By Michael Tolinski
Most new additives now can be viewed as tools for creating novel product features, rather than just for speeding up processing or protecting polymers from heat and light. And like the contents of a good toolbox, these tools are diverse in form and function. This yearly update focuses on some of the newest of these handy additives; many of them come from companies that have never before been covered in this annual report.
Continuing interest in inherently bacteria-resistant products has driven the release of a number of new antimicrobial additives. “Developed in response to hygiene concerns, antimicrobial agents have already proven effective in enhancing the freshness of end-products across a wide array of industries,” says Vaman Kulkarni, director of business development for Americhem Inc. Accordingly, the company has introduced its nShield™ antimicrobial masterbatches; their non-migratory, thermally stable formulation is said to inhibit discoloration, degradation, and odors caused by bacteria, when used in synthetic fibers and plastic articles such as artificial turf and automotive interior parts.
The effective agent in most antimicrobials typically is silver, a material known by ancient Romans to be antibacterial, notes the Swiss supplier Sanitized AG. There are different ways in which the silver ions can be delivered via an additives system. The company’s product is composed of small ceramic glass particles that encapsulate the silver; this reportedly permits higher transparency when it’s used in polyolefins, polystyrene, polyurethanes, and various coatings.
One new silver-based product is targeting an obvious sector for antimicrobials: medical applications. ColorRx® AM from LTL Color Compounders, Inc., is formulated for FDA (U.S. Food and Drug Administration)-regulated and FDA-approved medical devices, where it helps control pathogenic bacteria that cause hospital-acquired infections. It’s reportedly available in masterbatch form or as a “ready-to-run” compound.
Companies are also collaborating to expand their antibacterial options. Last spring, compounder RTP Company expanded its line of antimicrobial compounds and masterbatches to include the BactiBlock® ionic silver-based agent from additives specialist NanoBioMatters. Proven by testing to be compatible with multiple polymers, the additive uses an easily dispersed and colorable clay carrier, says RTP, and combats algae and fungi (mold and mildew) as well as bacteria.
But it’s sometimes necessary to repel much bigger critters, like rodents, dogs, cats, and nuisance insects (flies, mosquitoes, ants, cockroaches, wasps, and bees). Greenhouses, garages, sheds, and tents are logical places for using products with a pest-repelling additive, like Ecosmartplastics’ ESPRepellem™, a natural, “green” biodegradable additive in an LDPE base. The company touts its use in garbage bags, in which the additive’s scent keeps away swarming flies and raccoons, while the company’s biodegradation-enhancing additive in the bag later helps break it down.
Additives That Monitor & Trace
Additives are also on guard against very different kinds of intrusions. “Major restaurant chains and food producers are insisting that plastic and rubber pieces that may contact food products during processing be metal- or X-ray detectable,” explains John Collins, manager of plastics and processing for Eriez. So the company has introduced the PolyMag® XRD plastic additive, which lends X-ray contrast to plastic moldings. The contrast makes broken plastic pieces in food detectable to X-ray food-inspection systems, safeguarding consumers against contamination. The company says the FDA-compliant masterbatch can be used in food-contact articles such as bins, paddles, pails, pallets, scoops, shovels, conveyor buckets, belts, gaskets, and grommets.
Other additives help protect against illicit acts, such as product counterfeiting and tampering. Ampacet’s masterbatches address these issues with the company’s SecurTrace™ molecular tracers. The additives reportedly allow all kinds of consumer and medical packaging to be traced and verified, providing distinct security signatures for each product that are detectable using various means, depending on the level of security required.
Traceability ultimately helps protect a producer’s brand, important because “The global market and the advances in printing and packaging technology mean that risks to a company’s brand abound,” says Douglas Brownfield, the company’s strategic business manager. The tracers “also can aid quality by validating that a package contains the right Ampacet colorants or additives at the level specified,” he adds.
Colorants Do More Than Just Color
Plastic colorants may not have the novelty of the additives described above, but they’ve made remarkable strides in the decades they took to develop, as evidenced by the presentations scheduled for the 50th-anniversary CAD RETEC® conference of SPE’s Color & Appearance Division (which took place September 30 through October 2 in Louisville, Kentucky, USA). “The coloring of plastics has come a long way since a small group gathered in Rochester, New York, in 1962,” says Jim Figaniak, current CAD chair and president of LTL Color Compounders. “We want to recognize our history as we enthusiastically look to the future.”
