Milliken's Hyperform nucleating additive is making waves in a variety of injection molding and extrusion-thermoforming applications in packaging, automotive and appliances. Most recently Saudi polypropylene supplier National Petrochemical Industrial Company employed Hyperform HPN-20E in a new PP grade to achieve better shrinkage control and improved stiffness without affecting impact performance.
|Washing machine tub can be molded in a 13%-
plus faster cycle time by adding a Hyperform
Speaking at the recent 2015 SPE ASEAN Seminar in Jakarta, Indonesia, Niraj Pavagadhi, Technical & Application Development Manager, Asia Pacific - Plastic Additives, at Milliken introduced additional examples of where Hyperform HPN is assisting processors with cycle time reductions, eliminating warpage and sink marks, and delivering better clarity and lower haze.
For example, dimensional control of parts molded using pigment masterbatches is challenging with different colored pigments giving rise to different dimensions in the same product and uncontrolled changes in dimensions leading to rejects and productivity limitations. "When pigments are added to resins, the pigment particles act as nucleating agents but this can result in adverse effects such as warping, particularly for blue pigments," explains Pavagadhi. "Hyperform can eliminate this effect by creating isotropic shrinkage in the machine and transverse directions." Use of Hyperform HPN overrides the nucleation effect of pigments and enables shorter cycle time, higher productivity and high part quality regardless of the pigment.
Milliken's Pavagadhi introduced an example of Hyperform HPN-20E being used to increase the output of carbonated soft drink closures regardless of the pigment color used. Without Hyperform, the maximum output achievable was 520 caps per minute (cpm) for white pigment but this could be increased to 600 cpm with Hyperform without sink marks occurring.
The thermoforming process can also benefit from the use of Hyperform HPN-600ei according to Pavagadhi. In the production of thermoformed polypropylene (PP) cups, HPN-600ei improves optical properties like gloss, haze and clarity, and moreover, top load strength. "Converters often cold-feed PP sheet for thermoforming in order to realize clearer packaging but this can result in warping and chilled water is also required," notes Pavagadhi. "By using a HPN-600ei, haze becomes independent of roll temperature so you may get by with tap water. This will result into significant energy savings. Further, top load strength is improved." Another advantage is a wider thermoforming window.
Hyperform HPN has also used in an automotive door panel molded from a PP grade to reduce warpage. In the appliance field, meanwhile, addition of HPN-68L to a 40 MFR impact copolymer PP grade led to a 7-15% increase in productivity for molding of a 6 kg washing machine tub.