By Zhao Hongfu, Sun Zhanlin, Chen Jiaping, Xinjiang Tianli Petrochemical Holding Co., Ltd.

Changes in the world’s C5 resource pattern provide an opportunity for large-scale development of dicyclopentadiene (DCPD) separation and deep processing by domestic enterprises. Compared with developed countries, domestic enterprises still have a number of gaps to fill in the use of DCPD.

Most DCPD made by foreign firms is used in house, domestic production will benefit from shifting raw material supply

   DCPD is mainly extracted from light cracked fractions, and secondarily, extracted from the benzene head fraction of coal tar. Larger domestic DCPD devices all use light fractions from pyrolysis as raw material. The purity of the DCPD separated from the lighter fractions is 80%~85% in general. Most DCPD is directly used in the production of modified unsaturated polyester resin (DCPD modified UPR); a small part is used for the production of petroleum resin; the remaining parts are refined to a purity of not less than 95% and then used to make adamantane (tricyclodecane), glutaraldehyde, 2-chloro-5- chloromethylpyridine (CCMP), ethyiidenenorbomene (ENB) and other fine chemical products. DCPD can also be disaggregated into cyclopentadiene, and further produce synthetic resins, pesticides, medicine, flavorings and other intermediates.
   Most of the DCPD produced by foreign companies is in producing high value-added chemical products. For instance, Sunrise (an Exxon company) uses DCPD to produce EPDM elastomers, and Texmark produces fine chemical products, amantadine and cyclopentadienol.
   The larger DCPD devices in China use light cracked C5 fraction as raw material. There are over 15 major producers, with combined capacity exceeding 200 kt/a in 2015. Domestic crude DCPD is produced not only from the large-scale C5 full-separation enterprises, such as Sinopec Shanghai Petrochemical Company Limited, Xinjiang Tianli Petrochemical Company Limited, Shandong Yuhuang Chemical (Group) Co., Ltd., Shandong Lu Hua Chemical Co., Ltd. Ningbo Jinhai Deqi Chemical & Industry Co., Ltd., but also from a some separation enterprises with smaller production scale. While the C5 full-separation enterprises operate at relatively high rates, other separation enterprises operate at low rates, mainly due to a shortage of raw materials and low profitability. Major manufacturers and their capacities are shown in Table 1.

Table 1  Major manufacturers of DCPC in China

Industrial applications focus on five major areas, and China has achieved self-sufficiency

   DCPD petroleum resin
   DCPD petroleum resin, also known as light distillate alicyclic petroleum resin, incorporates pure DCPD resin as the basic component, along with polymers produced from monomers such as amyl dioprene, isoprene, styrene, and alpha methylstyrene. It has good solubility, compatibility, water resistance, acid and alkali resistance, and can be used as a full or partial substitute for rosin, dry oil, terpene resin and so on. It is widely used in paints, inks, adhesives and rubber and in other industries.
   In China, DCPD resin is produced mainly from low concentration DCPD as the raw material. The color of the resin is dark, and its performance is poor, while imported DCPD petroleum resin, made by the hydrogenation process, is more white or transparent. Although DCPD hydrogenation resin has been produced by several enterprises in China, it is still at the initial stage in terms of technology and product performance. In 2015, the DCPD petroleum resin produced in China was still mostly DCPD petroleum resin and mixed C5 petroleum resin of low quality, which was mainly used in making ink and in other fields with low requirements for resin color and performance.
   Modified unsaturated polyester resin
   Modified UPR products with DCPD have superior thermal stability, chemical resistance and ultraviolet radiation resistance, as well as good electrical and mechanical strength, high gloss, good air drying, and can replace ordinary unsaturated polyester resin. They are used in various kinds of glass fiber and plastic products. They are widely used in boats, electrical appliances, bathrooms, architecture and so on.
   Ethylidene norbornene
   Ethylidene norbornene (ENB) is also known as ethylidene norbornene. The method of industrial production is to produce vinyl norbornene (VNB) by reaction of cyclopentadiene or DCPD with 1,3- butadiene by Diels-Alder reaction, followed by isomerization. ENB and VNB are both important third monomers for the production of ethylene-propylene-diene monomer (EPDM).
   China has built only two ethylene-propylene-diene monomer (EPDM) units, both in Jihua. One employs the solvent-based poly-method and was introduced from Mitsui Corporation in Japan; the other is based on proprietary technology developed by FasTech in Italy. With continuous refinement of performance requirements for ethylene propylene rubber, EPDM has become a trend in the functionalization of ethylene propylene rubber.
   Polydicyclopentadiene
   Polydicyclopentadiene (PDCPD) is a thermosetting resin with high impact resistance and high bending modulus. It is a new engineering plastic. It has a broad application prospects in transportation, electrical equipment, sports and entertainment facilities, civil construction materials, casting, communication and other fields.
   At present, the only global PDCPD products are METTONLMR produced by Japanese Sojitz, PENTAM produced by Japanese ZEON, and Telene and Prometa, both originally produced by Cymetech and now purchased by Materia Inc. in the United States. The combined annual output of PDCPD in those three companies is about 30 kt, which consumes about 30 kt of DCPD.
   Chinese enterprises that independently research, develop and produce PDCPD include Zannan Technology (Shanghai) Co., Ltd. and CNPC Haike Gas Company Limited. In 2015, DCPD consumed annually in making PDCPD products in China had reached 10 kt.

