Highly efficient UVLED curing process with IR irradiation. Heraeus K.K. Noblelight Division Kazuo Ashikaga & Kiyoko Kawamura

Transcription

1 Highly efficient UVLED curing process with IR irradiation Heraeus K.K. Noblelight Division Kazuo Ashikaga & Kiyoko Kawamura

2 Table of contents Introduction Radical curing system irradiated by LED Direct irradiation (excitation) system to photoinitiator Sensitized initiation system IR plus LED hybrid irradiation process in radical curing system ationic curing system Sensitized cationic curing system IR plus LED hybrid irradiation process in sensitized cationic curing system Summary 2

3 uring reaction systems examined by 395nm LED irradiation Direct irradiation (excitation) Initiator Sensitized irradiation Sensitizer T DA Resin system Radical initiator ationic initiator H H 2 R olyester acrylate (M-81) n H 2 H HK (184) B H 3 I + H 2H(H 3) 2 F 6 - IMMH (25) H 2 H H 2 H 2 H 2 H H 2 Epoxy resin (828) E eq : 184 MEA (AM-9G) DMDE (651) HM (1173) 3

4 hoto-cleavage reaction of T h 3 * Absorbance T absorption and LED 395nm emission spectra Wavelength(nm) T Abs LED Relative Intensity Highly reactive and sensitive to oxygen inhibition Good spectra matching between T absorption and monochromatic LED 395nm emission 4

5 uring behavior in T initiation system observed under step-wise irradiation T Energy uring behavior by step-wise LED irradiation 2% 4% 1x4 pass 2x1 pass 5x6 pass 1x3 pass 1x2 pass 2x2 pass 5x6 pass 1,x3 pass Not cured Not cured Not cured Not cured 1x2 pass 6% bservations 2x2pass 5x2 pass 1,x2 pass Iradiation enegry (mj/sq.cm) Substrate: 1μmET film oating thickness: 1μm Formulation: HDDA/LR929 = 4/6 UV condition: LH1 H-bulb Stepwise irradiation: every 1, 2, 5 and 1,mJ/cm 2 T: BASF Irgacure T Tack free surface could be easily obtained by every 1mJ/cm 2 stepwise irradiation Every 1,mJ/cm 2 irradiation did NT provide tack free surface No cure! 5

6 ontinuous or intermittent LED irradiation in T system Normal lamp on irradiation continuous Irradiation Time (msec) 2ms irradiation with 15ms dark time 17ms interval irradiation Intermittent Irradiation 15ms 2ms 15ms 2ms Time (msec) onversion (%) Acrylic double bond conversion (M-81 w/4%t) Irradiation energy (mj/sq.cm) Tacky surface Tack free surface Almost same double bond conversions were obtained by both continuous and intermittent irradiations Tack free surface was provided by only intermittent irradiation 2msn15msff continuously n 6

7 G analysis for obtained polymers hoto-initiated polymerization of mono-functional monomer olymer conversion (%) olymer conversion Irradiation energy (mj/sq.cm) 2mn-15mff ontinuously n olymer conversions are almost same against irradiation energy for both irradiation systems Mn for polymers provided by continuous irradiation is almost constant against irradiation energy Mn for polymers obtained by intermittent irradiation is increased with increasing irradiation energy Mn (methoxy polyoxyethlene acrylate) AM-9G from Shin-nakamura hemical Number average molecular weight (Mn) Irradiation Energy (mj/sq.cm) 2mn-15mff ontinuously n 7

8 Storage modulus changes against double bond conversion Real time measurements of double bond conversion and rheology changes by LED irradiation Fiber cable from UV-LED to cone Rheometer Storage modulus and double bond conversion are increased with increasing irradiation energy by intermittent irradiation FT-IR Little storage modulus change was observed by continuous irradiation, even under high double bond conversion UV-LED 7 Intermittent irradiation 1 7 ontinuous irradiation G' G" onversion(%) G' G" onversion(%) Energy(mJ/cm2) Energy(mJ/cm2) G' [a] G'' [a] onversion G' [a] G'' [a] onversion 8

9 What happens, when T is irradiated by LED? hoto-cleavage reaction h >36nm Initiation and propagation reactions Rapid recombination in highly viscous media or M M Rapid radical coupling with diphenylphosphonoyl radical to terminate propagation reaction M + Major termination process by steady LED irradiation Secondary cleavage reaction is induced by shorter wavelength UV (< 36nm) irradiation, to reinitiate polymerization in case of mercury lamp irradiation h <36nm M + M M + Ex. Mercury lamp irradiation 9

10 re-ir plus UVLED hybrid irradiation for T initiation system re-ir UVLED Schematic lamp layout for re-ir plus UVLED UV curable materials are activated by IR irradiation before UVLED irradiation Higher double bond conversion (ca.15%) was provided by pre-ir irradiation Emission spectrum of carbon emitter a.u Wavelength(μm) Temperature(deg.) Double bond conversion against irradiation energy in T initiation system 1 onversion(%) Film temperature against linespeed Linespeed(m/min) 1.6kW 3.2kW 6.4kW Irradiation Energy(mJ/cm2) UV LED nly UV LED IR: arbon IR ZB2/3G Substrate: 1mmET Equipment: radiation thermometer 1