The group’s members still have a lot of challenges to deal with. Some new applications are particularly sensitive to colorant selection, explains Steve Duckworth, Clariant’s global medical segment head. “Within the pharmaceutical packaging sector there has been increased awareness of, and much discussion of, extractables and leachables from plastics, and how changes in the materials may often result in unintended contamination of the drug.” In response, Clariant’s Mevopur® colorants reportedly are pre-tested to address industry concerns, providing confidence for customers who want the try new color options in their packaging, Duckworth adds. Covering the standard color range, the colorants are compatible with resins such as Eastman Chemical’s Tritan™ polyester copolymer and Topas Advanced Polymer’s cyclic olefin copolymer.
Special colorants also allow medical workers to do their jobs better, sometimes in unexpected ways. For example, medics in the field benefit from having extra light shed on their tasks, especially when quickly cutting through the clothing of injured people. So RTP Co. provided a color masterbatch containing a phosphorescent, glow-in-the-dark masterbatch for the glass fiber–reinforced nylon component used in the medics’ trauma shears, capable of emitting an eight-hour-long “afterglow.”
But mostly, colorants are used in common plastic products for catching consumers’ attention, differentiating brands, or creating a certain user experience. To multiply designers’ options, manufacturers are expanding their color palettes. Thermoplastic sheet specialist Kydex, LLC, this year launched a library of 64 colors for products in aviation, mass-transit, retail, and medical fields, expanding its standard 36-color library. “We recognize that color is at the center of every design concept, and that it is our job to inspire our customers to push the envelope when it comes to their designs,” says Kydex president Jim Medalie. Like palette expansions by other companies this year (see p. 32 of the June 2012 PE), this one includes new colors with cool names, such as “Tangents,” “Tempest,” “Impulse,” and “Resolve.”
Increased colorant options especially help industry segments that use a lot of plastics but would rather not paint them. The automotive industry, for one, is looking to avoid the production and environmental costs of painting, which is as much as 30% of the cost of a car part, cites PolyOne Corp. So the company is developing its OnColor™ FX Smartbatch™ concentrates to help automotive manufacturers use more molded-in-color parts. “We understand the challenges inherent in molding colored plastic parts to meet carmakers’ high standards,” says Christoph Palm, general manager for PolyOne Color & Additives Europe. Issues with color matching, consistency, and long-term performance complicate the goal. But the company has seen some success in Europe in replacing painted plastic exterior trim parts with those containing Smartbatch special-effect metallic pigments, Palm adds.
Meanwhile, there’s still plenty being done with the most basic of pigments, black. The Shepherd Color Company added a new black, designated 10P950, to its Arctic® range of infrared-reflecting color pigments. The pigment’s high solar-heat reflectivity suits plastic applications that must resist heat buildup, a common problem in dark products. Based on a brown hematite mineral pigment, the 10P950 is also UV-light stable, the company says, making it useful for siding, roofing, doors, windows, extrusions, and interior and exterior automotive parts.
As the polar opposite of opaque black is another popular color aesthetic for plastics: untinted transparency, which is fostered by clarifying additives. Transparency is valued in consumer goods like food-storage containers, as highlighted in a recent announcement of a new application for the Millad® NX™ 8000 polypropylene clarifier from Milliken & Company. The company also stresses that the additive reduced processing temperatures by up to 40°C and allowed 15% faster cycle times for the German manufacturer of the containers.
Addressing PVC’s Issues
PVC is sometimes treated as an aging workhorse material whose public image has taken a beating, but a steady stream of new additives is still being created for it. Some additives makers and compounders are focusing on improving PVC’s “green” profile, as with Teknor Apex’s well-publicized BioVinyl™ compound. The material is formulated with Ecolibrium™ biobased phthalate-free plasticizers from Dow Chemical’s Electrical and Telecommunications unit. The companies claim a 40% reduction of greenhouse gases when creating this compound, and 60% renewable content, since about half of the PVC molecule is based on seawater, and the bioplasticizer loading is over 30%.
