Polymers / Laminations / Adhesives / Coatings / Extrusions

Innovations Highlight Division Conference

The registrants at the annual technical conference of the Polymers, Laminations and Coatings Division on August 27-29, 2001, at the Sheraton San Diego Hotel and Marina responded enthusiastically to the many innovative features at the event. An extremely popular session at the meeting was “Flexible Packaging Case Studies: An Interactive Workshop” organized by Dante F. Ferrari, AT Plastics, Inc., and Virginia P. Cushing, Mica Corp. The daylong session had twelve presentations covering various aspects of converting for flexible packaging such as baggy webs, winding problems, adhesion difficulties, contamination control, etc. After a short technical presentation on the subject, the audience separated into small groups to solve a practical problem from the presenter.

Another innovation at the meeting was a session on “Styrenic Materials” that included papers on “Styrene Butadiene Copolymer Processing” by Mark Brown, Chevron Phillips Chemical Co., “Employing Styrene-Butadiene Copolymers In Modified Atmosphere Packaging” by Roland M. Planeta, Barrier Films Corp., “Fundamentals Of Styrene-Butadiene Copolymers In Flexible Packaging by James A. Keane, Chevron Phillips Chemical Co., and “Special Considerations For Printing On Styrene Based Substances” by Joseph Kelly, INX International Ink Co.

“The session on ‘UV/EB Materials For Flexible Packaging’ organized by Elmer Griese, Cork Industries, Inc., also received rave reviews from attendees,” said Harry Cordatos, Westvaco Corp., Technical Program Chairperson. “The success of the many papers devoted to flexible packaging ensures that future division conferences will have a larger number of offerings devoted to this important component of the converting industry.”

Networking Opportunities

The conference featured many opportunities for the registrants from Australia, Belgium, Brazil, Canada, Chile, Finland, France, Germany, Mexico, the Netherlands, New Zealand, South Africa, South Korea, Sweden, Switzerland, Turkey, and the United States to network and compare the flexible packaging and converting industries in a global context. Cordatos noted that “session breaks, the Table Top Reception following the New Technology Showcase, and the Conference Gala Event were especially popular venues to greet old friends and meet new ones.” Meetings of the Extrusion Coating Committee, Film Extrusion Committee, Flexible Packaging Committee, High Barrier Committee, International Planning Committee, and Marketing Committee of the Polymers, Laminations and Coatings Division also offered opportunities for conference registrants to interact with people in their areas of interest while planning future committee activities.

The keynote speaker was Edward L. Cussler, Department of Chemical Engineering and Materials Science, University of Minnesota. Professor Cussler was also the winner of the Best Paper Award for the Polymers, Laminations and Coatings Division in 2000. He spoke on “Fick's Second Law Or Diffusion For Dummies.” His talk described the applications of Fick's second law to many physical phenomena including those involving diffusion. His humorous and historical presentation of the topic captivated his audience.

New Technology Showcase

As in previous years since its inception, the New Technology Showcase continued to be a strong success at this conference. Twelve presentations lasting no longer than five minutes offered information on new commercial developments by leading suppliers to the converting and flexible packaging industries.

Another popular session was “Film Extrusion: Innovations And Troubleshooting” organized by William N. Hellmuth, Battenfeld Gloucester Engineering Co. The papers in this session were “Seal Through Vegetable Oil Contamination” by Daniel J. Falla, Dow Chemical Canada, Inc., “A Consultant's Viewpoint Of High Precision Coating For The Converting Industry” by Chris Watson, Watson Consulting, “Stretch Film Properties-Effects Of Equipment And Process Variables” by Michael V. Wainer, Gloucester Engineering Co., “A New High-Performance MVLDPE” by Richard W. Halle and Alan M. Malakoff, ExxonMobil Chemical Co., “Process Control Case Studies — Temperature Related Problems In Extrusion” by Derek Hook, Eurotherm Controls, Inc., and “Old Blown Film Dies Never Die — Or Should They?” by Rick Knittel, RK Associates.

Barrier Materials

Three sessions addressed current concerns in high barrier packaging materials. Dean A. Zimmerman, Procter & Gamble, spoke on “Flexible Packaging — An Overview.” He reviewed current barrier materials such as nylon, acid copolymers, EVOH, polyethylene, polyvinylidene chloride, EVA, and newer offerings such as nylon MXD6, cyclic olefin copolymers, and liquid crystalline polymers. His paper also included a discussion on barrier testing and the impact of leaks. In a paper entitled “Permeation Measurement: A Primer,” Craig Loebig, MOCON, Inc., discussed the basic theory and practice of permeation measurement. He included factors influencing permeation rate measurement, international standards, typical test conditions, film testing vs. package testing, fickian vs. nonfickian materials, and solubility and diffusion coefficients and their relationship to permeation rate.

