OPTIMIZATION FOR THE PRODUCTION OF UNSATURATED POLYESTER
RESINS
Description of the process
Industry scale optimization
1,2 2 1
J. P. Silva , J. Carvalho , E. J. G. Azevedo
1 - Instituto Superior Técnico, 2 – Resiquímica, S.A.
ABSTRACT
The present work aims the characterization of the elements of a polyester reactor and the optimization of
Unsaturated Polyester Resins process relating to its polymerization time. It consisted in resolution of
problems, evaluation of inherent relations and compilation of equipments and methods. A detailed flowsheet
and equipment information were elaborated and also an optimization process, consisting on the resolution of
problems and evaluation of equipments and methods.
An experimental method in the laboratory was developed to be adopted at the factory. It leads to a significant
reduction of the amount of time. With the new procedure, the total time of polymerization is reduced in about
1h20min.
Key-words: Unsaturated Polyester Resins, Production Time, Equipment, Set-Point, Maleic Anhydride,
Optimization.
1 INTRODUCTION 1.1 Process Description
In order to compare the most important factors The flowsheet for the process of unsaturated
witch influence the time production and its polyester resins in the chemical industry
optimization, were studied: glycol losses during Resiquímica, S.A., based on maleic anhydride,
distillation process, Set-Points which establish the phthalic anhydride and glycol (propylene glycol,
inherent distillation phase, and a method that ethylene glycol and diethylene glycol) is shown in
relays to a small modifying parameter to the fabric Figure 1.
method.
1
- Filtration equipment to clean the resin of gel
particles or extraneous matter which would
{
{ contaminate products derived from the resin.
1.2 Glycol Losses
The most common cause of gelled batches or
premature viscosity increase at high acid values is
Figure 1 – Flowsheet for the process of unsaturated loss of glycol through inefficient partial
resins in Resiquímica, SA.
condensers causing an increase in average
functionality. Clearly, these losses must be
The characteristics of this equipment are carried
compensated by the addition of extre glycol,
through manufacturing plant.
preferably at the start of the cook.
The essential elements of the polyester reactor
Because the losses at each stage of scale-up will
can be summarised as follows:
be different, the chemist must expect to adjust the
- A heated vessel of the correct capacity with
formulation to compensate. The glycol will be lost
direct oil heating which is pumped around a jacket
as a solution in the water which is separated
surrounding the reactor;
during the cook.
- An effective stirrer to efficiently agitate the
contents of the vessel;
- A vapour release at the top of the reactor leading
to partial and full condensers, the latter having a 2 RESULTS AND CONCLUSIONS
separating trap to enable water produced in the
cook to be collected; 2.1 Troubleshooting: Glycol losses
- The partial condenser fractionates and returns
reactants such as glycols to the reactor but allows The loss of glycol during distillation was
water of the reaction to pass trough to the full determined, as observed in Figure 2.
condenser where the refluxing solvent/water 40
lote 10027571
lote 10027873
lote 10027874
,mixture is liquefied and separated in the trap, the 35
lote 10027957
lote 10028003
30
refluxing solvent passing back to the reactor; lote 10028373
25 lote 10028381
%glicol(v/v)
- Service hatches to allow loading of raw 20
materials; 15
10
- Facilities for measurement of temperature at key
5
points in the reactor; 0
0 20 40 60 80 100 120 140
- An inert gas facility, nitrogen; tem po (m in)
- A separate blending and thinning vessel for Figure 2 – %Glycol losses during distillation phase.
dilution to slightly above specification solids and
final adjustment to within this specification; The loss of glycol during distillation was
determined. The current excess (11%) guarantees
2
the required composition according to the inherent 2.4 Vacuum operating system
losses.
Alongside this troubleshooting which is also The application of vacuum in order to minimize
related to the production time, several solutions the time production, therefore, a restructure of the
have been studied and presented as followed. energy integration is required, and can be seen in
Figure 4.
SP=102 ºC
2.2 Inert Gas
UF - Água
Refrig.
(d)
Application of inert gas flow facility, throw the
bottom of the vessel which allows a better mixture
between the raw materials. It increases the
velocity of the polymerisation reaction and the UF - Água
Refrig.
water extraction from the process.
2.3 Deviation between distillation CL-0012
column and vessel
(d) Tubos de borracha comercializados
The placement of a deviation between the
distillation column and the vessel to allow the flow Figure 4 – Integration system between partial and total
to go to its centre, promoting greater adherence of condensers.
the condensed glycol flow back to the reaction
mixture
2.5 Set-Point of the distillation
It is shown in Figure 3.
column temperatures and Hot
Utilities in the reactor
For different ranges of Set-Points related to the
distillation column, the parameters average
warming rate and distillation time vary, however,
not significantly.
Different variations of Set-Points can potentially
be less relevant than the other factor (oscillations
of the hot utility) for an effective warming rate.
