Polyurethane: Green Chain to Facilitate Energy Conservation and Environmental Protection

By Li Jianbo, China Polyurethane Industry Association

Polyurethane (PU), which is a new organic polymer material, has both advantages of rubbers and plastics, especially the advantages that other synthetic materials cannot match in the aspects of heat insulation, sound insulation, wear resistance, oil resistance, elasticity and flexibility, and is widely used in sectors such as chemical industry, light industry, textile, building, household appliances, transportation, aerospace and national defense, etc. It is not only closely related with people's life, but also plays an important role in the fields of energy-saving and consumption reduction that are vigorously implemented by the state and beneficial to the people's livelihood such as building energy-saving, electric appliances energy-saving and wind power.
In 2013, China’s total output of PU products reached 8.7 million tons, up 11.5% year-on-year, of which the output of PU foam plastics, PU elastic fiber (spandex), PU elastomers, PU slurry for synthetic leather and PU liquid for shoe sole, PU coatings, and PU adhesives and sealants was 3.4 million tons, 400 thousand tons, 700 thousand tons, 2.55 million tons, 1.4 million tons and 500 thousand tons, respectively. China's production and consumption of PU products all rank first in the world.

I. Vigorous development of upstream raw materials

1. MDI

Due to the high technical barriers being formed by the high difficulty and complexity of production technology, only six countries (China, the United States, Germany, Japan, South Korea and Hungary) and seven companies (Bayer, BASF, Huntsman, Dow, Mitsui Chemical, Tosoh and Yantai Wanhua Polyurethane Co., Ltd.) in the world master the core technology of MDI (diphenylmethane diisocyanate) production, forming a high concentration degree of global MDI sector. The global capacity for MDI is concentrated in Europe, the United States and Asia. In 2013, the global capacity to make MDI reached 6.66 million t/a, of which the MDI capacity in Asia, Europe and the United States was 3.13 million t/a, 2.1 million t/a and 1.43 million t/a, respectively.
Because polymerized MDI has good heat insulation and high bonding performance, PU rigid foam made from it not only has a good heat insulation effect, but also has the advantages of lightweight, environmental protection and non-flammable, etc. Polymerized MDI also has a good bonding performance, most of PU adhesives are synthesized using polymerized MDI as main raw materials, and can be used in automobile, construction, anti-theft door, color steel insulation board and wooden artificial board sectors. The global demand for polymerized MDI was 4.08 million tons in 2013, accounting for 75% of the total MDI consumption.
Pure MDI has good mobility and resilience. With the increased demand for elastic fabric, the consumption of pure MDI in spandex sector has also increased. In addition, a small amount of pure MDI is also used in the coatings and adhesive sectors. In 2013, the demand for pure MDI in the world was 1.36 million tons, accounting for 25% of the total MDI demand.
China’s consumption of pure MDI has accounted for around 42% of the world total, and pure MDI in China is mainly used to produce PU shoe sole, synthetic leather slurry, spandex, thermoplastic polyurethane elastomer (TPU), adhesives and coatings. China’s pure MDI market is mainly concentrated in the eastern coastal areas, Jiaodong region of Shandong province, Wenzhou of Zhejiang province, Shanghai, Jiangsu province, Jinjiang of Fujian province and Anhui province, etc. The insulation of household appliances including refrigerator, freezer and water heater is the major consumption sector of polymerized MDI, and the consumption of polymerized MDI in this sector accounts for over 40% of the total. The pipeline heat insulation, vehicle and the insulation board for buildings come next. China’s polymerized MDI market is mainly concentrated in the eastern coastal areas, and the market in East China, South China and Northeast China is also relatively big.
At present, China has four MDI producers - Yantai Wanhua Polyurethane Co., Ltd., Shanghai Lianheng Isocyanate Co., Ltd. (a joint venture between BASF and Huntsman), Bayer and Nippon Polyurethane. At present, China’s total capacity to make MDI has reached 2.15 million t/a. In 2013, China’s consumption of MDI reached 1.7 million tons, of which the domestic consumption of polymerized MDI, and pure MDI as well as modified MDI was 1.08 million tons and 620 thousand tons, respectively.

2. TDI

TDI (toluene diisocyanate) is mainly used in the production of flexible foams, coatings, elastomers and adhesives, of which the consumption proportion of TDI in flexible foams and coatings is nearly 90%. At present, there are more than 20 TDI producers and over 40 TDI units in the world. The production and consumption of TDI in Europe and the United States has tended to be mature, and the new growth point in the future will come from Asia as well as some PU underdeveloped or backward regions such as the Middle East and South America. According to the current plans announced by major producers, there is basically no construction plan in North America, and the capacity proportion in this region will reduce to 18% by 2015. The capacity to make TDI will still grow constantly in Europe and Asia, and according to the current expansion plans, the capacity proportion in Asia will climb to 74% in the future.
China has six TDI producers including Gansu Yinguang Chemical Industrial Co., Ltd., Cangzhou Dahua Co., Ltd., Yantai Juli Fine Chemical Co., Ltd., Fujian Southeast Electrochemical Co., Ltd., Bayer and BASF. In 2013, China’s capacity to make TDI reached 890 thousand tons, the domestic market demand was 60 thousand tons, and China became the largest TDI producer and consumer in the world.

3. PPG

PU flexible foam is the major consumption sector of polyether polyol (PPG), and the consumption of PPG in this sector accounts for 57% of the total. PU rigid foam comes next, accounting for 27%. China, Western Europe and the United States are major PPG consumption regions in the world. With the rapid development of PU sector in china, a large number of PPG plants has been constructed or expanded, and the capacity to make PPG has also grown rapidly. Due to the low technical barrier of PPG production, there are more PPG enterprises in China. In 2013, the domestic capacity to produce PPG exceeded 3.0 million t/a. At present, China’s capacity to make PPG has been surplus.

