Antioxidants & UV stabilizers are 'cleaner,' more efficient.

The last year or two has been a fertile period for new developments in polymer stabilizers. Several new chemical types are just being launched or are approaching full commercialization. Recent introductions are characterized by low-dusting, easier-to-handle products. Multi-component blends continue to proliferate. Improved hydrolytic stability is a strong trend in phosphites. In uv stabilizers, all but a very few of the new entries are HALS types, including some low-cost versions and polymeric types with good permanence. There are even some entries in reactive uv stabilizers, although commercial progress for this category has been halting so far.

EASY-HANDLING ANTIOXIDANTS

Low dusting and ease of handling are continuing themes in antioxidant development. Recent introductions include the following:

* A pastille form of Irganox 1076 hindered phenolic is new from Ciba Additives Div. of Ciba-Geigy Corp., Tarrytown, N.Y. Irganox 1076FD resists dust formation, according to marketing director Joseph Puglisi. Also new is 1330 FF, a free-flowing, dust-free granular form of Irganox 1330 hindered phenolic.

* A new pastille form of Carstab DSTDP thioester from Morton International Chemicals, Danvers, Mass., is said to be easier to handle than standard flakes.

* New pelletized primary and secondary antioxidants are said to reduce dusting and ease pneumatic bulk handling without need for binders, says Michael Mashone, marketing manager of Uniroyal Chemical Co., Inc., Middlebury, Conn.

* A new addition to the Xantrix ADS (Additives Delivery System) from Montell Polyolefins' Functional Chemicals Group in Wilmington, Del., incorporates a liquid high-molecular-weight hindered phenolic in a free-flowing PP sphere.

BLENDS PROLIFERATE

Another thrust in the trend toward easier-handling antioxidants is the growing variety of multi-stabilizer blends in a single package.

Two new families of blends of high-performance antioxidants have been launched by Ciba. They combine a hindered phenolic (Irganox 1010, 1076 or 3114) with new high-performance phosphites that are hydrolytically stable. LC (Low-Color) Blends contain new Irgafos 12 phosphite and are aimed at color-critical PE and PP films and molded parts (see PT, May '95, p. 69). LM (Low-Melting) Blends include another new phosphite, Irgafos 38. When melted, these products have low viscosity and can be pumped or sprayed.

Ciba is also offering Irganox 311B FF and 313B FF - two new blends of Irganox 1330 phenolic with Irgafos 168 phosphite for PP slit film.

Earlier this year, GE Specialty Chemicals, Inc., Parkersburg, W.Va., launched its first liquid antioxidant blends (PT, May '95, p. 69). Weston 503B, 504B, and 505B contain different ratios of Weston 399 trisnonylphenyl phosphite (TNPP) and Ultranox 276 HMW phenolic.

Blends are just some of the new products to be commercialized in North America by Great Lakes Chemical Corp., West Lafayette, Ind., when it brings into full production a world-scale antioxidants plant in Tennessee late next year. One unit that is already completed will begin large-volume production of the NDB (No Dust Blend) family for polyolefins. NDB products use various phenolics as thermoplastic matrices to incorporate phosphites, uv stabilizers, and stearates into a free-flowing pellet (see PT, Dec. '93, p. 31). NDB and other Great Lakes blends were originally developed by EniChem of Italy, whose stabilizer business was acquired by Great Lakes last year (PT, May '94, p. 168).

Great Lakes will also be gearing up production of PAM (Phosphite/Amorphous) blends made by microencapsulating GE's Ultranox 626 phosphite with Anox 20AM phenolic (equivalent to Irganox 1010). The result is said to be a hydrolytically stable pellet that disperses efficiently.

Another Great Lakes blend family to be made in the new facility is called Anox TB, which combines a phenolic, a phosphite, and a thioester. These products are said to reduce yellowing in polyolefins without adversely affecting melt flow.

Mayzo Inc., Norcross, Ga., is developing more liquid antioxidant blends. Its first product of this type, launched in 1993, was BNX-1000, a synergistic blend of a hindered phenolic and four other antioxidants. Two developmental products are BNX-5000, a lower-cost version, and BNX-4000, which requires half the use level of BNX-1000.

PRIMARY ANTIOXIDANTS

Great Lakes Chemical recently introduced three specialty hindered phenolics. Anox 70 for polyolefin power cable is similar to Irganox 1035 and comes in granular and powder forms. Lowinox GP45 (powder and granules) stabilizes acetals, TP polyesters, and MBS impact modifiers for PVC. Lowinox HD98 powder is for nylons, where it can replace copper salts as a more environmentally acceptable option.

Mayzo has introduced BNX 1035, a powdered phenolic equivalent to Irganox 1035.

