effects of binders and additives on inkjet coating … of binders and additives on ikjtc ti pi tp st...
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Effects of Binders and Additives on I kj t C ti Pi t P St tInkjet Coating Pigment Pore Structures
Cathy J. Ridgway, Vesa Kukkamo and Patrick A.C. Gane
PaperCon 2011 Page 1320
Introduction
Aim: t id th t t h i i kj t ti h ito consider the pore structure change in inkjet coatings when using
certain binder types and polymer additives:
• Starch, PVOH, latex particulate, cationic polymer…………..- each/all can alter the pore volume and pore structure
- Positive?- Negative?Negative?
PaperCon 2011 Page 1321
Experimental
• Effect of particulate binder addition
• Loss of pore volume as function of additives- Cationic polymer additivep y- PVOH and starch- Latex (plus PVOH and starch)
• Implications for printability
PaperCon 2011 Page 1322
Material used:Modified Calcium Carbonate – an exampleModified Calcium Carbonate an example
Discretely bimodal pore size distribution
Intraparticlepores
Interparticle pores
PaperCon 2011 Page 1323
Particle size distribution:Narrow (nMCC) and broad (bMCC) compared to standard coarse ( ) ( ) pground calcium carbonate (cGCC)
100nMCC
70
80
90
r tha
n / %
nMCCbMCCcGCC
40
50
60
wei
ght f
iner
20
30
40
cum
ulat
ive
0
10
0.1 1 10 100particle si e / mparticle size / µm
PaperCon 2011 Page 1324
Forming the porous structures:Tablet PressTablet Press
applied pressure - 15 barapplied pressure - 15 barpp p
‘O’ ringsclamping bolts
pp p
‘O’ ringsclamping bolts
coatingrubber seals
clamping bolts
coatingrubber seals
clamping bolts
4 cm1.5 cmfunnel
membrane (d = 0.025µm)support funnel
membrane (d = 0.025µm)support
Tablets dried in oven 24 hours at 60 oC
PaperCon 2011 Page 1325
Coated Layer:Foil substrateFoil substrate
bench coated foil scrolled sample for porosimetry
(30 cm x 42 cm)
1.5 cm
PaperCon 2011 Page 1326
Effect of Particulate Binder Addition:Liquid “inert” SA binder containing coating in tablet form
1 2
1.6
2.0
] / c
m 3 g-1 MCC
MCC + SA latexcGCC
Liquid inert SA binder containing coating in tablet form
• Volume reduction on addition of SA latex
0.4
0.8
1.2
re v
olum
e [V
]
• cGCC has much lower total specific pore volume
0.00.001 0.01 0.1 1 10
diameter [d ] / µm
por
5.0
ogd
)] MCCMCC + SA latex
• Discrete bi-modal pore size distribution 2.0
3.0
4.0
ume
[dV
/d(lo
/ cm
3 g-1
cGCC
of MCC• Reduction of mid-size pore diameter
volume contribution due to latex filling connecting pores
0.0
1.0
0.001 0.01 0.1 1 10
pore
vol
u /
filling connecting poresdiameter [d ] / µm
PaperCon 2011 Page 1327
Latex sites itself interstitially*
CaCO3pigment
Reduction of connective
l{
particulatelatex binder
pore volume{
* Ridgway C J and Gane P A C Journal of Pulp and Paper Science 33(2) pp 71 78 (2007)* Ridgway, C.J. and Gane, P.A.C., Journal of Pulp and Paper Science, 33(2), pp. 71-78 (2007)
PaperCon 2011 Page 1328
Cationic Polymer Addition:Tablet formTablet form
Cationisation to provide water fastness when using anionic 0 5
0.6
d)]
nMCCbMCCnMCC + cationising agentbMCC + ti i i twhen using anionic
dye based inkjet inks:
7 pph PolyDadmac 0.3
0.4
0.5
e [d
V/d
(logd
m3 g-1
bMCC + cationising agent
0.1
0.2po
re v
olum
e/ c
m0.0
0.001 0.01 0.1 1 10diameter [d ] / µm
p
• bMCC has less pore volume than nMCC • as expected due to the difference in breadth of particle size distribution
• Cationising reduces fine pore volumed d ill it• reduced capillarity
PaperCon 2011 Page 1329
Cationic Polymer Addition (tablet form)
Sample
Total specific intruded volume / cm3g-1
porosity /%
nMCC 0.353 0.004 47.5 1 %
bMCC 0.313 0.003 44.7 1 %
nMCC + cationising agent 0.320 0.003 44.5 1 %
bMCC ti i i t 0 266 0 003 40 0 1 %bMCC + cationising agent 0.266 0.003 40.0 1 %
nMCC volume loss – 8.6 %bMCC volume loss – 16.1 %
Polymer addition to cationise anionic pigments will• deteriorate performance in respect to
• absorption rate
bMCC volume loss 16.1 %
abso p o a e• absorption volume
Implication:A move to pigmented inks (rather than anionic dye-based inks)
• would allow more cost-effective coating pigments to be used by retaining ou d a o o e cost e ect e coat g p g e ts to be used by eta gmore of the original pore volume delivered from the pigment manufacture.
