Research On The Preparation And Performance Of White Water-based Flexo Covering Ink Applied In Lottery Printing

Lottery is one kind of commercial bills. It is commonly used and is ofsignificant value. The printing of lotteries demands anti-counterfeiting methodsto ensure the confidentiality, which set higher requirements for the inkperformance and printing quality. White water-based flexo covering ink isextensively used in the printing of scratch area of lottery as a functional ink.Flexographic water-based covering inks that used in lottery printing, for nowanyway, are all relied on importation, in that domestic water-based inkproduct fail to meet the requirements. The market share of commercial lotteryis greatly increased with the gradually development of lottery industry. As aresult, covering ink, an essential material in the printing of lottery, has apotential and promising prospect. So the research and development offlexographic water-based covering ink is of the importance and urgency.In the preparation of water-based ink, the base ink is prepared bychanging the kinds and contents of pigment and grinding resin, pigment/resinratio, the kinds and contents of dispersant and the preparation process tostudy the influence of ink components and preparation process on ink coveringproperty (CP). Discussions on the relationships between morphology and inkopacity were conducted in order to further understand the factors affectingink’s opacity. The covering inks applied in the printing of lotteries not onlyrequires high CP but also demands liability for scratch, excellent adhesion andabrasion resistance. For the purpose of testing the ink’s scratch resistance,adhesion and abrasion performance, different testing samples’ of bindermaterials, additives’ type and content are prepared.The results show that: The pigment has great influence on the CP. Thewhite ink prepared by WP3produces satisfying CP. Factors like Pigment,grinding resin, the ratio of pigment to resin, the kind and content of dispersionand grinding time all have influence on the ink’s dispersion and CP. Inks with optimal dispersion and CP were obtained by the procedure and settings: Usepigment WP3and grinding resin GR1to prepare ink, set the pigment to binderratio to3:1, set D1:D2to1:1, set the grinding time to120min. In addition, theresult reveals that inks with fine dispersion and uniform particle sizedistribution tend to have less agglomeration and the surface morphology isneat and gentle. On the contrary, inks with poor dispersion and wider range ofparticle size distribution are liable to form agglomeration and the surfacemorphology is rough with sharp bumps and hollows. The kind of film-formingresin also affects the ink’s scratch resistance, adhesion, abrasion resistance.When the film-forming resin FR2and FR4is set to1:1, the prepared inks are ofappropriate adhesion, higher ink-transfer rates, resulting in high CP value,preferable scratch resistance, and adhesion and abrasion performance.Furthermore, proper content of glycerol (2%～3%)is helpful to improve thescratch tactile sensation quality;1%of the A2substrate wetting agent caneffectively reduce the surface tension of the ink, improving ink adhesion. Welldispersed inks tend to have uniformly distributed pigment particles, smoothfilm surface, and high abrasion resistance.