Klemen MOŽINA
1
, Vera RUTAR
2
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Papir za notranjost revije PAPIR je prispevala papirnica Gori~ane d.d., Sora Matt 90 g/m
2
MODIFIKACIJA GCC ZA KAKOVOSTNEJŠI 
IZPIS KAPLJI^NEGA TISKALNIKA
Gcc mODIFIcATION FOR BETTER PERFOmANcE 
OF INk-JET PRINTS
IZVLE^EK
Navkljub negativni medijski publiciteti papir ohranja vodilno vlogo med uporabljenimi grafi~nimi materiali. Razlog je v tem, 
da je papir izjemno odporen proti okoljskim vplivom in predvsem je tudi biorazgradljiv. Premazi, narejeni iz naravnih sestavnih 
delov, lahko nadomestijo ekolo{ko manj prijazne in cenovno dražje sinteti~ne materiale. Posebne lastnosti lahko zagotovimo s 
povr{insko aktivnostjo, to je kemijsko ali s spremembo geometrije pigmentnih delcev, ki se jo doseže bodisi z granulacijo bodisi 
z razporeditvijo razli~nih velikosti pigmentnih delcev oziroma njihovo obliko. Naravni kalcijev karbonat (GCC) se vse pogosteje 
in vse {ir{e uporablja v papirni industriji. Poleg zadostitve ustreznih opti~nih lastnosti je trend v izdelavi lažjih, z uporabo 
nanomaterialov, to je materialov nižjih gramatur oziroma tako imenovanih NMP . Zahteva po nižji specifi~ni energiji in proizvodnih 
stro{kih sili proizvajalce grafi~nih papirjev k povi{ani uporabi pigmentov. Vendar je, tako kot pri vsaki stvari, tudi v tem primeru 
uporaba pigmentov do neke mere smiselna. Tako je nastala pri inženirjih ideja o prilagoditvi delcev pigmenta, ki bi raz{irila krog 
uporabnosti in namembnosti. Modificirani GCC pigmentni delci, to je TCC (treated calcium carbonate), zagotavljajo prav {iroko 
uporabnost. V prispevku so predstavljeni ustrezni tehnolo{ki postopki obdelave surovega GCC in u~inek, ki jih modifikacija 
geometrije pigmentnih delcev, kateri obenem zvi{ajo funkcionalne lastnosti, kot so struktura papirja in povr{ina le-tega, 
doprinese. Rezultati raziskave slikovito predstavijo, kako inženirsko zasnovana modifikacija GCC pozitivno u~inkuje na v osnovi 
zastavljeno kon~no namembnost tako premazanega papirja, to je potiskljivost papirja s kaplji~nim tiskalnikom z barvami na vodni 
osnovi.
Klju~ne besede: GCC, modificirani pigmenti, premazan papir, kaplji~ni tisk, bleeding, wicking.
ABSTRACT
Paper is still the most common graphical material because of its traditional sustainability and biodegradability. Coatings and 
surface treatment with natural components and additives can replace unfriendly and more expensive synthetic materials, 
normally with special properties. However, special properties can be obtained with surface functionalization by chemical or 
pigment particle geometry modification. Surface geometry modification can be achieved with the application of the pigments 
and coating formulations with apparel properties, e.g. granulation, particle size distribution and particle shape. The natural 
ground calcium carbonate (i.e. GCC) usage in papermaking industry is more and more widely used. Beside optical properties, the 
trends of lightweight materials, i.e. reducing grammage by using nano materials and products (i.e. NMP), lower specific energy 
requirement and costs, forces increasing of pigments usage. After all, as everything has its own limits, the resemblance also 
happens with GCC pigment. Following the stated above, the pigment engineering appears with the idea of particles modification 
to increase its applicability and particularity. Modified GCC particles, e.g. TCC (i.e. treated calcium carbonate) enable wide range 
spectrum of the GCC raw material application. In the article, the right technological procedure to treat wet grinded GCC and 
the effect on the changes of the particle geometry, that are at the same time influenced on increasing functional properties, i.e. 
paper structure and its surface, are presented. Results of survey showed that properties of GCC coated printing paper, required 
for ink-jet printing with water-based inks had significantly improved.
