1. BARRIER PACKAGING IN THE REAL WORLD
Dante Ferrari
Celplast Metallized Products Limited

2. Outline Background Introduction Adhesive laminating conditions
Films
Laminate structures
Adhesive laminating conditions
Pre- and Post-Gelbo Flex Barrier Properties
Laminated MET PE
High Barrier MET PET
Top-Coated MET PET
Bond Strength of Adhesive Laminations
Summary
Conclusions
The intention of the work carried out jointly between Dow and Celplast was to look at a common adhesive lamination structure, the 3-ply pouch, and evaluate different metallized barrier films as well as alternative structures. Furthermore, three different adhesive methods were evaluated. The films, structures and adhesive methods used will be described in the introduction.
We wanted to evaluate the barrier properties not just in flat sheet form after lamination, but also after Gelbo flexing, to simulate what the barrier performance of these laminations would be under real world conditions.
Laminated bond strengths of the finished structures were also measured.
We will close the discussion today with a summary of the work and our conclusions to date.

3. Introduction
PE and PET are two of the most commonly used base substrates in flexible packaging
Two most important characteristic of a flexible package
Barrier properties
Lamination bond strength
What happens to the package in the real world?
In flexible packaging, PE and PET are two of the most commonly used substrates, and we will be using these films in this study here.
Barrier properties and lamination bond strengths are two of the most important characteristic of a flexible package.
As a metallizer, we provide results for barrier and bond to the converters and converters do the same for their customers. But one of the biggest questions is: what happens to the package in the real world? Can it retain the integrity of the original package that we supplied as it goes through the supply chain, onto the store shelf, and finally into the hands of the consumer?

4. Introduction
This study was designed to evaluate the practical barrier of pouches
The intention was to simulate flexing and handling that would be expected through the conversion and distribution chain
Barrier data was collected at various stages in order to estimate and compare the potential degradation of initial barrier through practical usage
Gelbo-Flex testing was used to simulate handling
To more fully understand barrier properties of finished pouch structures, we designed this study to evaluate the practical barrier of a pouch after going through the supply chain.
To simulate flexing and handling that would be expected through the lifecycle of a package, we used gelbo-flex testing. We tested the initial barrier of the package before flexing, then again after two different levels of flexing, to evaluate the degradation of barrier with handling.

5. Introduction: Films High barrier MET PE Sealant film
Previous studies1 have shown that in a 2-ply structure, barrier properties are similar to a 3-ply structure using a standard metallized PET film, using less material
1 “Sustainable Packaging: Reducing Material and Carbon Footprint with Metallized Barrier Sealants”, Packaging Films, Sept
Properties
Typical Value
Unit
Test conditions
Thickness
1.50
mil
OTR
0.06
cc/100in2/day
23ᵒ C, 50% RH
WVTR
0.07
g/100in2/day
38ᵒ C, 90% RH
Metal Adhesion
>300
g/in
MA-1
One of the barrier films used in this study was a high barrier metallized PE sealant film produced by Celplast. The table on this page shows the typical barrier values and metal bond strength of this film. This film is designed to replace a standard metallized PET barrier film as well as the sealant web in a standard 3-ply structure.
The barrier and metal adhesion test conditions are also listed for your reference. Note the metal adhesion test condition is MA-1. This is a modified version of the AIMCAL metal adhesion test method. It was developed by Celplast to allow us to measure higher metal bond strengths than the AIMCAL method allows for. This test method was presented at the 2004 AIMCAL Fall Technical Conference.

6. Introduction: Films Bi-axially oriented high barrier MET PET film
Properties
Typical Value
Unit
Test conditions
Thickness
0.48
mil
OTR
0.015
cc/100in2/day
23ᵒ C, 50% RH
WVTR
g/100in2/day
38ᵒ C, 90% RH
Metal Adhesion
400
g/in
MA-1
For one of the 3-ply structures, we looked at a high barrier MET PET supplied by Celplast, with the barrier values and metal bond strength shown here. This film would typically be used in a high barrier 3-ply pouch structure.

