printing ink technology for shrink sleeves - welcome to …€¦ · · 2017-10-04ink type solvent...
TRANSCRIPT
Product Success
� Sleeve/label’s graphics and color makes an
impression on the consumer
� Sleeve/label failure will be disastrous to product’s
success in marketplace
� Ink plays a critical role
� Ink formulation/selection must be done with the
sleeve/label application in mind
� What do we need to know about inks & coatings to
make the proper selection?
Printing Processes/Ink Chemistry Used
Print methodInk type
Solvent Water Oil UV
Flexo X X – X
Letterpress– – X X
Offset – – X X
Screen X – – X
Gravure X X – –
”Digital” X X X toner X
Inks Types - Generic Raw Materials
Ingredient Solvent Water-based UV curing Oil / Offset
Pigments Yes Yes Yes Yes
Resins Nitro Acrylic OligomersPhenolic
Alkyd
Diluents Solvents Water/amine MonomersMineral /
Vegetable Oil
Solvents > 30% < 5% ~0 Zero
Additives
Wax
Antifoam
Silicones
Plasticizers
Wax
Antifoam
Wax
Photo initiator
Stabilizers
Wax
Stabilizers
Fillers
Ink Raw Materials - Pigments
Organic:
•Carbon
•Diarylide
•Pyrazolene
•Disazo
•Naphthol
•Pthalocyanine
•Quinacridone
Inorganic:
•Titanium Dioxide
•Iron Oxides
•Metallic (Aluminum)
•Clay
� Pigments -� physically &
chemically stable
� non-soluble
� Denoted by Color Index Number (CI#)
� Red 57.1, Red 184, Red 177
� CI# indicates properties
� hue, fastness, cost1.
� important to know CI#!
� Heavy Metals Content� CONEG, RCRA, F-
963/EN-71
� Barium, mercury, hex. chromium, lead, cadmium, antimony, arsenic and selenium primarily
Colorant - Lightfastness
LIGHTFASTNESS CHART
0
10
20
30
40
50
60
70
80
90
100
0 24 48 72 96 120 144 168
HOURS IN FADE-O- METER
% C
OL
OR
AN
T L
EF
T
% Yellow Dye Colorant
% Pigment Yellow 12
% Pigment Yellow 14
% Pigment Yellow 74
Ink Raw Materials – Resins / Oligomers
Common
� Nitrocellulose
� Polyamide
� Acrylic (styrene and acrylic acid)
� Phenolic
� Epoxy Acrylate – used in UV/EB inks & coatings
� Urethane, Polyester – used in solvent and
UV/EB inks and coatings
This is the backbone of the ink-
Will affect adhesion, flexibility,
resistance properties, dry speed/cure,
and overall end performance of
printed material
Ink Raw Materials - Diluents
� Used to reduce viscosity, “thin” the ink
� Most common is H2O for waterbased inks
� Each solvent system has its own solvent best suited for it
� UV inks use monomer
� Diluents will affect dry/cure speeds also
Ink Raw Materials - Additives
� Defoamers
� Waxes/Silicones (COF)
� Matting agents
� Photoinitiator - UV
� Adhesion promoters
� Surfactants
� Optical Brighteners
Corona Treatment is Recommended
� Changing polarity of the substrate
� Changing surface of the substrate
� Changing chemical groups at surface
� New functional groups are created : -C=O, HOOC-, HOO- and
HO-
� These react easier with ink chemistry – creates good adhesion
� Don’t over-treat, each film supplier will have guidelines
Challenges for Inks for Sleeves
� Very high color strength, high cure speed and excellent press & print
performance, low odor and meet EHS regulations.
� Technical challenge to maintain ability to shrink, as ink is cross-linked
when drying/curing.
� Adhesion to wide range of substrates (PET-G, PVC, OPS, OPP, PLA,
Polyolefin) without the need of primers.
� Good surface slip properties; use for high speed seamers and applicators.
� Hazing of last down low COF over-print varnishes.
� Resistance to moisture, scratch, chemicals.
� Opaque White a key! Higher opacity opaque white with excellent COF
properties.
� Minimize “Cellotape” effect (which looks like ‘wet T-shirt’).
Why White is so important?
� Usually last down so COF is # 1 requirement
� Scratch resistance, adhesion and flexibility
� Opacity
Put the these factors together, and a white must exhibit stable COF,
and retain the maximum possible flexibility with the best adhesion
and opacity!
� Low COF (high slip) – last down
� High COF (low slip) – first down
Some people will print single bump of white and up to 3 bumps to
get opacity and performance.
All About SlipM.mostly with white or coating
� Static COF - spec ~0.4 – 0.5� is calculated from the force that is needed to start something that
is lying still on the surface.
� Dynamic/Kinetic COF - spec ~ < 0.25 � is calculated from the force that is needed to move something
over the surface once it has started to move.
� This value is always lower than the static COF. The dynamic COF is important for sleeves and should be low enough to make processing in seam machines easy and to make it easier to put the sleeves on the bottles.
� If the static and dynamic COF is too low, it can be difficult to handle the web during seaming.
� If the dynamic COF is too high the sleeves will not work on high speed sleeving.
Challenges with UV Printing
� Heat generation from UV lamps will distort films, especially thin films if there is not heat management techniques on press (“cool UV” systems, chill rollers, etc.)
� If you don’t have the proper ink formulated for “cool UV” systems (including chill rollers, chill plates or cool UV lamps) then your UV inks may not cure as fast or cure as well resulting in poor adhesion, poor moisture resistance, etc.
� Often the chill roller is too cool!
� Proper curing for both surface cure and through cure (which will affect adhesion) if applied with too coarse of anilox rollers or at too fast of press speeds
All of these challenges can be addressed!
What is UV LED for printing?
� UV LED is simply an alternative to conventional (mercury) curing!
� Only the wavelength and light intensity is different.
� And different ink technology is required.
16
UV LED Conclusion
� Optimization of UV Curing Process requires consideration of
not only the UV Light Source, but also the material being used.
� UV LED sources are equivalent or better than existing arc lamp
solutions, with material reformulation.
� The key to success is the relative higher power of UV LED and
dedicated formulation work.
� IDEAL FOR SHRINK APPLICATIONS!!!
Slide provided by Phoseon Technology
UV Flexo Printing Tips
� It’s all about CURE!
� Proper anilox roller selection, ink selection (blacks and whites
especially).
� High opacity white requirements for shrink applications slow
speeds as mercury light does not penetrate and cure inks that
are highly opaque.
� Denser blacks don’t cure at high speeds either and often waste
is generated when inks are found not to pass adhesion off
press or worse downline.
� Proper press speed for lamps – depth cure
� Maintenance of UV lamps, reflectors, etc.
� Chill roller temps
Waterbased Flexo Printing Tips
� Proper anilox roller selection and press speed
� High air velocity drying (not too much heat!)
� Catalyze inks (whites/last down) if going thru steam
tunnel
� pH maintenance is critical!
Solvent Printing Tips
� Solvents - particularly
acetates - damage film
• If too much solvent remains
in the film, over time (weeks,
months) shrink performance
can be affected.
• OPS Film is particularly
sensitive to solvent attack –
try dropping ethyl acetate
onto OPS shrink film!
Common problems –
“whitening” & shrinking after
� Correct solvent selection
� Correct viscosity
� Proper drying (air temp
and velocity and “clean”
air) – reduce levels of
retained solvents
UV/EB Web Offset Printing Tips
• One side of shrink films
generally is coated with
antistatic coating
• If you’ve lost the label
telling you which side of
the film is coated, curl the
film into a tube and blow in
it – the cloudy side is
coated
• Be careful with ink/water
balance
• Scumming is a particular
problem for seaming,
which can gum-up
seaming felts and lead to
open seams
• If you print this side, the fountain
solution can pick up the
antistatic coating and become
contaminated
• New fountain solutions are
available that will not
solubilize the anti-stat
coatings as easily
Digital Printing Tips
� Most digital inks need a
print primer to adhere to
the film
• Primer can be applied with a
standard flexo station
• Or can be applied in-line
• Note – you cannot seam the
primed area, so you will need to
cut-back the plate or sleeve on
the priming unit
� Alternatively, pre-primed
shrink film can be
purchased from several
companies
• pre-primed films can be
seamed
Typical Press-Side/Lab Tests
� Dyne Test
� Cure Test
� Tape Adhesion Test
� Resistance Testing
� Scratch/Crinkle
� Block
� Line Lube, etc.
� Rub Test
� COF/Slide Angle
� Shrink Test
Special Effects!
� Gloss, Matte or Tactile Varnishes
� Pearls / Iridescent
� Bright Metallics
� Fluorescents
� Security
Courtesy of K LASER
Cold Foil & Holographic Appearance
• Cold Foil Printing is an in-line
process that works on a rotary
flexographic presses closely
duplicating hot foil stamping.
• Regular anilox rolls and
photopolymer plates transfer UV
curable cold foil adhesive onto a
wide variety of stocks.
Heat Activated Adhesive
• Adhering to a container that
doesn't contain a locking
area for the sleeve.
• Positioning to a container
regarding orientation during
the shrinking process.
• Adhering to a position,
locking the sleeve to avoid
any orientation while on the
shelf.
• The industry has a variety
of patterns. The pattern of
heat activated adhesive
depends on the overall
sleeve and container
dimensions and the degree
of adhesion required.
Food/Beverage Packaging and Migration
� We Drink Bottled Water Every
Day
� Does 1 PPM or 1 PPB of
Impurities Matter?
� Can You See/Smell/Taste
Contamination?
Believe It Or Not. We as Consumers Don’t
Want Contaminates in Our Food/Beverage!
Why Does It Matter?
� It Matters Because The
Entire Supply Chain (Ink
Manufacturers, Packaging
Manufacturers, Brand
Owners) Cares About:
� Reputation
� Product Liability
� Impact on Profitability
The Brand Owners Have To Protect
Product Reputation
Common Principles Concerning Food Packaging & Migration:
� The responsibility for the compliance of the packaging does not lie with only one individual member of the packaging chain.
� Ultimate responsibility is with “person placing pack on market” – but we all have to work together.
� There shall be no unacceptable change/adulteration in the quality, odor or taste of the food/beverages
� There shall be no use of carcinogenic, mutagenic or reprotoxic substances (CMR substances)
� The migration of substances evaluated for food contact shall remain below defined limits
Ultimate Goal is to Protect
Human Health
� In principle there are no differences in the requirements
regarding
� UV cured or
� Solvent based inks or
� Water based inks
� Coatings or Adhesives of any chemistry
� The rule is always the same:
� <50 ppb (or <SML for Swiss list) for evaluated and approved
substances
� <10 ppb for all other substances
� And even lower than 10 ppb limit if the substance is considered
somewhat toxic
(based on daily intake calculations)
Migration and Ink Systems