Key words: GCC, modified pigments, coated paper, ink-jet printing, bleeding, wicking.
1 INTRODUCTION
The paper industry has realized high-speed 
inkjet printing as a vast new business 
opportunity. To provide high goals the 
R&D activities are going into a new, i.e. 
modified coating pigments, mostly on the 
bases of GCC development with special 
properties as the answer on the increasing 
market demands. �1, 2, 3� Overall, paper 
industry is in a transition situation, where 
its main goal is not just basic paper 
production, as it was in the past, but 
producing additional products, i.e. coated 
paper for specific purposes. Paper filler 
and paper coatings in the form of GCC, 
has become essential in making paper and 
are the most significant portion of used 
additives, in terms of weight percent, e.g. 
in range from 3 to 38 %. �4, 5, 6, 7�
Ink-jet printing is non-contact printing 
technique. The only contact is in the 
moment of ink transfer on the paper 
surface. For good reproduction and 
print quality, the coated papers are used, 
where the coated layer serves as micro-
porous substrate. Dye in ink penetrates 
into the micro-porous substrate along 
the capillaries and the depth of the 
penetration is the criteria for the printout 
quality. �8, 9� An ink-jet printing test for 
the vaterite-coated papers resulted in high 
print quality, without bleeding or wicking 
problems because of the good wettability 
tendency (similar with silica). In the paper 
coating substrate, the fixing agent, i.e. 
poly-DADMAC was added. �10� For liquids, 
e.g. ink or printing color, their penetration 
into the paper is more important than 
flow through the paper structure. Liquid 
penetration takes place by capillary flow 
in capillaries between particles in coated 
layer structure. The penetration flow 
is expressed by the Lukas-Washburn 
(Equation 1) and Young-Laplace equations 
(Equation 2). �11, 12� Liquid transfer on/in 

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paper surface is represented with Young-
Laplace equation:
      (1)
while wettability or liquid penetration is 
expressed by Lukas-Washburn – equation:
      
(2)
where is:
Δp – external pressure difference, 
γ
λ
 – surface tension, θ – contact angle 
between the liquid and the capillary wall, 
r – pore radius, η – fluid viscosity, 
p – liquid pressure in the nip, and 
h – distance travelled.
The Lukas-Washburn equation (eg. Equ. 2) 
predicts the depth of liquid penetration. 
In converting process, e.g. calendaring, 
paper surface, mostly coated surface, 
the external pressure compresses paper 
structure, which reduces pore volume and 
consequently reduces liquid penetration.
2 EXPERIMENTAL PART
In laboratory scale some trials of preparing 
and coating colour with modified GCC 
pigment were done in company Calcit. 
The main purpose of all trials was to 
find out the procedure of pigment 
modification to encounter the market 
demands for the ink-jet printing papers 
and paperboards. Cationic treatment 
captures the anionic dye and keeps it 
from spreading and wicking. The GCC, 
with special production procedure, the 
charge as well as the shape and size of the 
pigment particles were also modified.
The specific surface area increased and 
at the same time, the particles charge 
increased from 17 to 12 mV at pH 7.85. 
With the addition of weak and/or strong 
acids, we changed the specific surface 
area from 8 to 33 m
2
/g (i.e. Table 1).
3 RESULTS
Results of the investigation were outcome 
of the research work, namely grounded on 
the bases of preliminary idea of creating 
such a paper coating formula that ink-jet 
printouts would meet the final demand 
towards the highest possible quality. 
Therefore we have included SEM and 
image analysing software ImageJ.
The trials of coating base wood free paper 
with three coating colours, with standard 
wet grinded GCC pigment quality, 
modified pigment TCC2 and reference 
pigment, were done. 
The main differences between used 
materials, like specific surface area and 
mean particle diameter are shown in the 
Table 2.
