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Gas Barrier Coatings For Flexible Packaging

AIMCAL EUROPE WEB COATING CONFERENCE 2012

12th June Prague

Mike Leonard

Manager Functional Coatings Research

2

Gas barrier Coatings Definition & Background Market Information

Nanocomposite Gas Barrier Coatings Exfoliated Clay Composites Analysis of Clay Composite Coatings

Performance in Packaging Applications Environmentally Friendlier Packaging Coating Applications

Conclusions

Outline

3

Barrier Coatings: Definition

Prevent the penetration (or loss) of specific gases, light or aroma/odour which could compromise the integrity of the packaged product.

Typical Barrier Coatings: • Oxygen Barrier • Moisture Vapour Barrier • CO2 Barrier • UV Barrier • Aroma Barrier

4

History/Evolution Of Gas Barriers in Packaging

Glass & Tin Plastics First coatings

on plastics

Extrusion

Lamination

Excellent barriers

but heavy

Poor barriers, but light weight

Reasonable barriers

Especially PVdC and Al

metallisation

also

lightweight

EVOH-Excellent

O2 Barrier at medium

%RH

Thick laminates

SiOx & AlOx Ceramics

Emerging

Technologies

Excellent moisture

vapour and O2 barriers,

transparent but brittle

Organic polymer structures and

nanocomposites

All of these materials are in present use today

There is no one barrier technology that meets all requirements

Al Foil

5

Oxygen Transmission Rates of Typical Flexible Packaging Materials

0

2

4

6

8

10

12

14

16

18

20

Al Foil PET-Al PET-SiOx/AlOx

PET-PVDC PET-EVOH Nylon PET PP/PE

OTR

(cm

3 /m2 /d

ay; @

23o

C&

50%

RH

)

c. 100 >1000

Printable Oxygen Barrier Coatings will offer an alternative to existing High Barrier Options

(Sun Chemical Measurements)

6

Gas Barrier Coatings:

Market information

7

Market Overview - Barrier Materials for Food Packaging

Conversion from current barrier technology/ film is a multi $ million coating opportunity

Aluminum Foil (535)

MET-Films (205)

EVOH Resins (55)

Glass Oxides (34)

PVDC Resins (164)

Global Addressable (Printable) Market for Barrier Coatings potential –2,074,000tonnes

2008

Fresh Meat, 59% Processed Meat, 7%

Cheese & Dairy, 9%

Prepared Food, 2%

Snack Foods, 17%

Confectionery, 2% Dry Mixes, 2%

Coffee, 4%

Market Segmentation by Application

Source: ADC/Kline

8

Packaging market overview (barriers)

Coating Applications

PVdC EVOH Nylon Speciality Oxides Metallised Co-extrusions

Bags Lidding Stand Up Pouches Forming Webs Wraps

Chilled Food Dry Food Liquid Packaging

Market / Applications Package structure Barrier technology

Temperature & Relative Humidity are Important Considerations

9

Printable Oxygen Barrier Coatings A gap exists in the market for transparent barrier coatings;

free from halogenated compounds, converter applied, which afford high barrier performance.

10

Nanocomposite Gas Barrier Coatings Description, Preparation, Function & Analysis

11

Emerging Technologies

Nanocomposites – Highly dispersed/exfoliated silicates/clays

Sol-Gel Coatings – Inorganic/Organic composites formed in-situ

– e.g. Si(EtOH)4 Si(OH)4 ‘SiOx’ – Organically modified ceramic lacquers.

– vapor and barrier layer strategy

Epoxy Based Coatings

PAA & PGA-based coatings

Hydrolysis Condensation

12

Sun Chemical’s Nanocomposite Barrier Coatings

• Finely dispersed nanoparticulate (intercalated/ exfoliated) silicate mineral in a polymer solution/ dispersion

• The dispersion is applied using traditional printing and drying techniques

• The dried polymer coating on a film enhances the oxygen barrier performance of the substrate

Functional oxygen barrier of less than 1.0 cm3/m2/24h at 23oC & 75%RH

13

The influence of Exfoliated Minerals on Barrier Improvement

The generally accepted theory for barrier improvement is that dispersed/exfoliated ‘platy’ minerals increase the diffusion path length through a coating; ‘TORTUOUS PATH’.

