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| These are replies to a selection of questions about
fluoropolymers. Please click here
if you have any other questions. |
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| A1. How hard are fluoropolymers? |
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Generally fluoropolymers are harder than elastomers but
softer than most other plastics. The following diagram compares the hardness of
Fluon®, other fluoropolymers and common plastics.
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Fluon®PTFE |
Fluon®PFA |
Fluon®ETFE |
PVdF |
PP |
PA6 |
Rockwell Hardness
(R scale) |
20 |
50 |
50 |
110 |
85-110 |
110 |
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| A2. What is the specific gravity? |
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The specific gravity of fluoropolymers is 1.7 - 2.2. being
higher than that of other plastics. The following shows the specific gravity of
Fluon®, other fluoropolymers and common plastics.
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Fluon®PTFE |
Fluon®PFA |
Fluon®ETFE |
PVdF |
PP |
PA6 |
PVC |
| Specific Gravity |
2.1-2.2 |
2.1-2.2 |
1.73 |
1.76 |
0.9 |
1.1 |
1.35 |
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| A3. How are fluoropolymers processed? |
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| The following are typical processing methods suitable for fluoropolymers. |
| Compression moulding is the most popular processing method for
Fluon® PTFE, which has high viscosity even when taken above the melting point.
The PTFE powder is put into a mould and sintered, then cooled down to obtain a
billet. Afterwards the billet is machined if a refined or complicated shape is
needed. |
| This is a processing method for fine powder (coagulated dispersion)
Fluon® PTFE. The fine powder (CD) is mixed with a lubricant (Naphtha) and
firmed, then extruded from a die to obtain tubes, pipes and tapes. The lubricant
is evaporated off later on during sintering. |
| Usual processing method as general thermoplastics can be applied
for melt fluoropolymers, such as Fluon®PFA and Fluon®ETFE, which melt
over melting point. Extrusion, injection, blow, transfer, rotomoulding, and others
are available. Processing temperature of fluoropolymers is higher than that of
general thermoplastics because fluoropolymers have higher melting point, and processing
rate of fluoropolymers is slower than that of general thermoplastics because fluoropolymers
have larger melt viscosity. |
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| A4. World market of Fluoropolymers |
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| It is estimated that the world market for fluoropolymers is
between 80,000 and 90,000 tons per year. Although fluoropolymers represent only
about 0.1% of all plastics, their use tends to increase at a steady rate because
of their outstanding performance characteristics. It is estimated that the world
fluoropolymer market could be at 100,000 tons by 2005. PTFE occupies 70% of the
total demand for fluoropolymers. The USA accounts for the consumption of 40% of
all fluoropolymers. Japan consumes 10,000 tons of fluoropolymers per annum. |
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| A5. Safety of Fluoropolymers |
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Fluoropolymers have a high level of non-flammability as mentioned
on the 'Properties' page.
However when fluoropolymers are heated above their melting point they start to
decompose and give off decomposition chemicals.
In the case of PTFE (melting point: 327°C), decomposition takes place at about
400°C and decomposition chemicals can be detected.
Initially tetrafluoroethylene and hexafluoropropylene are detected, then perfluoroisobutylene
is detected at about 480°C and later carbonyl fluoride is detected at about
500°C.
These decomposition gases are toxic to some extent; in particular perfluoro-isobutylene
and carbonyl fluoride are highly toxic. Although fluoropolymers are fire retardant,
should a large scale fire take place, then toxic gases would be present and the
necessary precautions should be taken. |
| Remarks regarding processing |
Although there is no risk of such toxic decomposition gases
at the usual processing temperature, it is known that a particle-like substance
will be generated. This is considered to be the cause of the condition known as
"polymer fume fever" to the human body.
The symptoms of the syndrome are similar to those of influenza. The heat decomposition
gases from the fluoropolymers arise during processing whether it is short term
or long term processing and so a high concentration of these gases may be evident.
This is called "polymer fume." Although this condition has an incubation
period of several hours and after some time the condition does gradually disappear,
it disappears completely within 24 - 48 hours and no subsequent illness remains.
In order to prevent polymer fume fever it is advisable to ensure suitable ventilation
is installed in any processing environment.
Although natural ventilation may be adequate in many cases, depending on how the
processing equipment is installed when handling small amounts of polymer, it is
recommended that a local exhaust ventilation (LEV) system should be installed
to guarantee complete protection from 'polymer fume fever'. |
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| A6. Disposal of waste materials |
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As mentioned in A5., fluoropolymers generate toxic gases when
subjected to high temperatures.