11 energies for curing in intermittent/preir plus UVLED irradiations ontinuously N UVLED M81/AM9G/T=6/4/6 (Maximum speed) 116mJ/sq.cm (1m/min) ontinuously N re-ir lus UVLED M81/AM9G/T=6/4/6 (Maximum speed) 58mJ/sq.cm (2m/min) 3on/15off 195mJ/sq.cm (3m/min) 3on/15off 97mJ/sq.cm (5m/min) 4on/15off 278mJ/sq.cm (4m/min) 4on/15off 185mJ/sq.cm (6m/min) 5on/15off 399mJ/sq.cm (4m/min) 5on/15off 215mJ/sq.cm (9m/min) rocess time(msec) rocess time(msec) UV-LED Irradiation period Dark period UV-LED Irradiation period w/preir IR output: 3.2kW 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 11 review & Insights Event Kaz Ashikaga May 6, 218

12 Sensitized phenyl ketone initiation system Sensitizer hoto-initiator + Initiation species 9,1-Dioctanoyloxy anthracene HK Double bond conversion with and without pre-ir irradiations in M-81 system Emission spectra of UVLEDs and absorption spectrum for sensitizer and initiator 12

13 uring speed and energy under continuous/intermittent irradiations in sensitized systems M81/AM9G/184/581=6/4/8/1 ontinuously N 127mJ/sq.cm (8m/min) M81/AM9G/B/581=6/4/8/1 ontinuously N (Maximum speed) 14538mJ/sq.cm (.7m/min) ontinuously N 464mJ/sq.cm (2.5m/min) ontinuously N 16961mJ/sq.cm (.6m/min) 3on/ 15off 4on/ 15off 5on/15off M81/AM9G/651/581=6/4/8/1 ontinuously N ontinuously N rocess time(msec) >117mJ/sq.cm (<.5m/min) 1588mJ/sq.cm (.7m/min) 228mJ/sq.cm (.7m/min) (Maximum speed) 127mJ/sq.cm (8m/min) 254mJ/sq.cm (4m/min) 3on/ 15off 4on/ 15off 5on/15off rocess time(msec) M81/AM9G/1173/581=6/4/8/1 ontinuously N ontinuously N >117mJ/sq.cm (<.5m/min) >2224mJ/sq.cm (<.5m/min) >3192mJ/sq.cm (<.5m/min) (Maximum speed) 5976mJ/sq.cm (1.7m/min) 6773mJ/sq.cm (1.5m/min) 3on/ 15off 834mJ/sq.cm (.7m/min) 3on/ 15off >117mJ/sq.cm (<.5m/min) 4on/ 15off 926mJ/sq.cm (1.2m/min) 4on/ 15off >2224mJ/sq.cm (<.5m/min) 5on/15off 938mJ/sq.cm (1.7m/min) 5on/15off 3192mJ/sq.cm (.5m/min) rocess time(msec) rocess time(msec) UV-LED Irradiation period Dark period UV-LED Irradiation period w/pre-ir IR output: 3.2kW 13

14 Sensitized cationic initiation system with and without pre-ir irradiation Sensitizer hoto-initiator + H 3 I + H 2H(H 3) 2 F 6 - Initiation species 9,1-Dioctanoyloxy anthracene IMMH (25) ontinuously N 828/25/581=1/4/1 (Maximum speed) 29mJ/sq.cm (35m/min) ontinuously N 828/25/581=1/4/1 (Maximum speed) 253mJ/sq.cm (4m/min) 3on/15off 595mJ/sq.cm (2m/min) 3on/15off 238mJ/sq.cm (5m/min) 4on/15off 278mJ/sq.cm (4m/min) 4on/15off 158mJ/sq.cm (7m/min) 5on/15off 318mJ/sq.cm (5m/min) 5on/15off 198mJ/sq.cm (8m/min) rocess time(msec) IR output: 6.4kW rocess time(msec) UV-LED Irradiation period Dark period UV-LED Irradiation period w/preir 14

15 ost IR irradiation effect for cationic curing system 828/25/581=1/4/1 (Maximum speed) UVLED ost-ir ontinuously N+ ostir 3on/15off + ostir ff line IR irradiation 5m/min 5mJ/sq.cm (2m/min) 397mJ/sq.cm (3m/min) 4on/15off + ostir 222mJ/sq.cm (5m/min) 5on/15off + ostir 159mJ/sq.cm (1m/min) rocess time(msec) IR output: 6.4kW ost IR irradiation is efficient to increase curing speed for cationic curing system 15

16 Summary Intermittent irradiation can provide efficient curing in T initiation system by reducing termination reaction of propagation radicals by radical coupling. re-ir irradiation can remarkably accelerate curing speed for both intermittent and continuous irradiation processes in T 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. ost-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. 16