the development of the nano-layer blown film die pf4-2016

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The Development of the Nano-Layer Blown Film Die PF4-2016 By Tom Bezigian INTRODUCTION Polymer processing continues to evolve day by day, both in the largest corporations in the world, and in the smallest and most unlikely of places in the world. Many innovations happen in the laboratories of the world’s largest corporations. However, sometimes revolutionary breakthroughs come froman inventor’s backyard workshop. One such inventor, the principal at BBS Corporation in Spartanburg, South Carolina, USA, designs and builds his ownextruders, dies, air rings, motors, drive systems, andto what might be considered the most advanced blown film coextrusion dies in the world, all in his backyard workshop. This article will review the latest nano-layer blown film die technology from concept to production, including laboratory equipment, patents, test results, scale-up, and finally commercialization of an 82-layer blown film die capable of making nano-layer film with revolutionary results. BACKGROUND Most technological developments are extensions of existing technology, taken step-by-step in a process of continual innovation. Through the years, researcher Henry G. Schirmer has made many of these continual innovations to a number of film products, accumulating more than 100 patents to his credit. Most of these patents were written he was a senior research fellow at Cryovac Division of W.R. Grace & Co., now Sealed Air Corporation, where a full-scale pilot plant was at his disposal. Mr. Schirmer’s global experience while with Cryovac included both coextruded round and flat oriented films, shrink films, barrier films, and more. He is humble about his past achievements, one of the greatest of which is perhaps the development and scale-up of Cryovac’s first barrier bag process in the 1960’s. For those familiar with the industry, this piece of business has been, and still remains today, the “queen” of the packaging business, in use around the world for packaging of fresh and processed foods. Through the years, he has conceived, built, and developed various dies, processes and products. Equipped with only time, a large garage, imagination, and vast knowledge of polymers, coextrusion and processing, Mr. Schirmer began work in the Winter of 1996. He said, “It was a long, cold Winter the year I retired after a 33 years withCryovac at the age of 63. With nothing to do, and plenty of time on my hands, I sat in the office and pondered nano-layer film technology. It was then that when I started this work, not knowing where it would all end. I

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The Development of the Nano-Layer Blown Film Die

PF4-2016

By Tom Bezigian

INTRODUCTION

Polymer processing continues to evolve day by day, both in the largest corporations in the

world, and in the smallest and most unlikely of places in the world. Many innovations happen

in the laboratories of the world’s largest corporations. However, sometimes revolutionary

breakthroughs come froman inventor’s backyard workshop. One such inventor, the principal at

BBS Corporation in Spartanburg, South Carolina, USA, designs and builds his ownextruders,

dies, air rings, motors, drive systems, andto what might be considered the most advanced

blown film coextrusion dies in the world, all in his backyard workshop.

This article will review the latest nano-layer blown film die technology from concept to

production, including laboratory equipment, patents, test results, scale-up, and finally

commercialization of an 82-layer blown film die capable of making nano-layer film with

revolutionary results.

BACKGROUND

Most technological developments are extensions of existing technology, taken step-by-step in a

process of continual innovation. Through the years, researcher Henry G. Schirmer has made

many of these continual innovations to a number of film products, accumulating more than 100

patents to his credit. Most of these patents were written he was a senior research fellow at

Cryovac Division of W.R. Grace & Co., now Sealed Air Corporation, where a full-scale pilot plant

was at his disposal.

Mr. Schirmer’s global experience while with Cryovac included both coextruded round and flat

oriented films, shrink films, barrier films, and more. He is humble about his past achievements,

one of the greatest of which is perhaps the development and scale-up of Cryovac’s first barrier

bag process in the 1960’s. For those familiar with the industry, this piece of business has been,

and still remains today, the “queen” of the packaging business, in use around the world for

packaging of fresh and processed foods. Through the years, he has conceived, built, and

developed various dies, processes and products.

Equipped with only time, a large garage, imagination, and vast knowledge of polymers,

coextrusion and processing, Mr. Schirmer began work in the Winter of 1996. He said, “It was a

long, cold Winter the year I retired after a 33 years withCryovac at the age of 63. With nothing

to do, and plenty of time on my hands, I sat in the office and pondered nano-layer film

technology. It was then that when I started this work, not knowing where it would all end. I

envisioned polymer molecules and fillers aligning in the direction of flow, thereby improving

strength and barrier properties. The hope was that property improvements were significant

enough to become game-changers. In the end, this is what was born out of the

research”.Figure 1 A, B, C and D show Mr. Schirmer in his laboratory, with his homemade

extruders, dies, air rings and haul-off units.

Figure 1AThreehomemade extruders feeding into a Figure 1B Hank next to one of his homemade blown film

single 3-port feedpipe, which feeds the die lines

Figure 1C Hank demonstrating an 82-layer die and LSR Figure 1DAudrey & Hank Schirmer

Figure 1.Various equipment in the BBS Corporation laboratory, with its two principals, Hank &

Audrey Schirmer.Photo by Tom Bezigian

DISCUSSION

With extensive background in traditional plate-type and crosshead-type blown film dies, Mr.

