optimont® VTM-0

The flame-retardant film optimont® SC-VTM-0

With the BO-PET film optimont® SC-VTM-0, Bleher Folientechnik offers a VTM-0 compliant film. This means that the film has been tested and certified according to the UL 94 standard. Areas of application for a VTM-0 film include technical sectors with particularly high safety requirements, such as aerospace, medical technology, the automotive industry, as well as electronics and electrical engineering. In all of these areas, a self-extinguishing flame-retardant film is a prerequisite for safe operation and approval by the responsible authorities.

UL 94 film – what does this term mean?

Underwriters Laboratories (UL) is a U.S. company that has developed fire safety standards for many areas, which have mostly become worldwide standards. With the UL 94 regulation for the flammability of various plastics, UL has developed a test standard that provides meaningful statements about the fire behavior of different types of plastics and makes them comparable worldwide.

By classifying plastics into the fire protection classes defined there, manufacturers of plastic products assess whether a selected plastic guarantees the fire behavior required for the intended product. In the field of films, the UL 94 standard is referred to as VTM, which simply means “very thin material.”

The VTM standard as part of UL 94 certification

• UL 94 first defines the classification of various types of plastics so that they can be tested with regard to fire behavior. Uniform test standards allow classification into fire protection classes
• The materials are tested in twelve test classes under controlled laboratory conditions
• In six test classes, thicker plastic materials are tested, for example for housing construction, insulation, or structural parts of electrical devices
• Three test classes concern foam materials used for sound insulation, speaker covers, or similar purposes
• Three test classes finally concern thin films. They are often used as flexible printed circuit boards, but many other applications are also possible
• The thin films are divided into three test classes: VTM-0, VTM-1, and VTM-2. The strictest criteria apply to VTM-0 film such as optimont® SC-VTM-0

Certification as a VTM-0 film

Films that do not meet the criteria described above for thicker plastics may qualify for VTM classification. In the test procedure, the burning time after an initial flame application and then again after a second flame application is examined. The total burning time after ten flame applications as well as burning and afterglow times after the second flame application are also tested. Specific time values for the individual burning times classify the films into the test classes VTM-0, VTM-1, and VTM-2.

In addition, it is checked whether flaming dripping occurs or whether burning reaches the holding clamp. For certification in the VTM-0 protection class, rapid self-extinguishing is required, meaning before the holding clamp is reached. It is also required that flaming dripping does not occur. Flaming dripping represents a high risk for the spread of fires and must be excluded for VTM-0 films.

Areas of application for VTM-0 compliant films

Below are some examples of applications in which VTM-0 film can be used in the respective sectors.

• Electronics and electrical engineering VTM-0 films are used as insulating films in transformers, motors, and generators, as well as carrier and cover films for flexible printed circuits (FPCs). With appropriate coatings, VTM-0 films are also suitable as shielding films against electromagnetic interference (EMI) and as lamination material for displays, touch panels, and similar applications.
• Automotive industry In automobiles, interior components with increased fire protection requirements are manufactured from VTM-0 film. Cable insulation and insulating layers in vehicle technology, as well as labels and markings on electrical systems, are also produced from flame-retardant films.
• Aerospace In aircraft and spacecraft, insulation of onboard electronics is made from VTM-0 film. Cabin components in aircraft are also manufactured from flame-retardant films, as well as components of satellites and space probes.
• Medical technology In the medical sector, VTM-0 film is used as a protective film for device housings as well as for components in medical sensors and equipment.
• Packaging of technical products Protective packaging for sensitive electronic or optical components and shielding packaging with metallization to protect against electromagnetic waves are also manufactured from flame-retardant film.

Halogen-free film optimont® SC-VTM-0

In many films, halogens are used as flame retardants. However, these are considered harmful to health and can emit toxic fumes, especially during thermal disposal. optimont® SC-VTM-0 film, as a halogen-free film, is an alternative to flame-retardant films that contain such substances.

Due to the underlying BO-PET material, the film is also heat-resistant, tear-resistant, and dimensionally stable. The biaxially oriented film – hence the name component BO – is hazy and smooth on both sides.

optimont® SC-VTM-0 film can be supplied in cut sheet formats as well as as roll material in jumbo rolls, master rolls, short rolls, or narrow rolls, in thicknesses between 50 and 100 µm.

Environmental aspects of optimont® SC-VTM-0 film

The VTM-0 certified film from the Bleher product range is manufactured from PET material, which is generally recyclable. However, this is only partly the case for optimont® SC-VTM-0 film, because the additives used for flame protection prevent integration into the usual PET recycling stream.

Nevertheless, the BO-PET films, as described above, do not require halogens as flame retardants, which makes them significantly more environmentally friendly during thermal recovery than competing materials. Efforts to achieve enzymatic breakdown of film waste into its base substances, which could then be fed back into the production cycle, are still in the testing phase.

There is also already PET in which the component monoethylene glycol (MEG), which accounts for around 30 percent of the raw materials, is obtained from renewable raw materials, mostly sugarcane.

The importance of VTM-0 certification according to UL 94 for the economy

The production of components made from optimont® SC-VTM-0 film, which has been certified according to the UL 94 standard, makes it possible in many sectors to comply with regulations and thus enables market access in the first place. The UL 94 standard is recognized worldwide. Many standardization organizations, both national and international, take this regulatory framework into account or adopt it into their own standards. This also applies to the International Electrotechnical Commission (IEC), based in Geneva, which also operates globally.

For access to the global market, and especially to the U.S. market, UL 94 certification is indispensable. UL holds accreditation for the American market from the Occupational Safety and Health Administration (OSHA). Only with approval from this U.S. federal authority can market access for a product in the United States be achieved.