Annual Review of Global C6/C8 LLDPE and mLLDPE Markets


Linear Low Density Polyethylene (LLDPE) is composed of three types of ethylene copolymers based on the co-monomer used: ethylene/butene-1 copolymer, ethylene/hexene-1 copolymer, and ethylene/octene-1 copolymer.  Ethylene/hexene-1 and ethylene/octene-1 copolymers constitutes about 30% of total LLDPE global consumption with the balance (and the majority) being ethylene/butene-1 with roughly about 70%.   Hexene-1 and octene-1 are called higher alpha olefins (HAO) and consequently the ethylene/hexene-1 and ethylene/octene-1 LLDPE copolymers are also called higher alpha olefin LLDPE (HAO LLDPE).  mLLDPE uses either hexene-1 (for gas phase process and to a much less extent slurry phase) or octene-1 (for solution phase process) as co-monomer, and is often considered a specialty subset of HAO LLDPE. 
 
The catalyst technologies for these products are all quite different.  Standard HAO LLDPE, aka C6/C8 LLDPE typically uses a Ziegler catalyst with aluminum alkyl as co-catalyst, while mLLDPE requires metallocene catalysts and MAO (methylaluminoxane) or borates as activators.  Hardware modifications are also needed to accommodate the catalyst system. 
 
The metallocene catalyst basically contains a transition metal (e.g. Zr or Ti) complex of one or two cyclopentadienyl ligands.  Hundreds of structural variations have been developed.  For gas phase and slurry polymerizations, the complex is typically supported on an inert inorganic oxide material such as silica.  No support is used for solution phase polymerization.  The MAO (Methylaluminoxane) in a powerful solvent (e.g. toluene) is often used as activator or co-catalyst.  But borates and a mixture of borates and MAO have also been used to activate the catalyst. MAO in toluene media is often used in supported catalyst preparation but the toluene is washed away with aliphatic hydrocarbons before being stripped out of the system.  
 
Compared with standard HAO LLDPE, mLLDPE is noted for its significantly higher impact resistance, its clarity, and reduced orgnoleptics, but at the same time it poses reduced processability derived from its narrower MWD.  Since mLLDPE was commercialized circa 1997, extensive effort has been exercised to mitigate this by physical blending with LDPE or standard HAO LLDPE, use of processing aids such as fluoroelastomers, and/or  introducing long-chain branching via varying catalyst complex structure, and/or broadening MWD by polymerization process modifications .  With the modernization of fabricating equipment, multi-layer structures have been successfully constructed to optimize the properties/processing.  This has broadened the window of mLLDPE in film applications.  As the converting industry in emerging economies undergoes continued modernization, the demand for mLLDPE will accelerate.
 
Most of the HAO LLDPE and LLDPE reactors can swing back and forth between LLDPE and HDPE as demand dictates.  For gas phase process, at times when hexene-1 is in shortage, butene-1 has been used for less demanding applications.  Similarly for solution processes, hexene-1 is also sometimes used when octene-1 is in shortage or the price too high.  For solution processes, butene-1 is also used in place of octene-1 for less demanding applications.
 
For mLLDPE, hexene-1 co-monomer is used for gas phase and slurry phase polymerizations.  The octene-1 or hexene-1 is used for solution phase polymerization of mLLDPE.  To reap the benefits of metallocene technology, proper chain-length of comonomer is crucial.  This accounts for the reason why only hexene-1 or octene-1 co-monomers (but not butene-1) are used in commercial production of mLLDPE. 
 
There is a long list of mLLDPE producers with the major companies being Dow, ExxonMobil, and Prime Polymer.  Several other HAO LLDPE producers have the mLLDPE capability, developed or licensed, but only produce when market demand warrants it.
 
Film applications consume > 80% of the C6/C8 LLDPE & mLLDPE globally.  Demand is greatest in the more mature regions of North America, Western Europe, and Japan due to the higher availability of these grades and upgrades in converting processes to take advantage of the higher performance.  China, however is also a major market for mLLDPE where the butene-1 copolymer LLDPE has been the workhorse due to availability and cost.  Film converters in China tend to blend (or co-extrude) butene-1 LLDPE with HAO LLDPE or imported mLLDPE to improve the physical and optical properties.
 
Townsend's market report on C6/C8 & mLLDPE is published annually and provides a highly detailed and specific review of global supply and demand for Hexene (C6)/Octene (C8) & Metallocene LLDPE (mLLDPE) delivering critical data and expert analysis of global suppliers, catalyst & process technology, capacity, supply/demand, trends & drivers, intercountry trade and market dynamics. This report provides granular coverage of 100+ specific applications in 70+ countries.  Learn more.