Plastics Technology - Dedicated to improving Plastics Processing.
Issue link: http://pty.epubxp.com/i/827817
LyondellBasell's new PP random copolymer for caps, closures, and medical/pharmaceutical packaging boasts excellent homogeneity to meet high quality requirements in cast film extrusion and injection molding. PP in automotive bumper/grilles, side-sill panels, instru- ment panels, and door trim. Other target applications include wire & cable, due to easy processing, high elec- trical resistivity and heat resistance; and encapsulants for solar cells due to moisture and weather resistance and no lamination defects. Nexlene POPs, meanwhile, are characterized by enhanced toughness, excellent hot-tack and seal-initiation temperature, and superior transparency. Target applica- tions included packaging film (stretch hood, shrink, and silage); specialty film (thermal laminates and foam); industrial film (waterproof sheet, protective film); and specialty food-packaging films (barrier film, stand-up pouches, snacks, and processed-meat packaging). ADVANCES IN FILM, LARGE-PART FORMING Dow Chemical, Midland, Mich. (dow.com), discussed the latest on its Innate precision packaging resins launched in 2015. Made with a novel post-metallocene catalyst and a new pro- cess, these resins can incorporate various copolymers, according to Christina Serrat, application technology leader for packaging and specialty plastics. She said 1-mil film of Innate ST60 (0.85 MI, 0.918 density) exhibits significantly higher dart impact at similar mod- ulus and better optics than a competitive mLLDPE. In heavy-duty sacks, Innate shows outstanding toughness. In bag-in-box liquid packaging, Innate resins boast excellent stiffness/ toughness balance compared with mLLDPE. Moreover, Dow reports that downgauging with Innate shows a significant reduction in flex cracking. Overall, these resins are said to deliver film toughness without compromising stiffness or other properties. Houston-based Kraton Polymers (kraton.com) unveiled a developmental class of styrenic block copolymers. This new semi- crystalline block copolymer (SCBC) offers PE-like crystal- linity but is also said to be elastic, stiff, and strong. It is compatible with PE and can be used in conjunction with PE and oil to make elastic and soft compounds. Moreover, unlike conventional SBCs, the new polymers are resistant to oil and organic solvents. Other potential applications are elastic film for packaging, automotive soft-touch skins, and non-woven fabrics. Dow also discussed on-line compounding of TPO blends for large-part thermoforming and development in recent years of high- melt-strength (HMS) TPO for this purpose. Senior research scientist Kurt Koppi noted that TPOs have had limited acceptance in thermo- forming primarily due to processing issues: excessive sag, webbing, and inconsistent forming from lot-to-lot or within a lot. Key thermoformability findings, according to the Dow researchers, included the following: • For large-part thermoforming, slow sheet sag rate is desirable. • While with pre-compounded TPO, sag rate increases with sheet extrusion rate; the opposite occurs with on-line compounded TPO. • TPO made with POE/talc concentrate sags faster, while TPO made with PP/talc concentrate sags slower. • TPO sheet prepared via on-line compounding with a PP/talc con - centrate exhibits a sag rate very similar to that of pre-com- pounded TPO when sheet was extruded at a fast rate. • Such on-line compounded TPO sheets exhibit less thinning in the corners than those made of POE/talc concentrate. Dow says on-line compounded TPO sheet matches the perfor- mance of pre-compounded TPO sheet when a talc concentrate is used in the formulation vs. a POE. A simple single-flighted screw works as well as a high-performance screw for on-line compounding. And on-line compounding of TPO sheet offers the potential to reduce manufacturing cost by eliminating a separate compounding step. NOVEL ADDITIVES Solvay (through its Cytec acquisition—now Cyasorb Cynergy Solutions; cytec.com) unveiled two new proprietary stabilizers at the conference. Cyasorb Cynergy M535 UV stabilizer is designed for general PE injection molding applications, where it offers twice the performance of existing stabilizers at reduced concentrations. QUESTIONS ABOUT POLYOLEFINS? Visit the Polyolefins Zone and the Additives Zone. Unlike conventional styrene block copo- lymers, Kraton's new class of polymers is resistant to oil and organic solvents. 16 JUNE 2017 Plastics Technology PTonline.com P O LY O L E F I N S Close -Up On Technolog y