7. Introduction: Films Bi-axially oriented inline top-coated MET PET
Produced using proprietary in-vacuum EB top-coating process, which traps metal and improves barrier2
2 “Improve Barrier Properties and Significantly Reduce Your Carbon Footprint with In-line Metallizing and Top-coating”, AIMCAL Fall Technical Conference, 2011.
Properties
Typical Value
Unit
Test conditions
Thickness
0.50
mil
OTR
0.003
cc/100in2/day
23ᵒ C, 50% RH
WVTR
0.002
g/100in2/day
38ᵒ C, 90% RH
Metal Adhesion
>300
g/in
MA-1
For the other 3-ply structure, we looked at a novel in vacuo EB top-coated ultra high barrier MET PET supplied by Celplast, with the barrier values and metal bond strength shown here. As noted, the properties of this film have been reviewed in detail in a previous AIMCAL Fall Technical Conference.
It is worth noting that the top-coating itself has no inherent barrier properties. It improves the barrier of the metallized PET film by protecting the metal layer from the formation of pinhole defects that typically occur through substrate surface contaminants and handling of the film. The top-coating increases the thickness of the barrier layer by approximately 0.4 micron, or a little less than 2 gauge.

8. Laminate Structures 3 laminate structures were prepared:
SAMPLE 1 SAMPLE 2
MET PE: 2 ply Laminated Structure MET PET: 3 ply Laminated structure
Layer Description Layer Layer Description Layer Thickness Thickness
Clear PET
0.48 mil
Adhesive Lamination
MET PE Sealant Web
1.5 mil
Clear PET
0.48 mil
Adhesive Lamination
HB MET PET
PE Sealant Web
1.5 mil
Three different laminated structures were produced. Two of them are shown here.
For met PE, we laminated a clear, standard 1-side corona-treated 48 g PET to the metallized surface of the met PE to produce a 2 ply structure. This was introduced in the marketplace to help CPG’s meet their sustainability goals. As we all know, there is a tremendous pressure in the market place for sustainable products without compromising performance or increasing cost. Even thought it is a 2-ply structure, the high barrier met PE sealant film can provide a laminated barrier equivalent to a 3-ply structure containing a standard barrier met PET film. Less material is used to generate this 2-ply structure. In addition, energy consumption is reduced, production time is reduced, and cost of production is reduced.
For the high barrier met PET, clear 48 g PET was laminated to the metallized surface of the met PET in a first pass, then the PET side of the met PET was laminated to a standard 1.5 mil PE sealant film.

9. Laminate Structures Coated MET PET: 3 ply Laminated structure SAMPLE 3
Layer Description Layer Thickness
Clear PET
0.48 mil
Adhesive Lamination
HB Top-Coated MET PET
0.50 mil
PE Sealant Web
1.5 mil
The third laminated structure is shown here. It is similar to the 3-ply structure shown on the previous slide, but in this case clear 48 g PET was laminated to the top-coated surface of the coated MET PET in the first pass, instead of uncoated met PET. The PET side of the coated MET PET was then laminated to a standard 1.5 mil PE sealant film.

10. Lamination Conditions
Solvent-less
Two part polyester/polyether urethane
Standard 4-roll metering
Adhesive at 113 °F (45 °C), nip at 113 °F (45 °C)
Applied weight 1.1 – 1.25 lb./ream (1.8 to 2.0 GSM)
Corona Treater for primary and secondary set to 0.2 WD
Water-Based
Two part acrylic urethane
Standard gravure application
Applied weight 1.5 to 1.7 lb./ream (2.5 to 2.8 GSM)
Two zone dryer set to 170 and 180 °F (77 and 82 °C); nip at 180 °F (82 °C)
As mentioned previously, all of these structures were prepared using three different adhesive lamination methods. All laminating trials were carried out on Dow’s pilot laminating equipment near Buffalo Grove, IL. The first two adhesive application methods are described here.
The first, a solventless lamination, was carried out using a 4-roll metering system on a Comexi laminator, with close to 2.0 gsm coat weight applied in each pass.
The second, a water-based lamination, was carried out using a gravure applicator on an Egan laminator. This was followed by drying oven to 2.8 gsm dry coat weight applied in each pass.

