New nucleating agent already seeing use in commercial polyethylene products

Officially introduced at the K show last October by Milliken, Hyperform HPN-20E already has made its way into commercial use, according to officials at the firm. Processors of extruded films, blowmolded bottles, and injection molded closures all are taking advantage of the new additive to help cut their cycle times and drive productivity improvements.

Nucleation of polyethylene has been mentioned in scientific journals for decades but it has not been commercially successful. Milliken has long supplied its nucleating agents to processors of polypropylene to help them improve that material's physical properties, notably clarity and processability, and claims its new agent for PE can do the same for processors of this material.

According to the supplier, the Hyperform HPN-20E agent enables higher peak crystallization temperatures that can cut cycle times and drive productivity improvements of 10-20%, depending on the process and exact grade of PE processed. It can also increase oxygen and water vapor barrier performance between 20-40%, so that for extruded film or blowmolded bottles, processors and brand owners have the option to either use a thinner-gauge film or thinner walls to maintain current shelf life, or increase shelf life of products with the existing thickness. Improved barrier performance also reduces evaporation, so that personal care product manufacturers need not overfill bottles and containers to compensate for volume loss due to the permeation of water vapor, nor would they need to add additional fragrances to ensure a long lasting presence.

The additive can be used in high-density polyethylene (HDPE) used in blown film, extrusion blow moulding and injection moulding, as well as in linear low density PE (LLDPE), especially C4 gas phase LLDPE. It works by raising the peak crystallization temperature of PE and significantly increasing the rate of crystallization, which means parts can be de-molded faster in injection moulding and extrusion blowmolding, and line speeds can be increased in blown film extrusion.

Used as a clarifier in LLDPE blown film, especially C4 gas phase LLDPE, the additive could enable processors to reduce the amount of LDPE used in a typical LLDPE/LDPE blend solution where LDPE is used to improve optics and not melt strength.

According to Milliken officials in the company's offices in Belgium, who were contacted by Plasticstoday.com, commercial

applications already making use of the nucleating agent include: HDPE barrier film for cereal & dry food packaging; HDPE extrusion blowmolded personal care bottles, with the agent offering cycle time reduction; injection molded closures for cycle time reduction and pigment leveling; HDPE extrusion blowmolded for pigment leveling and cycle time reduction; MDPE in rotomolding for cycle time reduction, and in LLDPE for clarification on agricultural film.

Hyperform HPN-20E is commercially available worldwide as a powder additive or as a masterbatch.