Particleboard Industry

Particleboard Industry

• Particleboard is the most widely used wood-based panel in the forest products industry.
• It is mainly used in furniture, door skin, and flooring industries.
• Particleboard is an engineered wood product made of fine wood chips, definition: "an engineered wood-based composite manufactured from particles of wood...and/or other lignocellulosic materials...and a synthetic resin or other suitable binder, which is pressed or molded in a hot press."

Chronological Development of Wood-Based Panels

• 1830: Sliced veneer (France)
• 1896: Rotary veneer (Estonia)
• 1898: Fiberboard (wet process) (England)
• 1906: Plywood (USA)
• 1914: Insulation board (Germany)
• 1925: Hardboard (wet process) (USA)
• 1941: Particleboard (Germany)
• 1945: Fiberboard (dry process) (USA)
• 1966: MDF (USA)
• 1969: OSB (Germany)

Ideal Wood-Based Panel

• Should have no limitations on dimensions
• Should have a homogeneous structure
• Should have high mechanical properties meeting the needs of the place of use
• Should have low density as possible
• Should be minimally affected by moisture and heat
• Should have a smooth surface and be easy to process
• Should not be easily burned
• Should have fungal and insect resistance
• Should be easy to produce and have a low cost
• Should be widely used

Particleboard Properties

• Advantages:
  • Cost-effective
  • Smooth and flat surface
  • Lightweight and easy to transport
  • Minimal maintenance and easy to clean
  • Thermo-acoustic insulation properties
  • Eco-friendly
  • Dense, flat, stiff surface
  • Can be painted to produce a smooth quality surface
  • Can be dowelled together and traditional wood work joints may be cut
• Disadvantages:
  • Low strength compared to other fiberboards
  • Expands and warps in presence of moisture
  • Low durability and short life
  • Cannot support heavy loads
  • Can be toxic due to urea formaldehyde resin

Classification of Particleboard

• According to particle size, particle orientation, and binder type:
  • Normal (standard) particleboard
  • Oriented Strandboard (OSB)
  • Cement bonded particleboard
  • Okal type particleboard
  • Molded particleboard
  • Waferboard
  • Strandboard
• According to layer structure:
• According to pressing method:
  • Horizontal pressing: standard particleboard
  • Vertical pressing: Okal type particleboard
  • Hot-press molding: Molded particleboard
• According to particleboard density:
  • High density particleboard: ≥ 800 kg/m3
  • Medium density particleboard: 590 < x < 800 kg/m3
  • Low density particleboard: ≤ 590 kg/m3

Particleboard Classes

• Classified into seven different classes based on their properties according to EN 312 standard:
  • P1: General-purpose boards for use in dry conditions
  • P2: Boards for interior fitments (including furniture) for use in dry conditions
  • P3: Non-load bearing boards for use in humid conditions
  • P4: Load-bearing boards for use in dry conditions
  • P5: Load-bearing boards for use in humid conditions
  • P6: Heavy duty load-bearing boards for use in dry conditions
  • P7: Heavy duty load-bearing boards for use in humid conditions### Particleboard History
• Max Himmelheber from Germany is considered the inventor of particleboard, obtaining a patent in 1951
• The first particleboard in Turkey was established in 1953 and started production in 1955

Standard Grade Particleboard

• Approximately 85% of particleboard produced in Europe is of standard grade
• Thickness typically ranges from 16-19 mm
• Straight UF adhesives of low F:U ratio (1.00-1.10) are used for this grade
• Average gluing addition factor is 7-8%
• Press times in modern press lines vary between 3-5 s/mm

Moisture-Resistant Particleboard

• Typically bears a green color for distinction purposes
• Strict requirements are enforced for moisture-resistant boards due to demanding end-user applications

Fire-Resistant Particleboard

• Used in public buildings where fire safety regulations are crucial
• Adhesives used exclusively have a melamine content of 13-20%
• Fire retardants are used in solid form, usually in granulates with a particle size between 200-600 μm

Oriented Strandboard (OSB)

• A widely used, versatile structural wood panel
• Alternative to plywood
• Mechanical properties are good for structural applications
• Top and bottom layer strands are aligned perpendicular to the core layer
• Produced from water-resistant, heat-cured adhesives and rectangular shaped wood strands

Okal Type Particleboard (Extruded Particleboard)

• Introduced by Otto Keribaum in Germany between 1947-1949
• Uses woody waste, less glue, and has a low thickness swelling
• Can be produced in various thicknesses, including tubular forms