11. Lamination Conditions
Solvent-Based
Two part curing polyester urethane
Standard gravure application
Applied weight 1.6 to 1.7 lb./ream (2.6 to 2.8 GSM)
Corona Treater for primary and secondary set to 0.2 WD
Two zone dryer set to 170 and 180 °F (77 and 82 °C); nip at 180 °F (82 °C)
The third lamination condition was solvent-based. It was carried out using the same coating line as the water-based lamination: via gravure applicator followed by drying oven, with 2.6 to 2.8 gsm dry coat weight applied in each pass.

12. Bond Strength of Laminate Structures
The first measurements that were collected were bond strength data of the finished structures, taken at 24 hours after final pass lamination and again at 7 days.

13. Clear PET/Coated Met PET/PE Could Not Separate, PE tear
Bond Strength
All results below shown after 7 days, similar to 24 hour results
Solventless and solvent-based provided best bonds
Water-based gave high bonds, adhesive transfer to PE
Bond strength units of measurement are all g/in
Note: Blue highlight is the interface tested for bond strength.
ADHESIVE
PRODUCT
Clear PET/Met PE
Clear PET/Met PET/PE
Clear PET/Coated Met PET/PE
Bond, Hi/Lo
Mode of failure
Bond, H/L
Solvent-based
551/457
30 –50 % Metal Transfer
1454/488
PE stretch
1463/ 568
Destruct
Solventless
675/539
90 % Metal Transfer
> 1482
Could Not Separate, PE tear
1669/ 1038
PE tear
Water- Based
300/293
Adhesive transfer
549/505
584/553
The results are shown here. All tests were carried out using 10 in/min crosshead speed on an Instron unit, using a 90 degree peel angle.
Bond strengths and modes of failure did not change appreciable from the 24 hour tests to the 7 day tests, which are reported here.
As can be seen, while all laminations gave ultimate bond strengths that would be acceptable for most flexible packaging applications, the water-based adhesive system consistently performed worse than the other two adhesives.
The 2-ply metallized PE structure is the only one that exhibited metal transfer in any of the tests. However, bond strength at metal transfer would be deemed acceptable for the vast majority of flexible packaging applications.

14. Barrier Properties of Laminate Structure
In the next few slides, we will see what happened to the barrier properties of the various laminations.

15. Barrier & Bond Testing The laminations were measured for OTR:
Initial, after 20 and 270 flexes
ASTM D3985
@ 23°C and 0% RH
WVTR:
ASTM F372
@ 38°C and 90% RH
Bond strength
Initial, 24 hours and 7 days
Instron Bond testing -10 in/min
separation
90 degree peel
OTR: MOCONR Oxtran model 2/20 and 23C and 0% RH
WVTR: MOCONR Permatran-W Model 38C and 90% RH
Bond strength testing details are as previously described.

16. Gelbo-Flex Testing Automated or Manual operation
Flat material mounted as a tube on each end
Flex is both rotational (270 degrees) and compressive
This short video clip shows the Gelbo flex tester in action, for those of you that haven’t seen this test method firsthand before.
ASTM F392 specifies conditions D & E are to be used when evaluating gas barrier properties of a lamination after Gelbo flexing. These conditions require 20 and 270 Gelbo flexes to be carried out on each lamination, respectively.

17. 2 Ply Clear PET/MET PE Adhesive Lamination
First we are going to look at the 2 ply metallized PE laminate structure, laminated with 3 different adhesive systems.

