Printing Ink Technology For

Shrink Sleeves

Ink is an Important Brand Differentiator

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

print

� 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.

Sleeve – Label or Packaging?

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

Communication within the packaging chain

Thank youAny questions?

Contact us at:info.narrowweb@flintgrp.com