Other contestants are stepping into the ring. “The plasticizer market has become very dynamic in recent years,” says Rob Rosenau, president of PolyOne Performance Products and Solutions. “There is clear market interest in renewable technology as an alternative to traditional petroleum-based plasticizers.” PolyOne introduced its own plasticizer this year—its “fast-acting” (high-solvating) reFlex™ 100. Developed from plant-based feedstocks in collaboration with Archer Daniels Midland Company, the material was granted a “94% biobased” label from the U.S. Department of Agriculture’s BioPreferred® program. The company is offering the bioplasticizer as an alternative to conventional plasticizers such as BBP, DBP, and benzoates, given that various phthalate-based plasticizers have come under regulatory pressure. It reportedly has lower viscosity than traditional plasticizers, eliminating defects and improving process efficiency, while also acting as a thermal stabilizer and reducing the need for stabilizers in formulations.
Other less-publicized additives for PVC have also been announced this year, and some are “green” (or at least vegetarian). Clariant is offering its Licocare™ SBW11 TP lubricant, a chemically modified wax based on soya bean oil. The company claims it performs better than fatty acid–based lubricants, improving flow and dimensional stability in injection molding. It’s particularly suitable for processing rigid PVC, especially in the extrusion of cadmium/zinc-stabilized or tin-stabilized PVC, the company says.
And earlier this year, Struktol Company of America expanded its own line of combined internal-external lubricants for rigid PVC, for use in calendered or extruded sheet and profiles. The “V-Series” grade VLB 602 is specifically for clear extrusions, especially those that require printing, laminating, or bonding. Series options here include a vegetable-based (non-animal-based) version, VLB 618, which reportedly provides the same processing and visual characteristics as standard lubricants.
But after all, plant-based options have always been relatively common for certain kinds of additives, though sometimes the actual plants, like rapeseed, are not everyday household names. Croda Polymer Additives reports that it has updated the performance data for its Crodamide™ additives, which are based on high-erucic-acid rapeseed oil sourced from growers in northern Europe. The additives serve as lubricants or as release, slip, or anti-blocking agents for PVC, polyolefins, and other polymers.
Blending Fillers & Fibers
Sometimes unsung are the additives that aid in the processing of filled and blended engineering thermoplastics. Axel Plastics Research Laboratories has released one such process aid for PBT and PBT resin blends. MoldWiz® INT-35PHT “allows more flexibility in the incorporation of filler types and loading levels, as well as an easier cavity fill and release performance,” says Axel product manager Nancy Teufel. In trials with a PC/PBT blend, it decreased resin viscosity and fluctuations in torque over time, while increasing output 50%–100%, the company reports.
Additives also help incorporate fibers and fillers with resin, which is not easy with non-polar polymers. Here, Adell Plastics announced a new line of maleic anhydride–modified polyolefin compatibilizers to serve as coupling agents in compounding. They reduce the interfacial forces between polymers and fillers, improving adhesion and dispersion. The company’s EK-10-MAH material is targeted at coupling glass and other fillers with polypropylene; KK-10-MAH is for coupling glass, wood pulp, or other fillers with HDPE.
As for the glass fibers and fillers themselves, less-familiar supplier names are coming onto the scene, such as 3B-The Fibreglass Company. In addition to long-glass and chopped-glass fibers, 3B supplies an “eco-responsible” milled fiber-powder grade made from its glass manufacturing byproducts, says 3B’s Eric Martin. This MF 01 ER grade is primarily for reinforced engineering thermoplastics and thermosets. “The combined reinforcement and flammability performance proven in some complex thin-wall electrical and electronics applications opens up fresh opportunities for this new product,” adds Martin. Compared with a 20% mineral- filled nylon-6 compound, the company reports, a nylon with MF 01 ER provided better mechanical properties, especially unnotched Charpy impact strength.
One development for the smallest- particle-size fillers concerns multiwall carbon nanotubes (CNTs). SouthWest NanoTechnologies (SWeNT) has developed new grades in its SMW™ CNT line, one of which reportedly provides high electrical conductivity in compounds used in the cathodes of lithium-ion batteries. In polymers, the product’s good dispersibility creates good electrostatic discharge properties at lower filler loadings than those required with carbon black or other multiwall CNTs, the company says. This avoids property losses caused by heavy filler loadings, while broadening the range of applications of conductive polymer compounds. “We have already generated a great deal of customer interest in these materials, and resulting demand is driving us to increase capacity,” says SWeNT CEO David Arthur.
Toughening PC & PLA
Property-modifying additives are benefiting two resin types whose chemistries—and recent histories—are quite different: polycarbonate (PC) and polylactic acid (PLA). PLA’s biological nature continues to draw interest, though its impact strength and other property limitations will require better additives and process improvements to overcome. Meanwhile, the extremely useful PC has faced the trials of the BPA debate and a slowdown in the sales of CDs and DVDs.
