Effect of Substrate Contact Angle on Ink Transfer in Flexographic Prin=ng F. E. HIZIR and D. E. HARDT MassachuseEs Ins=tute of Technology Outline -­‐  Introduc=on -­‐  Mo=va=on and Objec=ves -­‐  Simula=ons . Methodology . Results -­‐ Conclusions and Future Work Flexography OLED Flexographic Prin;ng Prin9ng$plate$
Plate$
cylinder$
Prin9ng$substrate$
Impression$
cylinder$
[2] thin film transistor [1] RFID blade!
Anilox$
roller$
photovoltaic cell Ink$supply$
(Chambered$doctor$
blade$system)$
[4] [1] H. Kang et. al., Advanced Materials, 2012 [2] Wikimedia/meharris [3] Gyou-­‐Jin Cho/Sunchon Na=onal University [4] A. Hubler et. al., Advanced Energy Materials, 2011 [3] Ink Transfer in Flexography Flexographic Prin;ng Prin9ng$plate$
Plate$
cylinder$
Prin9ng$substrate$
Impression$
cylinder$
INK TRANSFER TO THE ANILOX ROLLER BLADING OF THE ANILOX ROLLER (fill the cells + remove excess ink layer) INKING OF THE STAMP (par=al cell evacua=on by ink spli_ng) INK TRANSFER TO THE SUBSTRATE (ink spli_ng) blade!
Anilox$
roller$
stamp substrate AIR Ink$supply$
(Chambered$doctor$
blade$system)$
INK anilox cell stamp Ink Transfer in Flexography Flexographic Prin;ng Prin9ng$plate$
Plate$
cylinder$
Prin9ng$substrate$
Impression$
cylinder$
INK TRANSFER TO THE ANILOX ROLLER BLADING OF THE ANILOX ROLLER (fill the cells + remove excess ink layer) INKING OF THE STAMP (par=al cell evacua=on by ink spli_ng) INK TRANSFER TO THE SUBSTRATE (ink spli_ng) blade!
Anilox$
roller$
Ink$supply$
(Chambered$doctor$
blade$system)$
stamp substrate AIR INK anilox cell stamp Mo=va=on and Objec=ves Flexographic Prin;ng Prin9ng$plate$
Plate$
cylinder$
Prin9ng$substrate$
Impression$
cylinder$
Ink Transfer from Stamp to Substrate -­‐ Thickness of printed product -­‐ Device performance Objec5ves -­‐ Guidelines for substrate and stamp design -­‐ Control printed layer thickness -­‐ Inves=gate contact angle effects blade!
Anilox$
roller$
Ink$supply$
(Chambered$doctor$
blade$system)$
substrate stamp Simula=on Domain Simula5on domain and its dimensions y"
direc0on&of&mo0on&&
SUBSTRATE&
LIQUID&
AIR&
8µm'
symmetry'
x"
STAMP&
2µm'
8µm'
Parameters used in the simula5on Ink$dynamic$viscosity$
0.1$N.s/m2$
Ink$density$
1000$kg/m3$
Air$dynamic$viscosity$
1.81e;5$N.s/m2$
Air$density$
1.16$kg/m3$
Gravity$accelera@on$
0$
Separa@on$speed$
0.1$m/s$
Volume$of$liquid$
32µm2$
Surface$tension$coefficient$ 1$N/m$
Simula=on Setup Interface Reaches Equilibrium Shape -­‐  Moving mesh interface is coupled with laminar two-­‐phase flow, phase field interface. -­‐  Ini=al velocity and pressure values are set to zero for the t=0$sec$
t=7.5$µsec$
t=50$µsec$
t=2.5$µsec$
two fluids. -­‐  Ini=al mesh displacement is set Ink splits into Two to zero. -­‐  Pressure is set to zero at right boundary which is defined as inlet. -­‐  Sta=onary boEom surface is defined as “weEed wall” with 60o ink contact angle. -­‐  Upper surface is defined as “moving weEed wall” with 60o t=810%µsec% t=872%µsec% t=925%µsec% t=990%µsec%
contact angle. Mesh Refinement (θtop= θboEom= 60o) Index&
INDEX&
0$
0$
!10000$
!20000$
Pressure&(Pa)&
!10000$
!20000$
!40000$
!30000$
Pressure&(Pa)&
!30000$!10000$
0$
2$
!20000$
!30000$
!40000$
!60000$
!50000$
!50000$!60000$
!70000$
4$
6$
Index&
0$
2$
INDEX&
!40000$
4$
4$
6$
8$
6$
0.09"
0.08"
8$
0.06"
8$
0.05"
0.02"
0.01"
A&
B&
C&
Test_1d$
A&
B&
Test_1d$
Test_1e$
C&
Test_1b$
!60000$
Test_1e$
Simula'on*domain*
at*t=0*s*
0.07"
A*
1b"
1d"
A&
B& 0.04"
Test_1d$
Test_1e$
C& 0.03"
1e"
Test_1b$
0.05"
0.03"
1""2""3"""4""""5"""6"""7"
"
7"
6"
5"
4"
3"
2"
1"
0.08"
B*
0.06"
1""2""3"""4""""5"""6"""7"
C*
0.04"
Test_1b$
!50000$
0.09"
8$
0.07"
0"
0"
6$
!50000$
!40000$
4$
!30000$
0$
!10000$
0$
Pressure&(Pa)&
2$
!20000$
2$
Velocity)magnitude)(m/s))
0$
Velocity)magnitude)(m/s))
0$
1"
A&
B& Index)
Test_1d$
Test_1e$
C&
2"
3"
4"
Test_1b$
5"
!70000$
6"
7"
8"
0.02"
Simula'on*domain*
at*t=0*s*
0"
0.01"
0"
!70000$
1"
!60000$
2"
3"
4"
5"
6"
7"
8"
Index)
Pressure%(Pa)%at%(1µm,%2µm)%
!70000$
A*
1d"
B*
1e"
C*
1b"
Simula'on*domain*
at*t=0*sec*
400000$
A"
Test_1d(
B"
Test_1e(
C"
Test_1b(
300000$
200000$
100000$
0$
0$
0.0002$
0.0004$
0.0006$
0.0008$
0.001$
!100000$
!200000$
!300000$
Time%(s)%
Maximum mesh element size for lef of domain: Aà0.25 µm, Bà 0.08 µm, Cà 0.06 µm Change in total mass < 2% "
7"
6"
5"
4"
3"
2"
1"
Si
at
Effect of Contact Angle plate contact angle=60
a)# Upper Lower plate contact angle=60
o o Transfer ra;o=0.5 Young-­‐Dupre Equa;on Wadhesion = γ . [1+cos(θ)] à θ Wadhesion t=0$
t=810$µsec$
t=922.5$µsec$
t=1015$µsec$
b)# Upper plate contact angle=30
o Lower plate contact angle=60o Transfer ra;o=0.65 t=0$
t=810$µsec$
t=892.5$µsec$
Results -­‐ Expected trend is observed -­‐ Results do not exactly match with literature -­‐ High computa=on =mes t=1015$µsec$
Conclusions and Future Work -­‐  Spli_ng of ink between two parallel plates is simulated -­‐  Ink transfer ra=o to the upper plate is found to increase with decreasing ink contact angle on its surface -­‐  High computa=on =mes due to fine mesh requirements is the main difficulty -­‐  Future work is to cover a larger range of contact angles in the simula=ons Thank you Q&A