Table 1: Modified pigment preparation.
Preglednica 1: Priprava modificiranega pigmenta.
Table 2: Pigments characteristics.
Preglednica 2: Karakteristike pigmentov.
Trials, No. Modification procedure Addition BET �m
2
/g�
/ raw material – dry 8.10
5 material with 10 % s.c. + 
weak acid
Ca(OH)
2
CO
2
29.10
8 – TCC2 material with 10 % s.c. + 
weak acid
Ca(OH)
2
CO
2
32.93
Pigment sample D50 �%� BET �m
2
/g�
standard quality 0.686 µm 12.24
TCC 2 1.241 µm 32.93
Ref. 1.353 µm 60.74
Figure 1: Standard product.
Slika 1: Standardni proizvod.
Figure 2: Modified product − TCC2.
Slika 2: Modificiran proizvod − TCC2
The following SEM pictures (i.e. Fig 1–3) 
of calendared coated paper surface show 
how coating structure is organized, 
especially on the micro and macro scale. 

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The effect of the particles shape and size 
on micro porosity of the coating layer is 
well seen from Fig. 1–3, where modified 
product TCC2 is in well relation with the 
reference one. GCC particles are more or 
less equally distributed on the surface, 
with as little as possible low number of 
micro and macro pores.
Coated papers were tested on inkjet 
printing. Pre-presses were done on 
the printer HP Officejet 6000 Printer 
(thermal 4800 × 1200 dpi, dye-based 
inks, min 1.3 pl). In the Table 3–5 are 
presented results of bleeding and wicking, 
determined by image analyzing software 
Figure 3: Reference product.
Slika 3: Referen~ni proizvod.
Table 3: Bleeding of black 8 on yellow.
Preglednica 3: »Krvavenje« ~rne 8 na rumeni podlagi.
Table 4: Bleeding of yellow 8 on black.
Preglednica 4: »Krvavenje« rumene 8 na ~rni podlagi.
Specimen
Picture of
bleeding
Area �%� Increment �%� Share �%�
standard
38.95 − 5.72 12.24
TCC2
55.56 10.89 32.93
reference
44.68 0.01 60.74
ideal
44.67
Specimen
Picture of
bleeding
Area �%� Increment �%� Share �%�
standard
38.16 1.86 5.12
TCC2
36.37 0.07 0.19
reference
36.29 − 0.01 − 0.03
ideal
36.30
ImageJ. The effect of the pigment 
particles modification on micro porosity 
and successful capturing anionic dye 
showed significantly clear, so spreading 
and wicking, evaluated by image analysis 
was minimized. In Table 3 are presented 
results of bleeding of black 8 on yellow 
background. TCC2 has an increment over 
10 %, which is not well enough and it 
is something to work on in the future 
researched.
From Table 4 is well seen the tendency 
towards lower increment of TCC2, which 
is just 0.07 %. However, same trend of 
lowering wicking can be seen from T able 
5, where TCC2 has increment of perimeter in 
just 0.63 mm or exactly 1.00 %. Mentioned 
results of image analyzes clearly indicate, 
how well were pigment particles modified 
and that our research is going in the 
right direction. Not simply grounding 
pigment particles of GCC into the nano 
size particles, but modifying them on 
such way, that surface is after treatment 
correctly charged, which will have an 
impact on the capturing water based 
printing ink of inkjet printer and hold the 
dye particles on the coated paper surface, 
which results in color satiation and has 
the end effect on clear picture and text 
reproduction as well as on the readability.

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Table 5: Wicking.
Preglednica 5: Sivenje.
Specimen
Picture of
wicking
Area �mm
2
� Perimeter �mm�
Increment of 
Perimeter
Share �%�
standard
38.16 1.86 − 2.80 5.12
TCC2
36.37 0.07 0.63 0.19
reference
36.29 − 0.01 0.56 − 0.03
ideal
36.30
4 CONCLUSIONS
Ground calcium carbonate (GCC) is the 
main component in the coating color. 
