Mitsui Chemicals boosting capacity for thermoplastic olefinic elastomerMitsui Chemicals boosting capacity for thermoplastic olefinic elastomer

Japanese resin supplier Mitsui Chemicals is expanding capacity to satisfy demand for Milastomer, a vulcanized thermoplastic elastomer (TPV) known for its low density, softness and processability. Construction work for 5000 tonnes/yr of additional capacity will commence in February 2017 at wholly owned subsidiary Sun Alloys Co., Ltd. and conclude in June 2017, with commercial operation start-up slated for October 2017. Currently Sun Alloys has overall compounding capacity of 60,0000 tonnes/yr for Milastomer and other Mitsui Chemicals products.

Mitsui Chemicals reports that demand has grown significantly for use in automotive materials, gaskets and civil engineering joint fillers, building materials, and grips, and is expected to continue to expand around the world in line with wider uses in automotive interiors and as weather strips.

In terms of automotive applications, Milastomer is employed in components such as resonator intake ducts, instrument panel skins, door trim, shift knobs, constant velocity joint (CVJ) boots, glass run channels, and weather strips.

TPVs are now the material of choice for glass run channels in vehicles manufactured in Japan. Although TPVs are more expensive than the traditionally employed EPDM rubber, overall costs are lower as a vulcanization step is not required for TPVs.

TPVs, however, have yet to make the same inroads into other type of weather seal components. They have has started to penetrate window seals (front and rear) although compression set properties are inferior to those of EPDM. TPVs have also penetrated to a certain extent in door seal applications (both body side and door side). These latter two applications are forecast for solid growth moving forward.

One drawback of TPVs, however, is that they have traditionally been difficult to foam to any great extent, meaning they have not been able to penetrate weather strip applications where EPDM can be foamed at a ratio of up to 70%, thereby reducing its density to 0.4. Hood and trunk seal applications typically use such high foaming ratios. Tier Is and material suppliers are, however, working on technologies to enable foaming ratios of up to 40%.