Q&A

1. Flame retardant requirements

ABS resin has excellent moldability, molded product appearance, and mechanical properties, so there is a high demand for flame-retardant grades in the electrical and electronic fields, primarily for use in copiers and printers. The demand for flame retardancy in these electrical and electronic fields is regulated by IEC, UL, JIS, etc. with the goal of preventing fires, and the level of flame retardancy required for the enclosures that cover the live electrical parts of the equipment is also quite high.

With the exception of PVC, which is inherently flame retardant because its structure contains chlorine, thermoplastic resins, which are essentially flammable substances, require flame retardant technology to comply with these standards and regulations. The most effective way to make general thermoplastic resins flame retardant is to suppress the combustion reaction by adding halogen-containing compounds (radical trap mechanism), and even in ABS resin, it is possible to impart extremely high levels of flame retardancy, such as UL94 V-0 and 5VA, by adding bromine-based flame retardants and antimony compounds.
 

2. Halogen-free requirements

Due to the recent rise in awareness of environmental issues in Europe, there is a movement to eliminate substances that contain not only chlorine but also halogens, in order to regulate toxic substances such as chlorinated dioxins.

Although the generation mechanism and toxicity of halogens other than chlorine, such as brominated dioxins and furans caused by bromine, have not been fully proven, the trend toward non-halogenated materials has led to a rapid increase in the demand for halogen-free flame-retardant thermoplastic resins such as ABS resin.
 

3.Halogen-free flame retardant technology

Technologies that have been considered to make thermoplastic resins halogen-free flame-retardant include compounding metal hydroxide compounds or adding phosphorus- or silicon-based flame retardants instead of halogen-based flame retardants.

To make ABS resin halogen-free, UL-94 V-2 grade ABS resin with added phosphorus-based flame retardant and UL-94 V-0 grade PC (polycarbonate) and ABS resin polymer alloy with added phosphorus-based flame retardant have been developed and marketed.
 

4. Further challenges in dealing with environmental issues

Similarly, as part of efforts to combat environmental issues, there is a growing demand for the recovery and recycling of used materials. However, alloy-based halogen-free flame-retardant materials such as PC/ABS have problems with recyclability compared to conventional flame-retardant ABS that uses bromine-based flame retardants, and research is currently underway into materials that can further address environmental issues in the future.