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Additives extending the performance boundaries.

To additives producers, new plastics designs are like moving targets, constantly shifting their requirements, frequently needing modified protection or enhancement of their basic functional properties. As a result, additive technology is highly dynamic, with improved products constantly emerging. And as end product performance/cost ratios become more demanding, additives are helping designers extend the inherent capabilities of the resins. Akzo Chemicals Inc. Two sulfur-containing PVC stabilizers provide excellent weathering performance. Stanclere T-5507, a liquid carboxylate modified mercaptide stabilizer, exhibits easy processing, superior heat stability, and protection from pigment-fading in light pastel to dark earth-tone pigmented systems. Weatherability for dark colors can be obtained with Stanclere T-197. The barium/tin powder does not detract from end-product heat-distortion properties.

For electroconductivity and avoidance of static charge accumulation, Akzo has developed Ketjenblack EC 300J and Ketjenblack EC 600JD, electroconductive blacks typically used at loadings of one fourth to one third those of standard materials. Ketjenblack EC products are generally insensitive to overprocessing or mechanical breakdown.

Akzo also has strengthened its Intercide ABF biocide product line. The company has begun a major expansion of its Brazilian OBPA (10,10-oxybisphenoxarsine) plant and has combined its research and microbial laboratories at the Dobbs Ferry, N.Y., corporate research center.

Multipackaging for the biocide product line is now offered. Varied concentrations of biocide/plasticizer combinations for flexible vinyls, and delivery in stainless steel totes, can be specified.

The Phosphorous Chemicals group has commercialized its intumescent flame retardant product line, which includes melamine-phosphate, -pyrophosphate, and -cyanurate. The products can be synergistic with other flame retardant additives. In addition, a bis-phosphate additive line for engineering resins has been introduced. Anzon inc. Anzon is addressing environmental concerns primarily with its Envirostrand and Fyrebloc nondusting antimony oxide product lines. TMS-HP is a high purity grade of antimony trioxide with very low levels of lead and arsenic. Also, alternative packaging systems, including semibulk packages, improve handling and waste disposal.

Ongard 2, an inorganic zinc/magnesium complex, is a strong smoke suppressant and flame retardant synergist. Smokebloc utilizes antimony trioxide with molybdenum and zinc complexes to give flame retardant and smoke suppressant properties. New additions are AZ-60 and AZ-70, zinc complexes aimed at smoke suppression and low heat release. Ultracarb, with a decomposition temperature about 500[deg.]F higher than that of aluminum trihydrate, has use as a flame retardant filler and smoke suppressant in PVC, PC, PP, EVA, and EPDM.

Anzon's Microfine, a submicron (0.3 micron particle size) antimony trioxide, helps optimize tensile and impact properties and, in thin walls, can improve electrical properties and surface finish. The Trutint product line offers antimony oxide grades with a wide range of tinting' strengths. Pyrobloc SAP2 and SAP5 provide low tintorial strength with low polymer reactivity, especially for PET and translucent parts. Atochem North America Pyronil 45 is a new brominated phthalate ester flame retardant for flexible vinyl wire and cable. Pyronil 63, a white crystalline solid with 63% bromine, is especially effective in flexible vinyl, thermoplastic polyesters, and PC. Thermoguard XS-70-T is a new heat-stabilized chlorinated paraffin for polymers that process below 240[deg.]C to 250[deg.]C. Atochem also offers Thermoguard antimony oxide as a synergist with halogenated flame retardants and a line of pelletized flame retardant concentrates.

The company says that Anoxsyn 442, an aliphatic sulfide synergist, is particularly effective in crosslinked PE and EVA wire and cable. Thermolite stabilizers protect a range of products against sunlight, heat, humidity, and other environmental factors. Thermolite 139 and Thermolite 380 stabilizers for siding and profiles provide vinyl with superior weathering and color stability.

Durastrength 200, an acrylic modifier, enhances weatherability and impact strength of vinyl compounds. Durastrength 200 LG is a similarly effective low gloss version. A One-Pack multifunctional additive package, in free flowing powder form, is designed for large volume vinyl applications.

Through a joint venture with Mitsubishi Rayon Co., Atochem recently introduced Metablen C-301 for vinyl bottles. The company says that clarity and low taste and odor characteristics can be provided at lower additive levels than previously. The Carborundum Co. Numerous grades of Fiberfrax alumina-silica ceramic fibers have been developed as additives for plastics. Fiberfrax 690070 has an aspect ratio ranging from 50 to 100 and, with reduced particulates, yields more reinforcing fibers per pound. Fiberfrax 6900-70S fiber, with the same advantages, is also surface treated to improve dispersibility and resin-to-fiber bonding in nylon, epoxy, phenolic, melamine, and polyurethane.

