High-performance films represent a very small market accounting for about 10% of all commercial plastic films by volume. Compared to their commodity counterparts, high-performance films possess greater tensile and impact strength, greater heat and moisture resistance, and improved gas barrier properties; some also display special electrical or electronic properties.
With thicknesses generally
less than 0.25 mm, high-performance films are
made in relatively small quantities for specialized
applications in packaging (mostly for food),
electronics, photography, magnetic media, automotive,
aerospace, signs and displays. These films tend
to be on the higher end of the price spectrum,
generally selling for more than US$4.per kg.
About 95% of high-performance films are made
of polyesters, nylons and polyolefins. The rest
are made of such materials as polycarbonates,
fluoropolymers, polyimides, polyetheretherketone
(PEEK) and other engineering resins.
Coating high-performance films with other polymers can improve their abrasion resistance, and their barrier, adhesion and antistatic properties. The films can also be metallized to alter their electrical characteristics or reduce their moisture permeability. The films may be used alone or as layers in laminated or coextruded structures.
films, mostly made of PET , are widely employed
in flexible packaging for food products, where
their strength, barrier properties, puncture
resistance and resistance to extremes of heat
and cold, make them ideal choices. Other assets
of these materials in packaging include high
clarity, ready machinability and printability.
They may be used plain or metallized.
Heat-shrink PET films are growing
rapidly - by some accounts more than 10% pa
- as food processors opt for packages with more
elaborate graphics. PET films are also finding
their way into heat-seal lids that bond strongly
to various substrates but can be easily peeled.
The films are used for dairy and snack foods,
for fruit cups, and for pharmaceutical products.
Oxygen and moisture-resistant barrier packaging
made from metallized PET films compete with
foils and with metallized oriented PP (OPP)
films. Metallization of the films, whether PET
or OPP, helps shut out ultraviolet (UV) light
that can hasten food spoilage. Polyester films
can be coextruded with other layers to create
labels for packaged products with high-quality
graphics and UV blocking properties.
Specialized grades of PET films can be embossed with holographic designs. This allows special effects to be added to the packaging of such goods as cosmetics, personal care products and sporting goods. Holographic PET films can also be incorporated into labels for product security and anti-counterfeiting applications. In the electronics area, PET films are integral components of advanced plasma and LCD (liquid crystal display) flat panel screens that are competing with CRT (cathode ray tube) displays.
Heat-stabilized nylon films
are known for their resistance to punctures
and chemicals and their quick-release properties.
This makes them very useful as bagging materials
in vacuum-bag layup processes used to fabricate
composites, particularly those used in the aircraft
Compared to ordinary nylon films, biaxially oriented nylon (BON) films feature improved abilities to seal in flavor and aroma, better flex-crack properties, as well as superior gas barrier properties, abrasion and puncture resistance. As a result, BON films find wide applications in food packaging, and as protective coatings, release coatings and lamination layers. Metallized BON also possesses good UV resistance. As a food packaging film, BON is frequently coated with PVDC, which gives the film added oxygen barrier characteristics, thus prolonging the shelf life of foods.
Nylon 6 also serves as the matrix for advanced nanocomposite films, in which microscopic plate-like clay particles are dispersed at low levels (less than 6% by weight) in a resin carrier. Because such composite films exhibit anywhere from three to six times the oxygen barrier and stiffness properties of the unfilled nylon, food processors can use the composites to down-gauge the thickness of their packaging. In the food industry, nanocomposite Nylon 6 films are being used in boil-in bags, standup pouches and vacuum packs. Nanocomposite films for packaging are also made with polyester and PP base resins.
Films made of oriented PP (OPP), particularly
biaxially oriented PP (BOPP), are receiving
much attention from food packagers because of
their exceptional moisture and oxygen barrier
properties and improved economics over metal
foil packaging. They are useful for enclosing
such products as corn chips, cookies, crackers
and pet foods. Unlike foils, the OPP films are
transparent and can be designed for useful configurations
such as stand-up pouches. OPP films can be metallized
for further improvement in barrier properties.
Such films are already in use for packaging
such foods as powdered beverages, nutritional
drinks, soup, rice and dried cheeses. Some grades
of metallized OPP films are heat sealable. Others
are intended as the inner layers of coextruded
packaging laminates containing other polymers
such as plain OPP or PET.
films include such materials as PTFE, polyvinyl
fluoride (PVF), polyvinylidene fluoride (PVdF),
ETFE and PCTFE. As a class, fluoropolymer films
combine excellent chemical resistance and dielectric
properties with heat resistance and moisture
Fluoropolymer films are used in the chemical industry to line tanks and in the electronics industry in circuit board laminates and wire insulation. In plastics processing, fluoropolymer films perform well as release agents in the fabrication of industrial composites. Fluoropolymers are used in the packaging of medical and pharmaceutical products and as a barrier for protecting sensitive electronics, such as those found in sonar buoys.
Polycarbonate film is noted for its high clarity, heat resistance and dimensional stability. Its many applications include reverse screen printing, pressure sensitive nameplates and membrane switch panels.
Various electronic devices, including timers and filters, employ wound Polycarbonate film capacitors, which have a very wide temperature range. In signs and other outdoor graphics applications, Polycarbonate films offer exceptional resistance to moisture and sunlight. Another use of Polycarbonate film is for in-mould labels for cell phones and automobile components. Such labels are easy to customize to provide product differentiation.
Polyimide films, best known for their ability to withstand heat, retain their dielectric properties at temperatures as high as 240° C. The films can be used to insulate the windings of large coils for motors. They allow wave soldering of flexible circuits without distortion. The films are also used in combination with inorganic insulating tapes to impart flame resistance to high-performance cables.
Films made of PPEK display resistance to high temperatures, chemicals, solvents, wear, hydrolysis, fire and smoke. Usage temperatures for the films can be as high as 260° C. They have similar applications to Polyimide films.