Given this fact, a fixed value of SP = 103ºC was
established, since this way, it provides a better
efficiency of distillation, reducing the amount of
glycols in the deposit of condensed materials.
Figure 3 – Deviation between distillation column and Following this analysis, the effect of total time
vessel.
reducing taking into account the existing two-
stage distillation was studied. It was verified that it
3
is lower for longer times of first stage distillation. Table 1 – Time savings for the Polymerization reaction
with the new method (Test 2).
With this, the trend of optimum temperature in the
Time saved with Test 2
reactor when it must connect to hot utility after
Viscosity (mPa.s)
exothermic is 170 º C in order to lower total time Test 330-354 427-455 503-523
distillation. 2 1h16min 1h31min 1h18min
With the new procedure, the total time of
polymerization is reduced in about 1h20min.
2.6 Method of introducing maleic
anhydride in an advance phase of
the polymerisation
3 REFERENCES
An experimental method (Test 2) in the laboratory
of investigation was developed to be adopted at [1] http://www.resiquimica.pt, Fevereiro 2008;
the factory. It not only leads to a significant
reduction of the amount of time for the production [2] OLDRING, Dr. P.; HAYWARD, G., Resins for
of unsaturated polyester resins, as well as Surface Coatings, Vol. III, SITA Technology, UK,
quantities of spent energy (electricity, utilities, 1987;
inert gas, among others).
It relates to the acceleration of the synthesis of [3] ZASKE, Oscar C.; GOODMAN, Sidney H.,
unsaturated polyesters containing maleic Handbook of Thermoset Plastics - Unsaturated
anhydride. Instead of introducing all the raw Polyester and Vinyl Ester Resins, William Andrew
material at the beginning, an amount will be Inc, 1998;
introduced into the reaction mixture at an
advanced stage of the reaction. [4] MALIK, Mona; CHOUDHARY, Veena; VARMA,
Results can be seen in Figure 5 and Table 1. I.K., Current Status of Unsaturated Polyester
Resins, Journal of Macromolecular Science Part
C: Polymer Reviews, Taylor & Francis Inc., 2000;
Test 2 Test 1
06:57 [5] MORRISON, R.; Boyd, R., Química Orgânica,
12ª Ed., Fundação Calouste Gulbenkian, 1983;
05:45
time (h:min)
[6] COULSON, J. M.; Richardson, J. F.,
04:33
Tecnologia Química, Vol. I, 3ª Ed., Fundação
03:21 Calouste Gulbenkian, Lisboa, 1989;
02:09
330-354 427-455 503-523 [7] PEREIRA, A.F., Estudo de Propriedades
viscosity ranges (mPa.s)
Eléctricas, Mecânicas e Dispersivas de Materiais
Compósitos de Nanofibra de Carbono em Matriz
Figure 5 – Polymerization time for the old and new de Poliéster Insaturado, Lisboa, 2007;
method (Test 2).
4
[8] BORDADO, J.C.M., Reactores de [18] Projecto.Det@lhe Engenharia & Construção,
Polimerização para Poliéster-Uretanos, Instituto Automatização no DP1, Setembro 2003;
Superior Técnico – Universidade Técnica de
Lisboa, 1989; [19] “Química Geral aplicada à Indústria das
Resinas – Parte I”; Resiquímica, Mem-Martins,
[9] BRUINS, Paul F., Unsaturated Polyester 2000;
Technology, Polytechnic Institute of New York,
Taylor & Francis, USA, 1976; [20] “Química Geral aplicada à Indústria das
Resinas – Parte II”; Resiquímica, Mem-Martins,
[10] http://www.wikipedia.org, Março 2008; 2000;
[11] VALÉRIA, Maria Rosa, Modificação de [21] Resiquimica SA, Manual de qualidade,
Resinas de Poliéster Insaturado com Edição nº3, Revisão nº1, Mem Martins, 2004.
Poli(organossiloxanos), Universidade de
Campinas, Brasil, 1999; [22] http://www.rhe-america.com, Julho 2008;
[12] PAUL, D. R.; Barlow, J. W., Keskula, H., [23] Resiquímica SA, Relatório de contas 2006;
Encyclopedia of Polymer Science and
Engineering, Vol. 12, 2ª Ed., John Wiley and
Sons, USA, 1986;
[13]
http://www.crayvalley.com.br/produtos/aplicacoes.
php, Julho 2008;
[14] Nitrokemia Ipartelepek, Method of
Preparation Of Unsaturated Polyester Resins
From Maleic Acid/anhydride, US4902773, 20 Fev.
1990 (Bodnar et al);
[15] http://www.patentstorm.us, Março 2008;
[16] Processing Unsaturated Polyesters Based On
Amoco Isophthalic Acid, Amoco Chemical
Company, USA;
[17] Farbwerke HOECHST AG, Technische
Auslandsplanung, Projektinformationen,
Deutschland, 1977;