Schirmer (also known as “Hank”) embarked on a two-decade development plan which has

concluded with patenting and commercialization of what Hank calls the “LSR” die, or Layer

Sequencing Repeater. The number of layers in the final film structure is determined by the

number and type of LSR’s used, with each LSR providing 25 nano-layers. The Schirmer die

basically consists of a base, which receives the various melt feeds, modular LSR disc assemblies,

an inner mandrel, and a die exit. A close-up photo of an 82-layer die and a 25-layer LSR module

is shown in Figure 2.

Figure 2. A Schirmer LSR die and an individual LSR module, lower right. Each plate is much thinner than a

traditional plate die, making the overall dimensions suitable for commercial use.Photo by Tom

Bezigian

Mr. Schirmer openlyshared the technology in depth, as it is protected by patent in the USA

under US Patent # 8,870,561 B2, as well as inCanada, Europe and China. While simple in

concept, the patent is quite detailed and complicated, and the reader is referred to the patent

for a full description of the die. The abstract of the patent reads:

“A layer sequence repeater module for a co-extrusion die includes a cell formed of a

plurality of thin annular disks stacked on top of each other in an axial direction of the

co-extrusion die. Each disk includes a plurality of openings aligned with openings in

the adjacent disks, thus forming multiple inner and outer melt passages. At least one of

the layer sequence repeater module includes at least one first cap disk, at least one

second cap disk, at least one distribution disk, at least one repeater disk and at least

one spreader disk. The layer sequence repeater module may be a separately assembled

and individually removable module of the co-extrusion die. Alternatively, or

additionally, the layer sequence repeater module may be incorporated into a module of

the co-extrusion die.”

The simplest description of the die is that it is similar to a typical blown-film coextrusion plate-

die, but rather than build layers sequentially, they are built in parallel

The key text in the US patent comes at Column 14, Line 38 in which the test reads,

“The layer sequence repeater module can be used to produce multilayer films having

large numbers of thin layers and superior orientation properties. The superior

orientation is believed to result because the thin layers are gently aligned in the melt

phase, with very little stress in the alignment. Each and every nanolayer surface is

formed separately between two metal die surfaces separated by a minimal gap before

the slow moving melt joins the common melt path within the annulus of the die.

Overall, there is more melt surface to polymer contact throughout a melt cross section

leaving a modular disk die with a layer sequence repeater module, than in a

conventional die. Also each nanolayer generated has a high ratio of surface area to

thickness. This condition requires a gentle, low stress melt alignment to avoid breakage

in the individual nanolayers”.

The secret of course is in the distribution of layers in the layer sequence repeater module,

which is shown in Figure 3 below. Essentially, the flow is divided symmetrically around the die,

and then combined and recombined in the die until the desired number of layers is achieved.

According to Mr. Schirmer, “Flow through the die can be upwards (traditional, in the direction

of polymer flow) or downwards (against the polymer flow), so as to recombine layers as

desired. As far as material selection, this die can process any traditionally coextruded resin

combination, including PVdC, polyamides, EVOH as well as any tie layers needed”.

Figure 3. A disassembled Layer Sequencing Repeater Module. Photo by Tom Bezigian

Schematically, Figure 3 can be represented as show in Figure 4. The first disk is the point at

which melt is introduced into the LSR. The second disk distributes the melt evenly around the

mandrel into 8 new feeds, which is received by the 3rd

disk. The 4th

disk is called the layer disk

which distributes the melt into its final position, as shown below.

Figure 4. Orientation of layers inside an LSR module, courtesy Alpha Marathon Film Extrusion

Technologies

The finished product of this coextrusion die technology can be seen in the sequence shown in

Figure 5. Each successive figure shows increasing magnification starting with a 5 micron scale

zooming into a 200 nanometer scale. In the last figure of the series, nano-clay particles with a

dimension of approximately 10-20 nanometers wide by 100-200 nanometers long can easily be

discerned as laying side by side, as predicted Mr. Schirmer early in the development process.

Figure 5ACoexnano-film at 5μ scale Figure 5BNano-clay filled PA / EVOH coexnano-film at a 1μ scale

Figure 5CCoexnano-film at 500nm Figure 5DCoexnano-film at 200nm scale

Figure 5Nano-clay filled PA / EVOH coexnano-film at various magnifications. The higher

magnifications clearly show the alignment of the filler in the nano-layers, as predicted by

Schirmer. Courtesy Alpha Marathon Film Extrusion Systems

Film Properties

It is well known that a phenomenon occurs in nano-technology in which non-typical behavior is

observed at the interface of nano-particles and nano-layers than otherwise expected or

observed in traditional materials. It is as if the adjacent molecules are sharing electrons in an

ionic manner, thus imparting new and unique properties heretofore unseen. The addition of

nano-clay particles align in such a way in the die so as to provide a more tortuous path for a

permeant, and thus improves observed transmission rates.

