Polypropylene for Automobile Market Races Along

By Yang Guiying and Gao Chunyu, Sinopec Economics & Development Research Institute

With the growing awareness of environmental protection, greater attention is paid to the recycling and reuse of automotive plastics. Of course, their application properties and processing properties must meet the auto makers’ requirements. Thermoplastic plastics are therefore more preferred than before. In the selection of thermoplastic plastics for automotives, the consumption of polypropylene (PP) is growing, due to the material’s excellent rigidity and heat resistance. For example, modified PP bumpers have replaced PC/PBT bumpers, and modified PP dashboards have replaced PC/ABS dashboards. By contrast, the consumption of ABS and PVC has decreased. The average consumption of PP and modified PP per sedan in the world is 60-90kg today.

Booming development of the PP industry

China’s PP industry started in the 1970s. Development has been rapid in the new century, especially since 2005. The capacity increased from 5.61 million t/a in 2005 to 15.40 million t/a in 2013 with an average annual growth rate of 13.5%. As shown in Figure 1, output increased for several consecutive years, going from 5.23 million tons in 2005 to 12.70 million tons in 2013, average annual growth of 11.7%. The self-sufficiency rate of PP in China made a drastic upgrading from 61.0% in 2005 to 72.4% in 2013.



Table 1   Large producers of modified plastics in China (kt/a)

Company                Capacity    Major products
Kingfa Sci. & Tech. Co., Ltd.    1 000    
Polyolefins, PC, PVC, masterbatches, PPE, AES, PLA, PS, ABS, reinforced PPS and ASA
China XD Plastics Co., Ltd.    400    
Modified PP, modified ABS, modified nylon, alloy plastics, engineering plastics and eco-friendly plastics, 117
varieties of them holding certificates from automotive manufacturers
Shanghai Genius New Material Group Co., Ltd.    200    
ABS, PP, HIPS, PC/ABS alloy, PC, PA, PBT, weather-resistant ASA, TPAC advanced composites and TSM
Shanghai Kumho-Sunny Plastics Co., Ltd.    200    
Modified PC/ABS, ABS, PS, AS, AES, PC, PBT, PET, PC/ASA, PC/AES, PC/PBT, PC/PET, PBT/ABS, PBT/PET, PA/ABS, PMMA/ABS, MPPO and SMA
Shanghai Pret Composites Co., Ltd.    120     
PP high-performance series, ABS series, PC alloy series, PA and PBT engineering series and LCP materials
Guangdong Super-Dragon Engineering Plastic Co., Ltd.        100    
Modified PP, modified HIPS, modified ABS, modified PPO, modified PA6/PA66, modified PBT/PRT, modified PC, conductor materials, abrasion-resistant materials, modified PPS, modified PEEK and PC/ABS alloy
Zhejiang Juner New Material Co., Ltd.    100     
Modified PC, modified PA6/PA66, modified PPO/PPE, modified PBT/PET, modified PP, alloy materials and thermoplastic elastomers
Nanjing Julong Engineering Plastics Co., Ltd.    100    
PA66, PA6, PP, PBT, PC, ABS, PPO/PA6 alloy, PC/PBT alloy and PA/ABS alloy
Beijing Julingyan Plastic Co., Ltd.    70    
Modified PP, modified PC, modified PE and PC/ABS


The PP capacity in China is mainly owned by Sinopec and PetroChina. The capacity of these two companies accounts for 67.5% of the national total. The coal-chemical and methanol-to-olefin sectors have developed rapidly in recent years and the proportion they hold is also getting higher. Nevertheless, as coal chemical enterprises entered the petrochemical sector rather late, and their products are mostly general-purpose varieties, so the consumption in the automotive sector is quite low.

PP resin enters the automotive sector

The development of the PP industry in China has promoted the application of PP resins in the automotive sector. Currently, about 80% of PP resins used in China for automotive applications are domestically made. PP resins for automotive uses are roughly classified into 3 categories:
(1) Low melt flow rate (MFR) PP copolymers. Automotive battery casings made of copolymerized PP with low MFR have no high requirements on properties of materials. Copolymerized PP with an MFR of around 2g/10min can usually meet the requirements. Varieties such as K8303 can therefore be directly used for injection molding. Almost all PP producers can produce such products.
(2) High MFR and impact resistant PP. Automotive bumpers made of PP with high MFR and impact resistance are large thin-wall products. They have high requirements on MFR, rigidity and toughness of materials. Producers of modified plastics therefore mostly use varieties with high MFR and impact resistance. In terms of this category, Sinopec Beijing Yanshan Petrochemical Co., Ltd. and Sinopec Yangzi Petrochemical Co., Ltd. started production rather early and have strong R&D ability. Their products have much better properties than those of other producers and are highly praised in the market. The 200 kt/a PP unit recently completed in Wuhan Petrochemical Co., Ltd. and PP units planned for construction in Shanghai Petrochemical Co., Ltd. and Guangzhou Petrochemical Co., Ltd. will use the technology from Japan Polypropylene Corporation (JPP). Products produced with this technology have high content of rubber phase and are more suitable for use in automotive components.
(3) Medium MFR PP copolymers. Automotive components made of copolymerized PP with medium MFR PP copolymers such as glove boxes usually have no high requirements on properties of materials. Producers of modified plastics are therefore not very particular about the selection of raw materials. Copolymerized PP with medium MFR can usually meet the requirements.

