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UV stabilization
of UV-curable systems:
how does it work?
Dr. Delphine Kimpel
Web seminar October 7 & 8, 2020
Agenda
1. Introduction
2. 100 % UV curable systems
Photoinitiator vs. UV absorber
Photoinitiator vs. HALS
3. Examples
4. Conclusion – BASF product portfolio
Our comprehensive portfolio enables solutions for various industries
BASF is the premiere provider of Performance & Formulation Additives for the paint and coating industries
Furniture
& Flooring
Architectural
Coatings
Industrial
Coatings
Automotive
Coatings
Adhesives
& Sealants
Construction
Coatings
Printing
& PackagingComposites
Lignin
StabilizersHALS
Process
StabilizersAntioxidants
Optical
Brighteners
Formulation
AdditivesUV Absorbers
Agenda
1. Introduction
2. 100 % UV curable systems
Photoinitiator vs. UV absorber
Photoinitiator vs. HALS
3. Examples
4. Conclusion – BASF product portfolio
100 % UV: from liquid into solid within a few nanoseconds
P Ph·
Low molecular weight, liquid High molecular weight, solid
Illustrations: Dr. Sebastian Berger
Opposite but not necessary contradictory
P
OO O
Bisacylphosphinoxide(BAPO)
O
OO
Benzildimethylketal(BDK)
O
N
S
O
α-Aminoketone (AAK)
O
Benzophenone(BP)
O
O
OPhenylglyoxylate(PG)
O
OH
α-Hydroxyketone(AHK)
P
OO
Monoacylphosphinoxide(MAPO)
N
NN
OH
N
NN
H Oh
DT
O OH
O OH
h
DT
„Phenol“ „Keto“
h
DTN
N
N
R
R
OH
N
N
N
R
R
OH
Open UV window is mandatory…
0,0
0,5
1,0
1,5
290 310 330 350 370 390 410
Absorp
tion
[a.u
.]
Wavenlength [nm]
aHK 0,1 % BTZ 0,5 % HPT 0,5 % BAPO 0,01 %
narrow UV window
w/ BTZ
Open UV window is mandatory…
0,0
0,5
1,0
1,5
290 310 330 350 370 390 410
Absorp
tion
[a.u
.]
Wavenlength [nm]
aHK 0,1 % BTZ 0,5 % HPT 0,5 % BAPO 0,01 %
broader UV window
w/ HPT
… as well as the right match between lamp emission and
photoinitiator chemistry
Illustrations: Dr. Sebastian Berger
for surface-curing (aHK chemistry)
for through-curing (BAPO / MAPO chemistry)
Right ratio surface cure / through cure PI for UVA use
50
60
70
80
90
100
aHK aHK:BAPO 19:1 aHK:BAPO 9:1 aHK:BAPO 3:1
Dou
ble
bo
nd
con
vers
ion
[%
]
w/o UVA w/ 5 % HPT
Aliphatic epoxy acrylate / aliphatic urethane acrylate
3 % PI
15 µm DFT
2 x 80 W/cm, 20 m/min
HALS do not interfere w/ free radical polymerization
◼ Transformation of HALS into nitroxy radical(ie reactive species) is slower thanphoto-initiation step (formation of free radicals)
J Tinuvin® 249, 292, 123
◼ Activated HALS do react with free radicalsand do stop the polymerization of the(meth)acrylate groups
L Lignostab® 1198, 1198 L
UV, O2 •O
Agenda
1. Introduction
2. 100 % UV curable systems
Photoinitiator vs. UV absorber
Photoinitiator vs. HALS
3. Examples
4. Conclusion – BASF product portfolio
Gloss retention upon Xe exposure
70
80
90
100
0 2000 4000 6000 8000 10000
Glo
ss @
60
°
Exposure [h]
non-stabilized HPT + non-basic HALS HPT + new HALS HPT + basic HALS
Laromer® UA 8987 N (aliphatic urethane acrylate) application viscosity 1 Pa.s w/ Laromer HDDA
4 % BZ/aHK + 1 % BAPO/MAPO 2 % UVA + 1 % HALS
40 µm DFT, 1 x 120 W/cm Hg bulb, 10 m/min
DIN EN ISO 16474-2
same
stabilization
properties
* cracks
Discoloration upon Xe exposure
0
1
2
3
4
5
0 2000 4000 6000 8000 10000
DE
*
Exposure [h]
non-stabilized HPT + non-basic HALS HPT + new HALS HPT + basic HALS
Laromer® UA 8987 N (aliphatic urethane acrylate) application viscosity 1 Pa.s w/ Laromer HDDA
4 % BZ/aHK + 1 % BAPO/MAPO 2 % UVA + 1 % HALS
40 µm DFT, 1 x 120 W/cm Hg bulb, 10 m/min
DIN EN ISO 16474-2
cracks*
same
stabilization
properties
Agenda
1. Introduction
2. 100 % UV curable systems
Photoinitiator vs. UV absorber
Photoinitiator vs. HALS
3. Examples
4. Conclusion – BASF product portfolio
Conclusions
◼ It is possible to combine UV-initiated polymerization with proper and long-lasting UV-stabilization.
◼ Presence of PI and/or PI residuals does not affect weathering stability.
◼ Right ratio between surface-cure PI and through-cure PI (4:1 – 3:1), UVA and lamp emission.
◼ For indoor applications: HPT
◼ For outdoor applications: HPT combined with classical HALS or NOR HALSor Tinuvin 5251, 5248
Dr. Delphine Kimpel
Senior Technical Sales Performance Additives Europe
Phone: +49 621 60-71503
Mobile: +49 174 34 97 520
E-Mail: [email protected]
Dr. Annette Barghoorn
Commercial Marketing Performance Additives Europe
Phone: +49 621 60-72352
Mobile: +49 1520 93 75 445
E-Mail: [email protected]
Internet: http://www.basf.com/additives
E-Mail: [email protected]
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