II. Brisk demand in downstream sectors

PU products mainly consist of PU foam, PU elastomer as well as elastic fiber (spandex), PU shoe and leather resin, PU coatings, and PU adhesives, etc.

1. PU foam

PU foam is divided into three categories-flexible foam, rigid foam and semi-rigid foam. The flexible foam is applied in mattresses, sofas, garment liner and car seat, etc. As a material with the best adiabatic performance, the rigid foam is mainly used in refrigerating units and equipment including refrigerator, freezer, cold storage and container, heating pipe and the roof of buildings, external wall insulation, air-conditioning conduit cold insulation, and wood substitute material, etc. The semi-rigid foam is mainly used in the interior decoration and energy absorbing materials of vehicles including car. China has many PU foam enterprises. In 2013, China’s total output of PU flexible foam and rigid foam reached 3.4 million tons, ranking the first in the world.

2. PU shoe and leather resin

PU synthetic leather, which is the best artificial leather for replacing animal leather, is widely used in footwear, bags and clothing, etc. In 2013, China’s consumption of PU synthetic leather fluids (commonly known as PU slurry) was around 2.05 million tons, and China became the largest PU synthetic leather producer and consumer, and also the most important exporter in the world. The domestic consumption of PU shoe sole fluids was around 500 thousand tons in 2013, also ranking the first in the world.

3. PU elastomer as well as elastic fiber

PU elastic fiber is an important fiber component being indispensable for spring clothing and high-grade fabric. China has become the world’s largest PU fiber (spandex) producer, consumer and exporter, and its capacity accounts for around 60% of the world total. In 2013, China’s consumption of PU elastomer reached around 500 thousand tons, and the domestic output of spandex was 400 thousand tons.

4. PU coatings and adhesives

PU coatings are widely used in high-grade wood paints, building coatings, anti-corrosive coatings, automotive paints and aircraft dope, etc. PU adhesives are extensively used in shoemaking, composite film, construction, automobile, and the special bonding and sealing of aviation/spaceflight. In 2013, China’s consumption of PU coatings, and PU adhesives as well as sealants reached around 1.4 million tons and around 500 thousand tons, respectively.

III. Broad development space in the future

1. The downstream market maintains stable growth

China has become the world’s leading producer and consumer of PU in view of total consumption, however, per capita PU consumption is still very low in China, and PU in China still has a great space for development.
(1) Furniture sector. Furniture sector is a major application field of PU flexible foam, and the mattress and sofa are manufactured mainly using block foam as raw material. On one hand, China is the world’s leading producer and exporter of furniture; on the other hand, with the acceleration of China’s urbanization, as the bulk durable consumer goods, the furniture’s overall trend is optimistic.
(2) Automobile industry. PU products used in the automobile industry mainly include flexible foam, rigid foam and semi-rigid foam plastics, PU elastomers (including CPU and TPU microporous elastomers), adhesives, sealants and coatings, etc. China's automobile industry has developed rapidly, and the domestic output and sales amount of automobiles have ranked the first in the world. However, the consumption of PU products per vehicle in China is only around half of that in foreign countries. With the improvement of automobile comfort, the application of PU in automobile industry will developed rapidly.
(3) Cold chain logistics. With the improvement of people's living standards as well as the development of planting and aquaculture sectors, fresh foods are often directly delivered to the sales terminals in China and even the whole world through the cold chain logistics system after being locally processed and quickly frozen. The transport equipment of cold chain logistics system like refrigerated train, refrigerated truck and refrigerated container all use PU rigid foam as insulating material. The storage facilities like cold storage are also assembled by using PU rigid foam sandwich board or constructed by using PU rigid foam spot spraying.
(4) Building insulation and waterproof. PU rigid foam is commonly used in foreign building insulation field. When being applied in exterior wall engineering, it can integrate heat insulation, waterproof and decoration, and has many advantages such as simple structure, long service life and high construction efficiency. PU waterproof material is mainly used in the concrete waterproof coatings for building roof, wall, ground, highway, railway, bridge and culvert, high-speed railway and city rail. With the improvement of building energy-saving and fire protection standards as well as the implementation of public basic construction, China will use a large quantity of PU rigid foam in the building insulation and waterproof fields.
(5) Wood adhesives. Isocyanate and PU adhesives can replace the traditional urea-formaldehyde adhesive to be applied in the artificial boards, and completely solve the problem of formaldehyde emission. With the improvement of people's living standard and the increasing awareness of environmental protection, the application of PU adhesives in high-end artificial boards will be promoted.
(6) Traditional application fields. Traditional sectors including refrigerator and freezer, shoe and leather resin, spandex and elastomer are closely related to people's basic necessities of life. With the gradual implementation of China's policy of stimulating domestic demand, these sectors will also grow steadily.

2. Concentration degree of raw material sectors is getting higher and higher

At present, the single set production scale of new MDI units has reached 400 thousand-600 thousand t/a, and the single set production scale of TDI units has also exceeded 100 thousand t/a. With the constant expansion of capacity, the industrial competition will be increasing fierce, and the scale advantages of enterprises will be increasingly apparent.

3. New technologies will achieve a considerable development

The development of technologies with energy-saving, safety and environmental protection is the future development trend. For example, the development of gas phase phosgenation technology for producing TDI, gradually eliminating chlorohydrin process of propylene oxide manufacturing, the development of HPPO process (synthesis of propylene oxide by propylene oxidation), the development of water based or solvent free PU products, the development of PU foam flame retardants with high efficiency and low toxicity, the research and development of new environmental friendly foaming agents, and the development of chlorine recycling technology in the course of isocyanate production as well as the development of biodegradable PU materials.