particles in the surface of fibers dissolved in alcohol, reacted with chromophore diazonium salt solution.