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  • Advances in Flexographic Printing Inks Technology. A Re-solubility Study on BOPP film.

    Michael D. Doyle II and David R. Constant. Advanced Materials Research, BASF Wyandotte

    110/7/2016

  • Objective

    The objective of this work was to study the effect of anilox cylinder cell size (with associated volumes) on ink resolubility. What is the difference between a larger and smaller cell for resolubility.

    How do various ink resin formulations affect resolubility.

    Develop a quantifiable test method to measure resolubility.

    210/7/2016

  • Introduction to Flexographic Printing and its use in packaging.

    25 years of growth and improvements Anilox

    Plate

    Inks

    Heavily connected to packaging 60% of packaging is printed flexo *

    92% of flexo workflow is packaging *

    Packaging growth up to $587.19 Billion by 2020**

    Flexographic Printing is taking market share from other printing methods. Increase in speed and quality

    * Young, D. (2016). Packaging Basics. Powerpoint presentation during Packaging Basics Course at Michigan State University.

    ** Packaging Strategies (2015). Packaging printing market worth $587.19 billion by 2020. Retrieved June 19th, 2016 from http://www.packagingstrategies.com/articles/88219-packaging-printing-market-worth-58719-billion-by-2020

    310/7/2016

  • Flexo Printing Methods

    Flexo Methods Enclosed chamber / Metering Roll

    Anilox cylinder

    Doctor Blade(s)

    Raised print surface

    410/7/2016

  • Anilox Cylinders

    Anilox cylinders are ceramic coated metal rolls with etched cells

    Lower Lines per Inch (lpi) anilox

    Coatings

    Spot Colors Custom colors i.e. CocaCola Red, Pepsi Blue

    Higher lpi anilox Process Printing (CMYK)

    Detailed printing

    510/7/2016

    Less lines per inch More lines per inch

    Larger cells Smaller cells

    Lower Quality Dot Higher Quality Dot

    4.84.3

    3.73.2 3

    2.5

    0

    1

    2

    3

    4

    5

    6

    300 360 400 500 550 600

    Cel

    l Vol

    ume

    (BC

    M)

    Anilox Lines per Inch

    Cell Volume (BCM) Of Banded Anilox Cell Volume (BCM)

  • What is Resolubility?

    Resolubility is the ability of the dried ink on the Aniloxcylinder or on the plate to be re-wetted

    Poor resolubility leads to: Less ink transfer from anilox cylinders to plates

    Dried ink on the print plate leads to dot gain:

    when a printing dot gains size due to dried ink around the dot

    causing larger than desired dots

    which negatively affects color strength and image resolution.

    Down time

    610/7/2016

  • Inks

    Inks for film printing must:

    Form a film on top of the substrate

    Be fast drying

    Have resolubility

    Have resistance properties: Scuff Resistance

    Block Resistance

    Resistance to water and other chemicals

    Cold/Hot Applications

    Two Ink types in todays market

    Solvent based

    Water based

    710/7/2016

  • Solvent-Based Ink

    Leads market for plastics film based printing

    Known for: High speed printing

    Demanding applications (freezer to microwave)

    Quick resolubility

    Waste Concerns Disposal

    Wasted ink

    High in Volatile Organic Compounds Shift to move away from VOC

    Work on alternative methods i.e. Water-based and Ultraviolet-based

    810/7/2016

  • Water-Based Ink

    Desirable to brand owners and converters Friendlier to environment

    Easier to handle

    Non-flammable

    Advancements and growth since 1980s

    Still faces challenges Resolubility and Printability

    High speed considerations

    Print defects

    910/7/2016

  • Equipment and Materials

    Mark Andy 2200XL Flexo Press

    120 Gauge BOPP substrate, 16 width Treated with in-line corona treater (2000 watts)

    36 dyne level before corona treatment, 44 dyne level after 2kW corona treatment.

    Full coverage (smooth, no print design) printing plate (polyurethane sheet) 20 Inch repeat (circumference of cylinder)

    Banded anilox cylinder 300 lpi (4.8 bcm) 600 lpi (2.5 bcm)

    1010/7/2016

  • Equipment and Materials

    X-Rite 508 Spectrodensitometer

    Pantone Color viewing light box D65 Illuminate (standard daylight)

    Zahn Cup #2 Ink Viscosity Inks adjusted to a viscosity between 25 and 30 seconds (~50-70 cP)

    Adjusted using 60% water and 40% dispersion mixture.

