| With the deepening of national environmental protection policy,solvent ink for printing and packaging has been seriously impacted because of its high VOCs emissions,and water-based ink has emerged as the times require.Gravure printing has attracted wide attention in the printing and packaging industry because of its high quality,suitable use of water-based ink and excellent printing effect.However,in the current domestic market,type of water-based gravure printing ink is few as well as quality is poor,and high-grade water-based ink almost all rely on imports.In this contribution,acrylic emulsion resin was used as the binder to prepare the corresponding water-based ink.The effects of resin structure,ink formulation and rheological properties on ink performances and printing effects were studied.Eventually,the formula of gravure printing water-based ink was determined,and excellent rheological properties were achieved.The main contents are as follows:1.Two kinds of self-made core-shell polyacrylic resin latexes were used as the binders to prepare the plastic water-based gravure ink.The effects of location of the crosslinking groups in the latex particles on the storage stability and adhesion of the ink were studied.It was found that,when the cross-linking groups are located on the inner layer of the latex particles,the storage stability of the relative ink,especially of the yellow ink,is improved greatly whereas the adhesion and other properties of the ink are not changed significantly.The effects of emulsion Tg and functional monomers on adhesion of core emulsions were studied.With the reduction of emulsion Tg,film-forming rate and film-forming quality are improved,which improves adhesion of the ink.It can also reduce the amount of additives used in the ink,thus reducing the VOC content of the ink.In addition,the adhesion of ink on the plastic substrates is improved introducing IBOA or HEA into the resin structure.2.In this contribution,the formulation of the ink was optimized.The effects of additives such as adhesion accelerators,leveling agents,wetting agents,wax emulsions and thickeners on the comprehensive performance of the inks were studied.It was found that,the adhesion of ink on BOPP film can be increased effectively with addition of adhesion accelerator.BYK-380N has the best leveling improvement on the ink film among the flat agents.When BYK-333 and BYK-380N were used as compound leveling agent,the effect was optimum,and when 333:380N=5:5,the effect of improving the leveling of ink film was the best;the wetting agent Superwet-360 has the best effect on reducing the surface tension of the ink,and when the content is more than 1%,the drying speed of the ink can be accelerated;the addition of the thickener PUR-42 can significantly increase the viscosity of the ink and prolong the drying time,so the added amount should not exceed 1%;the wax emulsion Silok-9003 has the best thermal adhesion resistance,but when the dosage is over 3%,the drying speed of the ink will be slowed down,so the best addition amount is 1%-3%.In addition,the adhesion of ink is decreased with the increase of wet film thickness.3.The effect of rheological properties on the printability of water-based ink with different thickener content were studied,and the suitable range of yield value and viscosity of the plastic gravure aqueous ink were initially defined.The results showed that when the content of thickener is 0.5%,the ink has suitable thixotropism and its temperature sensitivity nearly unchanged.The suitable yield value of plastic gravure water-based ink is 5-20 mPa,and the suitable viscosity is 20-200 mPa s. |
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