   Other cyclic olefin copolymers and polymers
   Cyclic olefin copolymer (COC) and cyclic olefin polymer (COP) are polymerized by DCPD and other monomers. DCPD phenolic resin has good heat resistance, electrical insulation and chemical reaction performance. DCPD propylene glycol copolymer resin is a copolymer of DCPD and propylene alcohol obtained by thermal polymerization with a softening point of 80~130℃. It can react with acrylic acid to make ink, a kind of liquid petroleum resin, which can make ink excellent in curing rate, printing quality and so on.
   The ZEONEX resin and ZEONOR resin of ZEON company of Japan are two transparent thermoplastic cyclic olefin polymers (COP) with improved optical properties, which can be used in the field of optics. Common copolymerization monomers also include carboxylic acid, vinyl acetate, styrene, maleic anhydride and pinene.
   Chinese COC/COP is still in the research stage.
   In China, because the supply of DCPD already meets the demand and the price is relatively low, imports have basically been eliminated from the market. The crude DCPD produced in China is basically consumed at home. Some refined DCPD is exported. In the last two years, the export volume of refined DCPD has increased rapidly. In 2017, the volume of exports exceeded 10 kt. The proportion of foreign DCPD hydrostatic petroleum resin in domestic consumption is large. Other injection grade products such as PDCPD and COC have developed rapidly in the United States and Japan, and China is not yet a player in this area.
Three supply and demand trends of the future
   In the future, with lightweight ethylene cracking feedstock becoming popular around the world, the supply of C5 will decrease, which will reduce the effective production capacity of DCPD. Future growth of capacity will occur mainly in Asia, especially in China. It is estimated that the global DCPD capacity will exceed 800 kt/a by 2020.
   In the coming five years, global supply and demand will have the following trends.
   The first is a shortage of DCPD in North America, Europe and Japan. The expansion of ethylene production in the Middle East and China and the adjustment of industrial structure in developed countries have resulted in a decrease in C5 processing volume in North America, Europe and Japan, and an increase in C5 processing volume in China.
   The second is a demand increase in the Chinese market. The transfer of C5 downstream products to China with relatively sufficient raw materials will increase the demand for DCPD in the Chinese market.
   The third is that China will become the main exporter. In order to maintain the balance of supply and demand, Korea, Japan and Europe need to import DCPD from China. China will also become the main exporter of DCPD because of the startups of many new separation devices in China that can produce DCPD products with different concentrations to meet different needs.
   However, compared with foreign countries, the utilization rate of DCPD in China is low, the high-end products are fewer, the use of DCPD is still in an early stage, and the separation technology for DCPD needs to be further promoted. Enterprises should increase the development of technologies for products such as PDCPD and COC/COP, and further develop downstream value-added products and promote such products’ applications.