    1110/7/2016

  • Ink Formulations

    1210/7/2016

    Formulations (%) Resin #1 Resin #2 Resin #3 Resin #4 Resin #5

    Pigment Dispersion 40 40 40 40 42.9

    Acrylic Emulsion Resin* 38.9 48 48 48 50.4

    Wax 3.3 4 4 4 4.2

    Surfactant 0.9 1 1 1 1

    Defoamer 0.010 0.1 0.1 0.1 0.1

    Water 16.9 6.9 6.9 6.9 1.4

    Total 100 100 100 100 100

    Viscosity (Zahn #2, seconds /

    Brookfield Equiv. in cP) 30 (70) 24 (50) 29(70) 27(60) 26. (60)

    *All resin formulations listed are different proprietary recipes*

  • Experimental Methodology

    Step One: Set Impression Impression is the action of setting optimal

    pressure of printing plate to both substrate and anilox cylinder

    Low speed to produce best possible image

    Too much pressure pushes ink outwards (see L L below)

    Step Two: Press run for one minute @ 210 fpm

    Step Three: Turn off press, disengage anilox cylinder from press

    Move carriage back, preventing rotation/rewetting of ink in the anilox

    Allow press to sit idle for two minutes

    1310/7/2016

  • Experimental Methodology (cont.)

    Step Four: Re-Start press Move carriage back into place, re-engaging anilox cylinder

    Re-start at 50 fpm

    Step Five: Insert tags into rewind roll at specific time markers Initial print (0 seconds)

    Print at 30 seconds

    Print at one minute

    Print at each additional minute up to nine minutes.

    1410/7/2016

  • Experimental Methodology (cont.)

    Step Six: Measure and average density of lighter blue dried area at each tag marker.

    X-rite Spectrodensitomer 508

    D65 Illuminated light box.

    Nine measurement points in each dried section.

    1510/7/2016

  • Results: 300 Line vs 600 Line Anilox Density Recovery

    1610/7/2016

    0.55

    0.65

    0.75

    0.85

    0.95

    0 2 4 6 8 10

    % R

    ECO

    VER

    Y

    MINUTES

    300 Anilox "Dirty"(Dried Ink) % Recovery

    Resin #1 Resin #2 Resin #3 Resin #4 Resin #5

    0.55

    0.65

    0.75

    0.85

    0.95

    0 1 2 3 4 5 6 7 8 9 10

    % R

    ECO

    VER

    Y

    MINUTES

    600 Anilox "Dirty" (Dried Ink) % Recovery

    Resin #1 Resin #2 Resin #3 Resin #4 Resin #5

    Less lines per inch

    More lines per inch

    Larger cells Smaller cells

    Lower Quality Dot

    Higher Quality Dot

    Notice not much differentiation in densities( % recovery) for any formulation

    Testing showed ink resin formulation #2 to be a very good performer, i.e. fast recovery,and #4 to be a poor performer

  • Results Profile of all six anilox bands tested, for one ink

    1710/7/2016

    0.55

    0.65

    0.75

    0.85

    0.95

    0 2 4 6 8 10

    % R

    ECO

    VER

    Y

    MINUTES

    Resin Formulation #5 Recovery of "Dirty" Anilox Cylinders.

    600 550 500 400 360 300

    A light water spray of the banded anilox cylinder immediately following the test showed dried ink that couldnt easily be re-wetted in the 600 lpi band.

    The 300 lpi anilox was generally NOT effective for showing density recoveryThe 600 lpi proved VERY effective for density reduction AND recovery

  • Conclusions

    We have developed a new, quantifiable test method using Banded anilox cylinders for comparing resolubility of water based ink formulations.

    Density measurements have proven to be effective for quantifying percent recovery of ink after drying.

    Formulations containing styrene, acrylic acid and a base tend to be more resoluble when there are more acid groups (and in turn more salt) present.

    1810/7/2016

  • Conclusions (cont.) Resolubility is more of an issue with higher lpi cylinders (600 lpi,

    2.5 bcm) than with lower lpi cylinders (300, 4.8 bcm) for a given ink formulation because ink will completely dry in a smaller cell quicker than a larger cell (since

    there is less to dry). Higher lpi anilox cylinders are desirable for best quality.

    This test methodology helps us differentiate between our ink formulations and also helps us specify ideal anilox cylinders for selected applications.

    Good resolubility is key for high performing water based inks. Next:

    Testing plate drying Halftones

    Testing to continue with higher lpi anilox cylinders 700 through 1400 lpi Improve abilities to differentiate ink formulations

    1910/7/2016

  • Advances in Flexographic Printing Inks Technology. A Re-solubility Study on BOPP film.ObjectiveIntroduction to Flexographic Printing and its use in packaging. Flexo Printing MethodsAnilox CylindersWhat is Resolubility? Inks Solvent-Based InkWater-Based InkEquipment and MaterialsEquipment and MaterialsInk FormulationsExperimental MethodologyExperimental Methodology (cont.)Experimental Methodology (cont.)Results: 300 Line vs 600 Line Anilox Density RecoveryResults Profile of all six anilox bands tested, for one inkConclusionsConclusions (cont.) Slide Number 20