Highly efficient UVLED curing processwith IR irradiation · RadTech 2018 Technology Expo &...
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Highly efficient UVLED curing process with IR irradiation
Heraeus K.K. Noblelight DivisionKazuo Ashikaga & Kiyoko Kawamura
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IntroductionRadical curing system irradiated by LED
Direct irradiation (excitation) system to photoinitiatorSensitized initiation system
IR plus LED hybrid irradiation process in radical curing systemCationic curing system
Sensitized cationic curing system IR plus LED hybrid irradiation process in sensitized cationic curing systemSummary
Table of contents
RadTech 2018 Technology Expo & Conference | Kaz Ashikaga | May 8, 20182
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Curing reaction systems examined by 395nm LED irradiation
RadTech 2018 Technology Expo & Conference | Kaz Ashikaga | May 8, 20183
Direct irradiation (excitation) Sensitized irradiation
O
O
C
C
O
O
DOOA
Sensitizer
Radical initiator Cationic initiator
TPO
HCPK (184)
DMDPE (651) HMPP (1173)MPEA (AM-90G)
Resin system
IMMPH (250)
Initiator
R O CO
CH
CH2
OCO
HC
H2C n
Polyester acrylate (M-8100)
Epoxy resin (828)Eeq: 184
BP
I+ CH2CH(CH3)2H3C
PF6-
CH2 O CH2 CH CH2
OOCH2CHCH2
O
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hP
OO O
P
O*3
P
OO
Photo-cleavage reaction of TPO
4
0102030405060708090100
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
300 320 340 360 380 400 420 440 460 480 500R
elat
ive
Inte
nsity
Abso
rban
ce
Wavelength(nm)TPO Abs LED
TPO absorption and LED395nm emission spectra
Good spectra matching between TPO absorption and monochromatic LED395nm emission
RadTech 2018 Technology Expo & Conference | Kaz Ashikaga | May 8, 2018
Highly reactive and sensitive to oxygen
inhibition
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0 500 1000 1500 2000 2500 3000 3500Iradiation enegry (mJ/sq.cm)
RadTech 2018 Technology Expo & Conference | Kaz Ashikaga | May 8, 20185
Substrate: 100μmPET film Coating thickness: 10μm Formulation: HDDA/LR9029 = 40/60UV condition: LH10 H-bulb Stepwise irradiation: every 100, 200, 500 and 1,000mJ/cm2
TPO: BASF Irgacure TPO
TPO Energy
2%
100x4 pass200x10 pass500x6 pass1000x3 pass
4%
100x2 pass200x2 pass500x6 pass1,000x3 pass
6%100x2 pass
200x2pass500x2 pass1,000x2 pass
Curing behavior in TPO initiation system observed under step-wise irradiation
Curing behavior by step-wise LED irradiation
• Tack free surface could be easily obtained by every 100mJ/cm2 stepwise irradiation• Every 1,000mJ/cm2 irradiation did NOT provide tack free surface ⇒ No cure!
Observations
Not curedNot cured
Not curedNot cured
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Continuous or intermittent LED irradiation in TPO system
6
0
10
20
30
40
50
60
70
80
0 500 1000 1500 2000 2500
Conversion
(%)
Irradiation energy (mJ/sq.cm)
20msOn150msOff continuously On
continuousIrradiation
Time (msec)
Time (msec)
IntermittentIrradiation
20ms 20ms150ms 150ms
Acrylic double bond conversion (M-8100 w/4%TPO)
Tack free surface
Tacky surface
20ms irradiation with 150ms dark time170ms interval irradiation
Normal lamp on irradiation
Almost same double bond conversions were obtained by both continuous and intermittent irradiationsTack free surface was provided byonly intermittent irradiation
RadTech 2018 Technology Expo & Conference | Kaz Ashikaga | May 8, 2018
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GPC analysis for obtained polymers
7
(methoxy polyoxyethlene acrylate)AM-90G from Shin-nakamura Chemical
0
1000
2000
3000
4000
5000
6000
7000
8000
0 1000 2000 3000 4000 5000
Mn
Irradiation Energy (mJ/sq.cm)
20mOn-150mOff Continuously On
0102030405060708090
100
0 1000 2000 3000 4000 5000
Poly
mer
con
vers
ion
(%)
Irradiation energy (mJ/sq.cm)
20mOn-150mOff Continuously On
Polymer conversion
Photo-initiated polymerization of mono-functional monomer
Number average molecular weight (Mn)
Polymer conversions are almost same against irradiation energy for both irradiation systems
Mn for polymers provided by continuous irradiation is almost constant against irradiation energyMn for polymers obtained by intermittent irradiation is increased with increasing irradiation energy
RadTech 2018 Technology Expo & Conference | Kaz Ashikaga | May 8, 2018
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Storage modulus changes against double bond conversion
8
0102030405060708090100
0
100
200
300
400
500
600
700
0 10 20 30 40 50 60
Con
vers
ion(
%)
G'
G"
Energy(mJ/cm2)G' [Pa] G'' [Pa] Conversion
0102030405060708090100
0
100
200
300
400
500
600
700
0 10 20 30 40 50 60
Con
vers
ion(
%)
G'
G
"
Energy(mJ/cm2)G' [Pa] G'' [Pa] Conversion
FT-IR
Rheometer
UV-LED
Fiber cable from UV-LED
to cone
Intermittent irradiation Continuous irradiation
Storage modulus and double bond conversion are increased with increasing irradiation energy by intermittent irradiation
Little storage modulus change was observed by continuous irradiation, even under high double bond conversion
Real time measurements of double bond conversion and rheology changes by LED irradiation
RadTech 2018 Technology Expo & Conference | Kaz Ashikaga | May 8, 2018
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What happens, when TPO is irradiated by LED?
