LLDPE - Linear low density polyethylene
LLDPE is a substantially linear polymer with significant numbers of short branches, commonly made by copolymerization of ethylene with short-chain alpha-olefins (for example, 1-butene, 1-hexene and 1-octene). LLDPE has higher tensile strength than LDPE, it exhibits higher impact and puncture resistance than LDPE. Lower thickness (gauge) films can be blown, compared with LDPE, with better environmental stress cracking resistance but is not as easy to process.
LLDPE is a polyethylene with a density < 965 kg/m,produced by a low pressure process.LLDPE is defined by a density range of 0.915–0.925 g/cm3 and its melting point is 122-127 °C. There are three broad types of polymerization processes based on the phase of reactants and products. They are gas-phase process, solution phase process and slurry phase process.
LLDPE was invented by DuPont in the late 1950's. DuPont Canada is also credited with operating the world’s first commercial LLDPE line, built in Corunna, Ont., in 1960. This 275 million-lb/yr. “Sclair” resin unit was later acquired by Nova Chemicals, which shut it down in 2004. DuPont Canada produced Sclair resins for film, injection, and rotational molding but did not introduce them to the U.S. market until about 1976 and then initially only for rotomolding. Several other companies launched LLDPEs at about the same time in 1977 and ’78. Dow Chemical began sampling a number of grades in 1977, using technology derived from its low-pressure HDPE process
The Dow Chemical Company, ExxonMobil, SABIC, IPIC, SINOPEC group, PetroChina Group, Japan PE/Mitsubishi, Braskem Group, Petro Rabigh/Sumitomo, NPC Iran, Formosa Plastics and Reliance Industries Ltd are some of leading producers of LLDPE.
The global consumption volume of LLDPE is projected to increase by 4-4.5% annually through 2017. Large input in the demand rise belongs to the packaging and construction industries. Moreover lucrative capacity additions scheduled for the developing markets are sure to further drive the LLDPE industry growth. The global capacity of LLDPE was 32 MMT and demand was around 28 MMT in 2015. The capacity is expected to increase to 34 MMT in 2016 with demand reaching 30 MMT.
In India total LLDPE capacity is expected to reach 1640 KTA by 2016-17 and 2190 KTA by 2017-18.
In 2016, Gail India Ltd commissioned a new processing line for polyethylene at its Pata petrochemical facility in Uttar Pradesh (UP) increasing its PE capacity by 400 KTA. Gail India Ltd has successfully started its first Unipol PE process line with the capacity to produce 400 KTA of polyethylene (PE). The total production capacity of Gail's petrochemical plant at Pata is now 810 TPA. Gail's flexible swing plant, which produces both high density polyethylene (HDPE) and linear low-density polyethylene (LLDPE), provides access to a full range of resin applications. PE major ONGC Petro additions Ltd (OPaL), is in the initial stages of starting up its two 360 KTA LLDPE/HDPE swing lines in February 2017. Reliance Industries Ltd (RIL), which is also a polyolefins major, is also on track to start up its LDPE and LLDPE/HDPE swing lines by the end of the first quarter.
The projected consumption of LLDPE in India in 2016-17 is pegged at 1695 KTA.
LLDPE is used for plastic bags and sheets (where it allows using lower thickness than comparable LDPE), plastic wrap, stretch wrap, pouches, toys, covers, lids, pipes, buckets and containers, covering of cables, geomembranes, and mainly flexible tubing.
Major Licensors of technology for LLDPE include Ineos, Basell, Mitsui and Westlake. Gas Phase technology is given by INEOS Technologies’ unimodal INNOVENE G swing process, which offers its condensing mode Enhanced High Performance (EHP) technology.
Lyondell Basell's bimodal and unimodalc SPHERILENE process developed for LLDPE and now capable of producing HDPE products, including a discussion of the LUPOTECH G process. Mitsui’s bimodal EVOLUE process developed for metallocene LLDPE products.
Univation’s unimodal UNIPOL swing process, which offers its Super Condensing Mode Technology (SCM-T), and its new bimodal HDPE process based upon a single reactor and novel catalyst system. Westlake’s ENERGX technology developed for installation in gas phase LLDPE plants.