WEB EXCLUSIVE: Topas cyclic-olefin copolymer (COC) from Topas Advanced Polymers Inc., Florence, Ky., is known for its sparkling clarity in medical, pharmaceutical, diagnostic, and optical devices and packaging, but it is also gaining ground as an adjuct to polyolefins in coextrusions and blends.

WEB EXCLUSIVE: Topas cyclic-olefin copolymer (COC) from Topas Advanced Polymers Inc., Florence, Ky., is known for its sparkling clarity in medical, pharmaceutical, diagnostic, and optical devices and packaging, but it is also gaining ground as an adjuct to polyolefins in coextrusions and blends. It is used with polyolefins in films for twist wrap, shrink-sleeve labels, and sealant layers in food packaging. Blends are especially promising area of growth, where COC adds stiffness, heat resistance, and puncture resistance. Polyolefin/COC blends could replace polyolefin/nylon coextrusions in boil-in-bags, according to Topas sources. In thermoformable films, addition of 10% to 15% COC to LLDPE reportedly maintains clarity and allows downgauging by up to half.
Because Topas COC is amorphous, it can be used to reduce shrinkage in HDPE. It also is said to significantly reduce warpage in short- and long-glass reinforced PP. By making part shrinkage more isotropic—or uniform in all directions—it can be of particular benefit in LGF-PP automotive parts.
These merits have prompted Topas to launch the first of a series of TopasBlend ready-made compounds. As reported in our February review of new materials at the K 2010 show, there are now three PP/COC blends available, with HDTs of 140 to 150 C (284 to 320 F). HDPE blends will follow for uses such as steam-sterilizeable pharmaceutical bottles or caps.
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