NPE 2000 News Wrap-Up: High-Volume Thermoplastics

NPE 2000 offered up new HMW-MDPE and HMW-HDPE film and molding resins with enhanced mechanical properties, plus new VLDPE resins, a hexene LLDPE with improved stiffness/ strength balance, and an LDPE for high-speed extrusion lamination. News in polypropylene included a grade for thin-gauge thermoforming, a resin specially tailored for blown film, and a novel family of PP-based copolymers for use as polymer modifiers and compatibilizers. Other show news included several advanced HIPS grades and an amber precolored PET for beer bottles.

 

HMW-MDPE for Film

A new class of lower density, bimodal HMW-PE produced with multi-reactor slurry technology was unveiled by Equistar Chemicals LP, Houston. The initial grade, Alathon XL 3805, has a density of 0.93 and MI of 0.05. Compared with typical HMW-HDPE, blown film made of this medium-density resin, exhibits improved contact clarity, softer feel, and improved tear resistance. At thicker gauges, tear and dart-drop properties increase dramatically over those of traditional 0.950-density HMW-HDPE. For 0.5-mil film, dart impact is 2.3 ft-lb and Elmendorf tear (MD/TD) is 20/40 g. At 4-mil thickness, film has 4.4 ft-lb dart impact and 420/750 g tear strength.

These new resins are aimed especially at blending with Equistar’s new Unipol-based Petrothene Select high-performance hexene LLDPE for blown film. The latter is said to have better processability and tear strength than mLLDPE. Blends can have an MI range from 0.05 to 0.924 and produce films with moduli from 100,000 to 47,000 psi. MD tear values of 250 g and dart impact of 1000 g are said to be achievable. These films combine the sealability of LLDPE with the stiffness of MDPE. Applications such as heavy-duty shipping sacks are a prime target. Downgauging of 30-35% is said to be possible.

Blends of up to 70% Petrothene Select in Alathon XL3805 reportedly maintain excellent high-stalk extrusion properties without need for a grooved-feed extruder. With conventional in-the-pocket extrusion and low BUR, films thicker than 3 mils are said to offer a balance of properties competitive with high-end hexene LLDPE. Using typical HDPE die gaps, film properties are said to improve further, so that gauges down to 1 mil can be extruded with the same balance of properties.

 

Paper-Like Film

Also new from Equistar is a stiffer bimodal HMW-HDPE film resin that is recommended for paper replacement. Alathon XL5906 has a secant modulus of 170,000 psi, which is over 40% higher than that of typical 0.950 density HMW-HDPE at the same thickness. Nonetheless, it boasts good dart-impact and tear strengths. Its MI is 0.57 and density is 0.959 g/cc. It reportedly provides good paper-like touch, feel, and stiffness at drawdowns below 0.4 mil. Coextrusions of XL5906 and a thin layer of LLDPE or LDPE are said to have high gloss and contact clarity together with paper-like stiffness.

 

HDPE for Large Parts

Equistar also fielded a new HMW-HDPE (0.950 g/cc) for large blow molded and thermoformed parts. Petrothene LP 5100 is said to combine excellent ESCR (over 1000 hr), high stiffness, and high melt strength. HLMI is 11.5. As a result, thermoformers do not have to trade off melt strength for ESCR. Large sheet is said to display low sag during thermoforming and can thus withstand longer “heat soaking.” Thermoformed parts are said to have uniform wall thickness and are free of wrinkles or creases.

Low sag is also an advantage in large-part blow molding. High tensile impact strength of over 200 ft-lb/in. is also important for large parts. Brittleness temperature is below -76 C.

Meanwhile, Nova Chemicals, Pittsburgh, has a new HDPE for blow molding small parts. Novapol HB-L354-A is an upgrade to Nova’s HB-L455-A. At 0.955 density and 0.30 MI, the new resin is said to have the same excellent balance of properties but also superior ESCR for HIC bottles, improved melt and impact strength, and excellent processability on high-speed, multi-head machines.

