Basic Introduction
HPC (Hydroxypropyl Cellulose) is a non‑ionic cellulose ether modified from natural cellulose. It is a renewable and biodegradable bio‑based raw material. Soluble in cold water and some organic solvents, HPC features excellent film‑forming property, high film flexibility and favorable rheology‑modulating performance. Being non‑toxic and food‑contact safe, it has become a popular additive and film‑forming substrate for degradable packaging coatings, paper‑plastic lamination and peelable films in Europe and America
Core Functions in Degradable Packaging
1. Film‑forming Substrate (Self‑standing Film / Paper Surface Coating)
When water‑borne system is coated on the surface of paper, paperboard and degradable substrates such as PLA and PBS, a highly‑transparent, flexible and continuous film will be formed after drying. It can improve surface smoothness, folding resistance and scratch resistance of the base material. Compared with starch and CMC, HPC film features lower brittleness and better flexibility, so it is not easy to crack when the package is bent.
2. Rheology Modification (Thickening, Levelling & Anti‑sedimentation for Water‑borne Coatings)
It acts as a rheological additive in water‑borne bio‑based coating liquids to adjust shear viscosity and improve coating workability. It avoids sagging during high‑speed coating and delivers uniform coating thickness. It maintains good stability in neutral water at ambient temperature with steady viscosity under neutral‑pH conditions, which perfectly meets the development requirements of your Finnish project: ambient‑temperature and neutral aqueous environment.
3. Barrier Improvement (Oil Resistance & Mild Oxygen Barrier)
Pure HPC coatings offer good oil resistance yet weak water resistance, with moderate water‑vapour barrier performance when used alone. When blended with glycerol, starch, nano‑fillers and chitosan, its oxygen barrier, oil resistance and water‑vapour barrier can be significantly enhanced. It is applied for oil‑proof coatings of food‑grade paper packaging, snack paper bags and surface coatings of compostable take‑away paper lunch boxes.
4. Adhesion & Interlayer Compatibilizer
In multi‑layer bio‑composite packaging, it serves as an interfacial compatibilizing and bonding additive, boosting the adhesion between different bio‑substrates and improving the inter‑layer peel strength of starch‑PLA and paper‑biofilm laminates.
5.Featured Smart Packaging (Cholesteric Structural Colour)
High‑concentration aqueous HPC solution has the self‑assembly property of cholesteric liquid crystal, which can form dye‑free structurally colour‑changing films. It can be developed into humidity‑ and pressure‑responsive smart degradable anti‑counterfeit packaging, representing a cutting‑edge application field.
