Process- and product-enhancing additives are helping the industry bounce back from recession.
By Michael Tolinski
Noticeable in 2011 was the development of a number of productivity-enhancing and market-expanding additives for molders and converters recovering from the Great Recession. Suppliers have been releasing new processing aids that increase the quantity of parts or product produced per shift, with the potential for lowering total costs per part. Meanwhile, other new additives have been developed that toughen or color plastics in unique, application-specific ways. As described in the examples below, such continuing activity indicates that the technological nexus of compounders, processors, and additives suppliers remains strong in the industry.
Process Aids & Nucleating Agents
One such additives specialist is PolyOne Corp., which is committed to providing “specialized, sustainable solutions that provide value to our customers, deliver economic benefit to their bottom line, and help them win new business,” says John Van Hulle, president of the company’s Global Color, Additives & Inks division. “We work with our customers to understand their goals, then provide solutions tailored to meet their needs and help them grow.”
As one example, the company’s new OnCap™ CTR performance additive is said to improve energy efficiency and throughput, increasing manufacturing capacity in molding and extrusion. In injection molding, PolyOne reports a 30% or greater cycle-time reduction possible with the additive, plus substantial scrap-rate reductions and improved part consistency, dimensional stability, and surface appearance.
Along the same line, Flow Polymers has announced patentable improvements in its SureFlo® line of additives for commodity resins. “Our goal has always been to produce a product that will aid in processing without having a detrimental impact on the cost of the end part,” says Michael Ivany, company president and CEO. The additives reportedly reduce cycle time and compatibilize dissimilar resins.
Another kind of additive with multiple process and product benefits is a new nucleating agent for polyethylene from Milliken Chemical, a division of Milliken & Company. Known normally as a provider of nucleating agents for polypropylene, the company “is now also focused on polyethylene, to meet a longstanding need in the packaging industry,” says Milliken’s Wim Van de Velde. The Hyperform® HPN-20E agent increases peak crystallization temperatures and rates, cutting cycle times and improving productivity by 10 to 20%, the company says. It reportedly also improves several PE product properties, such as 20-40% increased oxygen and water vapor barrier performance. A better package barrier extends the shelf life of dry foods, dairy products, and nutraceuticals; it also allows potentially thinner material gauges to be used and reduces evaporative losses of contained liquid products. The agent is for HDPE blown film, extrusion blow molding, and injection molding, as well as for clarified LLDPE blown film.
Flow Aids & Lubricants
Other additives specifically lubricate resin and enhance melt flow. The INT-41FPE MoldWiz additive from Axel Plastics Research Laboratories is said to improve HDPE flow by reducing viscosity by about 12.5 to 20% -- at only 1% loading in a compounding or molding formulation. The flow aid is an organic fatty amide blended with modified polymers, available in pellet or powder form.
New lubricants from Struktol Company of America focus on PVC and nylon 6 and 6/6. The Struktol® TR 063 lubricant for polyamides reduces viscosity while also improving filler and fiber dispersion and metal release. For example, the additive minimizes die build-up during strand pelletizing and compounding when added at 0.5-1%, the company says. It thus allows longer run-times and reduces contamination, while affecting physical properties less than other lubricants. Designed for PVC and some other thermoplastics, Struktol’s V-Wax E and V-Wax OP additives are reportedly drop-in replacements for traditional lignite-based montan waxes, whose availability has been impacted by raw material shortages. As lubricants or release agents, the organic waxes are comparable in cost and performance to standard waxes, says the company.
De-Nesting & Purging Aids
Downstream in an operation, additives can improve productivity in other ways. A new de-nesting additive masterbatch from Ampacet, called DeNestur™, is designed to help packaging thermoformers and injection molders increase line speeds and reduce waste by making it easier to release parts from the mold -- and from each other when parts are stacked tightly. Relevant applications include single-serve food and beverage trays and cups made from PET, PE, and PP. The company says the “no-stick” additive helps prevent build-up on molds and other surfaces, resulting in 25-50% reduced force for both mold release and part de-nesting. This reduced build-up and friction also reduces machine jamming, damage, and downtime, while allowing faster line speeds and easier stacked-container separation by the customer.
When a line is shut down for run changes, purging aids step in offer their own kinds of productivity improvements. Though not technically an additive, a purging compound can do what resins can’t do very well by themselves: thoroughly clean out barrel and runner systems. To this end, the Dyna-Purge® division of Shuman Plastics, Inc. released Dyna-Purge M, a non-abrasive, non-chemical thermoplastic purging compound that is said to “flow naturally” through resin pathways in injection molding and extrusion equipment. It includes two non-melting ingredients that scrub metal surfaces, plus a proprietary additive to remove contamination. The company says an independent study has shown that the product works faster than standard compounds, and reduces scrap and reject rates more.
