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Plastics in packaging.

A steady flow of new plastic packaging products strongly reflects the industry's response to environmental pressures. But keeping them totally out of the waste stream will require the availability of more comprehensive recycling infrastructures and greater industry/government/consumer commitment.

NYLON PRODUCTS

Flexible packaging opportunities are creating niche markets for nylons, says Earl Hatley, packaging resins industry manager, Engineering Plastics Group, Allied-Signal. The company introduced modified Capron nucleated nylon resins for easier processability, faster line rates in extrusion, enhanced package tightness, and dimensional stability. New Capron ABN amorphous nylon resin blends offer clarity and improved oxygen barriers in the presence of moisture. Allied-Signal also is looking at hybrid copolymers, alloys, and blends of nylon, as well as nontraditional high performance barrier polymers.

CLOSED-LOOP RECYCLING

Arco Chemical Co. recently introduced the first 25% recycled-content moldable expandable polystyrene (EPS) resin (Dylite R2595B), and a new line of high heat styrene copolymers (Dylark FG) designed for microwaveable food packaging. The Dylite material is intended for closed-loop recycling of EPS for the same applications as virgin resin. Dylark FG copolymers are available in impact, clear, and foam grades and are approved by the U.S. Food and Drug Administration (FDA) for conditions H through B. High heat rigidity and low temperature toughness permit freezer-to-microwave use. Compatibility of the impact grade with high impact polystyrene facilitates cost-effective tailoring for specific temperature performance.

IN-PLACE INFRASTRUCTURE

Last July, the major EPS producers and their resin suppliers formed the Association of Foam Packaging Recyclers (AFPR); through their 115 existing plant locations, they have established a nationwide infrastructure to collect EPS from industry, retailers, and consumers. AFPR members now are recycling EPS at a 20-million-lb annual rate. In vibration and drop tests, the recycled-content resin performs as well as the virgin plastic.

HEIGHTENED AWARENESS

"There are many recycling programs throughout the country--in communities, grocery stores, and businesses--and awareness for source reduction is growing," says Len Azzaro, director of marketing, Plastics for Packaging Industry Group, Dow Plastics, a business group of The Dow Chemical Co. "Stretch film, for example, occupies less landfill space than comparable packaging materials, and down-gaging technology is becoming more significant." The challenge is to retain or surpass the original resin properties with recycled-content resin. Across its polyethylene and polystyrene resin families, Dow has been formulating consistent, high quality, recycled-content resins for specific uses.

Over the next five years, Azzaro expects the most growth within packaging in the liner market, which represents the largest single use of polyethylene resin, and a shift to higher alphaolefin LLDPE and high molecular weight HDPE for cost and source reduction. He predicts the stretch film market, growing at 7% to 8% a year, will expand into bundling as a replacement for corrugated paperboard. Far from mature, this market also awaits development for food and consumer goods. Another growth market is reusable shipping cases. A recent lifecycle analysis by Franklin Associates, examining the environmental impact of reusable plastic cases and corrugated paperboard boxes, found the reusables to be less of an environmental threat.

POLYESTER ADDITIONS

Du Pont Packaging recently introduced a family of recyclable Selar PT extrusion blowmoldable polyester resins for liquor, cosmetic, and food applications. The company also announced a monolayer, high impact strength, heat stable, clear polyester container (made by a proprietary process and resin) for hot fill retort and microwave use. Also cited is the start-up of a 40 million lbs/yr Selar OH EVOH barrier resin plant in La Porte, Tex.

MONOLAYER COMPROMISE

"Compared with multilayer coextrusions, monolayer materials are a compromise of barrier properties and shelf life in favor of improved recyclability and cost," says James Caldwell, segment manager, Specialty Packaging Plastics, Eastman Chemical Co. As an alternative to multilayer barrier structures, converters are evaluating monolayer crystallized polyester terephthalate (CPET) for microwave-only packaging, utilizing its melt strength for wide-web forming, predictable shrinkage, fast forming cycles, heat resistance, and good oxygen barrier properties. When properly processed, monolayer CPET has provided one-year shelf life for retorted (250|degrees~F) rigid packaging; it is also a contender for rigid plastic food cans. Still unresolved is the optimum balance between adequate shelf life and recyclability. With over 225 million lbs recycled in 1990, polyester is the largest post-consumer plastic, according to the National Association for Plastic Container Recovery (NAPCOR).

