Molded pulp

Interior packaging for a faucet

Molded pulp, also named moulded pulp or molded fibre, is a packaging material, typically made from recycled paperboard and/or newsprint. It is used for protective packaging or for food service trays and beverage carriers. Other typical uses are end caps, trays, plates, bowls and clamshell containers.

For many applications, molded pulp is less expensive than expanded polystyrene (EPS), vacuumed formed PET and PVC, corrugation, and foams.

Molded pulp is often considered a sustainable packaging material,^[1] as defined by the Sustainable Packaging Coalition, since it is produced from recycled materials, and can be recycled again after its useful life-cycle.

Molded pulp products can be made waterproof with a spray or dip coating of wax.

Types of molded pulp

Several types of molded pulp can be manufactured by several processes.^[2]

Thick-wall

These products usually have wall thicknesses of 1/16" to 1/4" and are used primarily for support packaging applications. Thick-Wall is also commonly referred to as "Slush Molded." The surfaces are very rough on one side and moderately smooth on the opposite side. Product definition is moderate due to the use of relatively inexpensive single-pass molds and the use of mixed recovered paper and kraft paper slurries. Typical uses are for edge and edge protector, heavy item packaging, auto replacement parts, molded pulp pallet trays etc.

Transfer molded




A McDonald's spray-molded vacuum-formed cup carrier. The open slits are formed during molding.

Transfer molded products are usually thin walled, 1/16" to 3/16", and are the most prevalent type in use today. The process uses vacuum forming and take-off or transfer molds, where the mold is an extremely fine wire mesh in the shape of the upper/exposed surface. The fibrous slurries are frequently made up of a high percentage or entirely of recycled newspaper, which produces a relatively smooth surface on one side and a fairly smooth surface on the opposite side with good accuracy and definition.

Prior to the molding process, the mesh is mated with a vacuum chamber that draws water through the mesh into the chamber, with the mesh mold suspended above a liquid return pool. The fibrous slurry is sprayed from below onto the mold, and the vacuum draws the slurry tightly against the mesh, filling all gaps and spaces. When airflow through the mesh has been sufficiently blocked, the excess slurry falls into the return pool for recycling, and the mold advances onward to the drying process, following by separation of the mesh mold from the dried fiber plating.

Typical uses of transfer molded products are for packaging electronic equipment, cellular phones and other household and hardware items. Very high-capacity, high-speed transfer molding equipment is used to produce drink trays, cup carriers, wine shippers, egg cartons, egg trays, pulp bedpan liners, pulp urinals, fruit trays, slipper pans, commode pans, end caps, etc.

Thermoformed fiber

This newest form of molded pulp is the highest quality of thin walled products available today. The process uses "Cure-In-The-Mold" technology which produces well defined, smooth surfaced molded pulp products. After being formed, the product is captured in heated forming molds which presses and densifies the molded products. They are accurately formed and have the appearance of plastic material. The products are ejected from the heated molds in their finished state as opposed to being dried in a heated oven. Typical uses for this type are for point-of-purchase packaging and those applications where high definition and appearance are of prime importance.

Processed

This type of molded pulp product is that which has undergone some kind of secondary processing which is generally different from or in addition to, the basic production procedure. This could apply to any of the first three types. Secondary processing could be coating, printing, hot-pressing, die-cutting, trimming or manufactured using colors or special slurry additives. Uses are for many kinds of custom applications.

References

↑ Definition of Sustainable Packaging
↑ Grygny, J (2004), Update on Molded Fiber (Pulp) Packaging (IoPP Technical Journal ed.), Institute of Packaging Professionals

Books

Yam, K. L., "Encyclopedia of Packaging Technology", John Wiley & Sons, 2009, ISBN 978-0-470-08704-6

Packaging

General topics	Active packaging Child-resistant packaging Disposable food packaging Food packaging Luxury packaging Modified atmosphere/modified humidity packaging Package pilferage Package testing Packaging engineering Pharmaceutical packaging Reusable packaging Shelf life Sustainable packaging Tamper-evident Tamper resistance Wrap rage

Containers	Aerosol spray Aluminium bottle Aluminum can Ampoule Antistatic bag Bag-in-box Bags and flexible containers Barrel Biodegradable bag Blister pack Bottle Box Bulk box Carboy Carton Chub Clamshell Corrugated box design Crate Drum Envelope Flexible intermediate bulk container Foam food container Folding carton Insulated shipping container Intermediate bulk container Jar Jerrycan Jug Juicebox Keg Matryoshka doll Multi-pack Oyster pail Packet (container) Padded mailer Pail Paper bag Paper sack Plastic bag Plastic bottle Popcorn bag Retort pouch Sachet Security bag Self-heating can Self-heating food packaging Shaker-style pantry box Shipping container Skin pack Spray bottle Tin can Tube Unit load Vial Wooden box

Materials and components	Adhesive Aluminium foil Bioplastic Biodegradable plastic BoPET Bubble wrap Bung Cellophane Closure Coated paper Coating Corrugated fiberboard Corrugated plastic Cushioning Desiccant Double seam Foam peanut Glass Hot-melt adhesive Kraft paper Label Linear low-density polyethylene Liquid packaging board Low-density polyethylene Metallised film Modified atmosphere Molded pulp Nonwoven fabric Overwrap Oxygen scavenger Packaging gas Pallet Paper Paper pallet Paperboard Plastic film Plastic pallet Plastic wrap Polyester Polyethylene Polypropylene Pressure-sensitive tape Screw cap Screw cap (wine) Security printing Security seal Shock detector Shock and vibration data logger Shrink wrap Slip sheet Staple (fastener) Strapping Stretch wrap Susceptor Tear tape Temperature data logger Time temperature indicator Tinplate Velostat

Processes	Aseptic processing Authentication Automatic identification and data capture Blow fill seal Blow molding Calendering Canning Coating Containerization Curtain Coating Die cutting Electronic article surveillance Extrusion Extrusion coating Graphic design HACCP Hermetic seal Induction sealing Injection molding Laminating Laser cutting Molding Papermaking Plastic welding Plastics extrusion Printing Quality assurance Radio-frequency identification Roll slitting Shearing (manufacturing) Track and trace Vacuum forming Ultrasonic welding Vacuum packaging Verification and validation

Machinery	Barcode printer Barcode reader Bottling line Calender Can seamer Cartoning machine Case sealer Check weigher Conveyor system Extended core stretch wrapper Filler Heat gun Heat sealer Industrial robot Injection molding machine Label printer applicator Lineshaft roller conveyor Logistics automation Material handling equipment Mechanical brake stretch wrapper Multihead weigher Orbital stretch wrapping Palletizer Rotary wheel blow molding systems Shrink tunnel Staple gun Tape dispenser Turntable stretch wrapper Vertical form fill sealing machine

Environment, post-use	Biodegradation Environmental engineering Glass recycling Industrial ecology Life-cycle assessment Litter Paper recycling Plastic recycling Recycling Reusable packaging Reverse logistics Source reduction Sustainable packaging Waste management

Paper

History Manufacture/Papermaking

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Materials	Fiber crop Paper chemicals Papyrus Wood pulp Algal bloom (Shiro alga carta)

Specifications	Grammage Density Size Units of paper quantity Surface chemistry of paper Wet strength

Manufacture and Process	Bleaching of wood pulp Calender Conical refiner Deinking Paper pollution Environmental impact of paper Hollander beater Kraft process Organosolv Paper cut Paper machine Paper recycling Soda pulping Sulfite process

Industry	Paper mill List of paper mills In Europe In Canada In India In Japan In the United States

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