The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated - - PowerPoint PPT Presentation

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated - - PowerPoint PPT Presentation

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TAMPERE UNIVERSITY OF TECHNOLOGY Institute of Paper Converting The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board Mikko Tuominen & Johanna Lahti Session 12.4 Introduction Extrusion coated paperboards are

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SLIDE 1

TAMPERE UNIVERSITY OF TECHNOLOGY

Institute of Paper Converting

The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board Mikko Tuominen & Johanna Lahti

Session 12.4

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Introduction

  • Extrusion coated paperboards are applied successfully

especially in packaging industry

  • Packaging product requires special surface properties

from the materials, which extrusion coated paperboards

  • ften do not possess, such as printability and heat

sealability

  • Several methods have been developed to modify

surface properties, including flame, corona, and plasma treatments

  • These methods affect the surface energy, oxidation,

heat sealability and printability of surfaces, but how?

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Introduction

  • The effects of flame and corona treatment on surface

energy have been examined continuously up to eight months

  • The effects of flame and corona treatments on oxidation,

heat sealability, hot tack and printability are evaluated (right after treatment vs. six months later)

  • The co-effect of flame and corona treatments is studied,

(surface energy, heat sealability, and printability)

  • In addition, the influence of the treatment order, i.e.

which of the treatments (flame or corona) is applied the first, (surface energy, heat sealability, and printability)

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Experimental

  • In this study, 205 g/m2 paperboard was extrusion coated

with 15 g/m2 of PE-LD at pilot line of TUT (Institute of Paper Converting)

  • Flame and corona treatment were used to modify surface
  • f PE-LD coated paperboard
  • Surface energies were defined with contact angle

measurements (Pocket Goniometer PG-3)

  • Surface oxidation and chemical composition was defined

with ESCA (Electron spectroscopy for chemical analysis) and ATR-FTIR (Attenuated Total Reflection using Fourier Transform Infrared Spectroscopy)

  • Heat sealing and hot tack properties were defined with

KOPP Laboratory Sealer SGPE 20 measuring system

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Experimental

  • The samples were printed with a Xeikon DCP/50-SP

digital printing machine

  • The printing method in the Xeikon is based on a dry

toner web fed electrophotographic process

  • Toner adhesion was defined with a rub-off

measurement

  • Print quality, mainly print mottle, was analyzed both

visually (ranking list) and numerically (mottle value)

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Results

  • Surface energy

– The influence of treatment efficiencies and treatment order

  • Heat sealability i.e. heat sealing and hot tack

temperatures

– The influence of treatment efficiencies and treatment order

  • Printability

– Visual quality (ranking 1-5) and toner adhesion (rub-off) – The influence of treatment order

  • Oxidation and chemical composition

– ESCA and ATR-FTIR – The influence of treatment order

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Surface energy

The effect of flame and corona treatment on surface energy, (contact angle of water)

70 75 80 85 90 95 100 105

No treatment Flame Corona Flame and corona

Contact angle of water, (°)

1 day 3 days 1 week 2 weeks 3 weeks 5 weeks 2 months 6 months 8 months

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Surface energy

The effect of flame and corona treatment on surface energy, (contact angle of water), 3 times weaker treatment

70 75 80 85 90 95 100 105

No treatment Flame Corona Flame and corona

Contact angle of water, (°)

1 day 3 days 1 week 2 weeks 3 weeks 5 weeks 2 months 6 months 8 months

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Surface energy

The effect of flame and corona treatment on surface energy, (contact angle of water)

3 times weaker treatment 3 times weaker treatment

70 75 80 85 90 95 100 105

No treatment Flame and corona Corona and flame Flame and corona Corona and flame

Contact angle of water, (°)

1 day 3 days 1 week 2 weeks 3 weeks 5 weeks 2 months 6 months 8 months

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Surface energy

  • The corona treatment is more effective than the flame treatment,

but the co-effect of flame and corona is the most effective

  • The decay of surface energy over time is slowest with flame

treatment, also the co-treated test point retains surface energy better than the plain corona treated test point

  • When the efficiency of treatment is decreased, the effect of corona

treated and co-treated test points remains quite similar compared to more efficient treatment

  • On the other hand, the flame treatment somewhat looses its long-

lasting effect, when the efficiency of the treatment is reduced

  • Order of the treatments is significant. If the surface is first treated

with flame and later on with corona, the surface energy is much higher, but the decay over time is evident

  • On the other hand, if corona treatment is the first and flame

treatment the latter, the surface energy is clearly lower, although the decay is much slower

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Heat sealability (heat sealing temperature)

The effect of flame and corona treatment on heat sealing temperature

60 80 100 120 140 160 180 200 220

No treatment Flame Corona Flame and corona

Heat sealing temperature, (°C)

Complete seal 6 months later

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Heat sealability (heat sealing temperature)

The effect of flame and corona treatment on heat sealing temperature, (3 times weaker treatment)

60 80 100 120 140 160 180 200 220

No treatment Flame Corona Flame and corona

Heat sealing temperature, (°C)

Complete seal 6 months later

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Heat sealability (heat sealing temperature)

The effect of flame and corona treatment on heat sealing temperature

3 times weaker treatment 3 times weaker treatment

60 80 100 120 140 160 180 200 220

No treatment Flame and corona Corona and flame Flame and corona Corona and flame

Heat sealing temperature, (°C)

Complete seal 6 months later

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Heat sealability (hot tack temperature)

The effect of flame and corona treatment on hot tack temperature

60 80 100 120 140 160 180 200 220

No treatment Flame Corona Flame and corona

Hot tack temperature, (°C)

Complete seal 6 months later

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Heat sealability (hot tack temperature)

The effect of flame and corona treatment on hot tack temperature, (3 times weaker treatment)