Fiberfrax EF 122S, now developmental and with average diameter two to three times larger than most Fiberfrax grades, decreases fiber entanglement and thus aids dispersibility. These fibers have aspect ratios ranging from 30 to 70 and contain 20% to 25 % less particulate than some other grades. Fiberfrax milled fiber, with a diameter of 2 to 3 microns and average fiber length of 15 to 20 microns, provides the best dispersibility, minimally affects resin system viscosity, and facilitates maximum matrix loading to optimize wear, corrosion resistance, and compression strength. Climax Performance Materials Corp. The 1993 U.S. National Electrical Code will include a limited-smoke designation for electrical insulation and jacketing materials, such as those used in PVC-based riser cable. Jack Kearney, national sales manager, Climax Polymer Additives Group, says that the company's cost-effective zinc borate ZB-223 can be used as the main smoke suppressant in these systems, even though Climax's ammonium octamolybdate also generally is needed to help pass the more demanding UL 910 test for plenum materials. Recent work by Monsanto demonstrates that its new phosphate plasticizer and Climax's molybdenum-based compounds are highly synergistic in PVC.

Ultrafine zinc borates, being developed by Climax for wire and cable materials, improve dispersibility and enhance physical properties. The materials will have a very low mean particle size.

Flame retardant and smoke suppressant development at Climax's Golden, Colo., research facility focuses on improved functionality with cost effectiveness. Two areas are antimony oxide replacement and smoke suppression with heat stability. Du Pont Co. Recent developments at Du Pont include Elvaloy HP resin modifiers. The new additives offer nonmigration and improvements in strength, low-temperature impact, heat and chemical resistance, and weatherability of the conventional Elvaloy grades, but outperform them in processability, low temperature flexibility, higher heat resistance, and enhanced thermal, hydrolytic, and oxidative stability.

Another Elvaloy HP modifier eliminates the traditional trade-off in ABS technology between impact strength and melt flow. Addition of 6% to 7% of Elvaloy HP 4051 to an ABS resin can double its impact strength and increase its melt flow index by 18% to 36%, thus reducing molding cycle times. The modifier also can upgrade recycled ABS.

An emerging toughening system may open the way to direct molding of structural foam parts from a dry-blended mixture of materials such as PET bottle scrap, glass reinforcement, and an additive package. Du Pont is exploring licensing opportunities with manufacturers of products such as shipping pallets and various other industrial items.

Wendy Ho-Schnell, Kevlar Wearforce marketing manager, says, "The product line will become much more flexible in 1992. We will probably be offering ready-to-mold Wearforce pellets in addition to concentrates, and we will also introduce compounded pellets using the new 1.5 mm Kevlar floc. This means we can develop custom blends for specific applications."

Wearforce typically comes in the form of 1/4-in injection moldable pellets containing 30% to 35% Kevlar, which strengthens the carrier resins while minimizing abrasion effects. Du Pont has developed a new ready-to-mold pellet of 15% Kevlar and 10% Teflon in nylon. The combination, engineered for automotive parts, lowers the coefficient of friction. Ho-Schnell says that there is growing interest in parts reinforced with Kevlar to replace lubricated parts, for maintenance and environmental reasons. Common applications include bearings, gears, bushings, rollers, and wear guides. Engelhard Corp. Use of surface treated calcined kaolin reinforcements in engineering resins, particularly nylon, now is extended to commodity plastics. The Specialty Minerals and Colors Group offers Satintone calcined grades and Translink surface modified aluminum silicates.

Engelhard's ongoing field tests on mineral reinforcements for polypropylene indicate possible product introduction within a year. Also, in specialty film applications, the traditional Translink products are meeting needs for added stiffness, tensile strength, and opacity while retaining a high degree of elongation. David Doles, plastics product development manager, says that extending the additive product line to raise the performance of the lower-cost plastics puts the company "in a strong position to respond to changing demands in a market turnaround." Ferro Corp. The company's polymeric-type melt blendable Pyro-Chek LM is a brominated, low-molecular-weight polystyrene flame retardant with a minimum bromine content of 66%. In an HIPS system, other additives such as flow and impact modifiers, antimony trioxide, and black pigment for black applications often can be reduced. Typical UL 94V-0 loading levels of Pyro-Chek LM range between 12% and 15%, with antimony trioxide synergist between 3% and 4%. V-2 FR HIPS systems require Pyro-Chek LM loading of 4% to 8% with 1% to 2% antimony trioxide.