Therefore bury on an authorized landfill site. Disposal should be in accordance
with local, state or national legislation.
Fluoropolymers are chemically inactive and do not decompose or generate toxic
substances even when in landfill sites.
However, disposal methods may differ for filled compounds or when fluoropolymers
are used together with other toxic substances. |
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| A7. Resistance to Radiation |
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Perfluoropolymers, such as PTFE, PFA and FEP will deteriorate
if irradiated.
Fluon® ETFE is a copolymer of tetrafluoroethylene and ethylene and ethylene
does not deteriorate but crosslinks when irradiated. Fluon® ETFE is used as
a wire insulating material in nuclear power plants where thermal stability, steam
resistance and radiation resistance are required. |
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| A8. Uses in the semiconductor industry |
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Various chemicals are used in the manufacturing processes of
semiconductors. Fluoropolymers have excellent chemical resistance and are used
in various applications as parts or components that come into contact with strong
acids or strong bases. It is important that such parts should not damage the purity
of the chemicals, which may affect the efficiency of semiconductor manufacturing.
Fluoropolymers are used to meet these requirements. Mainly Fluon® PTFE and
Fluon® PFA are used in semiconductor manufacturing processes as chemicals
containers, pipes, piping joints, tank linings, tanks, wafer carriers, valves,
pumps, bellows, diaphragms, filters, housings etc.
In recent years the integration and micro-fabrication of semiconductor devices
has increased rapidly. Therefore the control of metallic impurities in the manufacturing
process has become of extreme importance. For such applications, the use of Ultra
Pure Fluon® PFA is recommended as it contains very low levels of metal extractions. |
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| A9. Uses in the battery industry |
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Aqueous dispersions of Fluon® PTFE are used for binding
active materials in rechargeable batteries used in small appliances, such as lithium
ion batteries and nickel-cadmium batteries.
Fluoropolymers have excellent chemical resistance, thermal stability and non-flammability
which is vital in the chemically severe conditions inside rechargeable batteries.
Fluon® PFA is used as a packing inside lithium ion batteries as a small and
complex moulding is required, in addition to chemical resistance and thermal stability.
These batteries are used in the latest personal electronic equipment, such as
a mobile phones, notebook PCs and portable mini-disc players.
More significantly fluoropolymers are either already used, or planned to be used,
as a binder etc. in fuel cells which are expected to be the power supply for automobiles
and many other applications. |
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| A10. Uses in the automobile industry |
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| In automobiles fluoropolymers are used to manufacture various
components. Where low friction is required fluoropolymers are used in brake pads,
automatic gear boxes and in power steering seals. Where thermal stability and
good electrical properties are required, fluoropolymers are used in the wire insulation
of electrical systems. Where chemical resistance is important fluoropolymers are
used in various parts of the fuel system. |
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Although PTFE is the most mature fluoropolymer with over 60
years since its commercialization, new applications are still being found today
since its outstanding features typical of fluoropolymers mean it offers all kinds
of benefits.
Fluon® PTFE is used in the construction industry, the chemical processing
industry, the automotive industry, the semiconductor industry, the electrical
industry and the textile industry. It also has applications in machinery and is
used as a wire coating. PTFE powder is used as an additive in other media such
as plastics, elastomers, paint and greases to improve friction and non-flammability.
As well as PTFE in powder form, aqueous dispersions of PTFE are also available.
Filled PTFE compounds are another type of PTFE which are suitable for applications
where improved creep resistance and minimum wear are required. |
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Fluon® PFA has very similar properties to Fluon®
PTFE and in addition Fluon® PFA is melt processable. The majority of applications
for Fluon® PFA are in the semiconductor industry in areas such as pipes, joints,
wafer carriers and tanks of semiconductor manufacturing machinery and equipment.
Particularly suitable for applications in this field is Ultra Pure Fluon®
PFA with its extremely low level of metallic extracts. In addition to applications
in the semiconductor industry, the other two main areas of applications are office
machinery/appliances and lithium ion battery packings. |
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Fluon® ETFE, a copolymer of ethylene and tetrafluoroethylene,
has excellent mechanical properties and radiation durability. Because of these
properties Fluon® ETFE is used as wire insulation in robots, nuclear power
plants and in precision instruments such as personal computers.
Fluon® ETFE Film and F-CLEAN® are films made from Fluon® ETFE. These films
have applications such as release films, wallpaper and greenhouses.
Fluon® ETFE powder is also available and is used in the chemical processing
industry and the automotive industry. It is used to coat pipes and other metal
parts by electrostatic coating. It is also used in rotomolding. |
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