EVALUASI SIFAT OPTIS DAN MEKANIS WATER-BASED COATING DENGAN VARIASI KONSENTRASI ADITIF PADA SUBSTRAT IVORY BOARD CETAK OFFSET

PT DIC Graphics merupakan perusahaan yang memproduksi water-based coating untuk aplikasi kemasan cetak offset. Pengujian ini bertujuan untuk mengetahui pengaruh variasi konsentrasi aditif (low, middle, high) terhadap sifat optis dan mekanis water-based coating yang diaplikasikan pada substrat ivory board 300 g/m². Variasi konsentrasi dilakukan terhadap kombinasi tiga jenis aditif, yaitu wax, anti-slip agent, dan anti-blocking agent. Pengujian dilakukan terhadap empat parameter, yaitu gloss (ASTM D523), rub resistance (ASTM D5264), coefficient of friction/COF (ASTM D1894), dan blocking resistance (ASTM D4946). Hasil pengujian menunjukkan bahwa peningkatan konsentrasi aditif menyebabkan penurunan nilai gloss dari 85,57 GU (WB coating A) menjadi 74,33 GU (WB coating C), serta penurunan nilai static dan kinetic COF. Sebaliknya, peningkatan konsentrasi aditif meningkatkan nilai rub resistance dari 2 (WB coating A) menjadi 4 (WB coating C) dan nilai blocking resistance dari 4 (WB coating A) menjadi 10 (WB coating C). Penurunan gloss dan COF diduga disebabkan oleh migrasi partikel aditif ke permukaan coating yang membentuk micro-roughness, sedangkan peningkatan rub resistance dan blocking resistance diduga disebabkan oleh partikel aditif yang berfungsi sebagai pelindung fisik permukaan. WB coating C dengan konsentrasi aditif tinggi merupakan formulasi paling optimal karena tetap memenuhi kategori High Gloss (>70 GU) dengan performa mekanis terbaik.
Kata kunci: water-based coating, konsentrasi aditif, gloss, rub resistance, blocking resistance

PT DIC Graphics is a company that manufactures water-based coating for offset printing packaging applications. This research aims to determine the effect of additive concentration variations (low, middle, high) on the optical and mechanical properties of water-based coating applied to 300 g/m² ivory board substrate. The concentration variation was conducted on a combination of three types of additives, namely wax, anti-slip agent, and anti-blocking agent. Testing was carried out on four parameters, namely gloss (ASTM D523), rub resistance (ASTM D5264), coefficient of friction/COF (ASTM D1894), and blocking resistance (ASTM D4946). The results showed that increasing the additive concentration caused a decrease in gloss value from 85.57 GU (WB coating A) to 74.33 GU (WB coating C), as well as a decrease in static and kinetic COF values. Conversely, increasing the additive concentration increased the rub resistance value from 2 (WB coating A) to 4 (WB coating C) and the blocking resistance value from 4 (WB coating A) to 10 (WB coating C). The decrease in gloss and COF is presumed to be caused by the migration of additive particles to the coating surface that forms micro-roughness, while the increase in rub resistance and blocking resistance is presumed to be caused by additive particles that function as a physical surface protector. WB coating C with a high additive concentration is the most optimal formulation as it still meets the High Gloss category (>70 GU) with the best mechanical performance.
Keywords: water-based coating, additive concentration, gloss, rub resistance, blocking resistance