The effects of high temperatures can be fought chemically and with fillers and reinforcements. Relating to the first way, Songwon has developed low-emission additives to help resin products resist degradation over extended service lives at high average operating temperatures. The company notes that traditional phenolic antioxidants and thioester stabilizers have difficulty meeting these requirements for thick-wall PP parts. Results show that 0.5% of the new thermal stabilizer in thick PP maintains thermal stability 50% longer at 150°C than PP with a standard stabilizer. “We are also able to meet these standards with reduced additive loadings,” adds Songwon’s Klaus Keck. “This in turn generates the additional benefits of low color distortion, often a problem when higher loadings are required.”
For reducing mechanical deflection at high temperatures, mineral fillers such as talc are useful additives. As an alternative to talc, Milliken’s Hyperform® HPR-803 synthetic mineral fibers, primarily for polypropylene, are similar in size to common talc particles, and have a high aspect ratio of around 40:1. The additive reportedly improves heat-deflection temperature and stiffness effectively by itself (at loadings about one-third as high as with talc) or in combination with talc.
The company’s Adam Watson reports a trial that used HPR in an injection-molded bumper support, demonstrating “that a compound containing 9% of HPR-803 could deliver 10% weight savings over a 20% talc-filled compound, and still maintain dimensional, stiffness, and impact requirements.” Cycle times, part weight, and surface aesthetics are also said to be improved, in comparison with talc-filled PP. The additive can be used in foams, extruded sheet, and extrusion blow molding, and one version, HPR-803i, is designed specifically for automobile interior PP applications.
Non-traditional mineral fillers for plastics can also bring “green” credentials. United Kingdom-based RockTron, in collaboration with Ford Motor Company, has introduced “eco-mineral” fillers made from coal-fired power station fly ash waste. The company’s spherical MinTron™ filler particles are potentially effective and lightweight substitutes for irregularly shaped calcium carbonate and talc particles.
Solar radiation resistance is a key property for automotive plastics. Clariant International Ltd. is focusing on the requirements of interior parts with its Hostavin® N845PP UV stabilizer for polyolefins. Surface deposits of additives can create fogging on windshields, but this grade reportedly is low-migrating and thus low-fogging (which is of particular interest to manufacturers of dashboards, center consoles, and door cladding, for example). The stabilizer is said to use a “non-traditional” carrier material and is compatible with polyolefins.
Colored plastic surfaces likewise must hold up under solar exposure, and companies are expanding their lines of pigments accordingly (see also the “Colorants” section below). For example, The Shepherd Color Company has added an inorganic orange pigment (designated 10P320) to its line of pigments with high solar reflectivity. Pigmented plastics can normally become very hot from absorbed infrared solar radiation, but IR reflectance enables even dark colors to stay cool, the company says.
Thermal protection likewise benefits plants in greenhouses, where excessive heat can be deadly. For use in translucent horticultural films, a grade of Minbloc® mineral additive from Unimin in North America reportedly has been improved in the way it absorbs near-infrared wavelengths by using a nano-scale antimony tin oxide coating on its mineral filler particles. When dispersed in PE and EVA copolymer, the modified additive can reduce thermal energy passing through the film by about 50%, with little effect on the transmission of useful light wavelengths to the plants.
Plasticizers with Alternative Chemistries
The options for non-phthalate plasticizers continue to expand with Ferro Corporation’s Santicizer® Platinum P-1000 for PVC, urethane, polysulfide, and other polymer systems. The plasticizer is efficient in calendering processes, and is said to exhibit low volatility, migration, and extractability in water and solvents, along with resistance to mold and bacterial growth.
Meanwhile, International Specialty Products Inc. (ISP) has recently presented the advantages of its PVC-softening Flexidone™ plasticizer, based on alkyl pyrrolidone chemistry. The plasticizer’s influence on properties such as gelling, viscosity stability, low-temperature indentation hardness, and tensile strength was compared with properties from conventional plasticizers. The plasticizers have also been shown to be cost-efficient, allowing manufacturers to use a lower-than-normal amount, and can be mixed with ratios of co-plasticizers or esters to create customized physical properties, the researchers conclude.
Efforts continue in developing better PLA modifiers, which are critical for expanding the uses of the brittle “corn plastic.” For instance, Dow Plastics Additives and PolyOne collaborated to produce OnCap™ BIO L masterbatches to toughen opaque injection-molded PLA products. The improved impact strength would allow PLA to be used in cold applications such as ice cream packaging, as well as for more semi-durable applications such as cosmetics packaging and electronic device housings. The masterbatch is based on Dow’s Paraloid™ BPM-520 modifier. “We’ve worked closely with PolyOne to offer an effective impact modifier which can be made available in user-friendly, pre-dispersed formats,” says Dow’s Robin Madgwick.