9
hP
OO O
P
O
P
OO
>360nm
Initiation and propagation reactionsO
P
O
or MM
Rapid radical coupling with diphenylphosphonoyl radical to terminate propagation reaction
P
O
P
O
M +
Photo-cleavage reaction
Secondary cleavage reaction is induced by shorter wavelength UV (< 360nm) irradiation,to reinitiate polymerization in case of mercury lamp irradiation
P
O hP
O
M + M M+
Rapid recombination in highly viscous media
Major termination process by steady LED irradiation
Ex. Mercury lamp irradiation
RadTech 2018 Technology Expo & Conference | Kaz Ashikaga | May 8, 2018
<360nm
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Pre-IR plus UVLED hybrid irradiation for TPO initiation system
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UVLEDPre-IR
0
20
40
60
80
100
0 500 1000 1500 2000 2500
Conversion
(%)
Irradiation Energy(mJ/cm2)UV‐LED Only PreIR+UV‐LED
Double bond conversion against irradiation energyin TPO initiation system
Schematic lamp layout for Pre-IR plus UVLED
0 1 2 3 4 5a.u.
Wavelength(μm)
Emission spectrum of carbon emitter
0
20
40
60
80
100
120
0 20 40 60 80
Tempe
rature(deg.C)
Linespeed(m/min)1.6kW 3.2kW 6.4kW
Film temperature against linespeed
IR: Carbon IR CZB2000/300GSubstrate: 100mmPETEquipment: radiation thermometer• Higher double bond conversion (ca.15%) was provided
by pre-IR irradiation
• UV curable materials are activated by IR irradiation before UVLED irradiation
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Preview & Insights Event | Kaz Ashikaga | May 6, 201811
Minimum energies for curing in intermittent/preIR plus UVLED irradiations
UV-LED Irradiation period Dark period UV-LED Irradiation period w/preIR
• Intermittent irradiation by LED is efficient to reduce the minimum curing energy and process time• The minimum energy for curing is remarkably reduced by pre-IR irradiation for both continuous and intermittent irradiations• Total process time for curing can be shortened by pre-IR irradiation• Intermittent irradiation process is still effective to reduce required irradiation energy for curing• Shorter LED emission time during intermittent irradiation provides more advantages to reduce total energy for curing• Emission time and total process time should be balanced in intermittent irradiation process
0 100 200 300 400 500 600 700 800 900 100011001200
50on/150off
40on/150off
30on/150off
ContinuouslyON
Process time(msec)
M8100/AM90G/TPO=60/40/6Minimum
required energy(Maximum speed)
10160mJ/sq.cm(1m/min)
195mJ/sq.cm(3m/min)
278mJ/sq.cm(4m/min)
399mJ/sq.cm(4m/min)
0 100 200 300 400 500 600 700 800 900 100011001200
PreIR+50on/150off
PreIR+40on/150off
PreIR+30on/150off
PreIR+Continuously ON
Process time(msec)
M8100/AM90G/TPO=60/40/6 Minimum required energy(Maximum speed)
508mJ/sq.cm(20m/min)
97mJ/sq.cm(5m/min)
185mJ/sq.cm(6m/min)
215mJ/sq.cm(9m/min)
UVLED Pre-IR Plus UVLED
IR output: 3.2kW
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Sensitized phenyl ketone initiation system
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O
O
C
C
O
O
+
Sensitizer Photo-initiator
Initiation species
Emission spectra of UVLEDs and absorption spectrum for sensitizer and initiator
9,10-Dioctanoyloxy anthracene HCPK
Double bond conversion with and without pre-IR irradiations in M-8100 system
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0 400 800 1200 1600 2000 2400 2800
50on/150off
40on/ 150off
30on/ 150off
Continuously ON
PreIR+Continuously ON
Process time(msec)
M8100/AM90G/184/581=60/40/8/1 Minimum required energy
1270mJ/sq.cm(8m/min)
4064mJ/sq.cm(2.5m/min)
