Sustainable bio-based coatings for paper: Advances, challenges, and future prospects in pulp industry

Conventional coated papers that rely on petroleum‑based polymers create major recycling and biodegradation problems in the pulp industry. They contribute to microplastic pollution and carry a high carbon footprint. This review examines bio‑based alternatives such as starch, PLA, chitosan, and nanocellulose coatings, drawing on 85 peer‑reviewed studies published between 2018 and 2025. We compare barrier properties, mechanical strength, and life cycle impacts. Nano‑hybrid coatings achieve WVTR values as low as 5–15 g/m²/day, close to polyethylene at 10, while life cycle assessments show 40–60% reductions in CO₂ emissions. Despite these gains, scalability remains a challenge, especially in humid climates like India. Rod‑coating and spray methods appear promising for small mills, and mineral additives can reduce costs by 25–35%. Commercial products from companies such as Stora Enso and Huhtamaki demonstrate technical viability, but economic barriers (20–50% price premium) and regulatory gaps slow adoption. Key research needs include performance data for tropical conditions and hybrid nano‑formulations. We propose policy incentives and pilot‑scale trials to bridge these gaps and advance circular paper production.