Impact modification is just as important for flexible and thermoformed PLA. Moreover, for food packaging PLA, the modifier must also be FDA-approved; this accomplishment was reported earlier this year by Teknor Apex Company regarding its Terraloy™ 90000 series masterbatch. When used at up to 20% in PLA, the masterbatch is said provide high impact strength while maintaining clarity. (The masterbatch series is formulated with a Biostrength® impact modifier from Arkema, Inc., and Ingeo® PLA carrier polymers from NatureWorks LLC.) Teknor Apex reports that with the masterbatch, Gardner impact strength increased by multiple times over that of neat PLA in tests of cast film tapes, specifically increasing by 9 and 16 times for 5% and 10% masterbatch loadings, respectively; meanwhile, haze values increased from 4.1% to 4.5 and 6.5%, respectively. In short, the impact modifier “[expands] the value of this key bioplastic in a wide range of packaging applications where clarity is essential,” says Teknor’s Edwin Tam.
PLA’s susceptibility to hydrolysis is another Achilles’ heel being addressed by new additives. Rhein Chemie (a subsidiary of Lanxess) offers additives for improving hydrolysis resistance, thus extending PLA’s service life. Its BioAdimide™ 100 grade reportedly improves hydrolytic stability by up to seven times over that of neat PLA, while its BioAdimide 500 XT acts as a chain extender, increasing the melt viscosity of extruded PLA by 20-30% percent. The two grades can also be combined, the company says.
“By hydrolytically stabilizing PLA, you open up the possibility to make PLA a suitable candidate for durable markets previously out of reach,” explains Fei Tan, of Rhein Chemie’s Engineering Plastics Division in Shanghai. And “By improving the melt viscosity of an extruded PLA, you make it more stable and easier to process in extrusion, blow molding, or filament applications.”
Some additives-makers are covering the full the range of additives needed for PLA. Plastics Color Corp. has expanded its line of SoluPLAs™ concentrates and masterbatches to address not only the PLA limitations focused on above, but also to enhance its mold-release, de-nesting, UV absorbance, and anti-static properties. All the additives can be formulated to meet FDA medical, pharmaceutical, and food-contact requirements, the company says.
Users of conventional resins for packaging have ever-expanding options in additives. Polyvel, Inc., for instance, has expanded its offerings in antifog additives for polyolefin food packaging, now targeting more cold applications with its faster-acting VF-P05. The additive is said to reduce condensation efficiently in both refrigerated and hot conditions, performing equally well in homopolymer and copolymer PP.
Focusing on static-free high-speed packaging applications, Danisco A/S has developed a new polyglycerol ester antistatic for PE film, designated Grindsted® PGE 308. The additive has food-grade status and is said to be particularly useful for operations that package powdery products, where any static charge can cause powder to cling to the packaging, resulting in a poor heat seal. Thus the antistat is suitable for packaging materials like cereals and coffee – performing efficiently even in low-humidity conditions, explains Bjarne Nielsen of Danisco.
More useful features in packaging, such as oxygen scavenging, can integrated with packaging material using unusual kinds of additives. A supplier of organoclay additives, Spain-based NanoBioMatters, has developed oxygen-scavengers that are said to be less costly and more convenient alternatives to conventional methods, such as oxygen-scavenging packets and UV-activated systems. The company’s O2Block® additive maximizes the shelf-life of food and pharmaceutical products packaged in PE, PP, PET, and PLA. The organically modified clay, dispersed into the polymer, is functionalized with active iron, and the clay’s layered structure is said to enhance the iron’s scavenging efficiency. “The effective dispersion maximizes the access to the active iron, which ensures minimum reaction time and a very uniform protection of the packaged goods,” says Ole Faarbaek, vice president of NanoBioMatters North America. Used in loadings of 1 to 10%, the additive is supplied as a micronized powder or in a masterbatch.
Mass-Reducing Foaming Agents
Internal foam blowing agents reduce part mass and resin usage by creating a cellular structure in the part during processing. Americhem provides its nCore® line of chemical blowing agents for reducing the density and weight of packaging. The blowing agents allow 9 to 40% less resin to be used in a plastic package, reports Chris Miller, the company’s technology manager for molded products. “The lightweight packaging that results reduces shipping and handling costs,” adds Miller. The company also lists construction applications for nCore, such as plastic decking, pipe, window profiles, flooring, and paneling.