+

Polymer Matrix Layered Silicate

Mineral Dispersion

Exfoliated Nanocomposite

d1 d2

d2 > d1

O2 O2

14

Analysis of Nanocomposites: XRD

Cloisite Na+ - File: E-REQ09-4163-Cloisite-Na-EXFO-9-4-2009.raw - Type: Locked Coupled - Start: 2.250 ° - End

Inte

nsity

0

20

40

60

80

100

120

140

160

180

200

d - Scale

6102030

X-Ray Diffraction shows the increase in d-spacing (001) when the clay is successfully exfoliated.

Clay Nanocomposite;

<10% (w/w) Clay

30 20 10 6

d Spacing (Å)

d001=12.1 Å

Sample # 3 - File: E-REQ09-4163-Sapmle3-EXFO-9-4-2009.raw - Type: Locked Coupled - Start: 2.250 ° - End: 15.00

Inte

nsity

0

20

40

60

80

100

120

140

160

180

200

d - Scale

610203040 30 20 10

d Spacing (Å)

Inte

nsity

(Cou

nts)

15

Analysis of Nanocomposites: XRD

Nanocomposites with Higher Clay Loadings

Sample # 4 - File: E-REQ09-4163-Sapmle4-EXFO-9-4-2009.raw - Type: Locked Coupled - Start: 2.250 ° - End: 15.00

Inte

nsity

0

20

40

60

80

100

120

140

160

180

200

d - Scale

610203040

d=26

.466

51Sample # 1 - File: E-REQ09-4163-Sapmle1-EXFO-9-4-2009.raw - Type: Locked Coupled - Start: 2.250 ° - End: 15.00

Inte

nsity

0

20

40

60

80

100

120

140

160

180

200

d - Scale

610203040

35 Å

26 Å

30 10 20 30 10 20

d Spacing (Å) d Spacing (Å)

Nanocomposite;

c.25% (w/w) Clay

Nanocomposite;

c.40% (w/w) Clay

Intercalated composites or highly ordered exfoliated composites?

16

Analysis of Nanocomposites; Electron Microscopy

TEM: Nanocomposite Coating

Cast of Dilute Coating on Cu Grid (Sun Chemical)

SEM: Agglomerated Clay

17

TEM of Cross Sectioned Coating on PET Film

Clay Particles

18

The Effect of Exfoliation on the Visual Appearance of NanoComposites

19

05

101520253035404550

Unfilled Polymer 'MicroComposite'

Nanocomposite AnnealedNanocomposite

The Effect of Clay Exfoliation on the Oxygen Barrier O

xyge

n Ta

nsm

issi

on R

ate

(cm

3 /m2 /d

ay)

Oxygen Transmission Rates were measured with an Oxtran 2/21 at 23oC&75%RH.

20

Nanocomposite Coatings- Influence of Aspect Ratio

0

5

10

15

20

25

30

35

40

0 10 20 30 40

AR=1AR=25AR=100AR=200

Oxygen barrier vs Aspect Ratio

Oxy

gen

Tran

smis

sion

Rat

e at

23o C

& 5

0%R

H (c

m3 /m

2 /24h

)

Concentration of Mineral in the Coating (% (w/w)

0

0.5

1

1.5

2

2.5

25 100 200 500>1000

l

d Aspect Ratio = l/d

Lamination Bond Strengths vs Aspect Ratio

N/ 1

5mm

Aspect Ratio

21

Understanding the Role of Clay on Oxygen Barrier Performance; a Mechanistic Study

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0.00331 0.00336 0.00341 0.00346 0.00351 0.00356 0.00361

0% Clay15% Clay30% Clay45% Clay

Log

(OTR

)

1/T(K)

Arrhenius Plots used to determine the effect of changing clay concentration

on Oxygen Permeability

• Slope α – Ea (Activation Energy)

Therefore; no change in Ea

Polymer Matrix character does not change

Increase in diffusion path length the likely mechanism

O2

(% Clay = wt. % in the dry coating applied to PET)

22

Using Arrhenius Plots; Log OTR v. 1/T to Extrapolate Performance

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0.00331 0.00336 0.00341 0.00346 0.00351 0.00356 0.00361

Expt 1Expt 2Expt 3Expt 4

1.8-2.0

1.4-1.6

0.8-0.9

0.4-0.5

OTR Prediction at 4-5oC

Mocon Oxtran 2/21 Min Temp =11°C

23

Performance Clay Composite Coatings in Packaging Applications

24

Comparison of Functional Barriers on PET

Untreated polyester film OTR 100-110 cm3 / cm2

PVDC major disadvantage – contains chlorine & higher OTR AlOx / SiOx major disadvantage – brittle & higher OTR EVOH deteriorates over time in humid storage conditions

Oxygen transmission rate measured using a MOCON OX-TRAN® 221 within 24 hours of coating

0

1

2

3

4

5

6

7

8

9

PVdC Al PET AlOx SiOx PET EVOH ClayCompoiste

23ºC & 50% RH

Varies with grade and cost

PET: 50µ PE:EVOH:PE Extrusion

0.3µ dry coating weight

25

Influence of Coatings Thickness on Barrier performance

The clay composite coatings provide excellent barrier performance on both PET and OPP with dry film weights as

low as 0.2 g/sm (dry).

