By Luo Yan, Xinjiang Tianye (Group) Co., Ltd.
Excellent performance results in applications with high added value
Chlorinated polyvinyl chloride (CPVC) is a new-type polymer thermoplastic elastomer produced through the chlorination modification of PVC. Its heat distortion temperature and Vicat softening temperature can reach 90-120℃, being 10-40℃ higher than PVC. Its long-term application temperature is 95℃. CPVC has excellent mechanical properties. Its tensile strength is 50% higher than PVC and around 100% higher than ABS and PP. At temperatures close to 100℃, in particular, CPVC can still retain very strong rigidity. CPVC is highly resistant to chemical corrosion and still has strong resistance to acids, alkalis and chemicals at high temperatures, being much superior over PVC and other resins.
CPVC can replace traditional materials and meet the needs in chemical production equipment and anti-corrosion materials. It is used in hot sewage pipelines, electroplating solution pipelines and hot chemical reagent pipelines in plants and also wet chlorine pipelines in chlor-alkali plants. As CPVC has excellent flame-retarding and self-extinguishing properties, it can be used to replace metallic water discharge pipelines in construction industry.
Pains in the “core” of industrial development are yet to be soothed
1. Foreign enterprises conduct strict blockade to technology
The commercial production in foreign CPVC enterprises has experienced developments for over 60 years. Production process technologies are already quite matured. A complete CPVC application system has also been established. There are well-developed application sectors and markets. An industrial setup of serialized, specialized and refined product varieties has been formed. Foreign CPVC enterprises have absolute monopoly in both production and sales. They strictly hold CPVC technologies in secret. What is more, they exercise control on technology process packages and PVC special raw materials for the CPVC production. In foreign countries today CPVC is replacing PVC in water pipelines, municipal projects and buried power grids.
2. The CPVC sector in China is still at the stage for large-scale development
In the 1960s Jinxi Research Institute of Chemical Industry successfully developed solution-process CPVC and also achieved commercial production. In the 1970s Anhui Research Institute of Chemical Industry achieved success in using the aqueous-phase suspension process to produce CPVC. Shanghai Chlor-Alkali Chemical Co., Ltd. constructed a 10 kt/a CPVC unit using the aqueous-phase process through its own efforts and put the unit on stream in September 2011. With the constant increase of the market demand, the capacity of CPVC in China has made a gradual expansion in recent years but is also confronted with difficulties. The capacity of CPVC in China was 58.5 kt/a in 2012. There are more than 12 CPVC producers using either self-developed technology or imported technology in 2018 and the total capacity has reached 100 kt/a. CPVC projects with a total capacity of 300 kt/a are also being constructed or planned for construction.
Major CPVC producers in China today include Shanghai Chlor-Alkali Chemical Co., Ltd. (40 kt/a, already completed in October 2017), Weifang Gaoxin Chemical Technology Co., Ltd. (40 kt/a), Weifang Jinyida Plastic Industry Co., Ltd. (10 kt/a), Dongying Xuye Chemical Co., Ltd. (10 kt/a), Shandong Xiangsheng Plastic Industry Co., Ltd. (10 kt/a, a plan for 40 kt/a CPVC made in 2017), Jiangsu Lee & Man Chemical Co., Ltd. (20 kt/a, a plan for 50 kt/a CPVC made in 2016) and Jiangsu Tianteng Chemical Industry Co., Ltd. (5 kt/a). These enterprises all use the aqueous-phase process. Hangzhou Electrochemical Group Co., Ltd. uses the vapor-phase process and the capacity is 5 kt/a. Inner Mongolia Chenhongli New Material Co., Ltd. has made a plan for 100 kt/a CPVC. The complete process package introduced by the company from Noveon (Lubrizol) of the United States uses the UV light aqueous-phase suspension process. A production scale of 20 kt/a has already been formed today. After planned units are completed and reach designed capacities the company will become the biggest CPVC producer in China.
3. Product recognition is low, substitutes squeeze CPVC market
In China both CPE and CPVC use the aqueous-phase suspension process. As the CPE production process is quite matured and the product market scale is big, in most cases CPVC only has collateral production in CPE plants. Compared with CPE, CPVC has small capacity and its right to speak in market is in an inferior position.
