A Comparison of Aqueous Primers for Anchoring Vacuum Deposited Aluminum to Film Substrates

Ginger Cushing Business Manager Americas – Flexible Packaging AIMCAL Coating & Laminating Conference – Prague 2012

AGENDA

• Introduction • Objective of the Study • Experimental

– Materials – Trial

• Results/Discussion • Conclusion

Vacuum Deposition of Aluminum on Film Substrates • Substrate Preparation

– Smoothness • Adhesion to Film (BOPP and BOPET)

– Oxidative or chemical plasma – Coextruded skins – Chemical Primers

Objective of the Study

Develop a chemical primer that will: 1. Adhere well to treated film without a

separate adhesion promoter 2. Produce a smooth surface 3. Adhere well to metal 4. Yield a bright metalized film with good

Oxygen barrier

Materials • Uncoated film substrates

– 12µ BOPET – 20µ BOPP

• Barrier Primer A – 10% solids in water

• Barrier Primer B – 10% solids in water

• Aluminum for metalizing

Trial 1 – Preliminary screen on clear 12u BOPET

This image cannot currently be displayed.

“Banded” Cylinder

5.0 BCM5.7 BCM6.6 BCM6.9 BCM7.3 BCM9.2 BCM4.3 BCM

68.00"8.50"

0.50"

62.50"44.50"26.50"

8.50"2.75"

Volume (cc/m2) Measured Coat Weight (gsm)

11.3 0.5 10.7 0.47 10.2 0.45 8.8 0.39 7.8 0.34

Cell delivery 45%

Oxygen Transmission Rate

• Mocon Ox-Tran 2/21 • Unsupported film • 0% RH, 23oC • Average of 2 samples, each cycled 5

times

OTR at 0% RH for Primers A and B on 12u BOPET (no metalizing)

00.10.20.30.40.50.60.70.80.9

0.5 0.47 0.45 0.39 0.34

Oxy

gen

Bar

rier,

cc/m

2/da

y/at

m

Primer Weight, dry g/m2

AB

Average dry OTR on 12u BOPET across banded cylinder • 0.43 dry g/m2 primer coat weight • Primer A = 0.574 cc/m2/day/atm • Primer B = 0.380 cc/m2/day/atm

Trial 2 – Metalizing Tests

Method • Gravure coat 0.2 dry g/m2 of each coating to film

– Corona treat film prior to priming – Use smoothing bar – Dry thoroughly with hot air – Rewind

• Splice all the rolls together • Vacuum metalize the primed substrates to an

optical density of 2.0

Appearance

• All metal surfaces were bright and even.

Adhesion Tests

• Adhesion of coating to base film prior to metalizing by 3M 610 Scotch Tape

• Adhesion of metal to coated substrate by modified AIMCAL TP105

Silicone paper

EVA Coated PET Film

Test film (metal up)

Scotch 610 tape

Silicone paper

Adhesion Test Results

• Scotch Tape did not remove any coating from the substrate.

• Metal adhesion very strong, between 600 and 710 g/25mm

Film/0.2 gsm Primer/2.0 OD Metallizing OTR @ 0% RH

3.76 0.53

140

6.56 7.1

547

0

100

200

300

400

500

600

Primer A Primer B Plain Film

Oxy

gen

Bar

rier,

cc/m

2/da

y/at

m

12u BOPET20u BOPP

Next Steps

• Laminations of film-barrier primer-met/solventless adhesive/film barrier testing under way

• Elevated humidity testing in progress

Summary – Clear BOPET Film • Both primers exhibited excellent film

adhesion • Coating was clear and even. • Primer B was better than A.

Summary – Metalized Film • Metal adhesion excellent • Metal brightness excellent • Primer A barrier close to Primer B on

BOPP • Primer B out-performed Primer A in OTR

testing on BOPET

Discussion

• BOPET/0.4 gsm primer = 0.38 cc/m2/day/atm

• BOPET/0.2 gsm primer/2.0 met = 0.53 cc/m2/day/atm

• Why?

Potential Markets

• Dry contents – Chips, crisps – Crackers – Cookies, biscuits – Pasta

THANK YOU

Ginger Cushing Michelman, Inc. USA GingerCushing@michelman.com