Eastman's Kodar THERMX copolyester, a tough, clear film with extremely low extractables up to 500|degrees~F, has been used for thermoformed dual-ovenable trays. Studies by the FDA show the extractables of unoriented Thermx, in a fatty acid simulant, to be about one-tenth those of oriented heat-set PET. Thermx copolyester does not require orientation to achieve its heat resistance, reducing the complexity and capital intensity of manufacturing a high heat film. Its ability to heat seal to itself, without need for a special coating, makes ovenable bags and pouches a possibility. Adhesion of polyester lidstocks to crystallized polyester trays or frozen foods and dual-ovenable packaging is not easily achieved. Eastman's KODABOND heat sealable copolyester adheres to a variety of substrates, including amorphous PET, CPET, paper, foil, and glass, providing tough, retortable to readily peelable seals. Monolithic packages, with tray, lid, and heat seal all made from one family of polyesters, simplify recyclability.

Also, shrink films of Kodar PETG copolyester, offering blush (stress-whitening) resistance, good printability, and predictable shrink rates, are now available from manufacturers in North America, Europe, and Japan.

IMPROVED CRACK RESISTANCE

For coextruded flexible packaging requiring the high barrier properties of ethylene vinyl alcohol (EVOH), EVAL Co. of America has developed PEP-121 and PEP-122. Eval Co. says the materials provide three times greater flex cracking resistance than typical EVOH resins. Potential applications include coextruded film structures for bag-in-box packaging. Also, a new developmental XEP-140 EVOH copolymer barrier resin, with a softening range similar to that of polystyrene, can be used with polystyrene/LDPE and polystyrene/polypropylene form-fill-and-seal sheet. In multilayer sheet, the material is an excellent barrier to oxygen, gas, flavor, aroma, and solvent permeation and also permits less EVOH for comparable barrier properties. Possible uses include packaging for single-service puddings, apple sauce, salad dressings, and jellies.

POLYPROPYLENE GROWTH

Polypropylene for flexible packaging has had a 7% to 8% annual growth rate, according to Exxon Chemical Co. While the largest market is for biaxially oriented (BOPP) film, with well-entrenched products such as snack food packaging, the company sees new applications emerging for cast film, especially with random copolymers, for gains in clarity or impact. Efforts also center around improvements in heat seal, barrier, and organoleptic properties. Heat seal applications have been met using high level random copolymers developed within the last two years and terpolymers currently under development. Jim McKinley, marketing manager, polypropylene, says that H|P.sup.3~, developed in 1991, improves the water-vapor barrier of monolayer OPP films and, in some applications, can replace a conventional polyvinylidene chloride (PVDC)-coated film.

Among industry uncertainties in the '90s, Exxon Chemical sees a need to understand the impact of recycled polymers on virgin resin outlets and the intervention of new catalyst technologies in new or existing capacity. The expectation is that virgin resin will continue to be more cost effective than today's post-consumer recycle offerings, and, unless recycling is legally mandated, resin suppliers will see only nominal inroads from the post-consumer segment. Material deselection, however, will be another story. Jerry Laird, marketing manager, High-Pressure Polyethylene, suggests that even monolayer structures may be under threat of deselection in favor of more widely publicized and intensively recycled polymer types.

The need for rapid entry of new products and packages, the short life span of those products, and the recent downscaling of end-user and converter technical and development staffs are accelerating team approaches of suppliers and customers, especially where the science itself is undergoing refinement. Exxon Chemical emphasizes that customers in the '90s will expect consistently good product quality, rapid response to needs, and flawless support services as standard entries for doing business.

Export markets for many U.S. and European suppliers have been pressure-relief valves in times of high capacity or failing domestic demand, serving to maintain full-capacity economics without damage to the domestic market. Exxon Chemical says that aggressive capacity growth being planned in Central Europe and the Pacific Rim over the next six to eight years could steadily dry up export opportunities, and the successful suppliers will be those who can tactically identify and service the attractive export possibilities.

Exxon Chemical's Escorene 9214, for injection stretch blowmolded rigid packaging, provides oriented polypropylene containers for Daily's orange juice and Bristol-Myers Squibb's Excedrin. Uses of a new family of film products, which contain 25% post-consumer recycled HDPE from milk and water bottles, include overwrap for paper towels, tissue paper, napkins, and diaper bags. The company is also looking at noncontact food packaging as a market for post-consumer recycled films.

Polypropylene shrink label film, used with rigid polypropylene containers, is replacing PVC in some applications, fostering recyclability by avoiding the need to separate labeling from the package.

SCHOOLS IN THE LOOP

Within the beverage area, GE Plastics is focusing on hot-fill juice packaging, and returnable, refillable water and milk containers. Nick Caffentzis, packaging industry manager, says that GE and D & L Manufacturing have introduced a returnable, hollow handle, gallon-size polycarbonate bottle--an alternative to gallon-sized HDPE bottles for milk, water, and refrigerated juice. The bottles are size- and volume-stable, and are washed and refilled an average of 50 times.

Karen O'Donnell, packaging industry manager, School Milk Bottles, says that throwaway half-pint, HDPE-coated paper milk cartons constitute at least 25% of the solid waste collected daily at schools. In June 1991, three schools in Saratoga Springs, N.Y., started using Saratoga Dairy's reusable half-pint milk bottles of Lexan polycarbonate resin. The bottles now are being supplied in fourteen school districts in the upstate New York area. The dairy picks up the empties in 50-bottle crates and returns them for sterilization and refilling. Each reusable container eliminates up to 100 disposables from the solid waste stream. After about 100 trips, the bottles can be reground for use in new products, such as bottle-carrying crates and building applications.

Coextrusion blowmolded, hollow handle, gallon-sized hot-fill bottles of polycarbonate/amorphous nylon for cranberry juice, being market tested by Ocean Spray in Pennsylvania, weigh 9.25 lbs when filled, compared with glass containers at 11.5 lbs. The polycarbonate blend provides glass-like clarity and improved impact resistance.

In the evolution of microwave packaging, aluminum predominated in the '70s; crystallized PET and coated PET and paperboard reigned in the '80s; and polypropylene and polystyrene are significant in the '90s. Adriaan boon von Ostade, industry manager, Food and Food Service Industry, GE Plastics, says blending 50% Noryl PKN with 50% polystyrene improves high temperature performance and permits trays with thinner walls and 20% to 30% less weight than polypropylene, and which retain stiffness up to 220|degrees~F. Available in solid sheet (PKN 4728, PPO/HIPS) and foam packaging (PKN 4717 PPO/PS) grades, the materials, which have started to penetrate supermarkets and delis for microwave-only fresh refrigerated foods, can be processed in polystyrene equipment and are compatible with polystyrene recycle systems. Compared with polypropylene, walls can be 34% to 44% thinner.

GE sees its PBT-based Valox PKG 1530 resin, developed for direct coextrusion with high impact polystyrene without need for a tie-layer, as a cost-effective alternative to aluminum lidding for one-portion cups. The material withstands 400|degrees~F heat sealing and has good peelability and tear strength.

IMPROVED FILMS

Among the recent product introductions from Hercules' Packaging Film Group are opaque-white Vision 370W OPP film, which offers excellent bonding to containers and slip consistency for high machinability. A clear grade, Vision 370C, can be used as the outside ply in laminations with the 370W grade. Hercules T523-2 OPP slip-modified film possesses a thermally stable coefficient of friction to meet requirements of vertical packaging machines. PST 2 OPP coextruded printable film combines new sealant technology and hot-slip for high speed performance. Another new product, UBS OPP ultra-barrier sealable film, uses a PVDC latex coating to achieve strong moisture and oxygen barriers, and features a 75|degrees~F heat seal range. Also, Ultimet MST 3 high barrier, metalized OPP film exhibits craze-free performance in extrusion laminations and offers an 85|degrees~F heat seal range for efficient runs on high speed packaging equipment.