Ciba recently launched the first of a number of new products based on entirely new chemistry for improved long-term heat stability. Fiberstab FS 410 FF is a granular product based on hydroxylamine for use in PP and PE fibers. It is a basic stabilization package for use primarily by resin producers. It reportedly overcomes the hydrolytic stability problems associated with some phosphorus-based products and is very low in color.

Pilot quantities are currently available of a new hindered phenolic based on thio-bis-monobutylated paracresol. Initial trials with Prodox 46S from PMC Specialties Group, Cincinnati, show that it offers excellent color stability in LDPE.

Another new hindered phenolic from PMC, now in early commercialization, is Prodox 316. It's based on distyryl paracresol and is intended to compete with workhorse Irganox 1076 as a low-cost liquid antioxidant. PMC is also now offering Prodox 1010, 1076, and 3114 hindered phenolics (equivalent to Ciba's similarly designated Irganox products), as well as Prodox 168 phosphite (equivalent to Ciba's Irgafos 168).

By year's end, Uniroyal Chemical will bring out Naugard EL, a new line of "synergistic" antioxidants for wire and cable. The company won't release further details at present.

Hoffmann-LaRoche Inc., Industrial & Agricultural Products, Nutley, N.J., will bring out a powder form of its Ronotec 201 liquid alpha-tocopherol (vitamin E) stabilizer next year. Ronotec 201 is designed to replace BHT without use of secondary antioxidants or hindered phenolics in PP fibers, HDPE milk and water jugs, and HDPE packaging films. Ronotec 201 liquid sells at three times the price/lb of hindered phenolics such as Irganox 1010 and 1076. However only 20% as much Ronotec 201 is required, so the use cost is actually 40% lower than that of traditional hindered phenolics.

New data confirm the lower taste and odor conferred by vitamin E. Earlier studies at the Rutgers University Center for Advanced Food Technology in New Brunswick, N.J., showed that vitamin E reduces objectionable taste and odor in HDPE water jugs, as compared with either BHT or Ciba's Irganox 1010. A more recent Rutgers study, verified that addition of vitamin E to packaging-film resin dramatically lowers the level of volatile aldehydes, compared with packages containing traditional hindered phenolics, thereby reducing off-taste and odor. Aldehydes are among the most potent odor-causing substances; their presence is noticeable at levels as miniscule as 0.1 ppb [ILLUSTRATION FOR FIGURE 1 OMITTED].

The German parent company of BASF Corp. Colorants, Mt. Olive, N.J., recently came out with its own patented vitamin E product called Uvinul 2003 AO. This liquid is aimed at PP, HDPE, ABS, and PUR foams.

SECONDARY ANTIOXIDANTS

The first of a new family of solid phosphites based on a novel butyl ethyl propanediol chemistry in place of traditional pentaerythritol derivatives has been developed by GE Specialty Chemicals. Polyolefins business leader Paul Roscoe says new Ultranox 641 meets customer needs for a high-activity stabilizer with superior hydrocarbon solubility and improved handling.

Available in a pastille, the product exhibits synergism with hindered phenolics and thioesters similar to that of pentaerythritol-based products, as well as excellent hydrolytic stability. Ultranox 641 is stable up to 575 F and is typically used at lower levels (0.05 to 0.1%) than those required with many other phosphites [ILLUSTRATION FOR FIGURE 2 OMITTED]. It is also said to offer good gas-fading performance. Price will be competitive with other solid phosphites.

The product recently received FDA approval. Initial targets are polyolefin films and fibers. Other potential uses include molded polyolefins, PET, PBT, styrenics, and specialty PVC applications. Initial commercial quantities are expected by mid-1996, and full production is slated for early 1998.

Doverphos S-9228, a HMW pentaerythritol diphosphite, is now fully commercial from Dover Chemical Corp., Dover, Ohio (PT, Dec. '93, p. 29). S-9228 is structurally similar to GE's Ultranox 626. It is said to show better hydrolytic stability than other diphosphites without need for inert fillers or tri-isopropanolamine (TIPA). S-9228 is for use in polyolefin films, fibers, and molded products. Its high melting point makes it suitable for resins processed at more than 500 F. Current price is around $10/lb.

Dover has also introduced a new high-purity liquid tris-nonylphenyl phosphite (TNPP). Doverphos HiPure 4 contains a maximum of 0.1% residual nonyl phenol, whereas most TNPPs reportedly have levels of 0.3-0.5%. Enhanced hydrolytic stability reportedly can be achieved with a minimal amount of TIPA, and there is no effect on the level of residual nonyl phenol. The product is FDA-sanctioned for food-contact packaging and medical devices.

HALS: WHERE THE ACTION IS

Ciba Additives has added three new low-dusting HALS to its Performance Plus product line for polyolefins. Designed for demanding applications, they reportedly can replace traditional workhorse HALS such as Ciba's Chimasorb 944 and Tinuvin 622. At similar use levels, the new grades are said to offer superior performance at lower cost.

* Tinuvin 783 is a HMW HALS that has FDA approval for food contact at high use levels (up to 0.6%). It's suitable for fibers and rotomolding [ILLUSTRATION FOR FIGURE 3 OMITTED].

* Tinuvin 111, also HMW, is for agricultural film because it has very low interaction with pesticides and low color. It's also recommended for TPOs.

* Tinuvin 791 has a broad MW distribution and is aimed at thick sections.

All three products are in free-flowing bead form (FB grades) while 783 and 791 also come in granules (FF grades).

BASF, which came out with its first two HALS in 1993, now has a third, Uvinul 5050 H (PT, Nov. '93, p. 36). It's a low-melting granule aimed at all types of polyolefins and also nylon.

Great Lakes Chemical recently introduced Lowlite 76, a monomeric HALS for low-color applications. The product, which melts at room temperature, is designed for liquid systems such as PUR and unsaturated polyester. It can also be used in liquid-color concentrates for polyolefins.

The company is also now offering Lowlite 77 HALS (which competes with Ciba's Tinuvin 770) in a low-dusting, 2-mm micropellet.

Hoechst Celanese Corp., Specialty Chemicals, Charlotte, N.C., which entered the HALS market a couple of years ago, will be able to supply North America with commercial quantifies of its Hostavin N-30 and N-20 products when its new 4-million-lb/yr plant in Germany starts up in January (PT, Nov. '93, p. 35). Hoechst is developing new versions of N-30 that will offer even greater extractions resistance.

Ferro Corp.'s Bedford Chemical Div. in Bedford, Ohio, has been in full production of its first HALS product, UV-Chek AM 806, since mid-1994 (PT, Nov. '93, p. 38). A complex oligomeric ester, the product has been aimed at polyolefins, TPOs, and nylon. Ferro is developing a synergistic blend of AM-806 and UV-Chek AM-340 hydroxybenzoate ester.

PMC Specialties is the latest addition to the ranks of HALS suppliers. It offers Univox 770, an equivalent to Ciba's Tinuvin 770.

Montell is offering new Xantrix ADS concentrates that carry high levels of liquid HALS in a free-flowing PP sphere. One incorporates a HALS that is said to be more tolerant of acidic pigments than traditional HALS.

REACTIVES PROGRESS SLOWLY

Great Lakes continues research on reactive HALS, but business director John Boles is cautious about its potential: "While we have the fundamental technology, we don't yet know if there is a market for it. Work on reactive HALS in the industry has been taking place for over 15 years, yet nothing commercially viable has been introduced." (Philadelphia-based Elf Atochem North America, which launched several reactive HALS in 1993, is no longer actively pursuing these products.)

However, Clariant Corp. (formerly Sandoz Chemicals), Charlotte, N.C., plans to offer commercial quantities early next year of a new type of light stabilizer with reactive functionality. Described as both a HALS and a uv absorber, PR31 is a low-MW methylated tertiary HALS (Clariant also plans to offer an acetylated version). The product remains mobile within the matrix polymer, allowing it to migrate to the surface, where it becomes photo-reactively grafted to the host polymer when it is struck by light (PT, Dec.'93, p. 14).

It reportedly imparts very high light stability to organic pigments and has synergistic effects with other uv absorbers. It also shows very low reactivity with antioxidants and thus very low color. This free-flowing, non-dusting powder reportedly can be used in all polyolefin applications, PUR, ABS, TP polyester, and unsaturated (thermoset) polyester. Clariant has applied for FDA food-contact approval. After three years of test marketing worldwide, a commercial-scale plant is being completed in Switzerland.

And there is also action in reactive non-HALS stabilizers. Noramco Corp., New Brunswick, N.J., is now commercializing its reactive Norbloc 7966 benzotriazole (PT, Nov. '93, p. 35). Thanks to a methacrylate ester group, the new product can copolymerize with vinyl monomers or can be grafted onto unsaturated polymer backbones. It is designed for use with PVC, acrylics, PS, ABS, and SAN. It reportedly does not contribute to color. Commercial price is expected to be under $40/lb.

NON-HALS UV STABILIZERS

Great Lakes has three new benzotriazoles - Lowlite 55, 26, and 27 - designed for engineering thermoplastics, including ABS, polyester, PVC, and TPOs.

Mayzo has introduced BLS 1710, a hydroxyphenyl benzotriazole that is said to be equivalent to Tinuvin P.