Printing Ink Technology For Shrink Sleeves

Transcription

1 Printing Ink Technology For Shrink Sleeves

2 Ink is an Important Brand Differentiator

3 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?

4 Printing Processes/Ink Chemistry Used Print method Ink 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

5 Inks Types - Generic Raw Materials Ingredient Solvent Water-based UV curing Oil / Offset Pigments Yes Yes Yes Yes Resins Nitro Acrylic Oligomers Diluents Solvents Water/amine Monomers Phenolic Alkyd Mineral / Vegetable Oil Solvents > 30% < 5% ~0 Zero Additives Wax Antifoam Silicones Plasticizers Wax Antifoam Wax Photo initiator Stabilizers Wax Stabilizers Fillers

6 Ink Raw Materials - Pigments Pigments - physically & chemically stable non-soluble Denoted by Color Index Number (CI#) Red 57.1, Red 184, Red 177 CI# indicates properties hue, fastness, cost. important to know CI#! Heavy Metals Content CONEG, RCRA, F- 963/EN-71 Barium, mercury, hex. chromium, lead, cadmium, antimony, arsenic and selenium primarily Organic: Carbon Diarylide Pyrazolene Disazo Naphthol Pthalocyanine Quinacridone Inorganic: Titanium Dioxide Iron Oxides Metallic (Aluminum) Clay

7 Colorant - Lightfastness LIGHTFASTNESS CHART % COLORANT LEFT % Yellow Dye Colorant % Pigment Yellow 12 % Pigment Yellow 14 % Pigment Yellow HOURS IN FADE-O- METER

8 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

9 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

10 Ink Raw Materials - Additives Defoamers Waxes/Silicones (COF) Matting agents Photoinitiator - UV Adhesion promoters Surfactants Optical Brighteners

11 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

12 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 ).

13 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.

14 All About Slip.mostly with white or coating Static COF - spec ~ 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.

15 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!

16 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

17 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

18 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

19 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!

20 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

21 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

22 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

23 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

24 Special Effects! Gloss, Matte or Tactile Varnishes Pearls / Iridescent Bright Metallics Fluorescents Security

25 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. Courtesy of K LASER

26 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.

27 Sleeve Label or Packaging?

28 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!

29 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

30 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

31 Migration and Ink Systems 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)

32 Communication within the packaging chain

33 Thank you Any questions? Contact us at: