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News update: flame retardants '93.

Flame retardants are seeing a renaissance of R&D activity, judging from an outpouring of new products and applications developments that is unprecedented in recent years. The news includes inorganic fillers and synergists, phosphorus compounds, intumescents, and halogenated types for all sorts of thermoplastics, thermosets and foams. What follows is a review of the past year's developments, many of which have been covered in previous issues.

NEWS IN INORGANICS

Inorganic flame retardants, such as magnesium hydroxide, have gained greater attention lately as potential alternatives to halogenated FRs. One supplier that has seen growing use of Mg([OH).sub.2] for this reason, especially in polyolefins, is AluChem, Inc., Reading, Ohio. In 1994, the company will introduce a clean (99.9%-325 mesh), mechanically ground magnesium hydroxide (based on natural brucite) with a 2.5-micron particle size. The product will be aimed particularly at wire and cable applications, where it reportedly could offer better retention of physical properties. It will be priced similarly to precipitated alumina trihydrate (ATH) in the mid-30[cts.]/lb range. (CIRCLE 31)

Meanwhile, AluChem recently introduced a silo-blended ATH product. A whole truckload is blended in a silo, explains sales manager Tony Barnhorst, to achieve more uniform particle size distribution. (CIRCLE 32)

Lonza Inc.'s Inorganic Chemicals Div., Fair Lawn, N.J., recently expanded its line of magnesium hydroxide products with the introduction of Magnifin H-5. A relatively new player in Mg ([OH).sub.2], Lonza has offered Magnifin H-7 and H-10 for the last four years. According to plastics market manager Steve Johnson, "The new H-5 allows us to meet UL 94V-O at lower loading levels in such polymers as PP and nylon." (CIRCLE 33)

Lonza has also developed a new line of proprietary coatings for its Mg([OH).sub.2]. Now in a semi-commercial stage, these products include silanes and other organic coatings that are said to be more compatible with certain polymers. Some of the coated Magnifin products are now being geared to injection molding applications. Johnson explains that up to now, Lonza has aimed its Mg([OH).sub.2] mainly at extrusion because injection molded parts have thicker walls and require higher loadings, which had been a problem. (CIRCLE 34)

Also new from Lonza this year is a second generation of coatings for ATH that are said to enhance dispersion in polyolefins and PVC. (CIRCLE 35)

In the last year, Morton International's Industrial Chemicals & Additives Div., Danvers Mass., introduced a new coated Mg([OH).sub.2]. Product manager Robert Stennick says the proprietary fatty acid coating on new Versamag T02 helps improve the rheological and physical properties of filled polymers, despite the required high loading levels--typically 50-60%. Versamag TO2 is targeted for extruded polyolefin sheet, wire and cable. (CIRCLE 36)

Also new from the company are two ultra fine grades of Versamag and

Elastocarb magnesium carbonate, which are milled products with very small particles for improved dispersion. Versamag UF is recommended for polyolefins and both rigid and flexible PVC. About 50% of the product's particlesize distribution is less than one micron. Elastocarb UF is for polymers such as EVA with processing temperatures lower than 400 F, since the filler's heat stability is similar to that of ATH. About 40% of the product's particle-size distribution is less than onemicron. (CIRCLE 37)

Two new magnesium hydroxide grades are available from Alcan Chemicals. First, BAX 1091 is designed for wire and cable, both thermoplastic and elastomeric. The product has an ultrafine particle size of 0.7 microns. Second, Flamtard M7 (5 microns) is formulated for injection molded and extruded thermoplastics and other polymers. (CIRCLE 38)

AmericaHaas (the Philadelphia-based joint venture of Ameribrom and Rohm & Haas), through an arrangement with Dead Sea Bromine and Dead Sea Periclase of Israel, is now importing several grades of FR-10 magnesium hydroxide (PT, March '93, p. 71). Both coated and, uncoated versions are available. According to AmeriHaas sources, Dead Sea Periclase is starting up a new, large-scale plant dedicated to this product. The manufacturing process produces large single crystals (2-3 microns) with a lower specific surface area than seawater-derived Mg([OH).sub.2], and also produces a lamellar form that is said to provide better processing and properties. Since its crystal aspect ratios are kept within a closely defined range, says AmericaHaas, FR-20 allows much higher flowability and better maintenance of polymer color than similar types of flame-retardant fillers. (CIRCLE 39)

Georgia Marble Co.'s Industrial Products Div., Kennesaw, Ga., where a high level of transparency is required. (CIRCLE 45)

New data are also available from U.S. Borax Inc., Valencia, Calif, on the company's Firebrake 415 zinc borate. While the company's standard Firebrake ZB grade releases its bound water at around 550 F, this newer version is stable at almost 780 F (PT, July '92, p.57). More recently, according to technical services manager Dr. Kelvin K. Shen, Occidental Chemical Corp. in North Tonowanda, N.Y., reported that tests in nylon showed that Firebrake 415 both enhances flame retardancy on its own and can improve the thermal stability of OxyChem's Dechlorane Plus 25 chlorinated organic flame retardant, thus increasing its processing-temperature window significantly. (CIRCLE 46)

U.S. Borax also recently presented data indicating that boric acid may have promise as a flame-retardant and smoke-suppressant synergist (PT, March '93, p. 71). (CIRCLE 47)

Buckman Laboratories, Memphis, Tenn., is looking to expand its line of borate-based FR additives. The company introduced last year a barium metaborate monohydrate called Bulab Flamebloc (PT, July '92, p. 57), which acts as a synergist with phosphorus and/or halogen. In many cases, it reportedly can replace antimony oxide on an equal weight basis; otherwise, it can allow reduced antimony levels. This product begins to release its bound water at around 392 F, and use levels are typically in the range of 3-10 phr. It is priced between 87 and $1.50/lb, depending on quantity. It is aimed at PVC, nylon and some other common engineering thermoplastics that are not processed at very high temperatures. (CIRCLE 48)

More recently, Buckman has been investigating different sorts of borate compounds, such as calcium borate, some of which could become commercial next year. The company is also looking into halogen-containing borate compounds.

Nyacol Products Inc., sub of PQ Corp., Valley Forge, Pa., has introduced a new FR pellet concentrate for polyolefins. EAM 3-8 contains antimony pentoxide (0.03 microns average) and a proprietary, melt-blendable brominated aromatic compound in a 4-MFR PP carrier for injection and blow molding and sheet extrusion. It's also avail able in an 8-MFR PP carrier for PP fibers. The same product reportedly works well in HDPE and some copolymers. The product's principal advantage is its low use levels--letdown to 1% active ingredient is said to be effective for a UL 94V-2 rating. The final product remains translucent and reportedly retains properties equal to those of virgin polymer. (CIRCLE 49)

Earlier this year (PT, March '93, p. 22), we reported on Nyacol's new ADP480 concentrate of colloidal antimony pentoxide and halogen in PP for PP fibers and molded parts. The company is also developing colloidal-sized nonhalogen concentrates, such as zinc borate and magnesium hydroxide which could be launched next year.

PHOSPHORUS & INTUMESCENTS

FMC Corp.'s Process Additives Div., Philadelphia, commercialized one of its developmental halogen, phosphorus-based products in May. Reoflam PB-460 contains both aromatic bromine and phosphorus in the same molecule, a combination that results in superior flame suppression, processability and improved resin properties (PT, March '93, p. 22). It is aimed at automotive, computer and business-machine parts molded of PET, PBT, polycarbonate and blends of these resins, particularly PC/ABS. More recently, FMC reports that it has demonstrated that phosphorus and bromine are highly synergistic in 2:1 polycarbonate/PET blends (see graph, p. 47). FMC principal scientist Joe Green provides this example: a UL 94V-0 PC/PET requires 12% of a typical brominated additive (containing 51% bromine) or 13% of triphenyl phosphate (9.5% phosphorus), compared with only 6% of PB-460 (60% bromine, 4% phosphorus). According to Green, similar synergy has been observed in PC/ABS. (CIRCLE 50)

Meanwhile, FMC anticipates commercially launching its developmental PB-370 in the fourth quarter. This product contains 3% phosphorus and 70% aliphatic bromine and boasts even better uv stability than PB-460. It will initially be aimed at PP fibers, textiles and molded parts. Green notes that the market has been awaiting a suitable flame retardant for PP fibers and textiles. "We expect great interest, here, in that PP is so much cheaper than flame-retardant polyester." Among the key advantages of PB-370 in molded PP parts is that the additive is melt blendable and as such, easily incorporated into the polymer. In addition, it maintains its white color and is not highly pigmenting, so less color pigment is necessary and color matching is easier. Use of 5% PB-370 with 2.5% antimony oxide in PP provides a 94V-2 rating, says FMC. Developmental work is also under way on use of PB-370 in molded ABS. (CIRCLE 51)

Another recently introduced flame retardant that looks promising in PC/ABS and other engineering-resin blends is Fyrolflex RDP, an oligomeric aryl diphosphate ester from Akzo Chemicals, Inc., Dobbs Ferry, N.Y. (PT, Sept. '92, p. 104). Containing 11% phosphorus, Fyrolflex RDP is low in color and high in FR efficiency at relatively low use levels. It is also said to be stable, less volatile and less plasticizing than other phosphorous FRs, and provides increased melt flow. Akzo reports that as little as 8% Fyrolflex RDP provides UL 94V-0 in PC/ABS at 1/16 in. when used in combination with small amounts of powdered PTFE. The company is currently exploring its efficiency in TP polyesters. (CIRCLE 52)

A novel nonhalogen phosphorus-based FR is available from EniChem America, Inc., N.Y.C. A thermoplastic pellet form of a phosphinic PET copolymer (6% phosphorus), EniFlam 6P behaves like a halogen in that it shows FR activity in both the vapor and solid phase (PT, March '93, p. 25). Applications include PET fiber, PC/PET blends, as well as nylon, polycarbonate, and even PP fibers or other thin-section PP products.

New intumescent flame retardants including phosphorus-, melamine- and other nitrogen-based products, have also been brought to the market in the past year. Such products foam up at combustion temperatures to form a thick insulating char layer. Suppliers say they require lower loadings (2530%) than inorganics like ATH and Mg([OH).sub.2]--causing less degradation of material properties--and have lower specific gravities that halogenated FRs (1.9 vs. 3.2 for decabromodiphenyl ethers), which translates into lower volume cost for the molder.

Hoechst Celanese Corp.'s Polymer Additives Div., Charlotte, N.C., is conducting trials of new Hostaflam TP AP750, an ammonium polyphosphate (APP)-based intumescent (PT, March '93, p. 25). This halogen-free, fine, white powder is aimed at PP and other thermoplastics. A 26% loading reportedly provides UL 94V-0 in PP at 1/16 in. According to Helmut Ricke, flame retardants marketing manager, AP-750 has overcome some of the limitations of Hoechst's Exolit IFR intumescent line. AP-750 has improved heat stability (550 F vs. 440 F) and much lower moisture sensitivity. The company hopes to offer AP-750 commercially in the fourth quarter. (CIRCLE 53)

Earlier this year, Great Lakes Chemical Corp., West Lafayette, Ind., commercialized the first two products of a planned new line of nonhalogenated, phosphorus-based intumescents for polyolefins and thermosets (epoxy and polyester). Both NH-1197 (previously called CN-1197) and NH1511, which has another nitrogen-containing compound blended in for added char formation, melt at 400-420 F. Also offered is MBR-40, a blend of NH-1197 with a small amount of halogen. (CIRCLE 54)

Also relatively new from Great Lakes are two low-viscosity liquid products with phosphorus, bromine and chlorine on the same molecule. Designated FM-836 and HP-36, they are said to provide high efficiency in urethanes and other thermosets. (CIRCLE 55)

Now fully commercial from the Polymer Additives Group of Albright & Wilson Americas, Richmond, Va., is Amgard NK, a novel intumescent for polyolefins based on an alkyl amine phosphate salt. Also offered is Amgard NP, a more efficient version with optimized particle-size distribution, (5-6 micron average). Alkyl amine phosphates are said to offer improved intumescent performance without the use of synergists such as pentaerythritol.

Amgard NK loading levels of 3040% are required to provide UL 94V-0 at 1/8 in. or 1/16 in. in PP, PE and EVA. The utility of these phosphorus compounds is greatly enhanced by the proper nitrogen and phosphorus ratio, apparently due to improved char structure. Studies by Albright & Wilson show that an optimum weight ratio of nitrogen and phosphorus of 1:6 greatly increases performance. Potential applications for these new flame retardants include molded cabinets, seating, and building panels. Flame retardants marketing director Robin Fourness says that in molded PP, low density and high efficiency make the Amgard products "as cost-effective as bromine-based flame retardants." (CIRCLE 56)

Meanwhile, the company recently reintroduced Antiblaze 1045. This bridged phosphonate ester is being produced at the company's new plant in Charleston, S.C. It is targeted for use in nylons and thermoplastic polyesters. (CIRCLE 57)

A newcomer to halogen-free flame retardants in North America is DSM Melamine Americas, Inc., Atlanta. Part of the Dutch international chemicals group, which claims to be the world's leading supplier of melamine, DSM Melamine Americas launched a range of melamine products in the second quarter of 1993. These have been commercially available in Europe for over two years. Five products are currently offered here, reports business development manager Remko Goudappel, including standard-grade melamine for urethane foam, and melamine cyanurate for nylon 6 and 66 and TPU. Typical use level to achieve UL 94 V-0 in unfilled nylon is 10%. R&D is exploring use of melamine cyanurate in glass-reinforced resins. (CIRCLE 58)

The other melamine products are aimed at polyolefins. Melamine 003 can be used as a component of a conventional intumescent system including ammonium polyphosphate and di-pentaerythritol. Melamine phosphates also have thermal stability adequate for use in polyolefins. Use levels of 25-30% are said achieve UL 94V-0. Not yet commercially available is melamine diborate, which has flame-retardant and smoke-suppressant properties, giving it potential in cable applications. (CIRCLE 59)

A non-intumescent melamine cyanurate flame retardant for nylons was launched earlier this year by Akzo Chemicals. A one-component system, Fyrol MC is active in the vapor phase, causing a dilution of combustible gases near the surface. Flame retardancy is further aided by the endothermic reaction of nitrogenous gas sublimation, resulting in lower combustion temperatures. This thermally stable additive can tolerate processing temperatures of about 570 F, Akzo says. Use levels as low as 6.5% reportedly can deliver UL 94V-0 in nylon 66; levels of 12-15% will do so in nylon 6. (CIRCLE 60)

Akzo also has a melamine phosphate called Fyrol MP. This developmental product is primarily intended as a synergist with other nonhalogen organic phosphates to improve flame retardancy of injection molded polyolefins. Use levels to achieve UL 94V-0 can run 8-20%, depending on the companion type of organic phosphate. (CIRCLE 61)

NEW HALOGENS, TOO

In response to increasing requests for flame retardants that can be directly reacted into the polymer, Great Lakes has developed a family of brominated reactive diols. The products, said to feature improved chemical and thermal resistance, can be used in urethane foams and elastomers and unsaturated polyester composites. (CIRCLE 62)

The company has also been developing new uses for its family of reactive brominated bisphenol-A carbonate oligomers tailored to meet different melt-flow and polymer compatibility needs (PT, March '93, p. 26). These low-molecular weight brominated polycarbonates are already used in PBT and are now aimed at ABS and HIPS. These additives reportedly act as flow enhancers and as compatibilizers of blends like ABS/PVC. Although priced in the range of $2.35-2.75/lb, with use levels of about 14%, the reactive carbonates are said to offer higher efficiency and uv stability than brominated epoxy oligomers. (CIRCLE 63)

For PVC, Great Lakes has two unusual products that have been marketed without fanfare for three years (PT, March '93, p. 26). One, called DP45, is a fully brominated form of DOP used as a plasticizer in wire and cable. The other, FR-756, is a disodium salt of tetrabromobisphenol-A, used in Europe in calendering compounds. (CIRCLE 64)

AmeriHaas says it has developed several grades of low-molecular-weight brominated epoxies within its new F2000 series for use in ABS and HIPS (PT, March '93, p. 26). These epoxy polymers and oligomers, which range in molecular weight from 700 to 50,000, are said to offer improvements in flow characteristics, impact and uv stability. F-2016, specifically designed for ABS, is said to be a more economical replacement for octabromodiphenyl oxide. (CIRCLE 65)

Several high-molecular-weight brominated epoxies, including F-2400, F-2300H and F-2400E, are also now offered by AmeriHaas for TP polyester, nylon, and blends of either one. They are said to feature improved flow, excellent uv stability, and enhanced thermal aging characteristics. (CIRCLE 66)

The company also says it is scaling up capacity for its FR-1025 pentabromobenzyl polyacrylate, slated for completion in mid-1994. This flame retardant is aimed at PBT and nylon, where it is reported to offer better flow than competitive materials, as well as exceptional uv stability. Due to its acrylic backbone, this white, meltblendable powder reportedly enhances wet-out of glass fiber reinforcements. (CIRCLE 67)

Elf Atochem North America, Philadelphia, added new Pyronil 63 (63% bromine) to its line of brominated phthalate esters earlier this year (PT, March '93, p. 25). This white free-flowing solid is aimed at styrenics and engineering resins. The product has a melting point of about 235 F that allows it to form a more homogeneous blend than most other filler-type brominated FRs. This characteristic reportedly helps retain physical properties such as impact strength and elongation. (CIRCLE 68)

The Functional Chemicals Div. of Himont Inc., Wilmington, Del., has supplemented its nonhalogen intumescent line with Spinflam MB 92/PP, a new low-halogen product containing ammonium bromide, a non-aromatic compound said to produce low smoke and noncorrosive gases (PT, March '93, p. 26). It's aimed at PP seating, electrical parts, pipe and fittings. Suggested loadings for UL 94V-2 are 4-5% for homopolymers and up to 8% for copolymers. (CIRCLE 69)

A new version of its Dechlorane Plus for use in HIPS is now offered by Occidental Chemical. (PT, March '93, p. 2). Addition of 18% Dechlorane Plus H with 4% antimony oxide achieves a UL 94V-0 rating at 1/8 in. and 94V-2 at 1/6 in. (CIRCLE 70)

Dover Chemical Corp., Dover Ohio, recently announced two new additions to its Chlorez line of chlorinated paraffins, both intended for flexible urethane foams. DD-9338 is a solid 23% chlorine/23% bromine compound with 15% melamine. Dover says the product also has potential in polyolefins and PVC. DG-9021 contains 4% phosphorus, 15% bromine, and 15% chlorine and is also said to have potential in epoxies. (CIRCLE 71)
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Author:Sherman, Lilli Manolis
Publication:Plastics Technology
Date:Sep 1, 1993
Words:3152
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