Rapid development of modified materials

Multinationals producing modified plastics today mainly include PolyOne, GE, DuPont and Dow Chemical of the United States, BASF, Hoechst and Bayer of Germany, Asahi Kasei, Techno Polymer, Nippon Steel & Sumitomo Metal, Toray and Mitsubishi of Japan, Samsung, LG, Kumho and Hyduai of Korea, ATO of France and DSM of Netherlands. Compared with producers in China, these multinationals have strong advantage in R&D and production integration.
Petrochemical multinationals in the United States and Europe mostly specialize in the modification of engineering plastics such as modified nylon, at the high end of the modified plastics market. Petrochemical enterprises in Asia that have established wholly-owned subsidiaries or joint venture subsidiaries in China mostly highlight the R&D and production of modified plastics from thermoplastic plastics such as modified PP and modified ABS. Examples include (1) Beijing Julingyan Plastic Co., Ltd., jointly established by Mitsubishi of Japan and Yanshan Petrochemical Co., Ltd.; (2) LG Chemical (Guangzhou) Engineering Plastics Co., Ltd., a wholly-owned subsidiary established by LG of Korea in Guangzhou; (3) Shanghai Jinchang Engineering Plastics Co., Ltd., jointly established by Japanese CHISSO Petrochemical Corporation, Japanese Itochu Corporation and Shanghai Petrochemical Co., Ltd.
Producers of modified plastics in China are mainly private enterprises. There are more than 2 000 producers, but most of them are small enterprises with an annual output of below 3.0 kt. Their products are mostly general-purpose engineering plastic masterbatches used as raw materials. Around 50 producers have an annual output of over 3.0 kt. Only a few producers have an annual output of over 10 kt. Table 1 shows large producers of modified plastics in China.
    
Development trend of automotive PP

Priorities in the foreseeable evolution of motor vehicles include reduced overall weight, minimization of tail gas emissions and the environment-friendliness and high recyclability of materials. The role of PP as a recyclable general-purpose resin in the development of automotives will be all the more pronounced. With constant improvements in the properties of PP raw material and composites, PP will continue to displace ABS in designs, and even partially displace engineering plastics such as nylon.
(1) PP with high crystallinity. PP with high crystallinity has great strength and can reduce the amount of reinforcing fillers added to PP-modified materials. The density of composites can therefore be lowered, furthering energy conservation. The strength of PP with high crystallinity developed by Hyosung of Korea is much greater than PP resins used in the automotive special material market in China. When it is used in PP modification, therefore, the amount of inorganic fillers can be reduced, the density of components can be lowered and vehicle weight can be reduced. The resultant lower consumption of fuels can also help protect the environment. Quite a few petrochemical enterprises in China are researching PP with high crystallinity. Judging from the present status, however, the rigidity of products cannot yet reach the property indexes of foreign products.
Suzuki Motor of Japan has developed a resin material called SSPP. The material has a density around 10% lower than PP varieties and also features excellent coloring properties. It is already used in “Escudo” bottom slip protection boards starting to sell on July 11, 2012. It is reported that no talc powder is added into SSPP. Only PS thermoplastic elastomer is added into PP resin with great rigidity. SSPP therefore has both rigidity and impact resistance. Compared with PP varieties today, SSPP has the same bending strength, but the weight of components made of SSPP is around 10% lower than other components of the same size. Moreover, as the material has higher transparency, its coloring property is excellent. Suzuki Motor will expand the application of SSPP in interior trim parts and exterior trim parts such as bumpers.
(2) PP with high MFR. There are two production methods for PP with high MFR: the hydrogen regulation process and the degradation process. The hydrogen regulation process uses hydrogen as molecular weight regulating agent. The molecular weight distribution can be effectively controlled, but the requirements for catalysts are quite high and the process operation is somewhat complex. The controllable degradation process uses peroxides as degrading agents and degrades PP long chains into short chains so as to attain high MFR PP resin. Due to the use of peroxides as degrading agents, however, the material has some odor and does not conform to the environment-friendliness requirements of automotive interior trim materials today. Quite a few companies such as Sinopec Beijing Yanshan Petrochemical Co., Ltd., Sinopec Maoming Petrochemical Co., Ltd. and Sinopec Yangzi Petrochemical Co., Ltd. have already mastered the hydrogen regulation process technology and gained certain advantage in the production of PP with high MFR.
(3) PP with high impact resistance. PP with high impact resistance is PP copolymers with high content of rubber phase. Its low-temperature impact resistance is closely related to the content and form of rubber phase it contains.
JPP has developed NEWCON series PP resin with the HORIZONE process. The highest ethylene content can reach 20% and the highest rubber phase content can reach 50%. The rubber layer also displays a unique continuous lamellar and acicular state. Such PP resin therefore has excellent room-temperature and low-temperature impact resistance and is an ideal resin for automotive bumpers and interior trim parts. Sinopec Wuhan Petrochemical Co., Ltd. has introduced the technology from JPP and constructed a 400 kt/a PP unit. Production started in August 2013. PP resins for automotives were successfully produced in January 2014, providing an excellent raw material to the modified plastic sector in China. Besides, enterprises subordinate to Sinopec such as Beijing Yanshan Petrochemical Co., Ltd. and Yangzi Petrochemical Co., Ltd. have been engaged for many years in new products, combining production, marketing and research. On the strength of many years’ technical development, they have become leading enterprises in China in providing new PP varieties with high impact resistance.