According to Ferro, test evaluations indicate that at detection levels of less than one part per billion, the product produces no polybrominated dibenzodioxins and dibenzofurans. Initially aimed at the HIPS market, Pyro-Chek LM has proven effective in flame retarded ABS systems as well and is finding application in HDPE, nylon, polybutylene terephthalate (PBT), and other proprietary resin systems.

Other Pyro-Chek flame retardant products are 68PB and 60PB dibrominated polystyrene. All three Ferro products can be supplied as a very fine powder; as a coarse powder, for lower temperature applications in which the flame retardant polymer cannot be dissolved into the matrix; and as a granule for more dust-free handling. FMC Corp. Joseph Green, principal scientist, Polymer Additives, R&D, Phosphorous Chemicals Division of the FMC Corp., says that PB-460 brominated phosphate, containing 4% phosphorus and 60% bromine, is an efficient flame retardant for polymers containing oxygen, such as polycarbonate, PBT, and PET, as well as in polycarbonate blends with PBT, PET, and ABS.

PB-460 has also been used as a melt-blendable flame retardant for PET fiber. PBa 370, brominated phosphate containing 3% phosphorus and 70% bromine, is of interest for polypropylene resin and fiber.

Only 6% PB-460 is required to achieve a UL 94V-0/5V rating in a 3:1 ratio PC/ABS blend, and it maintains the V-0/5V rating even at a 1:1 ratio. Also, based on cone calorimetry data, the resins containing PB-460 showed significantly longer ignition time, lower heat release, and peak heat release rate. Ignition time divided by peak heat release rate correlates with flash-over time in an actual fire.

KPB-370 is melt blendable into polypropylene, resulting in excellent dispersion. Fibers have been spun and textiles have been made. GE Specialty Chemicals Blendex 975, a new weatherable modifier for rigid polymers requiring good outdoor aging, provides excellent UV and thermal stability. The company says that impact strength is improved, and PVC formulations using the product do not require other impact modifiers or process aids. Blendex 975 is an intermediate modulus ASA copolymer made from acrylic rubber, styrene, and acrylonitrile. It can be alloyed with PVC and other miscible thermoplastics for molding, extrusion, or calendering.

Also offered is Blendex 977, a blend of Blendex 975 with a UV inhibitor added to the polymer for increased UV resistance.

As polyolefin fiber manufacturers move into residential carpeting, a concern is prevention of gas fading/yellowing when the carpet is exposed to airborne pollutants, such as nitrogen oxides and sulfur oxides, in warehouses, homes, and offices. The company says addition of Ultranox 626 phosphite antioxidant minimizes the effects of gas fading/yellowing and opens new opportunities for olefin carpet. The material works as a synergist with UV stabilizers. GE says that HALS can be cut by almost 50% with addition of Ultranox 626 antioxidant, thus lowering costs while preventing discoloration. Great Lakes Chemical Corp. DP-45, functioning as a secondary plasticizer in flexible PVC systems and affecting flame retardance and reduced smoke properties; and CN-1427, an excellent enhancer of heat distortion temperature as well as a smoke reduction additive, have been targeted for the PVC markets.

In the nonhalogen flame retardant area are phosphorus-based CN-1197, for epoxy and polyester laminate, and CN-1511, for V-0 polypropylene. Also, development of several halogen-based flame retardants includes PDBS, a new polybromostyrene (formerly CN-323) for polyester, polyamide, and HIPS applications. A range of molecular weights can be produced, although currently only 10,000 and 80,000 molecular weight products are being offered. Additionally, two reactive monomers, DBS (dibromostyrene) and TFP (trifluoropropene) are available for incorporation of bromine or fluorine into a polymeric backbone through reactive chemistry. J. M. Huber Corp. The Chemicals Division of J.M. Huber Corp. says that development of new carriers, special grades for high temperature resins, and an emphasis on the foaming of recycled resins are among the current activities involving the company's Activex endothermic chemical foaming agents. The enhanced performance of Activex, offered as either 100% active fine powder or 25% active concentrates in a variety of polymer-compatible resin carriers, is attributed to its highly controlled gas evolution in both extrusion and injection molding. Current materials that are used to foam polymers include polyolefins, modified polyphenylene ether, PVC, polystyrene, ABS, polyamides, thermoplastic elastomers, and recycled PET. The company maintains that control of the gas evolution makes the product suitable for blow-molded designs that previously could not be foamed. Monsanto Chemical Co. Convinced that the plastics industry no longer is looking for broad-based flame retardant additives, Monsanto is focusing on additive packages to solve specific problems, as lower cost "total" solutions. Santicizer 2148 is projected as a fire resistant replacement for fluoropolymers in PVC compounds, as cable jacketing for data, voice, and signal distribution in the plenum areas of offices.