Referring back to the key text in the patent, Mr. Schirmer says, “The LSR produces multilayer

films having superior orientation properties. The superior orientation is believed to be a result

of the thin layers being gently aligned in the melt phase, with very little stress in the alignment.

This allows the resulting film to be blown up to a 5:1 blow up ratio (BUR), which in turn

provides superior physical and barrier properties. The addition of nano-clay particles further

improves barrier properties without sacrificing physical properties as is normally seen in clay

filled films”.

Figure 6. Nano-layer repeat structure shown with cap layers.Image courtesy of Alpha

Marathon.

Test results show improvement in both physical properties, such as tensile and elongation, and

also in barrier properties, specifically oxygen transmission rate. Table 1 shows the OTR of

various films. The EVOH used in the film samples was Soarnol ET, 38mol% ethylene, and the

nylon was MXD6 with nano-clay particles. The properties suggest that this 82-layer nylon/tie

structure is well suited for a pouch application, perhaps for a frozen fish end-use, because half

as much nylon is needed compared to traditional blow film manufacturing techniques. This

would result is a large cost savings, as the nylon is the biggest cost contributor in that structure.

PE PE

25 alternating nano-layers of EVOH / amorphous Ny or Nylon/tie

T T

Composition OTR, 20°C 90% RH

(cc/m2·day·atm)

82-layer nanoNy/tie film, with total nylon

thickness of 14μ

31

29-layer nano film, with total EVOH thickness

of 3.05μ

24

BONY (25 μ), as reference 30

Cast PA (25 μ), as reference 40

Table 1.OTR of various films

Various combinations of 29-layer films are shown below. The control is all LLDPE, the first

variable is LLDPE/HDPE in the LSR, and the second variable is LLDPE/nano-clay filled HDPE in the

LSR. The possibilities for improvement are endless, as is shown in Table 2.

Secant Modulus Elongation, %

Haze, %

45°

Gloss

WVTR,

g/m2/day Composition MD TD MD TD

All LLDPE 140 103 750 900 7.7 52 20

LLDPE/HDPE in LSR 186 224 750 775 5.7 80 12

LLDPE/Clay-fill HDPE in LSR 265 328 725 900 7.9 82 11

Table 2. Various properties of different 29-layer nano film structures

Commercialization

With the technology reduced to practice, the next step became commercialization. Once

learning of this technology, Alpha Marathon Film Extrusion Technologies Inc. in Toronto,

Canada approached BBS Corp to license and sell the technology. Michael Taylor, Director of

Sales at Alpha Marathon said, “The BBS Layer Sequence Repeater technology is fascinating, and

we immediately saw the potential benefit with it. Alpha Marathon are a leading edge extrusion

technology company, and we are pleased to be the sole distributors of this technology”.

When asked about the benefits of this technology to the end user, Mr. Taylor said, without

hesitation, “Improved physical and barrier properties, and reduced cost. Test results have

confirmed that the LSR technology provides a higher barrier than is achievable via traditional

methods, which translates to approximately a 50% reduction in the high-cost barrier layer, thus

reducing cost to converters and providing a distinct competitive advantage. We have already

sold one complete 82-layer line for a packaging application in Asia, and we expect more lines to

be sold soon at the K-Show in Dusseldorf”.

The line that Mr. Taylor was referring was commissioned in July, and Packaging Films had an

exclusive view of the line running. Figure 6 is of the fully assembled line running in Toronto.

The line is fully automated, with HMI control, computer feedback air-ring control of gauge, and

every modern feature to be expected from North America. Mr. Taylor concluded by saying,

“Early results show that vast improvements in recycled film properties can be realized with

nano-layer coextrusion die technology. This is another large market we are exploring because

of the use if films for shopping bags. Improved strength could mean resource efficiency, which

is a direction the world is headed.

Figure 7. The LSR die being commissioned at Alpha Marathon Film Extrusion Technologies in

Toronto, Ontario. Photo by Tom Bezigian

Conclusions

A new era of coextrusion technology is upon us. From an individual inventor in a remote region

of the United States to an international film extrusion manufacturer in Canada to an Asian

packaging film manufacturer, the technology was imagined, developed, reduced to practice,

and commercialized. The benefits of this development are only just now being understood, and

is sure to grow based on improvements in strength, barrier properties, and resource efficiency.

Cooperation and information transfer around the globe is making this evolution in packaging

film technology possible.

Acknowledgements

All information in this article were procured either by personal interview or e-mail from the

inventor, Henry G. Schirmer in South Carolina, and Michael Taylor of Alpha Marathon Film

Extrusion Technologies in Toronto, Canada.