PaperCon 2011 Page 1330
Effect of PVOH and Starch Addition on Loss of Pore Volume (foil preparation)Pore Volume (foil preparation)
• PVOH absorbs up to ~ 30 % of its own weight of water
• creates loss of pore space by the presence of the swelling PVOH
• limits the absorption rate by reducing it to the interpolymer matrix diffusivity*
• overall reduced pore volume: 0.18 cm3g-1 compared to 0.31 cm3g-1
* Lamminmäki, T., Kettle, J.P., Puukko, P., Gane, P.A.C. and Ridgway, C.J., Journal of Pulp and Paper Lamminmäki, T., Kettle, J.P., Puukko, P., Gane, P.A.C. and Ridgway, C.J., Journal of Pulp and Paper Science, 35(3-4), pp. 137-147 (2009).
PaperCon 2011 Page 1331
Effect of cationising in the presence of PVOH and Starch Addition on Loss of Pore Volume (coating on foil)
0.30
] bMCC - anionicbMCC ti i
Addition on Loss of Pore Volume (coating on foil)
100 parts bMCC 5 parts PolyDadmac
0.20
0.25
[dV
/d(lo
gd)
3 g-1
bMCCc - cationic5 parts PolyDadmac plus 2.5 parts PVOH 2.5 parts starch
0 05
0.10
0.15or
e vo
lum
e [
/ cm
3
0.00
0.05
0.001 0.01 0.1 1 10diameter [d ] / m
po
diameter [d ] / µm
• Overall reduced pore volume on cationising in the presence of PVOH and starch: total pore volume 0 18 to 0 16 cm3g-1starch: total pore volume 0.18 to 0.16 cm3g 1
intra pore volume 0.04 to 0.02 cm3g-1
PaperCon 2011 Page 1332
Effect of Cationising on Loss of Pore Volume in presence of PVOH and Starchpresence of PVOH and Starch
Sample Total specific intruded specific volume / cm3g-1
bMCC + PVOH + starch 0.183 0.002
bMCCc + PVOH + starch 0 157 0 002bMCCc + PVOH + starch 0.157 0.002
bMCCc volume loss – 11.1 %
• Cationising has two effects when considered in soluble binder containing thin film coatings
• the dispersing quality is not as good as that of an optimised anionic dispersion e d spe s g qua y s o as good as a o a op sed a o c d spe s o• the slightly larger pore size of the interparticle structure indicates some
agglomeration/flocculation• the nanopores needed for high capillarity are reduced in volume
• the cationic polymer used to cationise the coating is also partly filling the poresthe cationic polymer used to cationise the coating is also partly filling the pores
PaperCon 2011 Page 1333
Latex Addition to Formulations with PVOH and Starch Additives: effect on pore volumeStarch Additives: effect on pore volume
100 parts bMCC 5 parts PolyDadmac 2 5 parts PVOH
0 12
2.5 parts PVOH 2.5 parts starchplus 5 or 10 parts polyvinyl acetate latex (PVAc)
0.08
0.10
0.12
/ cm
3 g-1
0.04
0.06
volu
me
[V]
bMCC
0.00
0.02
0 001 0 01 0 1 1 10
pore
bMCCbMCC + 5 pph PVAcbMCC + 10 pph PVAc
0.001 0.01 0.1 1 10diameter [d ] / µm
PaperCon 2011 Page 1334
PVAc Addition to Formulations with PVOH and Starch Additives: effect on pore volumeStarch Additives: effect on pore volume
Total specificSample
Total specific intruded volume /
cm3g-1
0 pph PVAc 0.102 0.001
5 pph PVAc 0.101 0.001
10 pph PVAc 0.078 0.001
• 5 parts PVAc particulate binder makes little to no difference in pore volume
• 10 parts results in reduced total pore volume10 parts results in reduced total pore volume
PaperCon 2011 Page 1335
Latex Addition to Formulations with PVOH and Starch Additives: effect on pore structure
0 140.160.18
gd)]
bMCCbMCC + 5 pph PVAcbMCC + 10 pph PVAc