Nova also introduced a high-flow hexene MDPE for rotomolding. Novapol TR-0735-U (0.935 g/cc, 6.8 MI) is said to provide fast cycling for thin-wall applications and to have an excellent balance of physical properties. It is uv stabilized for outdoor use and has good ESCR.

 

Brawny Pipe Resin

Brand new from Equistar is Alathon L5040 bimodal HDPE for electrical conduit, potable-water pipe, geothermal pipe, and pipes for oil, gas, and mining. The 0.949-g/cc, 0.40-MI material reportedly offers very high ESCR (>1000 hr), very good low-temperature performance (-75 C brittleness temperature), and good retention of properties at elevated temperatures.

Novapol HP-Y353-A is Nova’s new HDPE for corrugated pipe. At 0.9353 g/cc and 0.30 MI, it boasts enhanced stiffness, improved ESCR, and excellent processability. It reportedly displays excellent melt strength for gauge control and corrugation formation, making it suitable for large and small diameters.

 

VLDPEs for Food Packaging

Two new Sclair VLDPE film resins (0.908 and 0.906 g/cc) that meet FDA requirements for food contact were launched by Nova Chemicals. The lower density resin offers exceptionally low seal-initiation temperature. A third grade (0.912 g/cc) meets FDA extraction limits for cook-in bags.

 

Stiff, Strong LLDPE Film

A new hexene LLDPE from Equistar Chemicals is said to provide an excellent balance of stiffness and strength compared with typical LLDPE. Film made with Petrothene GA 605 (0.930 g/cc, 0.6 MI) is said to have excellent optical properties and can be coextruded as a surface layer to improve the gloss of standard LLDPE and HMW-HDPE films.

One-mil blown film of GA 605 has MD/TD stiffness of 49,000/58,500 psi, the result of its higher density (0.930 MI), and an ultimate tensile strength of 8700/5400 psi. Film strength is said to beat that of high-MI hexene resins and to match that of lower density hexene LLDPEs that are less stiff.

 

LDPE for High-Speed Lamination

A new LDPE said to allow for high-speed, lightweight extrusion lamination and coating of flexible packaging is newly available from Equistar Chemicals. Petrothene NA214-000 (0.918 g/cc, 10 MI) reportedly can be drawn down to coating weights of less than 7 lb per ream at line speeds exceeding 1500 fpm without the edge-tear problems common with other LDPEs. This material is said to run especially well on lines equipped with edge-bead-reduction dies, and to provide minimum neck-in with excellent edge stability (i.e., no edge weave or tear). It reportedly has very good sealing characteristics and is suited for use in paper/LDPE/foil/LDPE structures and film-to-film laminations (treated or chemically primed).

 

PP for Thin-Gauge Forming

A new PP for thin-gauge thermoforming comes from Dow Plastics, Midland, Mich. It is the latest addition to Dow’s portfolio of PP produced with Montell’s Spheripol process. New H110-02N resin is said to offer improved deep-draw formability while providing outstanding stiffness, top-load strength, and clarity in applications ranging from drink cups and dairy/deli containers to microwaveable trays for fresh or frozen precooked meals. This is the first of several new thermoforming grades planned by Dow.

 

PP for Blown Film

Dow Plastics also introduced Inspire 112 blown-film extrusion grade, the first of its Inspire Performance Polymers family of specially-tailored PP resins. Dow will not reveal what catalyst type is used, but global new-business development manager Carlos Ruiz says Inspire resins are made using the same principles as those for producing polyolefins with its Insite metallocene technology.

With 0.4 MFI, Inspire 112 boasts better melt strength than other PPs, plus dart impact of 150 g and tensile modulus (2% secant) of 125,000 psi. It is said to have good clarity for liquid stand-up pouches and bakery-film overwrap. It also boasts good puncture resistance for heavy-duty shipping sacks; and it melts at over 320 F, offering high heat resistance for autoclavable bags. Pet-food bags, meat and poultry packaging, hot-filled bags, industrial bundling films, and thin-gauge films are other target applications.

The material is said to exhibit excellent bubble stability in both conventional and high-stalk, air-quenched blown-film lines. It can even run on PE film lines with only slight adjustments, Dow claims. The resin is also said to blend well with Dowlex octene LLDPE or Elite mLLDPE.

