ZnO-cellulose composite paper (with speechbubbles)

ZnO-cellulose composite paper
Production and structure
Marco Lucisano, Hjalmar Granberg, Dina Dedic, Anders
Mähler, Per-Åke Turesson, Anurak Sawatdee, Mats
Sandberg
This is a copy of our presentation at EMRS
2015, in Lille, France. I have added speech
bubbles to guide you through the slides.
Please feel free to contact me if you have
questions and comments:
marco.lucisano@innventia.com

www.innventia.com © 2015  2
This is a story of two kinds of materials, one
generally considered a high-tech material.

…and one often described as low tech: paper.
This is the storage facility of a paper mill
where newsprint is produced.

At the heart of the paper mill, the paper
machine…

3.200.000 m2/y (2010)
Now, if we try and estimate the world
production of 300 mm silicon wafers in 2010,
we would land approximately at 3.2 Mm2,
which is a huge surface.

3.200.000 m2 = 7 h
Yet, a 5 m wide paper machine running at
1500 m/min would produce 3.2 Mm2 of paper
in slightly more than 7 hours, not even one
work shift.

Ubiquitous electronics
So, if the technology, science and industrial
practice of papermaking could be applied to
the production of an active substrate for
electronics, then a lot of passive surfaces in
today’s world could become active, leading us
into a world of ubiquitous electronics.

We could start covering all walls of all
buildings with solar cell panels.

Or paving roads with sensors…

Papermaking
Now, a basic introduction to papermaking.

You need fibres, very often from wood, but
other sources are used as well…

Minerals, also known as fillers, are used to
improve opacity, printing properties and
production economy, since they are generally
less expensive than the fibres. Kaolin clay,
calcium carbonate are two examples of fillers
commonly used in papermaking.

A number of chemicals are used either to
improve the runnability of the process or to
give the final product the attributes and
properties it needs (strength, colour…).

And you will need a lot of water…

A paper machine is a large piece of process
equipment with two main functions:
- To produce an even piece web of paper
according to specifications, and
- To remove all the process water added to
operate the process.

ZnO in paper
So, what about using zink oxide tetrapods in
papermaking…
Can we load paper with ZnO to produce an
active substrate?

Zinc Oxide Tetrapods
This is what they look like…
It is a material available in bulk quantities (good for
papermaking) and used for example in shoe soles, car
tires and some biomedical applications.

Laboratory sheet forming
We did a series of laboratory pre-studies to investigate
the optimal recipe as to fibres, functional chemistry,
dosage strategy…

This is what they looked like…
Some of the formulations we tested were better then others, in the picture we can
clearly see that some are more flocculated than the others.
We used the result of the pre-trials to prepare our pilot scale production on the
FEX pilot papermachine at Innventia. FEX operates at conditions that are very
good replicas of those found in industrial practice.
A description of the FEX-machine is available at www.innventia.com/FEX

Trial recipe
 Fibres: 70% long fibres (hardwood), 30% short fibres (birch)
 Grammage: approx. 80 g/m2
 ZnO-content: 0% – 15% – 30% – 45%
 Retention aid: Percol 1510, 750 g/ton
 Size: AKD, 7500 g/ton (in selected trial points)
 Fourdrinier former
 Machine speed: 100 m/min

Zinc Oxide Tetrapods
Zinc oxide tetraprods are classified as a ceramic
nanomaterial. Debated toxicity among researchers, most
pointing to low. Still, precautions are needed until the
issue of potential toxicity is solved. Due to the needle
shape of the tetrapods particular care is taken when
particles are handled in dry state.

Workers’ safety is paramount and the staff wears face
masks with air filters when handling dry ZnO and dry
paper.

Samples reeled wet after the presses, marked before
drying.

The dryer was enclosed in a ventilated tent, since we
assumed that most dust would arise when handling dry
paper.

Micrographs

0% ZnO
Micrograph of paper with 0% ZnO.

15% ZnO
Micrograph of paper with 15% ZnO.
Tretrapods and fragments can be
observed on the surface of the sample.

30% ZnO

45% ZnO

45% ZnO
Micrograph of paper with 45% ZnO at three different
magnifications. The images clearely show that ZnO could
be retained in the sample.
This is important in papermaking…

Does it work?

ZnO Cellulose composite paper – UV-sensing properties
(Mats Sandberg, Monday, May 11th)
Photocurrent @ 5V of ZnO-
Cellulose composite sheets with
different composition
Hg lamp 2 mW/ cm2
30% 30%A 45% 45%A
15% 15%A
0%
Yes, it does, as shown in this diagram from the
presentation “ZnO-cellulose composite paper -
UV-sensing properties” by Sandberg, Sawatdee,
Peterman, Granberg, and Turesson, also
presented at EMRS on Monday, May 11th, 2015.
…and with this material we are not
simply printing a sensor on top of a
passive paper substrate. Here the
paper itself is part of the solution.

One more thing

Paper is not “just paper”. Papermakers have
technologies to design sheet structures and use
different raw material compositions along the
thickness direction of something as thin as
newsprint or copy paper. It is called stratified
paper.
What could be done with stratified paper
electronics in 2, 3, 5 or more layers?

Researchers in papermaking are also developing
paper-like materials with the soft feeling of a
fabric, papers that are highly stretchable, and
papers on which one can “print stiffness”. All of
this on a paper machine! Remember 7 hours to
produce 3.200.000 m2!
Could this degree of structural design be used for
large scale substrates for electronics?

And this is an example of a paper material
designed to move as a response to its
environment.
So what about active substrates that move?

We have shown that we can take a material
that is today available in bulk...
ZnO tetrapods

3.200.000 m2 = 7 h
…and use a mature and well trimmed
production process, to produce a new
materials with new exciting properties.

Boosting business with science www.innventia.com
… what more can we do combining the old
and the new? Where are the first large scale
applications and who wants to join forces…

ZnO-cellulose composite paper (with speechbubbles)

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