Deproteinization of Natural Rubber Latex and Its Pale-Colored Thin Films

The non-rubber components present in natural rubber latex can contribute to the dark color of dried films and may cause allergic reactions. This project aimed to develop light-color rubber films with minimal protein contamination. Various additives were incorporated, and a leaching procedure was implemented to address this issue. The evaluation focused on protein content, color changes, and swelling properties of thin natural rubber films. Texapon N70 proved effective as both a latex stabilizer and leaching agent, while Uniphen P-23 served as a preservative. The combined use of these additives facilitated the removal of soluble serum through appropriate incubation, leaching, and centrifugation processes. The introduction of additional centrifugation cycles improved deproteinization and color reduction; however, it led to a loss of rubber mass and an increase in manufacturing costs. Increasing the amount of Texapon N70 and introducing alkali potassium hydroxide (KOH) further enhanced the efficiency of deproteinization and color reduction. The optimal conditions determined in this investigation were as follows: 0.5% w/w Texapon N70, 0.5% w/w KOH, 1% w/w Uniphen P-23, a 60-min incubation period, and a single leaching cycle with distilled water. These conditions resulted in a 90.57 ± 1.20% decrease in protein contamination and a color change (ΔE) of 433.69 ± 20.23. This successful condition can be replicated and scaled up for further applications.