 

PP Copolymers for Blends

Montell Polyolefins, Wilmington, Del., introduced the first of its new PP-based Interloy Polymers family, designed as “building-block” materials to help compounders create new resin blends. Interloy copolymers of PP/PS and PP/PMMA are based on the same technology as Montell’s Hivalloy products, but are intended for use as modifiers for other polymers. At 10% or lower levels, Interloy reportedly can compatibilize blends of polyolefins and engineering resins. At higher loadings (15-50%) it can be used to enhance properties of other polyolefins and engineering resins.

For example, Interloy reportedly can enhance stiffness, tensile strength, and melt strength of PP homopolymers and copolymers. Interloy can also improve barrier properties, weatherability, printability, and performance in film lamination and metalization. It is also useful as a coupling agents in mineral- or glass-filled polyolefins.

Montell is also developing new Adflex and Adstif PP resins, made with its Catalloy process, for use as blending agents. “We now have Adflex products for impact modification that are equivalent to plastomers in performance and cost (70¢ to $1.05/lb),” says marketing manager Omar Boutni. By year’s end, Montell will introduce grades with improved cost/performance. Also to be launched later this year is a high-gloss Adstif grade with improved stiffness—300,000 to 350,000 psi versus 250,000 psi of current grades—for molded appliance and auto parts.

Montell has also started full-scale production of its new Pro-fax Ultra resins, which have 50 to 100 MFI right out of the reactor (no peroxide treatment). Now under evaluation is a 1700 MFR grade for use by compounders as a flow enhancer in place of peroxides that cause odor and discoloration.

Three Profax Ultra HMS (high-melt-strength) branched-PP grades are also newly offered to compounders to improve melt strength in deep-draw thermoforming or blow molding of large and complex parts. The grades are PF623 (18 MFR), PF633 (5.5 MFR), and PF814 (2.8 MFR).

Montell is also introducing its polybutene-1 resin to compounders as a means to improve creep resistance for peelable seals.

 

Advanced HIPS Debuts

An ignition-resistant HIPS for consumer electronics is the latest addition to the patented Styron-A Tech advanced HIPS family from Dow Plastics. Styron A-Tech 2220 is said to offer a unique combination of high flow (16 MFI) and “practical toughness” unmatched by other HIPS. It is said to allow for easy processing of large tv housings with excellent aesthetics—tight knit lines, uniform gloss, and good depth of color. This resin meets UL 94V-0 and has notched Izod impact of 2.0 ft-lb/in., tensile yield strength of 3000 psi, and Vicat temperature of 201 F.

At least three more Styron A-Tech grades will be introduced this year. Among them will be two packaging grades for extrusion and thermoforming. One is a stiff, tough resin for food-service disposables and packaging. It has 3.3 MFI and Vicat of 221 F. Its notched Izod value of 2.1 ft-lb/in. and tensile yield strength of 3600 psi compare with 1.8 ft-lb/in. and 3200 psi for the current leading high-stiffness HIPS, Dow says.

The second upcoming resin will be for low-temperature food packaging or food-service articles exposed to foods with high fat or acid content. It has a notched Izod impact of 2.7 ft-lb/in., versus 2.0 ft-lb/in. for the leading high-ESCR HIPS, according to Dow.

A third developmental grade is for extruded and thermoformed refrigerator liners. It is said to combine chemical resistance to foods and PUR foam blowing agents with easier thermoformability.

 

Amber PET for Beer

A precolored PET designed for beer bottles has been developed by Eastman Chemical Co., Kingsport, Tenn. AmberGuard PET is said to provide light protection at least as good as that provided by amber glass. The color is reacted into the backbone of the resin, eliminating the possibility of its extraction into the beer and ensuring consistent color quality, which is more difficult to achieve with color concentrates. The new PET has been designed for use as the outer and/or inner layer of structures that incorporate Eastman’s new Imperm nylon barrier nanocomposite, which entered commercial production last month. AmberGuard could also be used as a monolayer with a barrier coating. Sample quantities are available now, and full-scale production is being planned.