Materials.

Materials

New alloys offering a wider range of property combinations and novel grades that provide enhanced processability for existing product lines represent the developments for engineering TPs introduced at NPE. Developmental PPs with significant new properties--from ultrasoft to super hard--and better processability for applications from appliances and autos to packaging were also seen. The new PPs include reactor-made copolymers and alloys and compounds made with new additive technology.

CLEAR, TOUGH ALLOYS

Four new injection molding grades in the Zylar ST series, engineered to provide high clarity, stiffness and impact resistance, are being introduced by Novacor Chemicals Inc., Leominster, Mass (see table).

The four Zylar grades are copolymers and terpolymers based on a proprietary compatibilization technology that combines acrylic, styrene and butadiene. Priced between $1.22 and $1.43/lb tl, the Zylar ST series features superior mold-flow properties with melt processing temperatures below 430 F, according to Courtney L. Gibbs, marketing operations manager for Clear Performance Plastics. He also says Novacor is developing extrusion versions of the Zylar ST line.

All four grades have a specific gravity of 1.05, a gloss reading of 150, and a haze rating between 2.8 and 3.1%. The four alloy grades have a refractive index of 1.56, and a light transmission reading between 87% and 88%. In addition, all four grades have a water-absorption rate of 0.1% for 24 hours, and a mold-shrinkage rate of 0.004 in./in.

Along with clarity and toughness, the Zylar ST grades offer property advantages in medical device applications, exhibiting resistance to alcohol--a typical weakness for acrylic grades. The Zylar ST series also offers stability to gamma sterilization, with regard to color and property retention.

NEW NYLON GRADES, ALLOYS

A new thermoplastic alloy that pairs nylon 6 as a matrix resin and an unnamed functionalized olefin as the dispersed phase is debuting in two developmental grades from Akzo Engineering Plastics Inc., Evansville, Ind. Steven R. Gerteisen, manager of new product development, says the new unnamed modified nylon alloy, designed strictly for injection molding, is being introduced in two versions: M (unfilled) and M1915 (30% glass filled).

Gerteisen says the proprietary technology to create the new alloy includes a separate polymeric compatibilizer as well as a reactive extrusion process. The alloy was designed as an intermediate material to fit a cost/performance gap between reinforced nylon and PP. The new alloy offers a two-thirds reduction in moisture absorption compared with standard nylon 6 grades for increased dimensional stability, while providing faster cycle times compared with glass-filled PP, he says.

Both versions of the new alloys are now available for test market sampling and are expected to be fully commercialized by the end of the year. M1915 is priced at $1.63/lb tl, while M1914 is priced at $1.92/lb. M1915 has a specific gravity of 1.26, tensile strength of 17,200 psi, flex strength of 23,000 psi, flex modulus of 1.1 million psi, elongation of 4.3%, notched Izod of 1.6 ft-lb/in., and HDT of 330 F (at 264 psi).

A new series of flame-retardant, glass-filled nylon 66 grades is being introduced to expand the Ultramid line of BASF Corp., Parsippany, N.J. All of the new grades are rated UL94 V-0 at 1/8 in. While the new compounds employ a phosphorous flame retardant, they do not contain a cadmium-based heat stabilizer, which results in improved phosphorous stability for low-smoke density and toxicity, according to the company. New Ultramid grades include A3X2G5 and A3X3G5, both 25% glass filled; A3X3ZG5, 25% glass filled with an impact modifier; A3X2G7 and A3X3G7, both 35% glass filled; and A3X3G10, 50% glass reinforced.

New enhancements to the Zytel line of Du Pont Co., Wilmington, Del., include a series of new intermediate toughened grades that exhibit reduced mold deposits, and a new series of high-impact, super-tough grades with improved weatherability, gloss retention and color stability.

BLOW MOLDING POLYESTERS

Du Pont also is introducing a new family of Selar PT polyester resins that incorporate Du Pont's "high-melt viscosity" (HMV) technology, which permits the polyester resin to be processed by extrusion blow molding (PT, Feb. '91, p. 23).

A company spokesman would not reveal details of the HMV technology, saying only it was a rheology modification process that provides control over the resin's molecular weight, melt strength, crystallinity and toughness--factors that help broaden the material's processing window. The spokesman says Du Pont's new Selar grades have a lower molecular weight than comparable grades of extrusion blow molding polyesters recently unveiled by Goodyear Tire & Rubber Co. and Eastman Chemical Co. (see PT, June '90, p. 62). "Our grades are not as dependent on molecular weight for melt strength, and are not as shear-sensitive as competing resins," he says.

Two new grades of Selar PT being introduced for blow molding applications include PTX267, a homopolymer with an inherent viscosity of 0.95. The resin is priced at about 90 [cents]/lb tl, and is suited for larger bottles requiring handles. PTX279, a copolymer with a 0.91 inherent viscosity, is priced at about 82 [cents]/lb tl and designed for smaller bottle applications.

