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  • Writer's pictureBona House Materials

What is PU?

Updated: Apr 28, 2023

PU, fully known as polyurethane, is a high molecular compound, which was produced by Otto Bayer in 1937. There are two types of polyurethane: polyester type and polyether type. They can be made into polyurethane plastic (mainly foam plastic), polyurethane fiber (called spandex in China), polyurethane rubber and elastomer.


Flexible polyurethane is mainly a linear structure with thermoplastic properties. It has better stability, chemical resistance, resilience, and mechanical properties than PVC foam materials, and has less compression deformation. Good performance in heat insulation, sound insulation, shock resistance, and gas prevention. Therefore, it is used as packaging, sound insulation, and filtering materials.


Rigid polyurethane plastic is light in weight, excellent in sound insulation, thermal insulation, chemical resistance, good in electrical properties, easy to process, and low in water absorption. It is mainly used as structural material for building, automobile, aviation industry, and thermal insulation. Polyurethane elastomer has properties between plastic and rubber, oil resistance, abrasion resistance, low temperature resistance, aging resistance, high hardness, and elasticity, mainly used in the shoe-making industry and medical industry. Polyurethane can also be used to make adhesives, coatings, synthetic leather, and so on.


Polyurethane emerged in the 1930s. After nearly 80 years of technological development, this material has been widely used in the field of household appliances, construction, daily necessities, transportation, household appliances, and other fields.


Polyurethane (PU) was first developed in the 1930s by German scientists. The physical properties of this material are different from those of polyolefin materials at the time, and scientists named it polyurethane. With the end of the Second World War, the chemical manufacturing industry in the United States flourished, and in the 1950s, polyurethane flexible foam was synthesized, which was an important landmark research in the chemical industry at that time and provided a solid technical foundation for the future development of the polyurethane industry.


  • Global PU market situation

The global polyurethane market is mainly distributed in developed countries in Europe and the United States, and the Asia Pacific region is mainly represented by China, Japan, and South Korea. These countries and regions account for 90% of the global polyurethane market, with China accounting for half of the global polyurethane consumption. There are a wide variety of polyurethane products worldwide and they are used in various fields. By the end of 2016, the global total production of polyurethane had reached about 22 million tons.


  • Domestic PU market situation

China's polyurethane industry is mainly concentrated in the Yangtze River Delta region. In recent years, with the continuous development of industrial manufacturing technology, the Bohai Rim Production Area, the Pearl River Delta Production Area, and the Northwest Manufacturing Industrial Base centered in Yantai are all booming. Under the pressure of domestic environmental protection, various enterprises began to seek transformation, with the main development direction of creating green and environmentally friendly polyurethane production processes, gradually eliminating outdated production capacity. It is expected that in the next few years, China's polyurethane products will be mainly used in the fields of construction, furniture, and sports. By 2016, China's polyurethane consumption has reached 11 million tons, creating about 350 billion yuan of direct economic benefits for China.


  • Overview of main raw material market

The main raw materials of polyurethane include diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), and polypropylene glycol (PPG), all of which have become international commodities. The production technology and equipment for these raw materials are very complex, and product competition is quite fierce. As a result of long-term development, production is relatively concentrated.


It can also be divided into aliphatic isocyanates and aromatic isocyanates. Currently, aromatic isocyanates are the most widely used, such as MDI and TDI.


MDI

The production technology and equipment requirements of MDI are relatively complex, and the production technology is controlled by several giant enterprises around the world. More than 95% of global MDI production enterprises are concentrated in Asia and Europe. Compared to the two, the growth rate of the European market is slower than that of Asia, but its MDI industry started early and the market is relatively mature.


On June 1, 2015, the China South Korea Free Trade Agreement was officially signed, resulting in changes in the tax rate of polyurethane raw materials. The export tax rate of China's polymerization MDI decreased faster than the import tax rate. With the increase in domestic aggregate MDI market capacity and output, import dependence decreases and export dependence increases. The implementation of the China South Korea Free Trade Agreement will have a significantly greater impact on China's aggregate MDI exports than on aggregate MDI imports.


TDI

In 2015, the price trend of TDI in various regions of China fluctuated greatly, and the firm offer of manufacturers became the sole driving force for the rise of TDI prices. However, due to the impact of demand, the trend declined several times, repeatedly breaking new lows. The price range for the entire year of 2015 was lower than that of the previous two years, and the high level of the TDI market has disappeared. In addition, the overall operating rate of domestic TDI manufacturers in 2015 was lower than in 2014, resulting in a significant reduction in production.


PPG

PPG is one of the main raw materials for the production of polyurethane products. The usage of PPG in polyurethane foam can reach more than 90%, accounting for the largest proportion. Due to the large scale of production equipment for polyether polyols, the production capacity is mainly concentrated in several large multinational companies such as BASF, Bayer, Dow Chemical, and Shell. The polyether polyol manufacturers in China have only formed a certain scale through technology introduction and independent research and development. In recent years, with the expansion of production by large manufacturers, the variety and specifications of polyether polyols are basically complete, and the quality and stability of products have also greatly improved.


  • Classification of PU products

PU Polyurethane products mainly include the following: foam plastics, elastomers, fiber plastics, fibers, leather shoe resins, coatings, adhesives and sealants, among which foam plastics account for the largest proportion.


