Inquiries

Heat-resistant automotive resins Chemical manufacturer G Company Research and Development Department

Advanced polymer alloys via heat-resistant monomer copolymerization

Improved heat resistance while maintaining moldability and transparency

Mobility
Resin Modification Surface Modification Durability/stability

Company G, a major resin manufacturer, was approached by a client automobile parts manufacturer seeking to improve the heat resistance of molding resins used in vehicle interior parts.

* This is a hypothetical example posted as a reference for those with similar challenges

Challenges

Countermeasures against rising temperatures inside a car. We want to improve heat resistance while maintaining moldability and transparency...

Mr. Z, a researcher at Company G, receives a call from the sales representative and attends a meeting with the client's representative.

Our client is developing interior components for their next-generation car models, and is considering improving the heat resistance of components used around the instrument panel to cope with the rising temperatures that are caused by the integration of interior functions such as sensors, displays, and lighting due to the recent advancement of electronics in automobiles.

"We were considering using transparent ABS resin for the instrument panel components, as it combines moldability, impact resistance, and transparency, but we heard that the lack of heat resistance of conventional transparent ABS resin was an issue," said Z.

The customer's request was to increase the HDT, an indicator of heat resistance, by 20°C while maintaining the moldability and transparency characteristics. Mr. Z first considered alloying highly heat-resistant polycarbonate (PC) with transparent ABS resin.

As Mr. Z had aimed, the target level of heat resistance was achieved, but transparency was reduced even when considering the type of PC and the alloy ratio. Therefore, as the next step, we considered alloying highly transparent polymethacrylate (PMMA) with transparent ABS resin.

"By adjusting the refractive index of both components, controlling their compatibility, and controlling the fine phase separation, we managed to create an alloy that maintained moldability and transparency. However, we were unable to achieve the target heat resistance..." (Mr. Z)

Therefore, we decided to consider improving heat resistance by replacing PMMA with a high Tg type PMMA. To make PMMA high Tg type, it is common to copolymerize highly rigid monomers.

Additionally, the area around the instrument panel is exposed to direct sunlight and is prone to temperature rises, so light resistance (to yellowing, fading, etc.) was also required. Therefore, we chose a copolymerization monomer that also took light resistance into consideration.

Mr. Z began to consider heat-resistant monomers for copolymerization, but he needed to select a monomer that would not reduce the light resistance and transparency of PMMA. His search for monomers with multiple requirements proved difficult.

Key Challenges

  • We received a development request to improve the heat resistance of molding resin as a heat countermeasure for interior automotive parts.

  • In order to achieve both transparency, moldability, and impact resistance, improvements were considered based on transparent ABS resin, and alloying with PC was considered, but although heat resistance improved, transparency decreased.

  • When considering alloying transparent ABS resin with PMMA, the target heat resistance was not achieved, so alloying with a high Tg type PMMA was considered. Heat-resistant monomers that can be copolymerized to improve the Tg of PMMA were investigated, but no satisfactory ones were found that were not only heat-resistant but also light-resistant and transparent.

Solutions

Solution Summary

  • IMILEX™-C (N-cyclohexylmaleimide) is a heat-resistant monomer that can effectively improve the heat resistance of copolymers.

  • Copolymerizing IMILEX™-C with MMA improves the heat resistance of PMMA, and alloying it with transparent ABS resin creates a molding resin with a good balance of transparency and heat resistance.

This heat-resistant monomer was introduced in the e-mail newsletter. By copolymerizing it with MMA and alloying it with transparent ABS resin, it achieves both improved transparency and heat resistance.

Mr. Z continued his research into heat-resistant monomers. One day, in his favorite Nippon Shokubai newsletter, he came across an article introducing IMILEX-C, a monomer that can improve the heat resistance of PMMA while maintaining its transparency.

The keywords of maintaining PMMA transparency and improving heat resistance gave Mr. Z an idea that this could also be applied to copolymer components of high Tg PMMA.

I immediately made an inquiry through the website, and a sales representative from Nippon Shokubai called me immediately. We explained the current issues and made an appointment for a technical consultation.

Mr. Z received a detailed explanation from the sales representative about examples of how IMILEX-C can be used and the know-how required for copolymerizing maleimide monomers.

Mr. Z used advice from Nippon Shokubai regarding copolymerization conditions for maleimide monomers to prototype a copolymer using IMILEX-C and alloy it with transparent ABS resin. The prototype alloy achieved the target heat resistance and was also satisfactory in terms of transparency and light resistance.

Mr. Z is relieved to hear that the prototype review is going well. After consulting with his boss, he is now preparing to present a prototype of an alloy of transparent ABS resin and high Tg PMMA copolymerized with IMILEX-C at a regular meeting with the client.

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