>1170mJ/sq.cm(<0.5m/min)
1588mJ/sq.cm(0.7m/min)
2280mJ/sq.cm(0.7m/min)
0 400 800 1200 1600 2000 2400 2800
50on/150off
40on/ 150off
30on/ 150off
Continuously ON
PreIR+Continuously ON
Process time(msec)
M8100/AM90G/BP/581=60/40/8/1 Minimum required energy(Maximum speed)14538mJ/sq.cm(0.7m/min)
16961mJ/sq.cm(0.6m/min)
>1170mJ/sq.cm(<0.5m/min)
>2224mJ/sq.cm(<0.5m/min)
>3192mJ/sq.cm(<0.5m/min)
0 400 800 1200 1600 2000 2400 2800
50on/150off
40on/ 150off
30on/ 150off
Continuously ON
PreIR+Continuously ON
Process time(msec)
M8100/AM90G/651/581=60/40/8/1 Minimum required energy(Maximum speed)
1270mJ/sq.cm(8m/min)
2540mJ/sq.cm(4m/min)
834mJ/sq.cm(0.7m/min)
926mJ/sq.cm(1.2m/min)
938mJ/sq.cm(1.7m/min)
0 400 800 1200 1600 2000 2400 2800
50on/150off
40on/ 150off
30on/ 150off
Continuously ON
PreIR+Continuously ON
Process time(msec)
M8100/AM90G/1173/581=60/40/8/1 Minimum required energy(Maximum speed)
5976mJ/sq.cm(1.7m/min)
6773mJ/sq.cm(1.5m/min)
>1170mJ/sq.cm(<0.5m/min)
>2224mJ/sq.cm(<0.5m/min)
3192mJ/sq.cm(0.5m/min)
UV-LED Irradiation period Dark period UV-LED Irradiation period w/pre-IR
Curing speed and energy under continuous/intermittent irradiations in sensitized systems
IR output: 3.2kW
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Sensitized cationic initiation system with and without pre-IR irradiation
RadTech 2018 Technology Expo & Conference | Kaz Ashikaga | May 8, 201814
O
O
C
C
O
O
+
Sensitizer Photo-initiator
Initiation species
9,10-Dioctanoyloxy anthracene
I+ CH2CH(CH3)2H3C
PF6-
IMMPH (250)
0 100 200 300 400 500 600
50on/150off
40on/150off
30on/150off
ContinuouslyON
Process time(msec)
828/250/581=100/4/1Minimum
required energy(Maximum speed)
290mJ/sq.cm(35m/min)
595mJ/sq.cm(2m/min)
278mJ/sq.cm(4m/min)
318mJ/sq.cm(5m/min)
0 100 200 300 400 500 600
PreIR+50on/150off
PreIR+40on/150off
PreIR+30on/150off
PreIR+Continuously ON
Process time(msec)
828/250/581=100/4/1 Minimum required energy(Maximum speed)
253mJ/sq.cm(40m/min)
238mJ/sq.cm(5m/min)
158mJ/sq.cm(7m/min)
198mJ/sq.cm(8m/min)
UV-LED Irradiation period Dark period UV-LED Irradiation period w/preIR
IR output: 6.4kW
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Post IR irradiation effect for cationic curing system
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UVLED
Post-IR
0 100 200 300 400 500 600
50on/150off +PostIR
40on/150off +PostIR
30on/150off + PostIR
Continuously ON+PostIR
Process time(msec)
828/250/581=100/4/1 Minimum required energy(Maximum speed)
50mJ/sq.cm(200m/min)
397mJ/sq.cm(3m/min)
222mJ/sq.cm(5m/min)
159mJ/sq.cm(10m/min)
Off line IR irradiation 50m/min
• Post IR irradiation is efficient to increase curing speed for cationic curing system
IR output: 6.4kW
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• Intermittent irradiation can provide efficient curing in TPO initiation system by reducing termination reaction of propagation radicals by radical coupling.
• Pre-IR irradiation can remarkably accelerate curing speed for both intermittent and continuous irradiation processes in TPO initiation system.
• Intermittent irradiation can also work to reduce total energy for curing in sensitized phenyl ketone initiation systems, however, no process time advantage can be observed for intermittent irradiation process, presumably due to different initiation mechanism.
• Post-IR irradiation can efficiently work for the sensitized cationic initiation system with continues LED irradiation and total energy required for curing can be reduced with shortening process time.
Summary
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