26

Influence of Relative Humidity & Coat Weight

Higher Coat Weights are Generally needed at Elevated %RH

Clay Composite coating 12μm PET, tested at 50%RH and 75% RH, at 23ºC

27

Oxy

gen

Tran

smis

sion

Rat

e (c

m3 /

m2 /

day

@ 2

3C)

0

5

10

15

20

25

30

45 50 55 60 65 70 75 80 85

Clay-CompositePET-PE/EVOH/PEPET-PVDC

Relative Humidity

Performance Benchmark – Effect of Humidity

28

0

5

10

15

20

25

30

35

40

10 15 20 25 30 35 40

PVdC-PETClay CompositePE/EVOH/PE-PET

Clay-composite coating improved performance at elevated temperature

Temperature ºC

[5.6 gsm wet]

Oxy

gen

Tran

smis

sion

Rat

e (c

m3 /

m2 /

24 h

rs)

Performance Benchmark – Effect of Temperature at 75% RH

29

Flexibility of Barrier Coatings

0

1

2

3

4

5

6

7

8

9

0 5 10 20 50

No. of Gelbo Flexes

PET-AlOx

PET-Clay-Composite

PET-SiOx

OTR

@ 2

3oC

& 5

0%R

H (c

m3 /m

2 /24h

)

PET-EVOH

PET-PVDC

Oxide-coated films have poor flex resistance ( Performance improves when laminated and coated)

30

0

1

2

3

4

5

6

7

1 2 4 6 8 10

Clay Composite 1Clay Composite 2PET PVdCPET SiOxPET PE EVOH PE

Chilled Foods-Real Time Packaging Performance

2-4 ºC Temperature External Humidity 43%RH Internal Humidity 100% RH Non Invasive measurement

Time (weeks)

% O

xyge

n In

gres

s

Clay composite coatings perform as well as EVOH Structures

31

Key Packaging Trends

Coating Applications

2. Visible product contents

1. Rigid to flexible

3. Light weighting

4. Single piece packs

32

Trend #2: Visible product contents

Coating Applications

Longer shelf life. Visible content packs with high oxygen barrier

33

Trend #4: Single piece packs

Coating Applications

Excellent oxygen and aroma / odor barrier for base substrates.

34

Light weighting

Coating Applications

Commercial 3-Ply Laminate

Removal of barrier film or foil and one layer of adhesive Lighter weight packaging (up to 30% reduction) Improved laminate integrity (post flexing O2 barrier improvement) Lower material and / or operational costs Improved recycling Improved shelf life

Polymer Film Ink Adhesive MET Polymer Film Adhesive

Polymer Film

Polymer Film Barrier Coating Ink Adhesive Polymer Film

2-Ply Laminate plus printable barrier coating

35

Conclusions SunBarTM Clay composite oxygen barrier coatings enable (transparent) barrier packaging having exceptional barrier

properties.

Oxygen Barrier Performance equivalent/superior to existing technologies

Can be applied by conventional printing methods

can reduce the environmental impact of plastic packaging.(lightweighting, improved recycling, Cl free, replace metal, more flexible)

Increasing the mineral aspect ratio provides improved barrier performance.

Improvements in oxygen barrier shown to result from an increase in diffusional path length (‘Tortuousity’).

36

Acknowledgements

Thank you for your attention

The Functional Coatings Research team at St. Mary Cray (UK) – Derek Illsley, Asad Khan, Robert Lines, Safraz Khan, Farid Azizian,Peter

Brownrigg

Analytical Departments at St. Mary Cray and Colours Group (USA) – Jayne Barnes, Hetal Patel, Lisa Clapp, Costas Nicolaou

Mike Leonard Manager - Functional Coatings Research

Sun Chemical Ltd

Cray Avenue St Mary Cray

Orpington, Kent BR5 3PP

Tel: +44 (0) 1689 894 173 Fax: +44 (0) 1689 894 020

Mobile: +44 (0) 7976 969873 Email: mike.leonard@sunchemical.com

Web: www.sunchemical.com