Comparison of Different Printing Ink in Deinking from Plastic Films Using Surfactants and Sodium Hydroxide Solution

The objectives of research are 1) to find the appropriate surfactant and concentration with sodium hydroxide solution for deinking of printed PVC film and 2) to compare the deinking results of different colors of printing inks produced in Europe and Japan. The PVC film sheets with European black printing ink were cut into small pieces and preliminary tested in different surfactant solutions; 2 types of anionic and 1 type of nonionic at 2% and 5% (w/v), respectively, mixing with 0%, 2%, and 4% (w/v) sodium hydroxide, respectively. The batch of 2-g PVC pieces in 100 ml solution was stirred at 750 rpm and 180°C for 15 minutes, and average optical density of residual ink on PVC pieces was analyzed. The optimal deinking was shown by using DOWFAX^TM 2A1 solution surfactants at 5% (w/v) and sodium hydroxide at 2% (w/v). The PVC film samples with other process colors of European and Japanese inks were then tested for deinking in the appropriate condition, showing that the European inks were easier deinked than did the Japanese inks determined by the less residual ink. Therefore, the appropriate anionic solution surfactant, concentration, and pH could be applied for deinking from printed PVC film to be further recycled.