Greaseproof and Barrier Stocks for Fills That Defeat Plain Kraft
High-density refining and fluorine-free dispersion coatings block lipid migration and moisture breakdown where unrefined kraft papers fail under aggressive fills.
Vegetable Parchmentization
Chemical Treatment
Concentrated sulfuric acid processing transforms water-leaf paper into a continuous, greaseproof cellulosic membrane. Specialty papermaking facilities execute vegetable parchmentization by passing unsized cotton or wood pulp sheets through a bath of cold concentrated sulfuric acid. Chemical exposure briefly dissolves outer cellulose microfibrils, forming a gelatinous amyloid layer over fibers.
Immediate washing and neutralization steps halt chemical action, locking the gelatinized cellulose into an impermeable non-porous structure.
Gelatinization Mechanism
Acid dissolution hydrolyzes surface cellulose, breaking inter-molecular hydrogen bonds and converting fibrous cellulose into amorphous hydration products. Subsequent washing precipitates this dissolved cellulose back onto adjacent fibers, fusing the entire web into a homogeneous single-ply sheet. The resulting material exhibits high barrier resistance to oils and organic solvents without requiring synthetic polymer coatings or fluorochemical sizing agents.
Physical strength properties, including wet tensile and burst resistance, increase substantially compared to the base sheet.
Packaging Application
Parchment paper produced through acid treatment provides essential grease isolation and heat resistance for food packaging operations. The material withstands elevated cooking temperatures and wet environments, making it suitable for butter wrappers and cheese packaging. Absence of loose surface fibers eliminates linting during direct food contact, meeting strict hygiene requirements.
Vegetable parchmentization creates a fully repulpable and biodegradable barrier substrate that satisfies circular packaging mandates without sacrificing grease holdout or wet strength performance. Packaging converters utilize parchment substrates where synthetic coatings cannot satisfy temperature or grease resistance requirements.