Meanwhile, Dow Plastics Additives has broadened its line of Surecel™ “foam cell promoters.” Grades include T-55 for free foam sheet, decking, and profiles, and T-50 for the lowest-density free foam sheet. The promoters resist cell coalescence, a common problem in foam extrusion; this reportedly makes them useful for increasingly popular cellular PVC building products. “[The T-55 grade] allows manufacturers to achieve lower density and reduce raw material costs with a wider processing window,” explains Dow’s Eric Lundquist. The T-50 grade delivers densities as low as 0.50 g/cc, reducing raw-material costs by as much as 7-8% per board foot. “This cost profile allows customers to compete against wood, while the process maintains the same uniform, fine cell structure you’d expect at higher densities,” adds the company’s Rob Martin.
Colorant Philosophies Evolve
But it’s the outer appearance of most plastic products that’s critical to their appeal, so makers of colorants and pigments spend much time coming up with new palettes every year. For Clariant Masterbatches, there are driving philosophies that dictate new hues and tones the company releases. In its 2012 ColorForward™ trend analysis and design process, team members identified themes related to trends of “confusion and contradiction” in today’s global society; this in turn drove them to create new series of shades with names such as “Bizarre” (a “fusion of translucent purple and yellow”), “Inner Strength” (“deep, dark non-black” and a “tinge of primal green”), “New Equilibrium” (“stable pearlescent brown”), and “Hyperlight” (said to be made up of different glitter colors that can only be produced in molded plastic).
There seems to be no end to the variety of possible shades, and names for them. Bayer MaterialScience LLC’s spring and summer 2011 color palette is said to “celebrate a diverse culture,” based on global megatrends. The company’s researchers of its LEDA® color line claim to have developed colors that are attractive around the world. For Bayer’s Makrolon® polycarbonate grades, new colors include “Aztec” (a “down-to-earth , chromatic orange”), “Free Fall” (“a cool blue”), “Maui” (“a warm brown”), and “El Dorado” (a yellow that “hints at the possibility of gold”).
Other pigment and colorant makers are focusing on specific application niches; for example:
Special Needs: Antimicrobials & Traceability
The next frontiers for additives are medical products and other applications with unique requirements such as antimicrobial properties. “Microbe growth is a serious problem in healthcare settings, and manufacturers are looking for ways to combat surface microbe growth on plastic parts in medical devices, hospital furnishings, and other healthcare applications,” says Larry Johnson, global healthcare marketing director for PolyOne. The company’s WithStand™ antimicrobial additives can be custom formulated with both organic and inorganic components that inhibit microbial growth. Given the complexity of each application, the company says it assists clients with additive choice and dosage; process, product, and specification development; and efficacy testing and claims development, in a variety of polymers.
The siloxane polymer-based antimicrobial of Biosafe, Inc. reportedly bonds tightly to treated surfaces of film, nonwoven fiber, sheet, and molded plastics, resisting leaching or migration. The material then provides long-term protection against bacteria, mold, mildew, and fungi by puncturing and rupturing their cell walls. The additive reportedly costs less to use than conventional, silver-ion-based antimicrobials (and late last year the company was granted a composition of matter U.S. patent for the polymer formulation). Biosafe has tested its effect on infectious microbes commonly found in hospitals, says company president and CEO Max Fedor. “Medical textiles treated with the polymer have demonstrated a 99.999% (5 log) reduction of certain microorganisms within five minutes.”
Another quality that medical products require is traceability – a unique feature that new additives can provide. There’s also been a growing desire for traceability in food, beverage, drug, and cosmetics packaging overall. Accordingly, Ampacet offers AmpaTrace™ molecular tracers, additives which provide distinct security signatures in consumer packaging materials. The tracers can help resolve security, counterfeiting, liability, and other concerns along various points in the supply chain, up to the retail level.
To create traceable product fingerprints that can be easily measured using visual, audible, or standard laboratory tools, special compounds in the additive masterbatch are varied by type, proportion, and concentration. Depending on the type of security needed, the molecular tracers can be infrared or UV activated, or ferromagnetic. The company says the technology can be applied to both rigid and flexible plastic packaging made with common processing methods.
“Studies have shown that about seven percent of all products sold are counterfeit, resulting in revenue losses of $200 billion in the U.S. alone,” says Rich Novomesky, Ampacet business unit manager. Besides helping detect this increasingly widespread counterfeiting, the tracers can also be used to identify the source of ingredients in a package for validation or litigation purposes, Novomesky adds. One might even expect a time soon when every product we pick up can be quickly linked to its exact material lot, and time and place of manufacture.
This fall, Mike Tolinski’s new book, Plastics and Sustainability, is scheduled for release by Wiley-Scrivener (www.plasticsandsustainability.com). Mike’s previous book, Additives for Polyolefins, was released in 2009 (www.elsevierdirect.com).