Polyurethane foam

Polyurethane foam plastics are divided into hard foam and soft foam, which have excellent elasticity, elongation, compression strength, softness, and good chemical stability. In addition, polyurethane foam has excellent processability, adhesion, thermal insulation and other properties, which are excellent cushioning materials.


polyurethane-rigid-foam
polyurethane-rigid-foam

Polyurethane materials have been produced throughout North America. It is reported that the overall average annual growth rate of polyurethane foam market in North America is expected to reach about 6%. It is estimated that by 2020, the growth areas are mainly concentrated in the market of polyurethane foam application in residential and industrial applications, as well as military applications. In addition, polyurethane will also be used in the medical industry to provide timely and effective treatment of wounds.


Polyurethane elastomer

Due to its structure having two chain segments, soft and hard, polyurethane elastomers can be designed to impart excellent properties such as high strength, good toughness, wear resistance, and oil resistance to materials through molecular chain design. Polyurethane, known as "wear resistant rubber," combines the high elasticity of rubber with the rigidity of plastics.


In the past year, due to the significant decline in the price of crude oil, and against the backdrop of the Great Depression of the global economy, the year-on-year growth of the polyurethane elastomer market in China has been slower than in previous years. The imbalance in the supply and demand ratio has seriously led to a downward trend in the price of polyurethane elastomers. However, this phenomenon only occurs in traditional polyurethane products. The market prospects for elastomer products with high technological content and innovation, such as Nano-polyurethane elastomer materials, are still very promising.


Polyurethane fiber plastic

In 2015, the overall price of spandex fiber market has been falling all the way, and the prices of various specifications of spandex fiber have fallen to historical lows, even breaking new records. By the end of 2015, the mainstream quotation for 40D spandex had been as low as around 36000 yuan/t, a decrease of 25.47% compared to the beginning of the year, creating a new historical low in the cycle.


From the perspective of the upstream and downstream of the industrial chain, the current situation faced by polyurethane fiber plastics is constrained by the continued downturn in the economic environment. In the downstream manufacturing sector, production and sales are not strong, supply exceeds demand, and there is a serious backlog; On the other hand, it is also due to the sharp decline in raw material prices.


The price of spandex has plummeted all the way, leading to a decline in industry profits. The continuous release of new intelligent production capacity has resulted in oversupply, which has also strongly impacted the spandex market. In addition, due to the shortage of funds in the downstream spandex industry and the vicious cycle of the industrial chain, China's spandex import volume plummeted from January to November 2015, resulting in a contradiction between supply and demand, which has become a serious injury to the decline in spandex prices.


  • Application field of PU products


Furniture industry

In the furniture industry, wood-like materials are one of the main application directions of polyurethane rigid foam. Wood-like materials are lightweight in quality, and have a density and strength comparable to wood. Using this material to make furniture, not only will there be no cracks after molding, but also can reduce the cost of production and manufacturing. With the increasing awareness of national environmental protection, wood-like materials will be more widely used in the furniture industry, thereby replacing natural wood in the position of furniture.


China is a major furniture production and processing country in the world, considering the total consumption of polyurethane in the furniture industry during the "12th Five Year Plan" period; During the "13th Five Year Plan" period, China's furniture industry is still focused on expanding domestic demand and stimulating urban consumption. As China's real estate policies continue to tighten, the construction speed of affordable housing and low-rent housing will continue to accelerate. China's furniture industry will not be impacted, and the demand for polyurethane by the public will increase by 5% annually.


construction industry

Polyurethane rigid foam is the preferred material used in the field of building insulation, with simple structure, long product life, high construction efficiency, high fire resistance rating, and low overall cost. With the continuous implementation of energy conservation and environmental protection policies in China, the construction industry will face more severe tests during the "13th Five Year Plan" period, and rigid polyurethane foam will be widely used in the field of building insulation. In addition, as an important waterproof coating, polyurethane is widely used in roof, exterior wall, basement, kitchen and bathroom, road and bridge parts of buildings. With the continuous development of China's rail transit and high-speed railway industry, polyurethane waterproof coating will also be widely used in the field of railway construction. Currently (in 2015), the consumption of polyurethane in the construction industry in China is about 1.25 million tons, accounting for 20% of the total consumption, while the total consumption in the same industry in developed countries is 35%. Based on data analysis, it is not difficult to find that China's rigid polyurethane foam still has great development space in the construction industry.


Transportation industry

There is also polyurethane in the transportation industry, which mainly includes soft, hard and semi-rigid foam plastics, as well as polyurethane elastomers, polyurethane adhesives, polyurethane sealants and polyurethane coatings. The total amount of polyurethane required for a molded car is around 30 kg, and the amount of high-quality polyurethane products used in cars is also an important factor in measuring the level of cars. China is a major automotive country, ranking first in the world in terms of both the number of manufactured cars and the number of cars owned. According to relevant data statistics, the consumption of polyurethane used in the automotive industry in China is nearly 400000 tons per year. With the continuous introduction of new energy vehicles, polyurethane consumption will have a broader growth space in the automotive industry.


In addition to the automotive industry, China's cold chain transportation industry is also another area of polyurethane development. With the continuous improvement of people's living standards in China, more and more people have a sharp increase in demand for flowers and aquatic products everywhere, which has driven the development of China's cold chain transportation industry. The transport vehicles in the cold chain transport industry usually use polyurethane rigid foam sandwich panels as thermal insulation materials. At the same time, a large number of polyurethane thermal insulation materials are also required in the construction of cold storage, which is also a major benefit to China's polyurethane industry.


other

Polyurethane can also be used for packaging fragile goods, especially in transportation packaging of some precision instruments, handicrafts, fragile goods, etc. This type of product can also be used in the fields of aviation, aerospace, automobile manufacturing, liquefied natural gas transportation vehicle (ship) manufacturing, and so on.


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