Approximately half of the more than 100 technical papers presented at the conference had extrusion coating or film extrusion topics as their subject. These included “Reducing Curl In Multilayer Blown Film,” a two-part paper by Barry A. Morris, duPont Packaging & Industrial Polymers, “Improved High Molecular Weight HDPE Films Via Coextrusion” by Leonard Cribbs, Equistar Chemicals, LP, “Quiet Unwinding Blown Stretch Film” by Guy G. Luneau, Eastman Chemical Co., and “Waterbased Primers For Extruded Polypropylene” by Richard B. Allen, Mica Corp.

The complete texts with graphics for all the technical presentations at the Polymers, Laminations and Coatings Conference are available on CD-ROM from TAPPI PRESS. Order on-line at www.tappi.org or call the TAPPI Member Connection Center at 1-800-332-8686 in the United States, 1-800-446-9431 in Canada, or +1-770-446-1400 from other locations.

Panel Discussions

Conference attendees always enjoy panel discussions because of the informal atmosphere they offer for panelists and audience to address many pertinent topics. The conference this year was no different as the registrants flocked to three panel discussions: “Ask The Converter Panel,” “The Web Is The Place To Be Panel,” and “What Do They Know — A Converter's Panel.” The “Ask The Converter Panel” ranged over the following list of subjects:

  • Profitability in the current business cycle
  • Industry trends
  • Future visions
  • Attendance at meetings
  • Training of plant personnel
  • Facility location
  • Importance of quality programs
  • Expediting new development time to market
  • Downgauging using new films
  • Behavioral safety programs
  • Status of recycling.

When speaking about industry trends, Jake Cahill of J. D. Cahill noted that he is “excited about what will happen in industry in the next 5-10 years.” In the area of quality programs, most panel members stated that it helped them to improve their quality but gave no new business.

David A. Markgraf, Enercon Industries Corp., organized “The Web Is The Place To Be Panel” to explore the roll of the Inernet for converters today. Yolanda J. Simonsis, Paper, Film & Foil CONVERTER magazine, talked on the use of web sites for trade magazines to obtain information. Ryan T. Schuelke, Enercon Industries Corp., told the audience how to make their web site work for them. Michael Denny, TAPPI, spoke on redesign of a web site. Before the question and answer session, Tim Fazio, paperloop, Inc., led the audience through a series of uses for a web site.

Panelists for “What Do They Know — A Converter's Panel” were Steve Tusing, C-P Converters, Thomas J. Dunn, Printpack, Inc., Bruce R. Jondle, Glenroy, Inc., John S. Ozcomert, Rexham Medical Packaging, Jeff Nanstad, Anagram International, Lisa Pierce, Food and Drug Packaging Magazine, and Clifford J. Maxwell, Mica Corporation, as moderator. Questions from the audience led the group to make comments on subjects such as the future of stand-up pouches, environmental aspects of a package, possible elimination of aluminum foil in packages, future of paper in flexible packaging, influence of imported packaging materials, and the use of solvent vs. aqueous inks.

Next Conference

The next conference for the division will be at the Marriott Copley Place in Boston, Massachusetts, on September 7-11, 2002. Cordatos will again be the Technical Program Chairperson. Anyone interested in presenting a paper at the conference should contact him by email at hxcorda@westvaco.com or by telephone at 301-497-1309 for additional information. More information is also available by calling the TAPPI Member Connection Center at 1-800-332-8686 in the United States, 1-800-446-9431 in Canada, or +1-770-446-1400 from other locations. Detailed information on the meeting that will be known as the PLACE Conference will also be available from the TAPPI web site at www.tappi.org as it becomes available. Cordatos says, “This meeting will offer in-depth analysis of established materials, technical coverage of new materials and processes, panel discussions providing end user perspectives, and hot topic information on the latest and greatest offerings in converting.”

Division Changes Name To The PLACE

To reflect the primary interests of the core membership and provide continuity with its publication, “the PLACE,” the Polymers, Laminations and Coatings Division of TAPPI has adopted the PLACE Division as its new name. Unveiled at the division conference in San Diego in August 2001, the acronym stands for Polymers, Laminations, Adhesives, Coatings, Extrusions.