18. PET/ MET PE : Oxygen Barrier
Solvent-based and solvent-less adhesive based laminate structures provided better barrier than water-based adhesive
The change in OTR values for all 3 structures were minimal even after 20 and 270 flexes
The effect of Gelbo-flexing is less significant for solvent-based and water-based lamination 5% 0%
5.9%
6.3%
13.3%
6.7%
The graph on this page shows the OTR values at different stages for each adhesive system: the blue bar represents the pre-flex value of the laminate structure, the red represents the oxygen transmission rate after 20 flexes and the green after 270 flexes.
The barrier values of the solventless and solvent-based laminate structures are slightly better than the water-based lamination, both before & after Gelbo flexing. This is possibly a result of the higher bond strengths leading to better protection of the metallized barrier layer.
We are also presenting the % change in transmission rate after flexing. For example, for the solvent-base laminate, after the first 20 flexes, the change in OTR is 6.7%, whereas for solvent-less laminate it is 13.3%, and for water-based it is 5%.

19. PET/ MET PE : Water Vapor Barrier
Initial barrier properties indicate that solvent-based and solvent-less adhesive systems produce a better laminated structure
After the first 20 flexes, the change in WVTR is higher for solvent-less laminate
3.7%
22.7%
18.8%
5.6%
50.0%
23.1%
Similarly, this graph represents the Water Vapor Transmission Rate for each of the 2-ply laminated structures. The blue represents pre-flex barrier, the red after 20 and the green after 270 flexes.
From the graph, you can see that the water vapour barrier is best for the solvent-based and solvent-less laminations, and once again, the water-based lamination exhibits the poorest barrier properties.
Interestingly, for these 2-ply structures moisture transmission appears to be more sensitive to Gelbo flexing compared to the changes we observed with the oxygen transmission rates. The overall % change is greatest for the solventless adhesive laminate.

20. 3 Ply Clear PET/MET PET/PE Adhesive Lamination
Now let’s examine the barrier properties of the 3 ply stucture using a high barrier MET PET film as the barrier layer.

21. PET/ MET PET /PE : Oxygen Barrier
All laminated structures showed similar Pre-flex barrier properties
After 20 flexes, the barrier of water-based laminated structure deteriorated faster than solvent-based and solvent-less laminate structure
11%
766%
71%
366%
450% 9%
All laminated structures showed similar pre-flexed oxygen barrier properties.
However, after flexing, OTR increases dramatically.
In all cases, the % change in transmission rate is highest after the initial 20 flexes, with subsequent flexes having a smaller relative impact.
The water-based laminated structure showed the largest deterioration in oxygen barrier after flexing. Once again, this may be due to the fact this adhesive system exhibited the lowest laminated bond strengths.
The solvent-based adhesive lamination gave the best post-Gelbo barrier performance. This may be due to the fact that the solvent-based system has a significantly lower stiffness modulus than the other adhesives. Therefore, during flexing much of the input energy is absorbed by the adhesive itself, rather than the metallized barrier layer adjacent to it.

22. PET/ MET PET /PE : Water Vapor Barrier
Excellent WVTR values with solvent-based adhesive lamination. No significant change after 20 or 270 Gelbo-Flexes
Initial WVTR value for water-based was better than solvent-less. However, after flexing the performance of solvent-less and water-based laminate was similar
11.1%
31.6%
221%
26.7%
Now let’s look at water vapour barrier pre- and post-Gelbo flexing. This time, the pre-flexed barrier values are very different, with solventless actually the worst performing of all the adhesive systems. However, as with the oxygen barrier, the water vapour barrier performance deteriorated most with the water-based system, again likely due to the poorer bond strength not allowing the structure to hold up and protect the metallized barrier as well after Gelbo flexing. Therefore, after flexing the performance of solvent-less and water-based laminate was similar.
The solvent-based 3-ply lamination had an outstanding initial WVTR value, and showed little to no deterioration after Gelbo flexing. For flexible packaging containing moisture sensitive products, this appears to be the best structure to use. Once again, this may be due to the fact that the solvent-based system has a significantly lower stiffness modulus than the other adhesives, so that during flexing much of the input energy is absorbed by the adhesive itself, rather than the metallized barrier layer adjacent to it. 0%
50%

