Machine-finished coated paper Machine-finished coated paper (MFC) has a
basis weight of 48–80 g/m2. They have good surface properties, high print gloss and adequate sheet stiffness. MFC papers are made of 60–85%
groundwood or
thermomechanical pulp (TMP) and 15–40%
chemical pulp with a total
pigment content of 20–30%. The paper can be soft nip
calendered or
supercalendered. These are often used in
paperbacks.
Coated fine paper Coated fine paper or
woodfree coated paper (WFC) are primarily produced for
offset printing: ; Standard coated fine papers: This paper quality is normally used for
advertising materials, books,
annual reports and high-quality catalogs.
Grammage ranges from 90–170 g/m2 and
ISO brightness between 80–96%. The fibre furnish consists of more than 90%
chemical pulp. Total
pigment content are in the range 30–45%, where
calcium carbonate and clay are the most common. ; Low coat weight papers: These paper grades have lower coat weights than the standard WFC (3–14 g/m2/side) and the grammage and pigment content are also generally lower, 55–135 g/m2 and 20–35% respectively. ; s: Art papers are one of the highest-quality printing papers and are used for illustrated books, calendars and brochures. The grammage varies from 100 to 230 g/m2. These paper grades are triple coated with 20–40 g/m2/side and have
matte or glossy finish. Higher qualities often contain
cotton.
Plastic coatings Plastic-coated paper includes coatings such as
polyethylene or
polyolefin extrusion,
silicone, and
wax, commonly used in products like
paper cups and
photographic paper.
Biopolymer coatings are available as more sustainable alternatives to common
petrochemical coatings like
low-density polyethylene (LDPE) or
mylar. It is most used in the
food and drink
packaging industry. Plastic is used to enhance properties such as water resistance, tear strength, abrasion resistance, and
heat sealability, etc. Some papers are laminated by heat or adhesive to a
plastic film to provide barrier properties in use. Other papers are coated with a melted plastic layer:
curtain coating is one common method. Printed papers commonly have a top coat of a protective polymer to seal the print, provide scuff resistance, and sometimes gloss. Some coatings are processed by
UV curing for stability. Most plastic coatings in the packaging industry are
polyethylene (
LDPE) and to a much lesser degree
PET.
Liquid packaging board cartons typically contain 74% paper, 22% plastic and 4%
aluminum.
Frozen food cartons are usually made up of an 80% paper and 20% plastic combination. The most notable applications for plastic-coated paper are
single use (
disposable food packaging): •
Liquid packaging board for milk and juice
folding cartons • Hot and cold
paper cups •
Paper plates •
Frozen food containers • Plastic-lined
paper bags •
Take-out containers •
Waterproof paper (also multi-use) •
Heat sealable paper • Barrier packaging Plastic coatings or layers usually make paper recycling more difficult. Some plastic laminations can be separated from the paper during the recycling process, allowing filtering out the film. If the coated paper is shredded prior to recycling, the degree of separation depends on the particular process. Some plastic coatings are water dispersible to aid recycling and repulping. Special recycling processes are available to help separate plastics. Some plastic coated papers are
incinerated for heat or
landfilled rather than recycled. Most plastic coated papers are not suited to
composting, but do variously end up in compost bins, sometimes even legally so. In this case, the remains of the non-biodegradable plastics components form part of the global
microplastics waste problem. Paper vellum is usually translucent and its various
sizes are often used as
tracing paper, such as
architectural plans. Its dimensions are more stable than a
linen or paper sheet, which is frequently critical in the development of large scaled drawings such as
blueprints. Paper vellum has also become extremely important in hand or chemical reproduction technology for dissemination of plan copies. Like a high-quality traditional vellum, paper vellum could be produced thin enough to be virtually
transparent to strong light, enabling a source drawing to be used directly in the reproduction of field-used drawings.
Others In commercial printing and other graphic-arts applications, printed sheets may receive a protective overprint coating—often a water-based aqueous coating—or a
UV coating (processed by
UV curing for stability), to seal the print, improve rub/scuff resistance, and control surface sheen. Aqueous coatings are commonly offered in gloss, satin, matte, and soft-touch finishes. A
release liner is a paper (or film) sheet used to prevent a sticky surface from adhering. It is coated on one or both sides with a
release agent. Heat printed papers such as receipts are coated with a chemical mixture, which often contains
endocrine disrupting and carcinogenic compounds, such as
bisphenol A (BPA). It is possible to check whether a piece of paper is thermographically coated, as it will turn black from friction or heat. (see
Thermal paper) Paper
labels are often coated with adhesive (pressure sensitive or gummed) on one side and coated with printing or graphics on the other. == See also ==