Originally created at about the end of World War II as the Paper Plastics Committee, the group has a long and distinguished history within the TAPPI organization. It has held yearly conferences continuously since 1946. Only one other TAPPI division has held continuous conferences longer. The committee became the Paper Synthetics Division around 1950. The first division name reflected the strong emphasis by TAPPI on the pulp and paper industry. Although the Paper Synthetics Division concentrated primarily on plastic substrates, the group fell under the TAPPI umbrella because it featured paper in its name, covered an industry that extruded plastics onto paper substrates, used many of the web handling processes familiar to the paper field, and included nonwoven materials — a direct substitute for paper in certain applications. Today polymer extrusion onto paper is still common and web handling still parallels that of paper. Conversely, a separate Nonwovens Division of TAPPI now covers that area of interest and paper is not a component of the division name.

In 1983, the Paper Synthetics Division became the Polymers, Laminations and Coatings Division of TAPPI. The new name was the idea of Walter E. Groedel, who is now retired. The group adopted his suggestion because the combination of those three nouns encompassed totally the interests of division members and the companies who employed them. Groedel won the Polymers, Laminations and Coatings Division Leadership and Service Award with accompanying Andreas Ahlbrandt Award on its inception in 1987 for his lengthy service in many capacities. Operating under its new name, the division expanded and grew considerably in the remaining years of the 20th century. Conference attendance soared to records of approximately 800 people, short course offerings and symposia proliferated, and new committees expanded the rolls of division members. Historically, the group was a pioneer within the TAPPI organization in short course development and an innovator in serving the needs of global members by holding meetings in countries outside the United States.

Scott B. Marks of E. I. du Pont de Nemours and Co. conceived the PLACE acronym that the division now uses in its name and this publication. Marks subsequently won the Division Leadership and Service Award and accompanying Andreas Ahlbrandt Award in 2000 for his many contributions to the group. The division logo is a circle containing the full words in the acronym devised by Marks with a depiction of three substrates stylistically undergoing a combination.

Improved Aroma Barrier Properties In Food Packaging With Cyclodextrins

by Will E. Wood
Cellresin Technologies, LLC
email:
wwood@cellresin.com

Application: A barrier composition comprising a polymer and dispersed cyclodextrin free of an inclusion complex can obtain substantial barrier properties from the interaction between the cyclodextrin with a permeant.

The market for high performance, value-added packaging is thriving as food manufacturers seek packaging that offers a better barrier to undesirable odor ingress while requiring this characteristic from progressively thinner and transparent films. Increasingly, paperboard for food cartons is using recycled and secondary fiber. This requires paperboard barriers that can reduce the transfer of mobile or volatile organoleptic contaminants present as paperboard components.

The strategy in this paper is to enhance conventional packaging materials using cyclodextrins in the structure as the active barrier. Using laboratory permeation examples and accelerated shelf life storage of packaged breakfast cereal, experiments will show that a membrane containing cyclodextrin can retard organic vapor transport by increasing lag time, reducing permeation, and abating volatile sorption by the packaged food product.

Chemistry

A cyclodextrin (CD) is a cyclic oligomer of α-D-glucose formed by the action of certain enzymes such as cyclodextrin glycotransferase (CGTase). Three cyclodextrins (alpha, beta, and gamma) are commercially available consisting of six, seven and eight α-1,4-linked glucose monomers, respectively. The most stable three-dimensional molecular configuration for these oligosaccharides is a toroid with the smaller and larger opening of the toroid presenting primary and secondary hydroxyl groups. The specific coupling of the glucose monomers gives the cyclodextrin a rigid, truncated conical molecular structure with a hollow interior of a specific volume.

The hydroxyl groups on a CD can be chemically substituted to change solubility, compatibility, and thermostability. Substitution can also change the binding strength between a CDn and the guest compound. CD molecules have available for reaction with a chemical reagent the primary hydroxyl at the six-carbon position of the glucose moiety and the secondary hydroxyl in the two and three carbon positions.

Use Of Cyclodextrins

The technology of putting CD in or on “films” was relatively unknown before 1976. The use of CDs as a carrier for controlled release or a permselective separation membrane has quickly grown. In 1999, more than 80 patents issued globally for putting CD in or on films. Today, twelve U.S. patents cover the use of CDs as a barrier in polymer membranes.

In the United States, CD manufacturers have submitted petitions for the use of b-CD in foods and g-CD in foods. Historically, the Food and Drug Administration has recognized that most processing aids used in the production of food contact materials do not require regulation as food additives due to the extremely low levels of migration and the absence of any safety concerns under the intended conditions of use. CD and its derivatives may be exempt from regulations as a food additive pursuant to the Federal Food, Drug, and Cosmetic Act.