SOURCE REDUCTION

New materials for injection molded and thermoformed packaging from Himont Corp. enhance source reduction, says Chuck Egli, market development manager. Added to the workhorse thin-wall injection molding grade, Pro-fax SD-242, with its melt flow rate (MFR) of 35, are Pro-fax SV-955 and SV-957 polypropylene, with MFRs in the 50 to 55 range. Other grades with MFRs up to 100 are available in developmental quantities.

Resins with high melt strengths and consistency permit downgaging in thermoforming. Pro-fax SD-613 polypropylene, for example, offers greater consistency in wall thickness because of the resin's strain-hardening characteristics and high melt strength. Relative to the need for heat resistance in microwaves, Egli says that "food processors are taking a second look at cost-effective plastics such as polypropylene as a possible alternative to PET and other more expensive materials."

SU 256M resin with improved clarity, balanced with impact resistance and low cost, is a contender for polypropylene bottles. Also Pro-fax SA-747N, a clarified random copolymer, may be used in injection stretch blowmolding applications.

TANDEM PROGRESS

Hoechst Celanese sees beverage containers experiencing strong growth through the '90s as broader use of polyester resins and recycling initiatives advance in tandem. The company joined the Coca-Cola Co. to pioneer methanolysis-based, closed-loop recycling of soft-drink bottles. (In methanolysis, the process recovers and purifies the polyester's basic components.) The company also intends to pursue the development of alternate new recycling technology with Coca-Cola.

E.E. Ebner, general manager, PET resins and administration, Hoechst Celanese Fibers Group, says the company is on schedule with projects for adding nearly 500 million lbs of new PET resin capacity in the U.S. and Mexico by 1995; has commercial-scale methanolysis-based technology on stream at Wilmington, N.C.; and is developing a recycle services center at Spartanburg, S.C.

Ebner projects polyester as a prime candidate for single-service containers with improved barrier properties for food-contact packaging that is more sensitive to carbonation loss and oxygen permeation and which maintains excellent shelf life.

METALIZED FILMS

ICI Films predicts a bright future for metalized polyester and polypropylene films. A high-performance snack foods packaging structure, based on metalized Melinex 850H heat sealable polyester film, contributed to the excellent sales growth reported by the Eagle Snacks Division of Anheuser-Busch. Five or six years ago, the major chip companies began to switch from coated glassine to metalized polypropylene and, more recently, to metalized polyester-based laminations. This trend is also seen in the confectionary industry, as replacements for paper-packaged products.

ICI Films is launching a heat sealable film, targeted towards snack foods, with one side chemically treated for improved metal adhesion. Another chemically treated film is for direct extrusion of polyolefin sealants. Also being developed is a cost-effective white polyester film for food and nonfood packaging applications, with potential also in the medical and lidding markets, where there is a need for an opaque white printing surface with the performance characteristics of polyester film.

ADDITIVE PACKAGES

New Durethan polyamide 6 resins from Miles Inc., Polymers Division, including grades B31F, B35F, and B40F, are available with additive packages designed to provide materials with extremely low gel counts, no dust, and a range of viscosity levels. Currently under development is a film grade Durethan resin for food packaging, with a low process temperature, improved barrier properties, excellent clarity, and a low gel count, compared with conventional polyamide 6 and copolyamide resins. The company says its Durethan C38F copolyamide film, particularly suitable for blown film coextrusions with polyethylene, EVOH, and other polymers, is increasingly used in the food, industrial, and medical markets. The material offers a combination of barrier, tear strength, puncture resistant, and thermoformability properties, and facilitates use of thinner film structures.