HIGH-FLOW ACETAL COPOLYMERS

Four grades of super-high-flow acetal copolymer, with melt-flow rates reaching as high as 90 g/10 min, are new additions to the Celcon line of Hoechst Celanese Corp., Chatham, N.J. Company officials decline to reveal the technology used to improve the flow rates of the new acetal grades. They did say the resins are capable of filling thin-wall parts down to 0.012 in., while reducing cycle time by up to 20% compared with existing acetals and maintaining the resin's traditional stiffness, strength and toughness.

Celcon MM3.5S was originally developed as a material for computer diskette shutters, and has a melt-flow index of 75 g/10 min. The grade has HDT of 230 F (at 264 psi), tensile strength of 8500 psi, and a flex modulus of 300,000 psi. Celcon M900 and M520, with melt indexes of 90 g/10 min and 52 g/10 min, respectively, are targeted as general-purpose grades. Celcon MC750, with a melt index of 46 g/10 min, is a mineral-filled grade, offering flex modulus of 790,000 psi, high structural rigidity, and dimensional stability.

NEW UHMWPE GRADES

Hoechst Celanese extended recent developments in its ultra-high-molecular-weight PE line by adding two new grades to its Hostalen GUR line. Processability of the new grades is further enhanced through new mold-filling simulation software developed by Advanced CAE Technology Inc., Ithaca, N.Y., for the Hostalen GUR line. Hostalen GUR 5121 is a general-purpose grade with reportedly superior flow characteristics, while Hostalen GUR 5150 is a high-wear/abrasion resistance grade. The two grades have tensile strength of 7000 psi and elongation at break of 350%.

Besides these new injection molding grades, Hoechst Celanese also is debuting Hostalen GM 9445 HT, a UHMWPE film grade. Described as a "high-tenacity" material with improved puncture, tear and abrasion resistance, it provides cost savings for blown film applications through source reduction by allowing as much as a 40% down-gauging in film thickness compared with linear low and low-density PE.

NOVEL PPS GRADES

A new grade of PPS that targets electrical applications expands the Fortron line offered by Hoechst Celanese. Fortron 4665B6 PPS is a glass/mineral-filled grade optimized for high flow, with applications for electrical components operating between 110 and 240 volts.

Doug Perry, director of marketing, says the new grade's high comparative tracking index of 275 volts enables the new Fortron grade to maintain dielectrical properties and resist the formation of conductive paths. Fortron 4665B6 has a specific gravity of 2.0, tensile strength of 15,100 psi, flex strength of 25,500 psi, elongation of 1.3%, and a HDT of 500 F.

A developmental grade of glass-filled PPS, designed as a low-density material for cost savings, is being introduced by Phillips 66 Co., Bartlesville, Okla. The developmental grade, Ryton BR87, has a density of 1.22 g/cc and tensile strength of 10,000 psi. When fully commercial, Ryton BR87 is expected to cost about 20% less than Ryton R-7.

Three grades of electrically conductive PPS are being unveiled by Mobay Corp., Pittsburgh, expanding its Tedur line. The new grades KU1-9552, -9553, and -9554, provide electrical properties ranging from conductive to antistatic, and offer HDT of about 500 F (at 264 psi) and a specific gravity of 1.80, according to Thomas S. Renegar, technical marketing manager. Mobay also is launching a series of neat Tedur PPS resins, intended for coating, compounding, encapsulation, film and fiber applications.

HIGH-FLOW PC, ABS

A new family of high-flow polycarbonate, designed for enhanced melt flow while maintaining the impact performance of standard PC, extends the Lexan offering of GE Plastics, Pittsfield, Mass. Six new grades are being introduced in the Lexan SP series, two of which (SP1212 and SP1252) are 10% glass reinforced. Along with their improved processing characteristics, the SP grades provide equivalent mechanical, electrical and optical properties as standard Lexan grades.

Lexan SP1210 and SP1310, two unfilled grades, both have a specific gravity of 1.18 and HDT of about 230 F (at 264 psi). SP1210 has a melt-flow rate of 16.0 g/10 min, while SP1310 has a reading of 10 g/10 min. The SP1210 grade has notched Izod of 16.0 ft-lb/in., tensile strength of 8700 psi, flex strength of 13,000 psi, and flex modulus of 345,000 psi, with slightly higher readings for the SP1310 grade. Both grades offer a tensile elongation at break of 110% and Rockwell hardness of 124. Compared with standard Lexan, the Lexan SP grades average 40 [degrees] F less in HDT.

GE Plastics points out the Lexan SP line is dried and processed at significantly lower temperatures than standard Lexan, offering processing advantages for lower clamp tonnages and reduced injection pressures. Unfilled Lexan SP grades have a recommended melt temperature between 450 and 600 F, while the two glass-filled grades range from 520 to 580 F.

