Friedrichshafen, Germany — A German research team is developing a way to mold biodegradable cellulose fibers in a project it calls "paper injection molding."

The work by Lüdenscheid, Germany-based KIMW Kunststoff-Institut Lüdenscheid was featured at Fakuma 2021 in Friedrichshafen.

KIMW Sales Manager Marius Fedler said that the material is, in fact, a biodegradable compound made from cellulose fibers, chalk and starch that can be processed like a thermoplastic by normal injection molding, including cases where hot runners are used.

Fedler says the Rapperswil, Switzerland-based IWK institute of materials and plastics processing technology at OST Eastern Switzerland Technical University has also supported KIMW in its work with the paper injection molding material.

Fedler pointed to a molded rectangular box displayed at the booth as having been molded with a Frankenberg, Germany-based Günther Heisskanaltechnik GmbH hot-runner system. Fedler said that the material doesn't leave any deposits on injection mold surfaces.

Parts molded in the material can be composted in conventional industrial compost plants that are used for established biodegradable plastics, namely under conditions of high heat and humidity.

But unlike many established biodegradable plastics, the KIMW material can also be composted in home composting programs, as these provide microorganisms that break down the material. KIMW left a 3- to 5-millimeter-thick spoon in the new material in such a composter and it disappeared entirely within five months.

Unlike conventional thermoplastics, this degradation progresses without leaving behind microplastic particles. The same applies to parts left in the open environment, Fedler said, although the rate of degradation is much slower then.

At Fakuma, KIMW showed a C-fix grip product, a device that enables doorknobs and handles to be opened without touching with the hand, a clear hygiene requirement during a pandemic. KIMW has distributed a large number of the C-fix "corona" grips in the Lüdenscheid area as a local contribution to combating COVID-19.

Some 18 companies have signed up for participation in the KIMW paper injection molding project, involving molders, packaging and medical components producers. Fedler rates the medical components area as particularly interesting, as single-trip biodegradable parts should have great appeal in the medical sector.

He added that Halver, Germany-based medical parts molder Meding GmbH has already introduced paper injection molding material into serial production. Meding has Arburg and Engel injection molding machines and can mold parts with injection weights of 0.1-3,000 grams.

Meding capabilities include foam molding, which is an area KIMW wants to investigate with the new material. But there are many other areas being looked at, such as coloring with color masterbatch, laser scribing through use of appropriate laser-sensitive additives, plasma vapor deposition, printing, welding and screw insertion. Fedler does not rule out some potential automotive applications, in view of that industry's pressing need to reduce CO2 emissions.

Moldings in the new material on display at the booth included a number of in-mold grained demonstration plaques, including a wood-effect grain. Such ability to mold structural graining is clearly of interest for automotive applications.

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