FRACTIONAL MELT RESINS

Two new Pethrothene hexene-based fractional melt LLDPE resins, GA 609-130 and GA 607-133, from Quantum Chemical Corp.'s USI Division, for extruding food grade and trash bag and heavy duty packaging films, offer possible reduced film gages and improved strength, toughness, heat seal, stiffness, and processability.

Also available is a new line of LLDPE resins, for blowmolding and sheet extrusion, that feature broad molecular weight distribution and excellent environmental stress crack resistance. The materials combine the melt strength of conventional LDPE blowmolding resins with the flexibility of LLDPE resins. Quantum says Petrothene GA 818-070 provides processing characteristics previously associated only with HDPE and conventional high pressure LDPE.

The USI Division has signed a license agreement with Mitsubishi Petrochemical Co, Ltd., of Tokyo, to produce, use, and market Modic polypropylene tie-layer adhesives. The company will begin sampling new polypropylene tie-layer resins under its own Plexar trademark. The new tie-layer adhesives are primarily designed for polypropylene-based multilayer rigid packaging, such as bottles and thermoformed containers.

Quantum's new plastics recycling plant in Heath, Ohio, primarily for HDPE and PET containers, can now produce up to 32 million lbs/yr of post-consumer resins. The recycled polyolefin resins will be marketed by the USI Division, and the PET resins will be sold to the fiber market and other markets. A new film grade material, GB TR109, a blend of 85% virgin butene LLDPE resin and 15% post-consumer resin, and also containing slip and antiblock agents, is for merchandise and trash bags, industrial liners, and other nonfood uses.

PRODUCT DIFFERENTIATION

Competition grows for limited warehouse and shelf space, and increased niche marketing requires greater packaging differentiation. William Gray, director of marketing, Sealed Air Corp., cites the trend to smaller, more fragile, shorter-life-cycle products and packaging's expanding role as a reflection of a product's total quality image.

In this context, high speed automated flexible manufacturing systems put a premium on quality control in the production process. Sealed Air's Instapacker foam packaging system improves productivity, providing custom foam protective cushions at the touch of a button. Up to 24 foam-filled bags per minute in a variety of cushion sizes can be delivered, and waste is reduced by regulating the precise amount of material to effectively cushion the product. No product-specific tooling or molds are needed.

The Company's Instaflex polyurethane foam allows resilient protection with a minimum of material. Compared with ten years ago, the total package weight to protect a computer, for example, is reduced by 54%, from 11.6 to 5.3 lbs. A 67% reduction can be achieved in the weight of the cushioning material, and an 85% reduction in its volume. In addition, the weight of the corrugated box is reduced by 49%. For the same protection level today, eight 2-inch-thick corner pads of resilient Instaflex foam replace two "picture frame" cushions of 4-inch-thick semirigid foam. Improvements in foam formulation, processing equipment, and packaging engineering expertise achieve the source reduction. Sealed Air's Instapak 808 system monitors foam processing variables to ensure consistent quality.

THE PAPER LOOK

A new line of matte finish biaxially oriented polypropylene (BOPP) films, from Toray Plastics America, Inc., for snack foods and other food-related packaging, has the look and feel of paper. Providing an "all-natural" or "old-fashioned" look, the Torayfan YM film, suitable for metallization and/or lamination with other oriented polypropylene film, PET, printed paper, and cardboard has clarity levels ranging from 30% (for 60 gage) to 40% (for 80 gage), and gloss levels as low as 13%. As the outer web in two-layer metalized laminations, the matte film provides the visual and textural qualities of paper with the technical benefits of OPP film. Also, scheduled start-up early in 1993 of a new line at North Kingstown, R.I., will bring Toray's total BOPP volume to more than 50 million lbs/yr.
COPYRIGHT 1992 Society of Plastics Engineers, Inc.
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Title Annotation:recycling packaging materials
Author:Wigotsky, Victor
Publication:Plastics Engineering
Article Type:Cover Story
Date:Apr 1, 1992
Words:3284
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