By Zhang Songchen, China National Chemical Information Center

Plasticizers are the most common type of plastic auxiliaries in daily life, and plasticizers account for more than half of all plastic auxiliaries. At present, there are over 100 varieties of plasticizers, mainly including o-benzenes, para-benzenes, epoxys, citrates, etc. Among them, the most common ones are phthalate compounds.

Environmentally friendly and non-toxic plasticizers become inevitable

   Excessive intake of phthalate plasticizers can cause a decline in immunity, and long-term intake of large amounts of phthalate plasticizers will lead to liver cancer. Phthalate plasticizers’ potential harm to infants and children is much higher than that to adults. Most of the European and American countries have imposed various restrictions on the use of phthalate plasticizers. Plasticizers must not exceed 0.1% in consumer products for children.
   In January 2016, China enforced a similar standard on plasticizers for toys as that in Europe. At present, nearly 60% of plasticizers in the domestic market are still phthalate ones thanks to their low prices. With the improvement of public safety and environmental protection awareness, traditional phthalate plasticizer manufacturers have felt the pressure, and the substitution of green and non-toxic plasticizers has become inevitable. The consumption structure of various plasticizers in China in 2017 is shown in Table 1.

Table 1   Consumption structure of plasticizers in China in 2017

   At present, non- phthalates plasticizers having development potential in the domestic market are dioctyl terephthalate (DOTP), citrate esters, trioctyl trimellitate (TOTM) and dioctyl adipate (DOA).

DOTP: it enjoys the fastest capacity growth

   Compared with the commonly used DOP, DOTP has better heat resistance and cold resistance, property of being more difficult to volatilize, more soft and better electrical insulation performance. It is widely used in cable materials under the temperature of 70°C and other various PVC soft products. DOTP has become the most popular choice among manufactures who used to produce DOP.
   The profits of the whole plasticizer industry have been decreasing for several consecutive years. However, the growth of DOTP capacity has continued in the past two years and the number of DOTP producers has reached nearly 30. The main plasticizer manufacturers such as Qilu Plasticizer, UPC and Weilianda all have expanded their DOTP capacities. In 2017, total DOTP capacity has reached 1.7 million t/a. It is expected that the figure will reach 1.85 million t/a by the end of 2018, with an average annual growth rate of 22% in the past five years.
   The rapid growth of production capacity is accompanied by a decline in utilization and an ups and downs in the industry's profit margins. In 2017, domestic DOTP production was 1.1 million tons, and the operating rate was only 65%. The supply side is expanding at a high speed. If downstream demand growth cannot keep up with the pace, it is difficult for DOTP companies to maintain a high profit margin. Low-price competition will only make the profits fluctuate around the cost.
   Most of the downstream sectors of DOTP are soft PVC products, of which cables account for 40% and rubber gloves account for 30%. Because downstream users have been used to consume DOP, DBP and other phthalate plasticizers, most of them are accustomed to purchasing traditional phthalate plasticizer products if there is no explicit regulation of using environmentally friendly plasticizers. Meanwhile, as DOTP and DOP have different components, and the price of phthalate plasticizer is generally RMB 200-300/t lower than DOTP, downstream users are inclined to buy phthalate plasticizers. Therefore, the next two years will see more adjustment in supply-demand of DOTP.

Citrate plasticizer: its green performance is very much anticipated

   Safe and environmentally friendly plasticizers such as epoxidized plant oils have been attracting attention as an alternative to phthalate plasticizers in recent years. Among them, citrate plasticizers have developed rapidly, and its consumption has doubled.
   The citrate plasticizers such as tributyl citrate (TBC), trioctyl citrate (TOC), and acetyl tributyl citrate (ATBC) are environmentally friendly plasticizers, which are non-toxic, easily biodegradable, low volatile, anti-bacteria and with same plasticizing effect as phthalate plasticizer. Europe and the United States have issued statements allowing citrate plasticizers to be used in sectors having high hygiene requirements such as toys, medical devices, foods and medicines.
   The citrate plasticizer needs only a simple synthesis process and can be produced by the general plasticizer production lines, whose utilization can thus be improved. In 2017, there were about 10 citrate plasticizer manufacturers with a total capacity of 80 kt/a and an annual production of about 60 kt. Since most of domestic citrate plasticizers are low molecular weight varieties, they have shortcomings such as high volatility and poor low temperature resistance, which limits the application. The research and development of multi-typed high molecular weight citrate plasticizers should be accelerated in the future.

TOTM: wires and cables are the major consumers

   As a non-toxic and environmentally friendly plasticizer, TOTM has excellent heat resistance, migration resistance and insulation properties. It combines the advantages of polyester plasticizer and monomer plasticizer, and its plasticizing efficiency and processing performance are similar to phthalate plasticizers. TOTM is mainly used in the production of high-end PVC cable materials and impregnating materials for pulsed and low-voltage power capacitors and synthetic leather plasticizers.
   By the end of 2017, the domestic TOTM capacity reached 180 kt/a, the output reached 130 kt, and the average operating rate was 72%. There are nearly 10 TOTM manufacturers, including Bolin Chemical, Henan Qing’an, UPC, Aekyung Chemical, and Shandong Lanfan.
   With the improvement of environmental awareness and the demand for TOTM from high-end PVC wires and cables, China's TOTM consumption has grown rapidly from 52 kt in 2010 to 125 kt in 2017, of which cables accounted for about 90%. Automotive interiors and pharmaceutical products are also consumers of TOTM.
   In the next five years, wires and cables will remain the most important derivatives of TOTM, while the demand from automotive and pharmaceutical industries will be huge and will grow fast.

DOA: its cost needs to be reduced and quality improved

   DOA is an excellent cold-resistant plasticizer with certain thermal stability and water resistance. DOA is usually applied together with DOP to sectors like agricultural films, electric wires, thin boards, artificial leather, outdoor water pipes, and packaging films for frozen foods. DOA can also be used as a low temperature plasticizer for many synthetic rubbers and as a plasticizer for resins such as nitrocellulose and ethyl cellulose. With the growth of PVC capacity and its wider application in cold-resistant fields such as cold storage, refrigerators, cold-resistant greenhouse films, cold-resistant packaging films, etc., the demand for DOA as a cold-resistant plasticizer has also been expanding.
   In 2017, the demand for DOA in China was around 40 kt. At present, China needs to import a large amount of DOA as there is a huge gap between the quality of domestic products and that of imports. There are about 40 DOA manufacturers in China, mainly located in Shandong, Guangdong and Zhejiang provinces. Its market is growing rapidly.

Planning in advance for the future competition

   In the next few years, the environmental protection standards will only become more stringent, and the limits on traditional phthalate plasticizers are likely to cover more fields other than toys and medical sectors. Foreign environmental-friendly plasticizer manufacturers are paying close attention to the trend of China's plasticizer industry regulation and upgrading as there is huge potential in the substitution of traditional plasticizers. For example, BASF's patented DINCH products for the replacement of phthalate plasticizers have excellent performance in low toxicity and low mobility and have a good development momentum in the field of toys and food packaging.
   As for domestic environmentally friendly plasticizers, in addition to the relatively mature DOTP, the production scales of most other non-phthalate plasticizer enterprises are still small with very few high-quality products. Domestic plasticizer enterprises must plan in advance, invest in research and development of new catalytic and separation processes, and vigorously develop and promote non-toxic, environmentally friendly and biodegradable plasticizers.