60 80 100 120 140 160 180 200 220

No treatment Flame Corona Flame and corona

Hot tack temperature, (°C)

Complete seal 6 months later

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Heat sealability (hot tack temperature)

The effect of flame and corona treatment on hot tack temperature

3 times weaker treatment 3 times weaker treatment

60 80 100 120 140 160 180 200 220

No treatment Flame and corona Corona and flame Flame and corona Corona and flame

Hot tack temperature, (°C)

Complete seal 6 months later

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Heat sealability

  • Corona treatment improves heat sealability and hot tack

by decreasing the sealing temperatures a bit

  • Flame treatment increases the sealing temperatures

remarkably at high efficiency level. When the efficiency is decreased, the increase in sealing temperatures is

  • nly minor
  • The co-effect increases the sealing temperatures

slightly at high efficiency level, but not anymore at lower efficiency levels

  • The treatment order has no significant effect on heat

sealing temperatures

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Printability

The effect of flame and corona treatment on printability

1 2 3 4 5 6 7

No treatment Flame Corona Flame and corona Corona and flame

Visual quality, ranking (1-5)

Visual quality (ranking) 6 months later

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Printability

The effect of flame and corona treatment on printability

5 10 15 20 25 30

No treatment Flame Corona Flame and corona Corona and flame

Rub-off, (%)

Rub-off (cyan) 6 months later Rub-off (magenta) 6 months later

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Printability

  • Corona treated test point was ranked the best and the

flame treated test point was the second

  • When both treatments were used together, the visual

quality was the poorest

  • The corona treated test point has the lowest print mottle

also by numerical measurement

  • The flame and corona treated test point has the highest

print mottle also numerically measured

  • Surface treatments clearly increase the abrasion

resistance of the printed images measured as rub-off values

  • The flame treated sample maintains its properties best
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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Oxidation and surface compounds

The effect of flame and corona treatment on oxidation

7,0 7,5 11,3 10,9 10,6 7,3 10,5 10,5 0,9 0,4

5 10 15

No treatment Flame Corona Flame and corona Corona and flame Surface content, (%)

Oxygen, (%) Oxygen, (%), 6 months later

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Oxidation and surface compounds

C-C & C-H bonds, (%) 98,2 89,9 90,7 87,3 86,0 6 months later 97,8 88,6 90,9 87,8 88,0 C-OH & C-O-C bonds, (%) 1,7 7,3 5,7 7,4 7,7 6 months later 2,1 6,4 6,1 7,3 7,0 C=O & O-C-O bonds, (%) 0,1 2,8 3,6 5,3 6,3 6 months later 0,1 5,0 3,0 4,9 5,0 Carbonyl-index 0,23 0,45 0,46 0,50 0,53 6 months later 0,24 0,42 0,34 0,44 0,52 Corona and flame No treatment Flame Corona Flame and corona

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Oxidation and chemical composition

  • The oxygen content on the surface of flame or corona treated

surface after treatment is equal, whereas the oxygen content on the surface of co-treated test point is around 30% higher

  • The oxygen content of the treated surfaces decreases a bit after six

months excluding the flame treated test point, in which the oxygen content increases over 30% after six months of aging

  • Flame treated test point has more C-OH & C-O-C bonds on the top

surface, whereas corona treated test point has more C=O and O-C- O bonds on the top surface

  • The amount of C-C, C-H, C-OH & C-O-C bonds and carbonyl-index
  • f the flame treated test point decrease a bit after six months,

whereas C=O and O-C-O bonds increase remarkably

  • The amount of C-C, C-H, C-OH & C-O-C bonds of the corona

treated test points slightly increases after six months, but the amount of C=O and O-C-O bonds and carbonyl-index decreases

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Conclusions

  • Surface energy

– Surface treatments clearly increase surface energy of PE-LD coated paperboard by oxidizing its surface – The co-effect of flame and corona, i.e. both the treatments together, is the most effective – The decay of the treatment effect over time is slowest with flame

  • treatment. However, flame treatment looses its long-lasting

effect, when the efficiency of the treatment is reduced – Order of the treatments is significant

  • If the surface is first treated with flame and later on with corona, the surface

energy is much higher, but the decay over time is evident

  • On the other hand, if corona treatment is the first and flame treatment the

latter, the surface energy is clearly lower, although the decay is much slower

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Conclusions

  • Heat sealability

– Corona treatment improves heat sealability by decreasing the sealing temperatures a bit – Flame treatment increases the sealing temperatures remarkably at high efficiency level. When the efficiency is decreased, the increase in sealing temperatures is only minor – The co-effect increases the sealing temperatures slightly at high efficiency level, but not anymore at lower efficiency levels

  • Printability

– Corona treated test point was ranked the best and the flame treated test point was the second – When both treatments were used together, the visual quality was the poorest

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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Conclusions

  • Oxidation and chemical composition

– The total oxygen content and the amount of different carbon and

  • xygen bonds on the top surface of PE-LD coated paperboard

after the treatments are definitely various – Especially interesting is that how the amount of certain compounds (C=O, O-C-O bonds and carbonyl-index) changes after six months of aging – This change, together with different migration rates of miscellaneous surface compounds, might explain the behaviour (surface energy, heat sealability and printability) of treated samples over time

  • The next steps

– To examine the effects of flame, corona and plasma treatment

  • n the surfaces of various polymers
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The Effects of Corona and Flame Treatment: Part 1. PE-LD Coated Packaging Board, Mikko Tuominen & Johanna Lahti

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Acknowledgements

  • The authors are grateful to Borealis Polymers Oy, Stora

Enso Oyj Packaging Boards, Stora Enso InnoCentre and lab staff of TUT and Stora Enso for all the measurements and the trial support