Dipping a Toe in the Water- Again

WorldCargo
news
CONTAINER INDUSTRY
three coats - but said that he saw no problems with the system.
“Aquaguard performed as well as, or
in some cases better than, current coatings in laboratory tests but we need to do
a run of 1,000 or more units to confirm
that there is no noticeable effect on productivity as well as analyse the field performance of this product,” he said.
With the rapid rebound in demand
for containers last year, CIMC has been
reluctant to carry out further waterborne
coatings trials at Taicang, but Triton is
likely to be one of the first customers at
the revamped Dalian factory, whereValpar
assisted CIMC in re-engineering the
coatings line to accommodate waterborne
products.
“We have a container coating system
that works and Dalian will be the first
opportunity to run commercial units at
full line speeds,” McCrory said.
Mark Chen, assistant director at
CIMC’s Containerisation Research Institute said that in addition to modifications to the ventilation and temperature
control systems at the Dalian plant, the
coatings line, which can apply both twoand three-coat systems, has been lengthened to allow for longer drying times.
Though there will inevitably be a learning curve, he said, once the painters have
become accustomed to the new facility,
Hazards
to health
The health hazards associated with
traditional solvent-borne coatings,
which have led to tightening emissions controls around the world, are
well known.
The solvents used in container
coatings - typically toluene, xylene and
methyl ethyl ketone (MEK), which
disperse the binders (resins), pigments
and additives in the formulation to
allow the coating to be applied, are
non-halogenated hydrocarbons that
vaporise at normal temperatures and
release Volatile Organic Compounds
(VOCs) into the atmosphere.
VOCs combine with nitrogen oxides in the presence of sunlight to form
ground-level ozone, a precursor to
smog, which is major pollutant in industrial areas and poses a risk to respiratory functions.
Direct exposure to solvent vapours
can also result in a number of other
risks to human health. Toluene, for
example, can affect the central nervous system and lead to cardiac arrhythmia, while xylene and MEK can cause
eye, nose and throat irritations, as well
as gastrointestinal and neurological
problems. Prolonged exposure can
lead to liver and kidney damage and
some types of cancer.
Traditional solvent-borne container coatings typically contain 400550 g/litre of VOCs, which is above
allowable limits in many areas of the
world and effectively precludes their
use in those areas. At present, no such
limits are imposed in China, but as the
Container Owners Association (COA)
points out in its recent report on
waterborne coatings, it is only a matter of time before the Chinese government introduces legislation to limit
solvent emissions that will require either substantial recovery and safe disposal of the VOC solvents or, more
likely - as at CIMC’s Dalian factory the substitution of VOCs by water as
the solvent.
According to Hempel, up to 80 litres of coatings are usually required to
finish a standard 20ft dry freight container, of which up to 55 litres are organic solvents. At recent production
levels of between 2M and 3M TEU/
year, the container manufacturing industry is emitting between 110,000t
and 165,000t of VOCs annually.
Though current waterborne container coatings still contain a small percentage of organic solvents, a wholesale switch to waterborne systems
would result in an annual reduction
in VOC emissions of up to 90%. ❏
March 2011
35_WCN_Mar_2011.indd 1
track time should be unaffected by the
introduction of waterborne systems.
Conventional approach
As one of the world’s biggest, and longest
established, manufacturers of container
coatings, Denmark-based Hempel A/S
has taken a more “conventional” approach
with its latest waterborne offering,
EcoBoxcoat, arguing that all the long
proven technologies available for solventborne coatings are also available for
waterborne equivalents.
The EcoBoxcoat series comprises a
two-component, zinc-rich epoxy primer
containing 80% zinc in the dry film by
weight, a two-component exter ior
midcoat based on new, fast-drying epoxy
binder technology, and single-component acrylic exterior and FDA-conform-
ing interior topcoats, which alone,
Hempel says, reduce VOC emissions by
40%.A two-component waterborne zinc
rich shop primer that can be applied on
existing primer lines at the same speed
as solvent-borne shop primers is also
available.