Phos-Chek P/40, which has UL 94V-0 ratings at 1/16 inch while keeping densities close to 1.0, is tailored for fire retarding polyolefins and their copolymers. Morton international Inc. The company offers a broad line of Vinyzene antimicrobial agents for thermoplastics, thermoplastic rubber, and polyester urethanes. More recent introductions have been biocides for rotational molded products.

Two new nonmetallic biocides offer good mildew resistance in vinyl and plastisol compounds. Added to Morton's existing Versamag magnesium hydroxide, Versamag UF magnesium hydroxide, and Elastocarb basic magnesium carbonate flame retardants/smoke suppressants is a system for rigid and flexible designs requiring minimal smoke.

A new low odor food-grade product, Advastab TM-404 methyltin heat stabilizer, is designed for PVC and PVC copolymer food packaging. Preliminary evaluations indicate a new standard for low odor performance, with enhanced stability for production of products with sparkle, clarity, and color.

A new generation of antimicrobials is based on isothiazolone chemistry. The isothiazolone products are expected to use the same basic chemistry with new carrier technology featuring enhanced processing and more compatibility in flexible vinyl systems. Vinyzene IT-3000 DIDP, a nonmetallic isothiazolone-based biocide, offers good mildew resistance in vinyl and plastisol compounds. Nyco Minerals, Inc. Dust control is an area of continued development for the company's specialty chemically surface modified wollastonite (Wollastokup) and other inorganic particulates for plastics. A $14 million program is projected to increase the company's production of wollastonite products by 50%. Improvements will include statistical process control and a new dust-free packaging system with highly accurate weighing capability. Occidental Chemical Corp. Dechlorane Plus H, for flame retardant HIPS applications, is a companion grade to Dechlorane Plus. Use of Plus H, with antimony oxide and other proprietary additives in HIPS, produces flame retardant materials with UL 94V-O ratings at both 1/8 and 1/16 inch, and a notched Izod up to 2.5 ft-lb/inch. The FR-HIPS formulations are nonblooming, nondripping in the UL-94 test, and have good ultraviolet stability.

R.L. Markezich, technical manager, Flame Retardants, says a benefit of using Dechlorane Plus to flame retard nylon is the ability to employ synergists other than antimony oxide to reduce loading levels. Owens-Corning Fiberglas Corp. Among a range of new or modified products are 158 Type 30 roving, featuring improved sizing for stronger glass-resin adhesion. Epoxy pipe, filament wound with 158, shows 15% higher burst strength than pipe made with 346, the current industry reference standard.

The company's 973 structural SMC roving enhances sheet processing by minimizing squeeze-out along the edges and improves sizing for automotive applications using 30% to 50% glass loadings. And 992BB roving, designed for translucent panels, has 16% better weatherability than other panel rovings, according to OwensCorning's 24-hr water boil tests. Quantum Chemical Corp. Quantum's USI Division's Spectratech FR 10107, a flame retardant polyolefin concentrate for extrusion of interior and exterior building panels, is based on alumina trihydrate. The nonhalogenated compound can be extruded as sheet for lamination to aluminum and plywood skins, as well as a flame retardant core between other materials.

The USI Division is working closely with agricultural film, drip tubing, and geomembrane extruders to develop black concentrates that have optimum processing characteristics and improved UV stability. The tailored Spectratech multifunctional black concentrates, which contain special antioxidant systems, also are designed to reduce die drool during cast film extrusion. Proper selection of black particle size provides optimum weatherability and processability. Rohm and Haas Co. The Plastics Additives business of Rohm and Haas offers an extensive family of Paraloid impact modifiers for viny) and engineering plastics. A range of recently developed additive products is based on the company's technology in glutarimide acrylic polymerization. Paraloid HT-510 copolymer, the first imide-based heat-distortion-temperature modifier for vinyl, boosts vinyl's service temperature about 43% over the previous high.

