Degradation behaviour and recovery of bisphenol-A from epoxy
resin and polycarbonate resin by liquid-phase chemical recycling
Yoshiki Sato
a
, Yasuhiko Kondo
b,
*
, Koji Tsujita
c
, Noboru Kawai
c
a
Division of Material Sciences, Graduate School of Natural Science & Technology, Kanazawa University,
Kakuma-machi, Kanazawa 920-1192, Japan
b
Institute for Energy Technology, National Institute of Advanced Industrial Science and Technology,
Tsukuba west, 16-1 Onogawa, Tsukuba-shi, Ibaraki-ken 305-8569, Japan
c
Technical Development Division, Victor Company of Japan Ltd., 58-7 Shinmei-cho, Yokosuka-shi, Kanagawa-ken 239-8550, Japan
Received 6 December 2004; received in revised form 13 January 2005; accepted 17 January 2005
Available online 5 April 2005
Abstract
In the liquid-phase cracking of bisphenol-A types of epoxy resin and polycarbonate resin at 440
C in the presence of solvents
such as tetralin, decalin or cyclohexanol, we recovered more than 40 wt% of phenol and isopropylphenol as monomers. On the
other hand, bisphenol-A, which was common monomer from epoxy resin and polycarbonate resin, could also be recovered with
high yield, when reaction was carried out at lower temperature of 300e350
C. However, degradation of polycarbonate resin did not
proceed in the thermal conditions without catalyst. Mechanistic difference between epoxy resin and polycarbonate resin in the
liquid-phase cracking is discussed on the basis of the product distribution from resins and their appropriate model compounds.
Ó 2005 Elsevier Ltd. All rights reserved.
Keywords: Liquid-phase cracking; Monomer recycling; Bisphenol-A; Epoxy resin; Polycarbonate resin
1. Introduction
Crosslinked epoxy and phenol resins are manufac-
tured for use mainly in electrical and electronic
appliances and automobile industry. The annual pro-
duction of thermosetting resins, such as phenol and
epoxy resins was about 1.26 million tons in Japan in
2003 [1]. For epoxy and polycarbonate resins, 195 and
409 thousand tons were produced in Japan in 2003,
respectively. The amounts of waste products from these
resins are expected to show considerable increase in the
near future. However, these condensation types of resins
cannot be cracked to low molecular weight compounds
and monomers by direct pyrolysis. From the product
distribution in the fluidised-bed pyrolysis over 700
C,
polycarbonate resin and phenoleformaldehyde resin
produced 25 and 50 wt% of residue with 46 and 28 wt%
of oil, respectively [2]. Sometimes coke formation causes
serious problems by plugging of continuous operation
processes. These resin materials are manufactured by
condensation polymerisation, during which small mol-
ecules such as water and alcohol are released. Therefore,
it is very effective to crack them with additives, such as
water, alcohol, oil, etc. to produce stable low molecular
weight compounds. We already reported the effect of
hydrogen donating solvents on the liquid-phase cracking
of thermosetting resins, such as phenol resin [3]. In the
presence of tetralin, 40e74 wt% of phenol compounds,
as monomers, were recovered from the reaction of
phenol resin and epoxy resin at 430e450
C. Therefore,
the development of the industrially feasible process for
the recycling and reuse of these resins is an important
and urgent social problem and environmental subject.
* Corresponding author. Tel./fax: C81 29 861 8412.
E-mail address: y.kondou@aist.go.jp (Y. Kondo).
0141-3910/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.polymdegradstab.2005.01.015
Polymer Degradation and Stability 89 (2005) 317e326
www.elsevier.com/locate/polydegstab