Long-fibre compound helps Danish moulder clean up

HP-Industrial turned to specialty compounder RTP Company for help in developing a compound that would meet the complex requirements of a seemingly simple industrial application.

To meet the stringent handling and sanitation requirements of the food and pharmaceutical industries, HP-Industrial, a Danish manufacturer of professional cleaning tools, wanted to develop an industrial broom handle that would eliminate areas where bacteria could potentially develop.

The design called for a one-piece broom handle with no joints or seams, and a surface that was both smooth and completely sealed.

HP-Industrial turned to specialty compounder RTP Company for help in developing a compound that would meet the complex requirements of a seemingly simple industrial application.

First and foremost, the handle required strength and rigidity.

It also required chemical and heat resistance to withstand repeated cleaning with hot water or steam, as well as various detergents and disinfectants.

The handle's length of 1500-2000mm demanded a material with high flow characteristics and a generous processing window.

Additionally, the material was required to meet the FDA's extraction limits for polypropylene, and be fully recyclable.

To meet these requirements, RTP Company recommended using an RTP 100 Series long glass fibre reinforced polypropylene compound with a flow enhancement package.

Unlike traditional methods of reinforcing plastics where increased modulus usually corresponds to a reduction in impact strength, the higher aspect ratios of long fibres absorb energy and distribute the load more evenly throughout the resin matrix.

The result is that both modulus and impact properties are increased simultaneously, making the long fibre compound suitably strong for HP's project.

Coupled with the material's high flow package, the long fibre polypropylene compound achieved a fully filled, structurally sound broom handle.

To accomplish the design requirements, an injection mould with a 2000 x 32mm long flow length was built, and an internal core was used to achieve a consistent 2mm wall thickness throughout the entire handle.

Processing adjustments provided a smooth, resin rich surface.

According to HP's Niels Sorensen: "The surface finish is equal to that of an unfilled resin; there is no visible evidence of the reinforcing fibres".

And, because of the compound's heightened resistance to creep and fatigue, the handle is able to hold dimensions well, both out of the mould and through time under load.

Added Sorensen: "Our handles are totally straight when ejected from the mould without any warp and almost without shrinkage".

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