23. Solvent-based Laminations: Oxygen Barrier
After 20 flexes, the barrier of Met PE 2-ply laminated structure is close to High Barrier Met PET 3-ply structure, likely would be better than Standard Barrier Met PET 3-ply structure
Now, let’s compare the oxygen barrier performance of the 2-ply vs. 3-ply laminates directly in each of the adhesive systems. In this and the following slides, the 2-ply laminate performance is indicated by the blue bars, marked “met PE”, while the 3-ply laminate performance is indicated by the red bars, marked “HB met PET”. When looking at the solvent-based laminations, we can see that the pre-flexed oxygen barrier of the 3-ply structure containing the high barrier metallized PET is superior. However, when the flexed barrier numbers of the two structures are compared here it is apparent that the 2-ply structure with the metallized PE barrier layer holds up relatively well after flexing.
In fact, it is possible that a 3-ply structure with a standard metallized PET film, which would have an pre-flexed OTR value 3 or 4 times higher than the 3-ply structure containing the high barrier metallized PET, would actually not perform as well as the 2-ply structure after Gelbo flexing.

24. Solventless Laminations: Oxygen Barrier
After 20 flexes, the barrier of Met PE 2-ply laminated structure is nearly same as High Barrier Met PET 3-ply structure, is even better at 270 flexes
When comparing pre- and post-Gelbo flexed oxygen barrier properties in a solventless lamination, the performance of the 2-ply structure with a metallized sealant film is even more striking. Although in its pre-flexed form it has nearly an order of magnitude worse oxygen barrier than the high barrier metallized PET film, after Gelbo flexing the 2-ply lamination actually had a BETTER oxygen barrier than the 3-ply lamination.
Since the solventless adhesive used here has a significantly higher stiffness modulus than the solvent-based adhesive shown in the previous slide, during flexing the majority of the input energy is absorbed by the films adjacent to the adhesive, not the adhesive itself. This means that the metallized surface of a stiff barrier substrate, such as PET film, will be more likely to crack and become stressed during flexing than the metallized surface of a soft barrier substrate, like PE film.

25. Water-Based Laminations: Oxygen Barrier
After 20 flexes, the barrier of Met PE 2-ply laminated structure is better than High Barrier Met PET 3-ply structure
2-ply barrier after 20 flexes would be significantly better than Standard Barrier Met PET 3-ply structure
Similarly, when comparing pre- and post-Gelbo flexed oxygen barrier properties in a water-based lamination, the 2-ply structure with a metallized sealant film is also seen to be more robust than the 3-ply structure. Again, in its pre-flexed form it has an order of magnitude worse oxygen barrier than the high barrier metallized PET film, after Gelbo flexing the 2-ply lamination actually had a BETTER oxygen barrier than the 3-ply lamination.
The water-based adhesive used here has a high stiffness modulus, similar to the solventless adhesive shown in the previous slide. So, during flexing the majority of the input energy is absorbed by the films adjacent to the adhesive, not the adhesive itself. Therefore, the metallized surface of a stiff barrier substrate, such as PET film, will be more likely to crack and become stressed during flexing than the metallized surface of a soft barrier substrate, like PE film.

26. 3 Ply Clear PET/Coated MET PET/PE Adhesive Lamination
Now we turn our attention away from 2-ply structures and focus exclusively on 3-ply structures. In particular, we will compare the barrier results of the in vacuo coated metallized PET film with the high barrier MET PET film in equivalent 3 ply stuctures, laminating them under identical conditions to the same clear 48 g PET and 1.5 mil PE sealant webs.