Results

When a gas or vapor — permeant — does not interact with the polymer in a membrane, the permeability coefficient, P, is usually characteristic for the permeant-polymer system. This is the case with the permeation of many gases such as hydrogen, nitrogen, and oxygen through many polymers. If a permeant interacts with polymer molecules as is the case with the organic permeant test compounds used in this study, P is no longer constant and may depend on the pressure, film thickness, and other conditions. In such cases, a single P value does not represent the characteristic permeability of the membrane.

In these cases, the transmission rate, Q, is often used for practical purposes when the vapor pressure of the permeant at a specified temperature is applied across a film. Permeability of membranes to water and organic compounds is often expressed this way. In this paper, transmission rate characterizes thickness-normalized flow.

A major variable in determining the permeation coefficient is the pressure drop across a film. Since the transmission rate, Q, includes neither permeant pressure nor concentration in its dimensions, knowing either vapor pressure or the concentration of permeant under the measurement conditions is necessary to correlate Q to P.

When a penetrant diffuses through a barrier membrane in which it is soluble, a transient state exists before the steady state occurs. Fick's Second Law describes the situation that exists during this period. A useful solution in the present context where the membrane is initially free from permeant vapor and the penetrant pressure at the upstream face of the film is generally held constant giving a concentration in the surface layer. Diffusion is assumed to be concentration independent.

The first objective is to show that a compatible CD dispersed into HDPE and then formed into a thin flexible film retards organic vapor transport by increasing lag time and reduces the permeation rate. Films were tested using nine organic co-permeants.

A second experiment used a paperboard carton as the test membrane. Here the backside starch sizing applied to the board contained a water soluble CD. Organic permeants associated with paperboard off-flavor and taste were the permeants. In this specific experiment, the permeant mixture was injected upstream of the paperboard every 30 min. for 300 min. to simulate low, continuous permeant flow. Individual permeants on the downstream side were combined to give total transmission.

A shelf life study on freshly produced cereal and paperboard cartons verified the barrier properties. Package configuration is HDPE bag containing the cereal in a printed paperboard carton. The purpose was to measure organoleptic improvements in cereal packaged with cross machine direction (CD) barrier cartons versus non-CD cartons under accelerated shelf life conditions. Ingress permeation from out-gassing paperboard through the polyethylene liner bag containing the cereal should reasonably show up as an increase in cereal volatile mass. Seventy-six volatile organic compounds were measured in the cereal. Approximately fifty of these measured compounds are in the paperboard alone. Accelerated cereal storage methods replicated field storage conditions. Cereal was removed from the sealed polyethylene bag in the carton, cereal volatile mass analyzed by dynamic headspace gas chromatography mass spectrometry, and individual compound concentrations summed and reported as total volatiles. At two weeks, individual cereal cartons stored in their shipping boxes were removed from the shipping box, and the individual cartons continued in accelerated storage. Figure 1 shows a comparison of total volatiles in the cereal over five weeks.

Conclusion

The main objective of this paper was to compare barrier property measurements in thermoplastic and paperboard food packaging manufactured with and without CD. CD provides a two-fold benefit to food packaging materials. CDs improve barrier properties — diffusion rate and transmission rate — in HDPE film. Diffusion rates improved as much as 2.7 times. Transmission rates decreased 3.7 times. Diffusion and transmission rate improvements are permeant specific. In addition, barrier improvements in paperboard occurred in accelerated cereal shelf life studies as measurements of a reduction in ingress volatile sorption by the stored cereal indicated.

For information about the PLACE Division of TAPPI, see the web page at http://www.tappi.org/index.asp?rc=1&pid=15935&ch=6&ip=-1&fid=13 or access the TAPPI web site at www.tappi.org. For the complete papers whose expanded summaries appear in this section, go to the TAPPI web site at http://www.tappi.org/index.asp?rc=-1&ip=7&ch=1&subch=33.

Telephone inquiries are welcome at the TAPPI Service Line by calling 1-800-332-8686 in the United States, 1-800-446-9431 in Canada, or +1-770-446-1400 in other countries. Send FAX to 1-770-446-6947. Address mail to TAPPI, Box 105113, Atlanta, GA, 30348-5113. Contact “the PLACE” editor using e-mail at dbentley@unm.edu.

PEER-REVIEWED TECHNICAL PAPERS: Following are expanded summaries of complete papers that are available on the TAPPI web site at http://www.tappi.org/index.asp?rc=-1&ip=7&ch=1&subch=33


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