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Improving Hdpe Recycling

In order to advance the circular economy for plastics, all aspects of the recycling system must change, from collection to the expansion of end-use markets. The separation of all the different polymers that enter the recycling stream is one of the main problems the plastics recycling industry is currently experiencing.

The design of the package, consumer placement of products in the proper recycling bins, the capabilities of material recovery facilities, and finally the actual plastics recycling plants all contribute to the success of this separation at various points along the supply chain. For the purpose of producing useable feedstock for recycling, every stage of the supply chain is crucial.

Inseparable Materials Limit Recycling

Today, high-density polyethylene (HDPE) is one of the plastics that is recycled and used most frequently. However, polypropylene (PP) contamination is a significant issue in the recovered HDPE stream.

Because HDPE and PP both floats in the sink-float process, the main way to distinguish plastics globally is by density, PP specifically poses a barrier to HDPE recycling. The resulting recyclate becomes brittle and may not be able to meet the physical requirements of several applications, including blow molding and pipe, when PP levels in the recovered stream exceed about 10%. Typically, these bales are either landfilled or downcycled for use in lower-value industries.

The ideal package would be manufactured entirely of HDPE, including the closure and the container, in order to improve the quality of the HDPE recycling stream, lessen PP contamination, and maintain end markets.

Due to established closure designs, materials, and molding techniques, PP closures are used on blow-molded HDPE containers. A wide range of liquids works well in blow-molded HDPE containers, which are frequently used for shampoo, detergent bottles, automotive lubricants, drinks, and milk. The closures, on the other hand, have not been appreciably lightweight, therefore there is now a larger weight ratio of PP to HDPE in these HDPE containers.

Fortunately, new technology has been created that enables HDPE to take the place of PP closures, providing a whole package that is more recyclable while still maintaining the package performance criteria for HDPE bottles.

The Value of Monomaterial Packaging

The closures of HDPE blow-molded containers can be made out of HDPE rather than PP or other materials, which has two advantages for sustainability and improves circularity. Recycled HDPE resins have less PP contamination, improving the quality of the material. As a result, additional end markets can include HDPE made from post-consumer recycled materials in their goods and packaging.

The demand created by brand owners and consumer packaged goods firms for recycled packaging content helps to close the gap in supply by increasing the overall amount of usable plastics in the recycling stream.

There is a substantial supply of recycled HDPE (HDPE), including alternatives for food contact, thanks to the U.S.’s strong HDPE bottle recycling infrastructure.

Given the volume that is already available and the prospective expansion of rHDPE, an ample and dependable stream for HDPE closures should be accessible. A truly circular economy can be reached by switching to HDPE in the closure because both the closure and the container can be recycled and reused in the same package.

Advancements Enable the Monomaterial Capped Container

An entirely new future where HDPE is perfectly suited for caps on blow-molded bottles is made possible by advancements along the whole value chain, from materials to molding processes and designs.

Materials: This advancement in package sustainability is made possible by enhanced HDPE resin designs and formulas, which offer performance qualities. Bimodal resins exhibit the greatest advancement in the performance of environmental stress-crack resistance (ESCR) and creep resistance in today’s resins. Due to a combination of factors, HDPE can be used in these closures and lighter parts can be created that still meet application requirements while using less material and having a smaller environmental impact.

HDPE that is intended for recycling is also better suited to facilitate circularity. The shredded, recovered plastics are re-extruded during mechanical recycling, adding more heat and shear. The characteristics of the plastic may deteriorate throughout this intensive process. With their strong ESCR and creep resistance, modern HDPE resins are better able to incorporate higher amounts of degraded recycled content while still delivering a product that performs as well as closures made with 100% virgin resin. This is in contrast to earlier HDPE resins, which could only be used once.

The effects of the recycled component are further minimized by thoughtful stabilizing additive composition. This improves the quality of the recycling stream, enabling even larger levels of recycled material. Although HDPE can be supplied with large doses of antioxidants to make up for deterioration, this is not a long-term fix. Active and degraded additives are subject to Food and Drug Administration limitations, and cutting-edge additive compositions guarantee the longest possible cyclical life of plastic while still adhering to regulatory requirements. Modern HDPE is well-positioned to support a more sustainable future thanks to this forward-thinking design.

Molds and Mold Technology

In addition to being successful in converting conventional PP closures to HDPE, mould design and moulding advancements have taken advantage of the benefits of contemporary HDPE to push the boundaries of closures. A larger amount of recycled material can be successfully incorporated by designing moulds with the intention of accommodating the ESCR characteristics of HDPE and HDPE. The most recent hot runner technology, which controls resin temperature through the runner system and transfers resin from the extruder to the mould, has been very successful in enabling not only the conversion from PP to HDPE but also the achievement of HDPE closures with 100 percent recycled content.

Mold designers have also been successful in utilizing new material formulas to enhance the performance of the wall section and hinge to produce lighter parts without compromising on essential performance criteria. Making wise use of HDPE’s advantageous moulding properties has also made tool design and demolding easier.

The market for carbonated soft drinks, which frequently uses two-piece, mixed-material closures, has benefited from advancements in mould technology as well. The relative flexibility of HDPE has been leveraged by sophisticated designers to integrate higher-performance sealing technologies into durable and frequently ground-breaking single-piece closures. Since these closures lessen contamination in the HDPE stream, the recycled material as a whole is of higher quality.

An integrated Design

A mono-material package should be completely recyclable. We must be able to use all of the recyclable material from these packaging in order to fully close the loop and progress the circular economy. The brands may design their products with HDPE and rHDPE in mind thanks to integration across the value chain.

Brand owners no longer have to choose between functioning elements for their goods and materials that are optimized for the HDPE recycling stream thanks to technological advancements in resin, design, and moulding. HDPE is the ideal material for a sustainable future and can be utilized for blow-molded container closures.