27. PET/ Coated MET PET /PE : Oxygen Barrier
Coated Met PET retains OTR properties better than HB Met PET in equivalent 3-ply structure, both before and after Gelbo flexing
In the slides in this section of the presentation, the high barrier, uncoated metallized PET 3-ply laminate performance is indicated by the red bars, just as it was in the previous section, and is marked “HB met PET”. Now the blue bars represent the in vacuo coated metallized PET film 3-ply laminate performance.
As described previously, the oxygen barrier of the in vacuo coated metallized PET film is nearly an order of magnitude better than the oxygen barrier of the high barrier metallized PET film. This relationship is maintained, not surprisingly, in the pre-flexed barrier properties of nearly all the 3-ply adhesive laminations we prepared, as can be seen here.
I would like to draw everyone’s attention to the oxygen barrier performance of each 3-ply laminate after flexing, particularly with the adhesive systems with a high stiffness modulus, the solventless and water-based adhesives. Although the barrier properties of both 3-ply laminates are compromised after Gelbo flexing, the in vacuo coated metallized PET film maintains its oxygen barrier better than the uncoated high barrier metallized PET film. We hypothesize that this is likely due to the fact that the 0.4 gsm EB coating applied to the metallized surface is soft enough that it is able to absorb some of the flexing stress, compromising the metallized barrier layer less than what we observe with the uncoated high barrier metallized PET film.

28. PET/ Coated MET PET /PE : Water Vapor Barrier
For solvent-based laminations, both met PET films perform very well
For solventless and water-based laminations, Coated Met PET retains WVTR properties much better than HB Met PET in equivalent 3-ply structure
Now we can examine the water vapour barrier performance of each 3-ply structure. Once again, the water vapour barrier of the 3-ply laminates using in vacuo coated metallized PET film are nearly an order of magnitude better than the water vapour barrier of the high barrier metallized PET film in the pre-flexed barrier tests.
The water vapour barrier performance of both solvent-based 3-ply laminations is outstanding, both before and after Gelbo flexing. In fact, all measured values were near the sensitivity limit of the MOCON equipment being used, around g/100 in2/day.
For the higher stiffness modulus adhesive systems, the differences in the water vapour barrier performance of each 3-ply laminate after flexing are even more striking than what we observed in the oxygen barrier performance. Although the water vapour barrier properties of both 3-ply laminates are compromised after Gelbo flexing, the in vacuo coated metallized PET film maintained its barrier significantly better than the uncoated high barrier metallized PET film. Again, we hypothesize that this is likely due to the fact that the EB coating applied to the metallized surface is soft enough that it is able to absorb some of the flexing stress, compromising the metallized barrier layer less than what we observe with the uncoated high barrier metallized PET film.

29. Conclusions
Bond strengths were higher with solvent-based and solventless laminations for all three structures being studied, water-based bonds still acceptable for most applications
The effect of Gelbo-Flexing on barrier properties was more significant for MET PET compared to MET PE
For solventless and water-based adhesive systems, 2-ply lamination with Met PE holds oxygen barrier better than 3-ply lamination with High Barrier Met PET
3-ply structures with Coated Met PET retain their oxygen barrier better (~ 2x) than the same structure using High Barrier Met PET, and retain their water vapour barrier much better (~ 3x)
24 hour and 7-day bond strengths were good in all nine finished laminations we tested here. Solvent-based and solventless adhesive systems gave the highest bonds in all the structures.
The oxygen barrier of the 2-ply laminations with a metallized PE sealant held up better during Gelbo flexing than the 3-ply laminations with a high barrier metallized PET film. This was particularly true for the high stiffness modulus adhesive systems, where the PE layer appears to absorb much of the energy applied to the metallized barrier surface from the Gelbo flex test.
Both the oxygen & water-vapour barrier of the 3-ply laminations with an in vacuo EB top-coated metallized PET film held up better during Gelbo flexing than the 3-ply laminations with a high barrier metallized PET film.

30. Special Thanks
A special thank you to Larry Jopko and the entire team at the Dow Chemical Adhesive Research Centre in Buffalo Grove, IL for preparing the laminations using Dow adhesives and carrying out the Gelbo Flex testing, bond strength testing and barrier measurements.