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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
GRAPHIC ARTS
A novel polyfunctional
high molecular weight co-initiator.
Renato Bottacchiari, Lamberti S.p.A.
Abstract:
Co-initiators have critical importance in UV curable formulations,
mainly in inks and low thickness coatings for their activities as
oxygen scavenger and hydrogen transfer substrate in type two photoinitiators.
Both UV curable inks and OPV can be largely used in development applications
as food packaging. One of critical issue of food contact application
is the migration of the components of the formulations including photoinitators
and co-initiators. The migratability of photoinitiators has been overcome
by the development of difunctional photoinitiators, while co-initiators
are still a matter of risk for their migration characteristics. For
this purpose we developed a novel polyfunctional high molecular weight
amine co-initiator. It is characterised by high reactivity, low-yellowing
and low odour properties. The novel co-initiator shows very low migratability
in different simulating fluids from the cured formulations. The combination
of co-initiator and difunctional photoinitiators offers possible solution
for the use of UV curable technology in food packaging applications.
Energy
Cure (EC) Flexographic Inks for PLA film
Andrew Seecharan, CYTEC Industries,
Inc.
Abstract: Packaging film manufactured using polylactic acid
(PLA) derived from corn has recently emerged as an alternative to
petroleum-based films. Since corn is a renewable resource, the environmental
advantage of PLA film is immediately obvious with the main marketing
driver for PLA film being the use of a sustainable bio-based resource
for manufacture. Other expected advantages include compostability
or recyclability, a natural surface energy of approximately 38 dynes/cm
which should facilitate ink adhesion, high clarity and suitability
for high shrink applications. PLA film is produced in various thicknesses
in gloss, matte or opaque forms. The various types of film may be
used for applications such as food trays, folding cartons, shrink
sleeves, lids, envelope windows and packaging overwrap. Notwithstanding
the natural high surface energy of PLA film, ink adhesion may be
less than ideal due to the apparent presence of a surface layer
possibly from migratory additives. In the laboratory, removal of
this surface layer by wiping results in improved ink adhesion. In
commercial application, corona treatment within a short time of
printing coupled with a sound stock rotation system may be necessary
to ensure consistent adhesion. Alternatively, corona treatment in-line
with printing may be used. The use of EC flexo inks on PLA film
is currently being explored with consistent adhesion being the main
challenge to date. In addition to adhesion, ink flexibility and
reactivity must be optimized for specific applications. This presentation
will provide an introduction to the applications of PLA film as
well as details on work completed to develop EC flexo inks for use
on PLA film.
A Method for Estimating VOCs from Thin Radiation-Curable Coatings
Robin E. Wright, 3M
Abstract: There is currently no established ASTM test method
for measuring VOC emissions from thin radiation-curable coatings.
The South Coast Air Quality Management District in California is
no longer willing to accept supplier and industry claims that emissions
from these coatings are negligible and has begun asking end-users
in the District to provide data supporting their continued classification
as low VOC coatings. In an effort to resolve the issue with the
District, a joint RadTech and ASTM task force has been working for
more than 10 years to develop a valid test method for measuring
the emissions from these coatings but the initiative was abandoned
earlier this year without resolution. In the absence of an industry-proposed
method to quantify the emissions, the South Coast Air Quality Management
District recently agreed to sponsor a 2-year research project with
Cal Poly San Luis Obispo to develop a test protocol based on headspace
analysis that Cal Poly had developed previously for architectural
coatings. While the general applicability of this method remains
to be demonstrated for thin radiation-curable coatings, it would
likely be expensive and would have to be run on each individual
formulation. As an alternative, this paper details a VOC test method
we have developed for monomers and oligomers based on ASTM Method
D-5403 that would allow raw material suppliers to provide accurate
and reliable VOC data on Material Safety Data Sheets. The District
has publicly stated that calculated VOC emissions for a coating
based on the weighted contributions of the emissions from the individual
coating components would be acceptable as long as the MSDS data
used is based on an established test protocol. VOC measurements
for a number of common monomers and oligomers are reported and examples
of calculated emissions for some representative ink formulations
are shown.
Self
- Initiating Resins in UV Offset Inks Designed for Packaging
and Other Applications
Sudhir Ananthachar, Ashland Drew Industrial
Specialty Additives
Abstract: Self-photoinitiating resins have been developed
specifically to meet the demanding product performance needs of
offset printing inks. Unique resin design capability through the
Michael addition reaction produces acrylic-functional resins with
outstanding pigment wetting, providing very high quality pigment
dispersions and printing inks. The hydrophobic/hydrophilic balance
of the system has also been tailored through rigorous resin design.
The product resins are self-photoinitiating, yielding the excellent
cure efficiency and low extractables necessary for packaging applications.
Resin design, properties and performance of offset ink formulations
will be discussed.
UV
Curing Flexo inks; from Raw Material to Finished Formulation
David Helsby, RAHN USA Corporation
Abstract: The paper outlines a detailed study raw material
selection for the formulation of a flexo ink series. The choice
of grinding vehicle chemistry combined with select co-oligomers
and monomer combinations to obtain an optimum and balanced UV curing
flexo ink series was evaluated. Starting point formulations are
proposed with platform or in-situ manufacturing methods. Advice
is also given on PI combination, eutectic mixes and dispersant selection.
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