The Paraloid EXL-4000 series, based on imide technology, offer increased melt strength and heat resistance for nylon 6; better optical properties and heat resistance for ABS and SAN; and improved heat resistance in PET; and are efficient carriers for pigments and fillers for PC.

Other recent developments include Solacryl acrylic polymers, a family of products for capstock in coextruded vinyl windows and siding. Three polymer systems give superior color hold and weatherability. The capstock products have been under development for two years, including 24-month outdoor exposure tests in Florida and Arizona. The polymer systems enable the vinyl building products industry to expand with a wider, darker color range that resists fading and chalking.

Paraloid EXL-3611, an additive f or nylon, imparts impact strength at low temperature without loss of stiffness. Paraloid EXL-5375 additive is designed for better impact strength in polyester microwaveable trays.

Paraloid HT-510 imide copolymer for hot-fill vinyl containers complies with U.S. Food and Drug Administration regulations. The additive raises the service temperature of vinyl to 195[deg.]F, permitting hot-fill packaging of such foods as tomato sauce, pancake syrup, fruit juice, jam and jelly, and pickled food. Rohm and Haas says that HT-510 sets a new standard of 1.0[deg.]F per percent additive used, about 43% better than the previous high of 0.7[deg.]F per percent additive. Union Carbide Corp. Unistab D-33 liquid antioxidant for polyolefins, from Plastics Additives Systems, a business unit of Union Carbide's Specialty Chemical Division, is a 40% dispersion of a high molecular weight, hindered phenolic antioxidant in a functional fluid. The additive enhances resin quality and consistency by dispersing uniformly-and by promoting uniform dispersion of other additives-in the polymer matrix.

Unistab D-33 also can reduce yellowing in polymers by preventing phenolic antioxidant/catalyst residue reactions. Because it is available as a pumpable liquid, the product permits precision delivery and solves metering problems often encountered with solid antioxidants. The company says it is also easier and safer to handle than similar additives in powder form.

The liquid antioxidant is effective in a variety of thermoplastic polymers, including HDPE, LLDPE, PP, and nylon. It can be used in film, fine fiber, stretched tape, and molded parts, and is well suited for high processing temperatures. Uniroyal Chemical Co. Several new chemical blowing agents are being added to the company's Celogen, Kempore, and Expandex product lines. In the area of vinyl plastisol foaming and flooring and other end uses, manufacturers have desired a foaming agent that will impart less residual color than the azodicarbonamide grades, the primary foaming agents used for many years. These materials, which are yellow to begin with, often produce a cream tint in the foamed part, which must be hidden with pigment if a white or pastel color finished part is wanted. This yellowness, which may be caused by a small amount of undecomposed foaming agent, has become an issue where the choice is for very light flooring colors.

Uniroyal's development grade, a modified azo, has shown promise toward overcoming this color problem both in tests at the company's labs and in some end user evaluations. Plastisols foamed with the modified azo demonstrated Hunter b values (a measure of yellowness) two to three units lower than plastisols foamed with unmodified azo. These plastisols contained no pigment, and the implication is that equal whiteness can be obtained with significantly reduced pigment loadings. Uniroyal says that this conclusion has been confirmed by vinyl foam producers as well.

In the area of crosslinked polyethylene, special azo grades of Celogen R9370 have been available in limited quantities. The company has recently increased its capacity for these additive types, and also has experimented with modified versions to meet demanding processing requirements while achieving maximum density reduction and retaining the very fine cell structures.

Uniroyal also has been working with its Expandex line of high temperature tetrazole-based foaming agents. Expandex 5-PT, 5-phenyl tetrazole, is a popular foaming agent for PC. A modified liquid tetrazole, available for sampling only, has a decomposition temperature and use range similar to that of 5-PT. In addition to the potential benefits of its being a liquid, lab testing indicates that use of the additive results in PC foams with higher impact at equal density, compared with 5-PT foamed PC.

Other higher temperature tetrazoles, Expandex 150 (use range of 640[deg.]F to 690[deg.]F) and Expandex 175 (use range of 700[deg.]F to 745[deg.]F), have also been experiencing increased levels of interest.
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Title Annotation:industry updates
Author:Wigotsky, Victor
Publication:Plastics Engineering
Date:Jul 1, 1991
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