Five major producers including Shanghai Chlor-Alkali Chemical Co., Ltd., Jiangsu Tianteng Chemical Industry Co., Ltd., Dongying Xuye Chemical Co., Ltd., Weifang Gaoxin Chemical Technology Co., Ltd. and Shandong Xiangsheng Plastic Industry Co., Ltd. are all making the production of CPE today. The profit margin of CPVC is bigger than CPE, but due to the lack of recognition to CPVC some sectors with no high requirements on products mostly use CPE to replace CPVC. CPE with low market price has also squeezed the market of CPVC that has relatively high price.
As PVC downstream enterprises lack recognition to CPVC or are driven by economic benefits, they use PVC with low price to replace CPVC with high price. There are therefore difficulties in promoting the application of CPVC products. As a result the demand of CPVC in China is less than 40 kt.
4. Raw material PVC powder fails to be totally produced by China itself, processing technology for special materials is imperative to be developed
PVC used as raw material for the production of CPVC in China today is mainly classified into two major categories of special material and common material. Enterprises mostly use imported PVC as raw material in production. Except Weifang Gaoxin Chemical Technology Co., Ltd. that uses PVC special powder produced by Qilu Petrochemical Co., Ltd. as raw material for the production of CPVC and Shanghai Chlor-Alkali Chemical Co., Ltd. that uses ethylene-process PVC produced by itself as raw material for the production of CPVC, most of other enterprises in China use imported PVC powder as raw material. Domestic enterprises are constrained by foreign enterprises in supply/purchase channel and market price and have technical bottlenecks in the processing of special materials.
Four drives help the CPVC sector achieve breakthroughs
1. Intensify the R&D of CPVC production technology, create PVC special material with independent intellectual property right
A great deal of work on the R&D of CPVC production technology has been done in China in recent years. For example, Hubei Research Institute of Chemistry has made research on the solid-phase process for the production of CPVC. CAS Institute of Plasma Physics and Tsinghua University have also launched research on the vapor/solid-phase process for the production of CPVC. Xinjiang Tianye (Group) Co., Ltd. has conducted lots of intensive researches on the R&D of the vapor/solid-phase process and achieved substantial phased achievements. The cyclic fluidized-bed process is used for the first time in history through the 1 kt/a split vapor/solid-phase chlorinated polymer process developed and designed by the company itself. The new production process has won over 10 patents. After more than two years of 1 kt/a commercial demonstrative production, Xinjiang Tianye (Group) Co., Ltd. has already used special PVC powder for chlorination developed by the company itself to produce CPVC recognized by market.
2. Gradually specify product standards
No national standards for CPVC have yet been set in China today. National standards for products related to CPVC are not complete either. Only enterprise standards are formulated in producers. CPVC producers therefore act in their own ways and product quality is unstable. Downstream product enterprises find it hard to make the application and market dissemination of CPVC with excellent properties.
The formulation and the perfection of product standards are essential to the improvement of CPVC product quality. CPVC product standards and market standards should therefore be specified in China. Serialized, specialized, refined and high-purity product brands should be developed.
3. Strengthen research on CPVC modification technology to extend application scope
In view of defects of CPVC in practical application such as great rigidity but inadequate toughness, high melt viscosity of melts, poor heat stability of products, narrow processing temperature range and easy thermal decomposition, research on CPVC modification should be strengthened. Modifiers such as ABS, CPE, MBS and ACR can be added into CPVC and grafting modification can be conducted to increase the impact strength, improve the processing behavior and reduce the melt viscosity of CPVC. Such research has not yet made advances in large-scale commercial application. It is also an opportunity for the development of CPVC modification in application.
4. Enhance product recognition, expand domestic demand
In China today CPVC pipelines are mainly used in anticorrosion and power materials. The consumption in civil uses is quite small. In foreign countries 57% of CPVC is used in civil sectors. There are therefore considerable market potentials in China. Great efforts need to be made by domestic CPVC enterprises in improving product processing behavior to meet the different needs of downstream clients.
Environment friendliness and long service life are development trends for plastic materials. The demand of CPVC has a huge development space in China. We should therefore introduce the concept of environmental protection into the development of the CPVC sector, truly achieve the application of environment-friendly pipelines, realize the localization of CPVC production technology and create our own “Chinese core” of CPVC production technology.