Molded Particleboard

• Has a three-dimensional formability
• Strong, dense, and resistant to scratches, temperature fluctuations, and staining
• Good durability, low maintenance, and steady performance under harsh conditions
• Produced in two stages: molding and final pressing

Inorganic (Cement) Bonded Particleboard

• Has advantages over resin-bonded composites, including fire and biological resistance, high durability, and low production cost
• Used for constructive frameworks, bearing purpose, fire protection, and other compliments for walls and floors

Waferboard and Flakeboard

• Waferboard is made from flakes called wafers, which are short, thin, and nest together for bonding
• Flakeboard is made from flakes thinner and longer than those used for waferboard
• Both are used for non-structural applications

Historical Chronology of Wood-Based Panels in Furniture Industry

• (No specific details provided in the text)

Raw Materials Used in Production of Particleboard

• Wood material:
  • Ideal wood density: 0.35-0.65 g/cm3
  • Ideal wood moisture content: 40-60% based on oven dry weight
  • Ideal wood pH: 4-5
  • Minimum extractives, knots, and bark
  • No fungi- or termite-damaged wood
• Other materials:
  • Annual plants (e.g., sugarcane, wheat straw, sunflower stalk)
  • Waste papers (e.g., cardboard, papers)

Wood as a Raw Material

• Approximately 90-95% of ligno-cellulosic material used for particleboard production is wood
• Workability: wood species should be easy to break into particles
• Density: ideal raw material density is 0.35-0.65 g/cm3, which is compressed to at least 5% above its natural density### Panel Density and Compression Ratio
• Compression ratio is proportional to panel density and inversely proportional to wood density
• The density of particleboard is affected by the type of wood used, with higher density woods resulting in higher density particleboards

Wood Density and Particleboard Density

• The density of particleboard varies depending on the type of wood used, with the following densities:
  • Poplar-Willow: 0.60 g/cm³
  • Pine: 0.72 g/cm³
  • Beech: 0.82 g/cm³
  • Oak: 0.95 g/cm³
  • Spruce-Fir: 0.58 g/cm³
  • Alnus: 0.70 g/cm³
  • Elm: 0.90 g/cm³

pH of Wood

• The pH of wood affects the curing rate of formaldehyde-based resins, with near-neutral species producing slow curing rates and acidic species producing rapid curing rates
• pH levels can vary between wood species, within species, and within the tree (heartwood vs. sapwood)
• pH levels can also change with storage time and conditions

Permeability of Wood

• The permeability of wood affects the quality of particleboard, with very permeable species producing poor-quality boards
• The way wood breaks down and the amount of extractives present can influence the contact angle between the adhesive and wood

Sources of Wood for Particleboard

• Round wood: the best source of particleboard furnish, with control over particle size, shape, and surface quality
• Wood residues: a cost-effective source of wood, including forest residues, sawmill residues, and joinery residues
• Recovered wood: a cheap and environmentally friendly source of wood, including demolition timbers, old furniture, and pallets

Adhesives Used in Particleboard Production

• Aminoplastic resins: the most important class of adhesives in the wood-based panels industry, including UF, MF, MUF, PF, and PMDI resins
• UF resin: the most widely used resin, with advantages including low cost, colorless, easy supply, and good mechanical properties
• Disadvantages of UF resin: high formaldehyde emission, low water and moisture resistance

Additives Used in Particleboard Production

• Hardeners (catalysts): to decrease pressing time, including ammonium salts, aluminum sulfate, and citric acid
• Paraffin or wax: to improve water resistance, with amounts typically below 0.5% (based on dry wood)
• Formaldehyde scavengers (catchers): to decrease formaldehyde emission, including urea, sodium metabisulfite, and ammonium phosphates
• Fire retardants: including phosphates, magnesium hydroxide, and borax
• Fungi resistants: including zinc borate, borax, and boric acid

Technical Properties of UF Resin

• Density: 1.284 g/cm³
• Solids content: 64-66% (weight)
• Viscosity: 400-700 cps
• pH: 8.0-9.0
• Gel time: 30-40 seconds
• Free formaldehyde: < 3 mg/100g dry board

Formaldehyde Emission from Particleboard

• Parameters affecting formaldehyde emission: tree species, wood acidity, F/U molar ratio, resin amount, density and thickness, hardener type and content, free formaldehyde content, moisture content, and environmental conditions
• Regulations and standards: International Composite Board Emission Standards (ICBES), European formaldehyde classes (E0, E1, E2), and California Air Resources Board (CARB) standards