By Song Enjun, Kong Fanzhi, Liaoning Oxiranchem, Inc.
In industry polycarboxylic water reducers (PCE) are usually synthesized through copolymerization between polyethenoxy ether macro monomers with terminal double bonds and unsaturated carboxylic micro monomers (such as acrylic acid) under the action of initiator. Polyether macro monomers are the key to the development of polycarboxylic water reducers.
Present market status of polyether macro monomers
In 2000 polycarboxylic water reducers were used in concrete construction for the first time in history in China. Starting from 2007 the concrete construction of high-speed rail roadbeds vigorously promoted the development of polycarboxylic water reducers. In 2011 the market of polycarboxylic water reducers made a drastic expansion. In 2013 polycarboxylic water reducers started to become a water reducer variety with the highest consumption. In 2016 the consumption of polycarboxylic water reducers accounted for 73.8% of the total water reducer consumption. In 2017 the total output of carboxylic water reducers reached 7.23 million tons (solid content 40%), being 145 times the total output in 2005.
Polyether macro monomers being sold in the Chinese market today mainly include MPEG, APEG, HPEG and TPEG. HPEG and TPEG hold a major share. In the total sales amount of polyether macro monomers in 2017, around 95% was HPEG and TPEG, 1.5% was APEG and the balance was MPEG.
The capacity of polyether macro monomers in China made a rapid increase during 2012-2014 and the average annual growth was 35-55%. After 2015 the capacity growth made an evident drop to around 5%. In 2017 the capacity of polycarboxylic water reducer polyether macro monomers increased by 9% to 2.50 million t/a and the output increased by 12% to 1.25 million tons. The operating rate was however kept at 45-50% for long years and the capacity surplus was serious. With the completion of new and expansion oxyethylation projects and the improvement of production technology, the capacity of polyether macro monomers will make a further expansion and competition among enterprises will become fiercer. As the capital construction scale in China tends to be stable, the consumption growth of polycarboxylic water reducer polyether macro monomers has come down from 34-55% during 2012-2014 to below 10%. The consumption growth is expected to be only 7.7% in 2018.
Development prospect of polyether macro monomers
The product structure of polyether macro monomers in China is quite unitary today. HPEG and TPEG take the lead. Researchers are making a constant development of new functional macro monomer varieties. Most typical examples are vinyl ether macro monomers such as VPEG and EPEG. Several producers of macro monomers such as Liaoning Oxiranchem, Inc., Fushun Dongke Fine Chemical Co., Ltd. and Shanghai Dongda Chemical Co., Ltd. have already launched the production of vinyl ether macro monomers and conducted their extensive trial use in the production of water reducers. New polyether macro monomers with EPEG as representative feature high activity of double bonds, simplicity of synthesis process and excellent performance of produced water reducers. The entire production process also meets requirements on greening, low carbon and environmental protection. New polyether macro monomers will surely become mainstream varieties in the market of polycarboxylic water reducers.
Aggregate resources in China are getting less and less today and their quality also has deteriorated. The solution is the reuse of scrap concrete. Great quantities of scrap concrete are generated in large-scale urban construction and wide-spread highway network renovation/retrofitting. Aggregate (“recycled aggregate”) needed in concrete can be produced through cleaning, crushing, screening, grading and mixing at a certain ratio. Concrete prepared with recycled aggregate as partial or total aggregate is called “recycled concrete”. Focus can be laid on the research and commercialization of special functional ethylene oxide derivative water reducer suitable for use in recycled concrete. Initial tests made by Liaoning Oxiranchem, Inc. show that polycarboxylic water reducers used in recycled concrete can be developed only when polyethylene glycol segments are contained and corresponding functional groups are added in the molecular structure.
Polycarboxylic water reducer polyether macro monomers have already developed into the biggest ethylene oxide downstream products. Benefitted from the sustained development of the capital construction scale, China has become the biggest market of polycarboxylic water reducers in the world. In future further research and development will still need to be made to new functional polycarboxylic water reducer polyether macro monomers that can have sustainable development.