The successful pigment engineering, like 
finer particle size distribution, effective 
dispersing system and other procedures 
that are reflected in modified specific 
area, charge etc., provide a satisfactory 
high values of significant properties of the 
coated paper surfaces that are used as a 
main graphic material in many different 
printing technics. Results of development 
work are outcome of the study, how 
does modified GCC pigment impact 
on micro-porosity of the coated paper 
surface and how it effect on capturing 
anionic dye in ink-jet printing technique. 
As presented in Table 4 and 5, the results 
are significantly well and the printouts are 
of high-resolution quality with very low 
bleeding/wicking. Information printed on 
such coated paper is clear and could be 
used also for smaller text/pictures as the 
standard, i.e. 10–12 pt, are.
5 LITERATURE
�1� The future of specialty papers to 2013, 
Leatherhead, UK, Intertech Pira, 124 pp, 2008.
�2� FRISK, R., KUKAMO, V. and VARNEY , D. 
Keeping up with the printer, PPI, 2010, p. 
39–42.
�3� RUTAR, R., RUTAR, V. and MOŽINA, K. Finer 
pigment for better print, 14
th
 International 
conference on printing, design and graphic 
communication Blaž Baromi}, MIKOTA, M 
(ed.), p. 36–45, Senj, October, 2010.
�4� JÖNSSON, J. and BERNTSSON, T. Analysing 
the potential for implementation of CCS within 
European pulp and paper industry. Energy, 
2012, Vol. 44, No. 1, p. 641–648.
�5� GAUDREAULT, R., Di CESARE, N., WEITZ, D. 
and van de VEN, T. G. M. Flocculation kinetics 
of precipitated calcium carbonate. Colloids and 
Surfaces A: Physicochemical and Engineering 
Aspects, 2009, Vol. 340, Np. 1–3, p. 56–65.
�6� LÓPEZ-PERIAGO, A. M., PACCIANI, R., 
GARCÍA-GONZÁLES, C., VEGA, L. F . and 
DOMINGO, C. A breakthrough technique for 
the preparation of high-yield precipitated 
calcium carbonate. The Journal of Supercritical 
Fluids, 2010, Vol. 52, No. 3, p. 298–305.
�7� ALINCE, B., BEDNAR, F . and van de VEN, 
T. G. M. Deposition of calcium carbonate 
particles on fibre surfaces induced by cationic 
polyelectrolyte and bentonite. Colloids and 
Surfaces; A: Physicochemical and Engineering 
Aspects, 2001, Vol 190, No. 1–2, p. 71–80.
�8� GANE, P . A. C. Viewing paper coating 
formulations as nano composites open the 
door to a new materials technology. Przegl. 
Papier, 2010, Vol. 66, No. 8, abstract.
�9� PATRICK, K. A tailored approach to kaolin 
products. Paper 3600, 2010, Nov/Dec, p. 
40–42.
�10� MORI, Y ., TOSHIHARU, E. and AKIRA, I. 
Application of Vaterite-Type Calcium Carbonate 
Prepared by Ultrasound for Ink Jet Paper. 
Journal of Imaging Science and Technology, 
2010, Vol. 54, No. 2, abstract.
�11� NISKANEN, K. Paper Physics, Papermaking 
Science and Technology. Book 16, 1998, p. 
287–294.
�12� HOLIK, H. Handbook of Paper and 
Board. Wiley-VCH Verlag GmbH & Co. KgaA, 
Weinheim, Germany, 2006, pp. 528.
1
mag., UL, NTF , OT , Katedra za grafi~no
in komunikacijsko tehnologijo 
2
dr., Pulp and Paper Institute Ljubljana 
Acknowledgement
Many thanks to Rok Rutar and Janja 
Juhant Grkman, from the company 
Calcit Stahovica, Slovenia, for samples of 
modified pigments and their participation 
in trials.
Obdelava kovin: struženje, rezkanje vrtanje.
Izdelava valjev, gredi in ostalih rezervnih delov za papirno industrijo.