Paper production from wood pulp is a sophisticated industrial process that transforms raw cellulose fibers into versatile sheet materials. This manufacturing method dates back to the 19th century when mechanical pulping was first developed, revolutionizing written communication and packaging solutions. Modern papermaking combines mechanical and chemical processes to create products with specific characteristics tailored to diverse applications.
The conversion of wood into paper involves several precise stages:
Logs are mechanically debarked, removing approximately 8-12% of their total mass as bark material. The debarked wood is then chipped into uniform pieces measuring 15-30mm in length and 2-5mm thick, optimizing the subsequent pulping efficiency.
Two primary pulping techniques dominate the industry:
Mechanical Pulping: Achieves 85-95% yield by physically grinding wood chips under pressure. This method preserves lignin, resulting in paper with higher opacity (90-96%) but lower strength.
Chemical Pulping (Kraft Process): Yields 40-50% cellulose fibers by dissolving lignin using a mixture of sodium hydroxide and sodium sulfide at 150-170°C. The resulting fibers demonstrate superior tensile strength (30-50 kN/m).
Chemical pulps undergo multi-stage bleaching to achieve brightness levels of 80-92% ISO. Refining mechanically treats the fibers to develop fibrillation, increasing the bonded surface area by 200-400% and significantly improving paper strength properties.
The pulp slurry, typically containing 0.5-1.5% fiber concentration, is deposited onto a moving wire mesh where water drainage reduces moisture to 18-22%. Press sections further decrease water content to 40-45%, followed by drying cylinders that evaporate remaining moisture to 4-6% final content.
Standard printing papers exhibit basis weights ranging from 60-120 g/m², with caliper thickness between 80-180 µm. The density typically falls in the range of 0.7-1.2 g/cm³, influencing both opacity and stiffness characteristics.
Tensile strength varies from 20-50 kN/m depending on fiber orientation and bonding. Tear resistance measures 300-800 mN (Elmendorf test), while folding endurance can exceed 100 double folds for premium grades.
Brightness levels span 70-95% ISO, with opacity ranging from 85-98% for various paper types. Gloss measurements show 20-70% reflectance at 75° geometry for coated papers.
Uncoated woodfree papers (60-100 g/m²) dominate office applications, offering 90-96% brightness with smooth surfaces (Parker Print Surf roughness 1.0-2.5 µm) optimized for ink absorption and dot reproduction.
Kraft linerboard (125-300 g/m²) demonstrates exceptional burst strength (200-600 kPa) and edge crush resistance (4-12 kN/m), making it ideal for corrugated containers subjected to stacking loads.
Filter papers utilize highly refined pulps with controlled porosity (10-100 µm pore size) and wet strength additives to achieve 80-95% particle retention efficiency for specific micron ratings.
Maintain storage conditions at 20-25°C and 45-55% RH to prevent dimensional changes exceeding 0.1-0.3% per 10% RH variation. Avoid temperature fluctuations greater than 5°C/hour to minimize curling and cockling.
Limit illumination to 50-100 lux for archival materials, as prolonged exposure to UV radiation (below 400 nm) accelerates oxidation, reducing paper strength by 10-30% per decade under poor conditions.
Use pH-neutral (7.0-8.5) storage materials and avoid direct contact with acidic substances that can reduce paper permanence from 100+ years to just 20-30 years through acid hydrolysis reactions.
For surface cleaning, employ soft brushes generating no more than 5 N of pressure. Dry cleaning methods should remove 90-95% of particulate matter without fiber disruption, while aqueous treatments require controlled humidity chambers for gradual re-drying.
Previous: Can You Heat Seal Wax Paper
Next: Pink Greaseproof Paper
Copyright © 2025 Dongguan Ruize Creative Arts New Materials Co., Ltd. All rights reserved.
