The Toyota engineering standard, “TSM 5746G Thermoplastic elastomer molding materials for exterior use,” describes the requirements for thermoplastic elastomer materials, excluding soft polyvinyl chloride materials, for use in exterior moldings such as windows, roofs, and bumpers. Parts manufactured from the materials specified in this standard must comply with the prohibitions and restrictions on environmentally hazardous substances contained in the TSZ 0001G standard. Exempted uses as defined in the EU end-of-life vehicles (ELV) directive must comply with the latest version of the directive.
In the high-risk automotive manufacturing world, where every component must withstand weather conditions, vibration, and daily wear and tear, material properties are key to guaranteeing a vehicle's longevity and performance. Among these, the TSM 5746G standard stands out as a critical benchmark for thermoplastic elastomers (TPEs) used in exterior molding. This standard defines the required properties for materials that form protective seals and trim components on vehicle exteriors. As electric vehicles and autonomous driving technology push the boundaries of design, standards like TSM 5746G are vital.
Thermoplastic elastomers are versatile materials that combine the elasticity of rubber with the processability of thermoplastics. Unlike traditional thermoset rubbers, thermoplastic elastomers can be melted and reshaped repeatedly, making them ideal for injection molding in mass production. They provide waterproofing, noise reduction, and aesthetic appeal in exterior applications such as door, hood, and trunk lid seals.
The TSM 5746G standard was developed to ensure these materials meet demanding performance criteria. This standard addresses challenges common in outdoor environments, such as UV degradation, ozone resistance, and thermal cycling. Compliance with the TSM 5746G standard is also a way for suppliers to partner with one of the world's largest automotive manufacturers, influencing everything from material selection to supply chain logistics.
In short, thermoplastic elastomers are a class of copolymers or polymer blends that exhibit elasticity at room temperature but can be melted and reshaped when heated. They bridge the gap between rigid plastics and soft rubbers, eliminating the need for chemical cross-linking (vulcanization). Common thermoplastic elastomer families used in automotive exteriors include:
Due to their superior weather resistance, TPS (Styrene-ethylene-butylene-styrene) based compounds are dominant in premium external sealing systems, while TPV (Tourism-Variable Pressure Vessel) based compounds are preferred where higher compression set resistance is required.
The TSM 5746G standard includes a comprehensive testing methodology focusing on the physical, chemical, and environmental properties of thermoplastic elastomers. The key elements of this standard are as follows:
These requirements are verified using standardized methods such as ASTM D2240 for hardness and SAE J200 for classification.
Following the publication of this standard, global suppliers have made their classes of polypropylene-based thermoplastic elastomers compliant with it. For manufacturers, compliance means investing in advanced compounds, often including stabilizers, fillers, and compatibilizers, to achieve multiple goals simultaneously.
Meanwhile, balancing cost and performance is challenging, as high ozone resistance may require more expensive additives. Recycling pressures increase complexity, and Toyota's progress toward its circular economy goals requires thermoplastic elastomers that are both durable and recyclable, which in turn encourages innovations such as bio-based elastomers.
The TSM 5746G standard continues to evolve. Toyota’s commitment to carbon neutrality is driving updates that include lower volatile organic compound (VOC) emissions and potentially up to 30 percent recycled content thresholds containing post-consumer resin. With electric vehicles accounting for over 20 percent of global sales, standards are now placing more emphasis on weight reduction. Thermoplastic elastomers under the TSM 5746G standard must support thinner profiles without compromising seal integrity.
In conclusion, the TSM 5746G standard ensures that a modest exterior coating contributes to safer and more efficient vehicles.
For many years, our organization, with its competent and experienced staff, has been understanding the needs of its customers, providing the advanced testing services they require, and assisting in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services to businesses in accordance with the "TSM 5746G Thermoplastic elastomer formwork materials for exterior use" standard.
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