effects of binders and additives on inkjet coating … of binders and additives on ikjtc ti pi tp st...

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 320

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


Material used:Modified Calcium Carbonate – an exampleModified Calcium Carbonate an example

Discretely bimodal pore size distribution

Intraparticlepores

Interparticle pores


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


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


Coated Layer:Foil substrateFoil substrate

bench coated foil scrolled sample for porosimetry

(30 cm x 42 cm)

1.5 cm


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


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)


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


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.


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).


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 32

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


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


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


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


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


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


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.


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


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