Page 47 from: June / July 2013

I N T H E L A B O R A T O R Y . . .

tations, he suggests the novel method
‘should lead towards better quality of
paper and especially board due to the
possibility of getting rid of long circu-
lated weak fi bres’.

‘Totally unexpected’
‘We came across the idea two years
ago in our spearhead programme that
targeted waste streams,’ Harlin recalls.
‘And, actually, we were surprised that,
with half a dozen tests, we already had
a reasonably useful sequence for the
process and material for proof of con-
cepts.’ This success was ‘totally unex-
pected according to text books’ – an
outcome he attributes to the VTT’s in-
house knowledge of pulp processes.  
‘We made the development with very
limited resources, relying most of all on
our team’s drive for innovation,’ adds
Harlin. Expressing his gratitude that the
team had been granted access to Tam-
pere University of Technology’s spin-
ning facilities, he concludes: ‘Overall,
we managed to run the project without
too much trial and error.’

Every year, Europe generates around 60 million tonnes of recycled paper
– of which cardboard makes up around
40%, estimates Finland’s VTT Technical
Research Centre. At the same time,
roughly 10 000 tonnes of diapers/nap-
pies and similar sanitary products are
discarded annually throughout Europe’s
metropolitan areas alone. However,
these numbers could see quite a
change in the years to come, argues VTT
research professor Ali Harlin.
The initial impact of its non-wovens
research is expected to be on compa-
nies that produce diapers/nappies,
sanitary napkins and cleaning cloths.
‘We also believe that the process could
be used to create certain fi lters due to
the quality of the fi bre,’ he adds. Devel-
opment of composites might also be
an option at a later stage but the VTT
team must still carry out the necessary
legwork to achieve the required
mechanical standards.

Competitive edge
One of the most promising aspects of
this work is that, despite previously ‘pro-
hibitive’ production costs, the manufac-
turing bill for VTT’s paper and cardboard-
based non-wovens is 20% lower than

its brightness following an acid wash
to remove metals from it. According
to Harlin, a patented carbamate tech-
nology is used to ensure the VTT team
can harvest ‘pure cellulose’ from the
dissolving pulp. This custom technol-
ogy breaks down the cellulose so it
can be spun into fi bres through spin-
nerets, and involves chemicals which
are not as dangerous as the common-
ly-used viscose process, the team
emphasises.
According to Harlin, the new method
consists of a ‘foam forming technolo-
gy’. What sets the VTT’s approach apart
is that the biodegradable non-woven
sheets are produced without transfer-
ring the fi bres to a wire-mesh mould in
water suspension. Instead, the
researchers have opted for a wet foam
consisting of water, foaming agents
and roughly 70% air; the cellulose is
mixed with the foam, poured into the
mould and then allowed to settle.
Before the sheet is left to dry for the
night, the liquid is extracted with the
help of a custom-made suction table.
Although ‘spinnability’ and fibre
strength have been optimised already,
Harlin says a whiter end product can
still be achieved. Sharing future expec-

that for non-wovens produced from
wood raw materials. ‘This means that
bio-based non-wovens are now more
competitive on price in comparison with
plastic-based products,’ states Harlin.
The Finnish scientists are confi dent that
their discovery will help increase the
usage of bio-based fi bres in dispos-
ables. ‘Recovering recycled fi bre is not
markedly more environmentally friend-
ly than production of pulp, but it
enables reuse of cellulose when it is no
longer valuable in paper-making and
reduces waste and sludge,’ he com-
ments.
‘The methods we apply are typical pro-
cesses applied in the pulping industry,
which makes our confi dence in terms
of the processability high,’ remarks
Harlin. First, the paper and cardboard
is shredded and then subjected to a
mechanical fractionation stage to
remove fi ne and inorganic materials.
Harlin describes cleansing the paper
and cardboard of fi ller material, lignin
and especially the hemicellulose as ‘the
most demanding step’ of the process.

Harvesting ‘pure cellulose’
Once this step is completed, the
resulting pulp is bleached to improve

A recycled
route to non-wovens
It is believed that a new discovery by Finland’s VTT
Technical Research Centre could pave the way for fur-
ther innovation in paper and cardboard recycling. Its
scientists have established a novel way to use such
material to create biodegradable non-wovens, such as
for hygiene and homecare products.

By Kirstin Linnenkoper

Every month, ‘Recycling International’ highlights a promising recycling-related research project with a global, technical, economic or social impact.
If you know of an interesting project which meets these criteria, contact our editorial team at [email protected]

For more information,
contact Prof. Harlin at:
[email protected]

RESEARCH

LED BY
SUPPORT FR

OM

Biodegradable
non-wovens

VTT Technical
Research Cent

re

Tampere Unive
rsity

of Technology

Prof. Marjo Määttänen
proudly shows the VTT’s
new innovation.
*Photos courtesy of the VTT.

RI-5_Laboratory.indd 47 17-06-13 15:15