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RadTech
UV/EB Technology Conference & Expo 2008
May 4-7, 2008
Lakeside Center at McCormick Place
Chicago, Illinois - United States of America
PHOTOINTIATORS
Advancements in Photolatent
Amines: Expanding the Scope
of Photolatent Base Technology
Kurt Dietliker, Ciba Specialty Chemicals
Inc.
Abstract:
Photolatent tertiary amines have recently been shown to provide an
attractive novel technology platform which allows the curing of formulations
that were hitherto not accessible for radiation curing. A first commercial
application that takes full advantage of these possibilities has recently
been introduced. The wide variety of formulations that undergo base-catalyzed
crosslinking requires the development of tailor-made catalysts in
order to meet different application profiles. While two different
catalysts have so far been extensively evaluated for a variety of
coatings, new developments are currently aimed at photolatent bases
that are suitable for the curing of industrially important resins
such as polyurethane lacquers. This paper will review the current
use of photolatent bases and report on the design and evaluation of
new catalysts that considerably expand the scope of this technology
into new formulations, providing the end user with the advantage of
full control of the curing process while producing coatings of outstanding
performance.
Modeling
Photoinitiators - A New Walk for R&D
T. Brian Cavitt, Abilene Christian University
Abstract: In this paper, we explore the use of existing quantum
mechanical analyses (modeling) software to model commercially available
Type I and II photoinitiators to produce a theoretical initiation
pathway replete with theoretical thermodynamic data that can then
be compared to experimental values for excited state singlet and
triplet energies. Furthermore, theoretical UV-Visible spectra can
be calculated and compared to the experimentally determined spectra.
The results thereof could provide a new approach to traditional
research and development (R&D) of photoinitiators.
Multiple
Photoinitiators for Improved Performance
Timothy E. Bishop, DSM Desotech, Inc.
Abstract: Higher levels of photoinitiator can increase extractables,
reduce weatherability, limit film thickness, and increase cost.
To achieve fast cure speed and limit these disadvantages, low levels
of multiple photoinitiators can be used. This approach takes advantage
of the different UV absorption spectra of three or four photoinitiators
to more broadly utilize the full UV output of the lamp. Real-time
FTIR data shows that multiple photoinitiators at a lower total level
can achieve faster cure speed than higher total levels of one or
two photoinitiators.
New
coinitiators for radical photopolymerization
Allonas Xavier, Department of Photochemistry
Abstract: In this paper the initiation reaction of double
bonds was revisited. Use of different coinitiators yields to alkyl,
aminyl, thiyl, and silyl radicals. Some of these radicals have completely
different initiation properties towards different kind of monomers.
Some insights into the mechanisms was provided, underlining the
effect of oxygen, nature of the double bonds, additives... It is
shown that new opportunities can be opened for radical photopolymerization.
Novel
Non-Extractable High-Efficiency Diarylketone Thioether Photoinitiators
Charles E. Hoyle, Univesity of Southern
Mississippi
Abstract: There has been considerable effort to develop highly
efficient non-extractable photoinitiating systems for food packaging
and electronic applications. To date this has proven to be somewhat
of an enigma. We report on the synthesis, characterization, and
photocuring efficiency of a wide variety of non-extractable photoinitiator
systems based upon thioether benzophenones and thioxanthones. These
non-extractable photoinitiators exhibiting the high efficiency of
conventional cleavage initiators are excellent candidates for food
and electronic packaging applications.
Reduction
of photoinitiator migration by control and optimization
of the UV-curing process
Katia Studer, Ciba Specialty Chemicals
Abstract: A number of parameters are expected to affect the
photoinitiator migration after a UV-curing process. The influence
of curing conditions on the extent of photoinitiator migration has
been observed with focus on the UV-dose and on the photoinitiator
structure. The amount of migrating species has been evaluated by
an analytical method specially designed. UV-dose indicating formulations
have been used to allow a fast optimization of the UV-curing process
so as to minimize the photoinitiator migration.
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