But PC’s application range is otherwise being expanded via impact modification. One recently developed modifier, designated M-731, is from Kaneka North America, LLC. “It was developed to meet a need for a domestically produced MBS [methyl methacrylate-butadiene-styrene] impact modifier for polycarbonate with high impact and hydrolytic stability,” explains Bill Renaud, vice president of the company’s modifiers division. “[Its] applications vary widely, as does the market for PC and PC alloys.”
Biopolymers like PLA will benefit even more from better impact modifiers (especially when the modifiers themselves are biobased). “Brittleness can be a real problem with biopolymer products,” says Robert Hu, R&D vice president for The HallStar Company. Thus the company recently patented a biobased polymeric succinate modifier for PLA, starch-based polymers, and polyhydroxyalkanoates (PHAs).
The product, HallGreen R-8010, enhances the flexibility and pliability of these materials, adds Hu. “And it provides tangible benefits at customers’ manufacturing facilities by increasing throughput and reducing energy consumption.” The company’s test results show performance benefits starting at 10% concentration and peaking at 30% loading levels, at which point the additive increases the compound’s elongation percentage at break tenfold, while reducing tensile strength by only 5%.
Greener Flame Retardants
Meanwhile, the race to develop greener alternatives in flame retardants continues. Along with a strong trend toward halogen-free FRs, suppliers continue to introduce alternative brominated FRs as replacements for unwanted traditional halogenated FRs. Chemtura’s Great Lakes Solutions business supplies its Emerald 1000 polymeric brominated FR as a substitute for decabromodiphenyl ether, for deca-BDE’s widespread applications in electronics, wire and cable, insulation, textiles, and transportation. The company says the product is a more sustainable choice, with “the advantage of being a drop-in replacement in most formulations.”
Some companies are pursuing halogen-free FRs full-throttle. Plastics Color Corporation’s flame-retardant system for polypropylene, FlamaSol FR™, avoids using two chemicals that are being phased out by the end of 2012, explains PCC development engineer David Witt. “FlamaSol FR contains no decabrome or antimony, two harmful chemicals, yet demonstrates better extinguishing results than our previous flame retardant.” The company says the FR is for construction materials (like electrical conduit, junction boxes, switch boxes), warehouse products (shelving and pallets), personal electronic equipment (computers, printers, and televisions), and other high-heat applications.
Meanwhile, Clariant announced a capacity expansion for its Exolit® OP non-halogenated flame retardants, starting a third production unit in Germany in 2013. This will triple the capacity of its original plant, which started production in 2004. The production increase is “in line with the increasing environmental and safety consciousness in the market” and the corresponding demand for the product, says Clariant’s Michael Grosskopf. Besides the new German plant, the company is reportedly looking to further expand the FR’s production capacity in Asia.
At the end of the day, another additive-like compound becomes essential. Purging compounds are getting more sophisticated, to quickly clean out ever-more sophisticated resin compounds from machines. Houston-based Neutrex, Inc., released its Purgex 602™ Plus, developed specifically for rapid changeovers from colored to clear (or from clear to colored) polycarbonate and polystyrene. Operating at temperatures from 360°F to 550°F (182°C to 288°C), the compound removes residual contamination from injection molding machines and hot-runner systems. It’s composed of nontoxic, non-abrasive active ingredients in a polystyrene carrier, using mechanical action plus a “foaming turbulence” to clean. Its active ingredients are even U.S. FDA-approved, the company adds.
For cleaning out the highest-temperature thermoplastics like PEEK, PEI, PPS, and PPA, the Dyna-Purge Division of Shuman Plastics, Inc., has released New Dyna-Purge® E2. The product’s effectiveness is backed up by a late-2011 study, says Tim Cutler, Dyna-Purge vice president. The study compared E2 with two products: a 50% glass-filled PC-based mechanical-abrasive purging product and a polyolefin-based chemical purging product. After purging high-heat resins, inspectors reviewed the “post-purge” resin for contamination and clarity. Only the Dyna-Purge product received a “pass” rating for each trial. Cutler says the study demonstrates that the E2 is more effective for high-temperature resins, “resulting in reduced scrap rates and improved changeover times”—two of the key factors by which the effectiveness of many tools in plastic processing is measured.