EcoBoxcoat is described as a “plug
and spray” product in that it is designed
to be used on existing container lines
with only minor modifications to airflow, temperature and humidity control.
Last October, Hempel successfully conducted a trial application of EcoBoxcoat
on seven 40ft high cube containers at
Maersk Container Industri’s Dongguan
factory in south China. According to
Kim Scheibel, group director, sales coordination, for Hempel, a 3-4 minute
flash-off time was easily achieved and
there was no delay to the factory’s normal track time.
A further 30 x 40ft high cube containers are scheduled to be coated with
EcoBoxcoat for Maersk Line at the
Dongguan plant at the end of this month
for extended field trials.
Meanwhile Hempel says the Maersk
Container Industri Qingdao reefer factory has been successfully using an
EcoBoxcoat 65% zinc-rich waterborne
shop primer for the past six months.
Hempel says it is sceptical about
claims for single-component products,
reasoning that cross binding of the reactive resins and catalyst, which promotes
polymerisation of the resin and hardener
in two-component products, results in a
more durable coating better able to withstand temperature extremes.
And while it is true that once the two
components have been brought together
the paint starts to cure, which limits pot
life to 4-8 hours, container manufacturers have been dealing with this issue without problems for decades.
According to Scheibel, based on extensive R&D work and the company’s
long experience of supplying container
coatings, Hempel also believes that zincbased primers are the only viable solution to meet current requirements for
container performance and service life.
Scheibel points out that in the past 10
years alone, over 20M containers have
been built using zinc-rich epoxy primers
and “an entire industry and affiliated industries cannot be wrong.”
Indeed, Scheibel cautions that the
term “waterborne coatings” should not
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30/03/2011 15:32:17
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be regarded as generic. Solventborne container coatings have
great similarities among the top
suppliers, which means that container factories can easily switch
between suppliers to fit their production flow. But there are material differences between new zincfree, two coat systems and zincbased three coat systems that mean
they will not be “intermixable”,
he says.
More of the same
Most of the other established container coatings suppliers, including Chugoku Marine Paints, Korea Chemical Corporation (KCC)
and Shanghai Mega Coatings,
have pursued a similar line to
Hempel and are now offering
two-component, three-coat,
waterborne systems comprising an
on-line zinc-rich epoxy primer,
epoxy midcoat and modified
acrylic exterior top coat, as well
as FDA-compliant inter ior
acrylic/epoxy topcoats.
KCC has carried out trials of
its new Ecosil waterborne series
on five 45ft units at CIMC’s
Shenzhen (SLEM) plant and five
20ft units at Singamas’s Shanghai
Baoshan Pacific facility, while
CONTAINER INDUSTRY
Chugoku has applied its Ekomate
waterborne coatings to a total of
500 TEU at CIMC plants in
Shenzhen and Nantong and
Dong Fang’s Lianyungang and
Jinzhou factories for China Shipping, Triton, KYK, Matson and
Transcity.
Shanghai Mega Coatings is
planning to undertake a 5-10 unit
production trial with its Megamar
waterborne series after successfully undergoing laboratory testing at the Singamas Technology
Development Centre.
Cosco Kansai, meanwhile, appears to be hedging its bets, offering both a “standard” zinc-rich,
two-component, three-coat
waterborne system and a zincfree, single-component, two-coat
system. Superficially, at least, the
latter is remarkably similar to
Valspar’s Aquaguard system even
to point that the primer goes on
green and surface dries to black
to indicate that the topcoat can
be applied.
A trial application of Cosco
Kansai’s two-coat waterborne system was carried out on 15 x 40ft
high cube containers built for
Triton at CIMC’s SLEM plant last
November and the company is
also anticipating further applications shortly at CIMC’s Dalian
plant.
