The flame retarders used, e.g., in textiles, are simply absorbed into
the fibres, but remain molecularly intact. These are free to be desorbed
and can thus easily enter into the environment, as persistent toxic
molecules. TBBPA is an entirely different kettle of fish. The
prepolymerisation reaction of classic epoxy resins (before
cross-linking) is between epichlorohydrin (which provides the epoxy
group), bisphenol-A (BPA) and sodium hydroxide (which provides the
sodium ion to capture the chlorine ion from the epichlorohydrin). As the
name implies, BPA consists of two phenol rings (ie, two benzene rings
with OH groups attached), which are monolinked together with a carbon
atom, which is also linked to two CH3 groups. TBBPA or
tetrabromobisphenol-A is structurally identical to BPA, except that four
of the non-reactive hydrogen atoms are replaced by bromine atoms. To
make the FR-4 or flame retardant polycarbonate resins, a proportion of
the BPA is replaced by TBBPA (typically about 20-50%). The bromine
compound therefore is reacted and forms an integral part of the resin.
IOW, it is not just simply absorbed into the fibres, like in kids'
pyjamas, and the bromine cannot be released without thermal
decomposition. It is therefore inherently safer, environmentally
speaking, at least until it is burnt.

Brian

MA/NY DDave wrote:
> Hi Brian, IPC LF Listservers,
>
> First of all thanks,
>
> Since bromine is one of those substances that the EU wants to reduce why do
> you believe, or know, TBBPA is acceptable compared to the other
> alternatives.
>
> Brian, Just trying to learn from a guru.
>
>
> Yours in Engineering, Dave
> YiEngr, MA/NY DDave
>
>

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