The coastal city of Barcelona, Spain, played host to this
years High Performance Fillers for Polymer Composites
(HPF) conference, held 4-5 March 2009, organised by Smithers
Rapra. There was a good variety of topics, covered by over 16
Kicking off the event was the keynote speech, Filler
and filler modifier markets and trends, presented by
market consultant Prof. Roger Rothon.
Rothon revealed that filler trends, using European markets
as the example, were strongly skewed towards elastomers
which consumed around 3-3.5m. tpa of the 5.5m. tpa filler
minerals produced in Europe in 2007. The second largest
consuming sector was thermoplastics, at 1.4-1.6m. tpa, while
thermosets consumed around 0.6m. tpa.
The main filler markets in Europe were stated as automotive
(especially tyres); wire and cable; flooring; household
appliances; and sealants. Regarding consumption in these
markets, Rothon was sombre: The alarming decrease in new
car sales is a major concern as very significant amounts of
filler are used in this sector.
Rather than attempting to forecast the future market in
terms of mineral tonnage and pricing, Rothon presented a unique
take on the market outlook, whereby a severity rating was
applied to each of the main filler minerals. The rating of each
mineral thus illustrated the expected impact of the economic
downturn on their production and consumption.
Under Rothons system, 0 equated to no
expected change, while 5 equated to a very
significant reduction. Rothon explained: The higher the
rating [of the mineral], the larger the expected fall, and the
longer before [market] growth returns.
As expected, minerals dependent on automotive end-uses were
rated as performing worst, including carbon black (rating = 3),
precipitated silicas (rating = 4), fumed silica (rating = 2.5),
and precipitated calcium carbonate (rating = 2.5).
Flame retardant fillers were also affected under
Rothons rating system, with aluminium hydroxide and
magnesium hydroxide given a rating of 2-3.
Fillers such as natural fibres and talcs, meanwhile, were
rated as 3-4.
Those fillers with less of an automotive link, such as GCC,
were given a severity rating of 2. Regarding these filler
minerals, Rothon stated: Their low cost and wide range of
applications will probably limit any effects [of the economic
downturn]. They may also see increased replacement
Rounding off the presentation, Rothon predicted filler
consumption by all markets to decline between 2008-2010,
meanwhile for the market between 2008-2013 he proposed that it
may be characterised by no or weak demand.
For the processing aspect of the market, Dr
Jürgen Roth, managing director of Powder Maker
Technologies (PMT) Jetmill GmbH, took the delegates through:
Jet milling technologies for enhancing the performance of
The main influencing properties on the effectiveness of
functional fillers, as highlighted by Roth, are particle aspect
ratio, particle shape and particle size distribution. This is
especially true for softer filler minerals such as graphite,
mica, talc and wollastonite.
The company presented some interesting results of tests
involving mica dry processed in its spiral jetmill, which was
showed to effectively delaminate particles from the feed
material while preserving their characteristic filler
properties. In addition, the jetmill provided a method of
classification by ejecting coarse material and waste particles
(such as silica), while accepting successfully processed
Lamellar particles with a steep particle size distribution
and good top cut have been demonstrated to improve a
fillers mechanical properties; namely charpy impact
strength, modulus and scratch resistance.
Roth summarised: Due to its integrated classifier
system, PMT Jetmill is able to produce steep particle size
distributions with an exact top cut and [fewer] ultrafine
Moving on to plastics, Polyhedral Oligomeric SilSesquioxanes
(POSS) was the focus of a talk by Chris
DeArmitt, chief scientist for USA-based Hybrid
Plastics Inc. superbly delivered by impromptu fill-in
POSS is essentially a hybrid compound, structurally
somewhere between silica and silicone. Unlike silica, however,
each molecule of POSS contains covalently bonded
functionalities which make them suitable for
As a functional filler in thermoplastics POSS can improve
melt flow while retaining mechanical properties, reducing
friction and acting as a flame retardance synergist. Rothon
also highlighted that, unlike nanoparticles, POSS molecules
dissolve easily in solvents and polymers.
Rothon outlined some of the existing applications for POSS
including packaging, aircraft components, optical
devices, and dental restoratives although new research
indicates that it could be used to accelerate healing and
impart biocompatibility to implants.
At current prices, a small (100g) sample of POSS can cost an
equivalent of 1,000/kg, while bulk buying of POSS
(1,000kg) costs an equivalent of 50/kg. Rothon, citing
these costs, warned against using POSS in applications where
more traditional, cheaper filler minerals are effective.
|Scanning electron microscope (SEM) image of
KMIs MIOX filler. Courtesy Kärntner
With automobile tyres accounting for a considerable
percentage of European filler mineral consumption, it is
unsurprising that this field of research continues to be very
In fact tyre technology has undergone a revolution over the
past few years, with the demand for more fuel efficient cars
leading to the development of so-called green tyres
made with silica compounds instead of carbon black.
Precipitated silica substituted for carbon black in tyre
tread has been shown to provide better wet traction, better
rolling resistance and an overall 5% improvement on fuel
efficiency for many vehicle types.