Cost factor
To all appearances, then, coatings
manufacturers seem to have the
technical problem of drying
times, one of the major obstacles
to the introduction of waterborne
coatings, licked and that in turn
has reduced the extent of the line
modifications needed to ensure
comparable track times to those
achievable with solvent-borne
systems.
But as the COA report on the
availability of waterborne coatings
points out, the challenge for coatings manufacturers is as much
commercial as it is technical and
data supplied to the COA suggest
that the cost of a typical zinc-rich,
two component, three-coat
waterborne system is currently
anything between 20% and 40%
higher than a solvent-borne
equivalent.
Williams at Triton suspects that
the reality is that such systems are
close to 50% more expensive at
present, although that could go
down if mass production could be
achieved.
Chen at CIMC, which started
research on waterborne coatings
in 2003 and has carried out over
100 trial applications of various
different products, agrees that
waterborne coatings will initially
be more expensive, but believes
that in the long run the differential will narrow due to economies
of scale.
Nevertheless, in a highly costconscious and conservative industry, the price may still be too high
to pay. At today’s prices, the cost
of a conventional solvent-borne
coating system equates to around
US$250 per 20ft box, or around
8.5% of the sales price.At the lowest indicated premium of 20%, that
would add US$50 to the price of
a container if waterborne coatings
systems were used - not particularly significant in isolation, perhaps, but very significant when
larger lessors and shipping lines are
ordering containers in the tens of
thousands.
Which may be where Valspar’s
unorthodox approach could be to
its advantage. McCrory claims that
while the Aquaguard zinc-free
waterborne primer may be slightly
more expensive than a zinc-rich
solvent-borne primer, the topcoat
Hempel will shortly be carrying out another trial application of its EcoBoxmate
waterborne coating system at MCI’s Dongguan plant
is around the same price and the
elimination of the intermediate
coat means that overall the
Aquaguard system should be cost
neutral.
Interestingly, however, Guotao
Liu, vice general manager, container coatings at Cosco Kansai,
says that his company’s zinc-free,
single component, two-coat system is 20-30% more expensive
than conventional solvent-borne
coatings.
Some manufacturers may also
apply a premium to recover the
cost of any necessary line modifications and to mitigate the risk of
warranty claims - usually shared
between the container manufacturer and the coatings supplier as they build up experience in
applying waterborne systems.
Price hikes
Coincidentally, these latest developments in the container coatings
industry are taking place against a
background of rising raw materials costs, which are pushing the
cost of solvent-borne coatings
ever higher.
Only last month, Hempel announced that it was being forced
to raise prices as a result of raw
materials suppliers increasing their
prices as well as shortages of some
raw materials and rising energy
costs. “In the past year, the average price of raw materials used in
coating manufacturing has increased significantly - anywhere
from 10 to 60% for key raw materials such as epoxy, titanium dioxide and industrial metals,” the
company said.
Furthermore, substantial in-
36
36_WCN_Mar_2011.indd 1
creases in crude oil prices have
negatively influenced the cost of
petrochemical-based products, including solvents.
But that is not to say that
waterborne alternatives will become more competitive.With the
exception of solvents, the main
raw materials are subject to similar cost pressures. For the time
being, at least, the price differential will remain and that is likely
to continue to be the biggest
stumbling block to the widescale
introduction of waterborne coatings in the container manufacturing industry.
The COA report sums the
situation up neatly. “It may seem
irresponsible that container owners continue to nominate solventbased paints for their containers
given the health and environmental problems caused by the discharge into the atmosphere of the
solvents from container production and the fact that a known alternative exists. However, the
commercial and technical risks of
making the switch act as a major
deterrent.
“The container industry is
moving back into profitability after the financial storm of 2008/
2009 but margins are not at such
a level to compensate the additional up-front costs of waterbased paint or to run the risk of a
possible warranty programme to
repaint containers if problems develop in service,” it says.
And as Scheibel puts it, in the
absence of legislation, making the
switch is likely to remain for the
time being a question of “cost versus conscience”. ❏
March 2011
30/03/2011 07:24:59