Development of world first iron catalyst for silicone curing that does not rely on rare metals

As part of the "Development of Innovative Catalytic Processes for Organosilicon Functional Materials," a project commissioned by the New Energy and Industrial Technology Development Organization (NEDO), Kitasato University and Osaka Metropolitan University have been working on the technological development of iron catalysts for silicone curing. They have succeeded in developing and commercializing the world's first iron catalyst suitable for silicone curing through a manufacturing process that does not rely on rare metals.

The iron catalyst they developed was exhibited at the NEDO booth at "nano tech 2026" held at Tokyo Big Sight in Koto City, Tokyo Prefecture, from January 28 to 30. Additionally, Tokyo Chemical Industry Co., Ltd. began sales of the commercialized iron catalyst on January 21.

Silicone is a polymer compound composed of silicon and oxygen. The curing of silicone with platinum catalysts is used in the production of release coating agents and silicone rubber products, which are utilized in a wide range of fields from industrial applications to medical materials and daily living products such as cooking utensils.

However, the platinum catalysts are dispersed within the cured material, making separation from the product difficult, and most are not recovered. The amount is estimated to be equivalent to approximately 3% of the world's annual platinum production.

Platinum is a rare metal with limited recoverable reserves and restricted mining regions, presenting high geopolitical risks, and its price tends to fluctuate. As a result, it has become a factor that contributes to the instability of, and increase in, manufacturing costs of cured silicone materials. As a result, there has been demand for the development of cured silicone manufacturing technology that does not rely on rare metals.

On top of this, platinum catalysts are susceptible to poisoning by heteroatoms such as nitrogen, sulfur, and phosphorus, leading to the issue of curing inhibition in silicones where additives and functional groups containing heteroatoms cannot be used.

For this reason, attempts have been made to develop iron catalysts that can be used for curing silicone materials, but they lacked catalytic activity and air tolerance, and there were no examples of commercialization.

Therefore, NEDO promoted the development of manufacturing process technology for organosilicon functional materials through a commissioned project from fiscal year 2014 to fiscal year 2021. As part of this initiative, NEDO worked with Kitasato University and Osaka Metropolitan University to achieve the current results.

Their outcomes successfully achieved both high catalytic activity comparable to platinum catalysts and air tolerance by optimizing the molecular structure of the iron catalyst for silicone curing applications. Since the iron catalyst they developed has extremely high activity, it can be reduced to one millionth (1 ppm) by mass ratio relative to silicone, enabling the production of colorless cured silicone without coloration from residual iron.

When experiments were conducted in air under the same conditions as actual manufacturing environments, it was demonstrated that cured silicone could be obtained without problems. Silicone curing tests were conducted with various compounds containing nitrogen, phosphorus, and sulfur added to the silicone material. All silicones containing any of these additives cured without problems, demonstrating that the iron catalyst can be used for manufacturing silicone materials that are difficult to produce with platinum catalysts.

Since fiscal year 2022, following the end of the commissioned project, Kitasato University has participated in the Matching Support Phase of NEDO's "Intensive Support Program for Young Promising Researchers," and is currently continuing development with silicone-related companies in the joint research phase.

The aim of this is to reduce the dependence on rare metals in related industries and contribute to building a sustainable and stable industrial foundation, with expectations for the development of new materials that were difficult to manufacture with conventional platinum technology.