The hydrophilic nature of silica, however, can be
problematic for the production of green tyres, as it does not
easily mix with non-polar hydrocarbon rubbers. Dr
Martin Saewe from Rhein Chemie Rheinau GmbH outlined
some interesting results from the companys research into
this mixing problem, with new work focusing on additives for
The first generation of green tyres was successfully
produced from rubber and silica because of an additional
organo-silane coupling agent, which improved the interaction
between silica particles and the rubber.
However, some accelerators (such as DPG) have been
highlighted as a health concern owing to their release of
aniline a carcinogenic, mutagenic, toxic substance
Rhein Chemie has undertaken significant research into the
types of silanes used in tyres. Saewe presented some
interesting results which showed that the use of a
non-mutagenic accelerator (namely Rhenocure ZBOP-S) could be
achieved while preserving the desired properties of the
Historically, the introduction of fillers into polymers was
developed as a method of reducing material costs. In more
recent years, however, the market has seen a move to developing
new filler mineral grades whose incorporation in polymers
actually increases polymer performance.
Christian Rupp of Kärntner
Montanindustrie GmbH (KMI) presented a talk on the
companys new high performance, micaceous iron oxide
grades, recently covered by IM (see IM
February 09, p.69).
Processing involves the use of PMT-Jetmills spiral
jetmill; the subject of an earlier presentation.
MIOX comprises highly lamellar particles that can be
processed to achieve an aspect ratio of up to 50:1. Although
Rupp did not give an indication of prices, he outlined the
fillers benefits to performance: increased charpy impact
strength, melt flow rate, e-modulus, scratch resistance,
thermal conductivity, oxygen permeability and sound
Julian Danvers, marketing director for Imerys
subsidiary World Minerals Inc., gave an engaging talk on,
Engineered calcium carbonate adding value to polyolefin
film extrusion and nonwoven spunlaid process.
|Cross sectional SEM image of a spunbond nonwoven
fibre containing FiberLink engineered calcium carbonate
at 20wt% loading. Courtesy Imerys SA
World Minerals has conducted significant research into the
role of inorganic additives, such as calcium carbonate, in
polymer film and sheet applications. These additives may take
the form of low grade chalk material, up to engineered
Tests conducted by World Minerals indicated that the
addition of calcium carbonate to polypropylene resulted in
breakage of the fibres in cases where the company had used a
CaCO3 with a top-cut that was more than the average
fibre diameter (16-18µ).
Recognising this, the company successfully introduced its
FiberLink grade a steep engineered CaCO3 with
a controlled particle size distribution into later tests
with polypropylene, with positive results. In nonwoven
micron-size fibres, the addition of FiberLink at up to 20wt%
processed well during the trials, and good dispersion of
particles was observed.
What this means for polymer producers (using powdered resin
for melt blown applications) is reduced cycle time, good web
formation and cost savings.
The European production of aluminium and magnesium
hydroxides for flame retardant fillers accounted for some
255,000 tpa in 2007, although this market was generally
dominated by aluminium hydroxide owing to its lower cost.
Although it is more expensive to produce, magnesium
hydroxide is ideal for niche applications which require a flame
retardant with greater thermal stability.
Gerry Spoors, development manager for Omex
Environmental Ltd, gave a presentation on a promising new
magnesium hydroxide grade currently under development by Omex,
which could pave the way for cheaper magnesium-based flame
The filler is produced via hydration of magnesium oxide,
which is specially dried to give a fine, free-flowing powder,
available in coated and uncoated versions.
Carbon nanotubes (CNT) as a filler material was the subject
of two talks at this years conference. Dr Vincent
Calard from Austrian Research Centers GmbH discussed,
Thermal and electrical properties of carbon nanotube
reinforced cyanate ester polymer, which assessed the
feasibility of using CNT as a filler for lightweight spacecraft
CNT has strength and stiffness properties several orders of
magnitude larger than steel and conductivity superior to
Also presenting the case for CNT was Marta
Martins from Portugals Institute of Mechanical
Engineering and Industrial Management (INEGI), who discussed,
Processing of carbon nanotube buckypaper/epoxy resin
Martins described a new approach that the institute has used
to produce highly loaded CNT nanocomposites by infiltrating CNT
skeletons with an epoxy resin, which produced a CNT loading of
more than 15wt% resin. The promising results may eventually
lead to the production of high performance structures, with
good thermal and electrical conductivity, based on CNT
All ears were primed as Kevin Breese,
advanced purchasing manager for the fabric care line of
Electrolux Major Appliances, presented, Holistic cost
savings: a performance/component-cost evaluation of
thermoplastic-performance filler composites.
Breese explained: A total cost model for the complete
filled polymer process, from material sourcing to forming the
part, has been constructed. The total cost model is based
on volume and volume fraction of materials and compounds used,
rather than using mass costs of materials which has
tended to be the norm.
Holistic cost attempts to account for all aspects of polymer
processing and property variation with filler content.
Illustrating this, Breese outlined the method of calculating
part cost, which uses compound cost (material and compound)
plus injection molding costs.
Breese believes that holistic cost can be used to look
for savings and new direction of materials a model
that may well become very popular during the course of the
The latest research in magnesium hydroxide flame
retardant fillers will be presented by Dr Guenter Beyer, of
Kabelwerk EUPEN AG, at IMs MagMin 2009 conference, 10-12
May 2009, Amsterdam. See p.14-15.