Page 298 - Engineering Plastics Handbook

258 Engineering Plastics

O

O
Cl
O
O

H N CH NH
TMAC 2 2 2
MDA

N O NH
H 2 2
ODA
Figure 12.1 Polyamide-imide monomers.

∗
1960s [4, 5] at Standard Oil of Indiana (Amoco) and branded under the
®
Torlon trademark.
A large driving market factor for these first polyamide-imides was the
need for a high-temperature-capable insulation for magnet wire. In
early 1961, Amoco Chemicals Company started a project to develop high-
temperature wire enamel with investigations into aromatic polyester
imides and polyamide-imides. From that development, the polyamide-
imide wire enamel products were based on trimellitic anhydride chloride
(TMAC) and 4,4′-methylenedianiline (MDA) and also TMAC and 4,4′-oxy-
dianiline (ODA) using the so-called acid chloride route (Fig. 12.1) and
were sold in both solution and powder forms. This development filled a real
need to have a readily soluble, lower-viscosity, lower-cost magnet wire
enamel than the polypyromellitimide wire enamels that were on the
market at the time, yet maintain high-temperature capabilities with a
glass transition temperature of 280°C.
Following this wire enamel introduction, Amoco began development,
in the mid-1970s, of melt processable polyamide-imide compounds for
the injection molding and extrusion markets [6].
Also in this time frame, wire insulation producers began producing
polyamide-imides using lower-cost isocyanate chemistry. This technol-
ogy largely supplanted the acid chloride route for the wire enamel
market.

∗
At the time, Amoco Chemicals Company was a wholly owned subsidiary of Standard
Oil Company (Indiana), which later changed its name to Amoco. Amoco Performance
Products, Inc., was created with the purchase of Union Carbide’s high-performance poly-
mer and carbon fiber groups in 1985. BP inherited the polymers business in its merger
with Amoco and then divested it to Solvay, where Torlon and the other high-performance
polymers are now within the Solvay Advanced Polymers, LLC, business unit.