A new high-flow grade of ABS, designed to meet specific application needs for the small-appliance market segment, is being added to the Magnum line of Dow Chemical Co., Midland, Mich. Magnum 9700 HF (high flow) has a melt-flow rate of 6.0 g/10 min, notched Izod of 5.0 ft-lb/in., tensile strength of 5200 psi, flex modulus of 340,000 psi, and flex strength of 11,000 psi.

SUPER-HARD AND SUPER-SOFT PP

Himont Inc. in Wilmington, Del., part of the Montecatini/Montedison group in Italy, presented a paper at NPE on a major new resin alloying technology to produce new super-hard PP alloys--Hivalloy ("High-value alloy")--with enhanced properties like HDT of 275 F, notched Izod impact strength of 5.61 ft-lb/in., and flex modulus of 261 kpsi, along with "excellent stress crack resistance and process stability," according to Himont.

PP has been compounded with materials like nylon and HDPE before, but this may be the first compounding with an amorphous material like PPE. Hivalloy alloying technology melds various resins, including styrenics and PPE, with either PP or other polyolefins. Hivalloy resins are available in developmental quantities from a pilot plant in Lake Charles, La., with capacity of about 10 million lb/yr. They can be used as is, as specific high-performance alloys, or as compatibilizers to blend a variety of dissimilar polymers.

Preliminary work is also under way at Himont to see if Hivalloy alloying technology can compatibilize mixed post-consumer plastic resins in recycling, says Himont director of business development Ken Dargis.

Himont also showed samples of the first commercial soft film grades of PP made by its much bruited Catalloy process: grades KS-020P, with flex modulus of 56 kpsi, and KS-056P with flex modulus of 18 kpsi, for calendered and extruded sheet to compete with PVC in markets like geo-membranes and pond liners.

Also made by the Catalloy process were the first PP air-quenched blown film grade: KS-031P, KS-011P, KS-052P, KT-021P and KT-011P to compete with PE film or layer with PE. Catalloy KS-052P was demonstrated blowing three-layer coex film (HDPE/PP/HDPE) at the booth of Alpine American Corp., Natick, Mass., (see Extrusion section and PT, July '91, p. 11). Both KT-021P and KT-011P are also suitable for coex sealable film on conventional cast film equipment. Himont says Catalloy films offer softness and low flex modulus with good puncture and impact resistance, low seal-initiation temperature, wide hot-tack range, and outstanding gloss and clarity.

NEW CLARIFIED HOMOPOLYMER PP

Phillips 66 Co. announced a new clarified homopolymer, Marlex BP571. With a melt-flow of 25 designed for thin-walled injection molded containers and injection stretch-blow molded food packaging applications like peanut butter jars or bottles for dried juices. Clarification is a combination of an additive package and a proprietary process, Phillips says. Melt temperature for BP571 is 390-427 F, with faster cycle times than traditional PP because of its high MFR, according to the company. BP571 is available in developmental quantities and "at a slight premium" to standard PP.

WAITING ON THE FDA...

A new developmental PP with an interesting new acrylic-based stiffener was introduced by Rexene Corp. of Dallas (displayed at GE's Polymerland booth). Rexene's 9402M (modified) is said to be a tougher, faster-processing version of 9402. It targets applications like refrigerator liners, small-appliance housings, and truckbed liners, to replace ABS.

Modified 9402M has 195 kpsi flex modulus (vs. 170 for plain 9402) and tensile strength at yield of 4.4 kpsi (vs. 4.2 for 9402). The modifier is also said to prevent sag, improve cycle time and meet taste and odor requirements. "It gives improved efficiency in thermoforming because it changes the recrystallization point," says Rexene quality service manager Jim Corley. The additive is loaded at 3-5% levels, though 0.1-10% levels have been tested.

The modifier is a patented acrylic polymer developed by Rohm and Haas Co., Philadelphia (see PT, Oct. '90, p. 13). It's under development with several resin companies under secrecy agreements. FDA approval of the modifier is still pending. "Several food-packaging opportunities with thermoformed PP could be opened up when FDA approval of the modifier occurs," says Rexene's Corley. Another obstacle has been processors' ability to extrude coex sheet. (Rexene is working with Newcastle Industries Feedscrew Div. in Newcastle, Pa., to develop a more efficient extruder screw for PP, says Rexene PP marketing manager Doug Gottliebsen.) For an existing job, processors may also need new molds or modified tooling because of PP's greater shrinkage than other resins. [Tabular Data Omitted]

PHOTO : New Zylar ST alloy series from the Clear Performance Plastics Group of Novacor Chemicals Inc. combines the properties of high clarity and impact resistance.