Starch Additives: effect on pore structure100 parts bMCC 5 parts PolyDadmac 2 5 parts PVOH
0.080.100.120.14
ume
[dV
/d(lo
g/
cm3 g-1
bMCC + 10 pph PVAc2.5 parts PVOH 2.5 parts starchplus 5 or 10 parts polyvinyl acetate latex (PVAc)
0.000.020.040.06
pore
vol
u /
• 5 parts PVAc shows latex depletion flocculation
• higher peak 0.000.001 0.01 0.1 1 10
diameter [d ] / µm
higher peak• 10 parts shows progressive closure of interconnecting pores
• lower and narrower peak• all show fine pores
• Soluble non-absorbent binder, eg. starch• can be disadvantageous due to loss ofall show fine pores can be disadvantageous due to loss of effective pores
• Particulate binder allows continued access to the nanopore region
• permeability is maintained• permeability is maintained• limited or no choice of cationically stable latex
PaperCon 2011 Page 1336
Comparison of soluble versus particulate binders
• Soluble non-absorbent binder• blocks access• fills pores
• Soluble absorbing binder• reduces pore volume• absorbs liquidq• diffusion rate limited
Particulate binder • allows continued access to the nanoporeallows continued access to the nanopore
region• permeability is maintained
- advantageous at low levelsg- But:
- limited or no choice of cationically stable latex
PaperCon 2011 Page 1337
Implications for Printability
Colour-to-colour bleedGood Colour-to-colour bleedGood
Poor
Very bad
Poor
Very bad
Print quality could be improved by:q y p y• reducing additives amounts by 1-2 parts • eliminating the need for polymer additives for cationising by moving
toward pigmented ink formulations• reducing use of soluble binders by replacing with particulate binders• reducing use of soluble binders by replacing with particulate binders
PaperCon 2011 Page 1338
Conclusions• All polymer additives reduce the pore volume of speciality calcium carbonate
inkjet pigment structures, particularly the fine high capillarity pores
• Coating pigments need to be cationised - requirement for anionic dye water fastness.
- This affects the fine pore region and therefore the capillarity and the absorption efficiency
• Soluble binders reduce available pore volume - Absorbing binders - the efficiency of absorption is reduced to that of the interpolymer
diffusion in the binder matrix, and the volume is reduced despite its absorbency, p y- Non-absorbing binders – volume is reduced significantly
• The use of particulate binder when used at low to moderate levels preserves the total pore volume and permeability of the structuretotal pore volume and permeability of the structure
- Higher levels of particulate binder lead to a loss of permeability but the capillarity is retained.
- A disadvantage of currently available particulate binders is that if cationising of the latex or the whole formulation is still required the stability of the dispersion islatex, or the whole formulation, is still required, the stability of the dispersion is compromised, and, once again, the capillarity is reduced.
PaperCon 2011 Page 1339
Acknowledgements
• Thanks to my Co-authors
Vesa Kukkamo Applications ScientistApplications ScientistOmya International AG
Patrick GanePatrick GaneHead of Research and Development
Omya Development AG
Professor of Printing TechnologyAalto University
PaperCon 2011 Page 1340