Generally amorphous polymers like Polystyrene (PS), Polyvinyl Chloride (PVC) and Polycarbonate (PC) have better clarity. PET is another polymer that provides excellent clarity despite its crystalline nature. Clear plastic products have better aesthetics and therefore command a premium when used in consumer products. PP is a widely used polymer on account of its lower cost and offers greater opportunity if it gets good clarity. Among the grades of PP, random or terpolymer offer the best clarity. However, it requires further improvement to match the clarity of PET.
Basell, the world's largest producer of PP and advanced polyolefins continually develops newer products. Recently it introduced functional PP grade using radiation technology- offering higher polarity due to introduction of either oxygenated components like alcohol of carboxylic acid groups. Oxypolypropylene is used as a dispersant for non-halogenated FR additives and as a component in engineering thermoplastic blends for better strength, melt flow rate and coloring. This additive is compatible with PC, polyesters, and other ETP.
Another grade from Basell - Metocene PP, has been derived from metallocene catalysis. Bottles made in Metocene grades can be blown on standard equipment. They are almost as clear as PET bottles-haze in sidewalls is 1.5%, and gloss is 82%, significantly better than conventional PP grades. Target applications are those where gas barrier needs are low, including flavored water, sports drinks, juices and applesauce, but not carbonated soft drinks or beer. They can be successfully used for moulded medical labware, optical disc cases, house wares, cups and containers.
Milliken has unveiled breakthrough clarity possibilities for polypropylene plastics with the launch of Millad NX8000. The material delivers previously unattainable levels of clarity, improving Clear polypropylene's ability to substitute clear materials such as plastics and glass in packaging and other unexplored product areas. It offers a step change in haze reduction compared to existing plastics clarifiers. Its typical 50% reduction in haze versus the current industry standard makes highly-transparent polypropylene an achievable reality for converters and end-product specifiers. PP clarified with Millad NX8000 can be used in applications such as food contact without imparting taste or odour onto the product. This enhances the already attractive package of unique benefits offered by polypropylene which includes low cost and density, stiffness/impact balance, and thermal and chemical resistance. Furthermore, PP clarified with this can be processed using all available technologies, allowing plastics converters and product designers to create attractive parts or plastics packaging regardless of the part design or process used.
In another innovation, Milliken has introduces clarified polypropylene plastics as a better option than PET for glass replacement in packaging applications Clear polypropylene (PP) clarified with Millad* 3988i. Not only does clear polypropylene have the potential to be a less-expensive plastics packaging solution than PET, due to a combination of raw material cost and lower density, but it may also deliver excellent clarity plus the added benefits of improved moisture barrier performance and higher hot-fill temperatures.
Before the advent of Milliken's advanced clarifying agents, PP was frequently not a practical plastics packaging material due to its haziness. Millad 3988i clarifier, a third-generation sorbitol acetal technology, produces excellent clarity suitable for most see-through packaging applications. In addition, compared to PET, PP offers the following benefits: Lower density C With a specific gravity of 0.9 g/cm3, PP is less dense than PET (1.27g/cm3). By requiring less PP per unit, manufacturers can save on material costs. Higher temperature resistance -- PP is much more heat-resistant than PET, making hot filling easier. Above 80 C, PET typically loses its integrity, while PP can withstand temperatures of up to 130 C. 2x-3x better moisture barrier performance C PP has a distinct advantage over PET in vapor barrier performance. Improved protection against moisture permeation helps protect contents and extend shelf life.
Polypropylene clarified plastics with Millad 3988i can be processed using one - or two-stage injection stretch blow molding and extrusion blow molding to make plastics bottles. The material is also suitable for injection molding, sheet extrusion and thermoforming.