Molded pulp or molded fiber (also spelled as moulded pulp or moulded fibre) is a packaging material, that is typically made from

recycled Recycling is the process of converting waste materials into new materials and objects. The recovery of energy from waste materials is often included in this concept. The recyclability of a material depends on its ability to reacquire the p ...

paperboard Paperboard is a thick paper-based material. While there is no rigid differentiation between paper and paperboard, paperboard is generally thicker (usually over 0.30 mm, 0.012 in, or 12 Inch#equivalences, points) than paper and has certain ...

and/or

newsprint Newsprint is a low-cost, non-archival paper consisting mainly of wood pulp and most commonly used to print newspapers and other publications and advertising material. Invented in 1844 by Charles Fenerty of Nova Scotia, Canada, it usually has an ...

. It is used for protective packaging or for food service trays and beverage carriers. Other typical uses are end caps,

tray A tray is a shallow platform designed for the carrying of items. It can be fashioned from numerous materials, including silver, brass, sheet iron, paperboard, wood, melamine, and molded pulp. Trays range in cost from inexpensive molded pulp tray ...

s, plates, bowls and clamshell containers. For many applications, molded pulp is less expensive than

expanded polystyrene Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It is a ...

(EPS), vacuumed formed

polyethylene terephthalate Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in fibres for clothing, containers for liquids and foods ...

(PET) and polyvinyl chloride (PVC), corrugation, and foams. Molded pulp is often considered a sustainable packaging material, 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 Waterproofing is the process of making an object or structure waterproof or water-resistant so that it remains relatively unaffected by water or resisting the ingress of water under specified conditions. Such items may be used in wet environme ...

with a spray or dip coating of

wax Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids, typically with melting points above about 40 °C (104 °F), melting to giv ...

Types of molded pulp

Several types of molded pulp can be manufactured by several processes.

Thick-wall

These products usually have wall thicknesses of 1.5 to 6mm (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 A pallet (also called a skid) is a flat transport structure, which supports goods in a stable fashion while being lifted by a forklift, a pallet jack, a front loader, a jacking device, or an erect crane. A pallet is the structural foundat ...

trays, etc.

Transfer molded

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 carrier A drink carrier, sometimes also known as a cup carrier, beverage carrier or cup holder is a device used to carry multiple filled beverage cups at the same time. There are many different designs for drink carriers, but they commonly include relat ...

s, wine shippers, egg cartons, egg trays, pulp

bedpan A bedpan or bed pan is a receptacle used for the toileting of a bedridden patient in a health care facility, and is usually made of metal, glass, ceramic, or plastic. A bedpan can be used for both urinary and fecal discharge. Many diseases can ...

liners, pulp

urinal A urinal (, ) is a sanitary plumbing fixture for urination only. Urinals are often provided in public toilets for male users in Western countries (less so in Muslim countries). They are usually used in a standing position. Urinals can be with ...

s, 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 that 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

Books

* Yam, K. L., "Encyclopedia of Packaging Technology", John Wiley & Sons, 2009, {{Paper Papermaking Packaging materials no:Emballasjekartong