Particle Board QC Inspection Checklist : Part 7 Raw materials Particles, adhesive & additives

Particle Board QC Inspection Checklist : Part 7 Raw materials Particles, adhesive & additives

Particle
• Raw material properties influence many board properties,
including board density, strength and stiffness etc.
• Can also influence the manufacturing process….
• Wood:
– Virgin wood, mainly softwood, but other species can be used
• Round wood
• Co-products (sawdust, slabs, etc.)
• Short rotation coppice (poplar)
– Recovered/recycled wood (“urban forest”)
• Pallet wood, packaging etc.
• Management can be problematic due to difficulties in identifying
contaminants (polymeric – paints and varnishes; preservatives – CCA).
• Non-wood:
– Agricultural by-products
• Wheat straw, bagasse, hemp, rice straw
• Basically any fibrous lignocellulosic material!

Wood raw material
• Species:
– Density (affects the “compaction ratio” and the way the chip deforms
under compression during pressing), strength and stiffness
– Chemistry: pH, buffering capacity, affect resin cure
– Extractives: may “interfere” with the bonding process or lead to
emissions problems
• Recovered wood:
– Contaminants:
• Metallic (large! Easily dealt with, but in preservatives such as copper
chrome arsenate – CCA – more problematic)
• Inorganic (grit, sand, cement…)
• Organic (e.g. paints/varnishes – problems with pressing; creosote)
– Identification of contaminants (materials management)

Non-wood raw material
• Basically any lignocellulosic material!
• E.g. wheat straw:
– High inorganic content
– Waxes

Raw material for particleboard

• By-products
• Poplar
• Birch
• Pine –
• Saw dust
• Mini chips
• Cutter chips
• Chips/board
Adhesives
• Primarily thermosetting resins
– Main type (90%) is Urea formaldehyde (UF)
• Low cost
• Rapid cure
• Adequate properties for many applications (brittle and susceptible to hydrolysis)
• “Low” formaldehyde emissions “E0”, E1 (E1 Classification <8m g HCHO/100g oven-dried
board)
– “Fortified” UF (melamine urea formaldehyde)
– Phenol formaldehyde (PF)
– MDI (methylene diphenyl diisocyanate) and pMDI. Zero formaldehyde release, but
careful handling needed
• Other adhesives
– Inorganic (cement bonded)
– Thermoplastics
• Renewable resource-based adhesives
– Tannin-based adhesives
– Lignin-based adhesives
– Glues based on vegetable oils
– Soy flour-based adhesives
– Furan polymer-based adhesives
• Binder-less boards using “activated” chips/particles (enzymatic or chemical)

Waxes (reduction in moisture uptake)
– Emulsion
– Molten wax
• Fungicides
• Flame retardants

 

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