28310
Olefi n Copolymer
Viscosity Modifi ers
Michael J. Covitch
CONTENTS10.1 Introduction ......................................................................................................................... 283
10.2 Classes of Olefi n Copolymers ............................................................................................. 284
10.3 Chemistry ............................................................................................................................ 284
10.3.1 Synthesis by Ziegler–Natta Polymerization ........................................................... 284
10.3.2 Synthesis by Metallocene Polymerization ............................................................. 286
10.3.3 Functionalization Chemistry ................................................................................. 286
10.4 Manufacturing Processes .................................................................................................... 287
10.4.1 Solution Process ..................................................................................................... 28 8
10.4.2 Suspension Process ................................................................................................ 289
10.4.3 Postpolymerization Processes ................................................................................ 289
10.4.4 Making the OCP Liquid Concentrate .................................................................... 290
10.5 Properties and Performance Characteristics ....................................................................... 290
10.5.1 Effect of Ethylene/Propylene Ratio on Physical Properties of the Solid ............... 290
10.5.2 Effect of Copolymer Composition on Rheological Properties in Solution ........... 292
10.5.2.1 Low-Temperature Rheology .................................................................. 292
10.5.2.2 High-Temperature Rheology ................................................................. 295
10.5.3 Effect of Diene on Thermal/Oxidative Stability ................................................... 299
10.5.4 Comparative Rheological Performance in Engine Oils ........................................ 300
10.5.4.1 Comparative Study of OCP Viscosity Modifi ers in a Fixed
SAE 5W-30 Engine Oil Formulation ..................................................... 300
10.5.4.2 Comparative Study of 37 SSI OCP Viscosity Modifi ers in an
SAE 15W-40 Engine Oil Formulation .................................................. 301
10.5.5 Interaction with Pour Point Depressants ............................................................... 302
10.5.6 Field Performance Data ......................................................................................... 305
10.6 Manufacturers, Marketers, and Other Issues ...................................................................... 306
10.6.1 EP/EPDM Manufacturers ...................................................................................... 306
10.6.2 Olefi n Copolymer VM Marketers .......................................................................... 307
10.6.3 Read Across Guidelines ......................................................................................... 308
10.6.4 Safety and Health ................................................................................................... 310
References ...................................................................................................................................... 31010.1 INTRODUCTION
Olefi n copolymer (OCP) viscosity modifi ers are oil-soluble copolymers comprising ethylene and
propylene and may contain a third monomer, a nonconjugated diene, as well. By virtue of their high
thickening effi ciency and relatively low cost, they enjoy a dominant share of the engine oil viscosity
modifi er market [1]. First introduced as a lubricant additive by Exxon in the late 1960s, the chemicalCRC_59645_Ch010.indd 283CRC_59645_Ch010.indd 283 12/6/2008 10:10:09 AM12/6/2008 10:10:09 AM