I. Future development direction of materials for the automobile industry
The future development of China’s automotive industry will gradually change from the pursuit of production capacity and scale to more attention to quality and level. Lightweight, green, comfortable and safe, will become the three themes of the future development of China’s automotive materials.
The rapid development of China’s PU industry, for the rapid development of China’s automotive industry to create the necessary conditions.
PU material products for the automotive industry mainly include soft, rigid, semi-rigid, foam, PU elastomer (including CPU, TPU microporous elastomer), adhesives, sealants and coatings, etc. (see Table 1).
Table 1 Automotive polyurethane products list
Species Auto parts Main performance and use status
High resilience cold molded soft foam seat cushions, backrests, headrests, decorative strips Excellent resilience, low hysteresis loss, high compression load ratio, good feel, good breathability, good self-extinguishing, low energy consumption during production, now more popular
Heat molding with filler soft foam seat cushions, backrests, headrests, foot cushions low raw material prices can be added to inorganic filler to improve product performance and reduce costs, can use simple structure and low cost of the mold
Semi-rigid foam dashboard filler, door pillar skin, control box, speaker seat cushion, armrest, headrest, sun visor with high density and compression strength, excellent energy absorption function, shock absorption and impact resistance, now used more
Self-crusting foam Armrests, steering wheels, air spoilers, headrests, door pillars, control boxes Smooth and high-density self-crusting surface layer with a low-density elastic foam core, more commonly used nowadays
Microporous elastomer steering wheel, filter gasket, sealing strip, anti-vibration pad and rubber than the density of softer, better dimensional stability, wear resistance, excellent flexural properties, good anti-aging properties
Hard foam Door panel lining, headliner, small refrigerator, imitation wood trim, muffler, sun visor Light weight, high strength, good automotive stability, excellent insulation performance (is the best organic insulation material), good anti-aging properties, now used more
Casting type elastomer (CPU) Dustproof seal, bearing sleeve, steering knuckle bushing, door gear block, steel plate spring lug bushing, automobile tire Large load capacity, high tear strength, wear resistance, oil resistance, hardness can be adjusted in a wide range
Thermoplastic elastomer Shock absorbing cushion, steel plate spring spacer, spring coil sheath, gear transmission unit, headliner and body parts High modulus, high strength, high elongation and high elasticity, excellent wear resistance, oil resistance, low temperature resistance and aging resistance. Available general plastic processing methods (injection molding machine) to produce a variety of products, waste can be recycled, there is a trend of expansion
Second, PU is the key material to achieve lightweight automotive materials
PU foam in the application of automotive interior parts: 2010 China’s automotive interior parts PU soft foam dosage of 152,000 t, PU hard foam dosage of 67,000 t. Mainly used in automotive instrument panels, seat cushions, backrests, headrests, doors, armrests, steering wheel assembly, car roof, door panels and seals and other parts. Reducing the density of PU foam is an important technical way to achieve the lightweight of automotive interior parts. At present, the main domestic technical pathway: the use of high solid content, low viscosity POP (graft polyether) and high functional, highly reactive polyether and other technical pathways.
RIM (Reaction Injection Molding), RRIM (Reinforced Reaction Injection Molding) and SRIM (Structural Reaction Injection Molding) PU products in automotive applications to achieve lightweight: RIM, RRIM and SRIM have been widely used in the automotive industry in Europe and the United States, mainly for bumpers, steering wheels, body panels, hoods, luggage compartment covers, radiator grilles, gear mudguards, spoilers, etc.. The weight of RRIM products is only half that of steel, which is an important way to realize the light weight of automobiles. At present, the domestic automotive industry RIM and other technologies, compared with Europe and the United States in the amount and quality still exists in a certain gap, to further strengthen the development.
PU material is a promising and important material for automobiles to realize plasticization. The current direction of development of the world’s cars (mainly cars and new energy vehicles) is lightweight. Lightweight is to improve fuel combustion efficiency and reduce vehicle emissions, is also an important technical measure to achieve energy saving and emission reduction of cars. The plasticization of automotive materials, plastic instead of steel, is the development of the inevitable trend and an important technical approach to automotive lightweighting. Different materials of automotive parts, energy consumption is different.
To produce the same weight (450 grams) of parts, for example, the use of plastic parts energy equivalent to 3.9 ~ 4.5 kg of gasoline, if the use of aluminum or steel, the energy equivalent to 5.3 ~ 6.8 kg of gasoline. statistics show that the weight of the car is reduced by 10%, fuel consumption can be reduced by 6% to 8%.
At present, the average amount of plastic used in cars in technically developed countries is 120 kg/car, and the average amount of plastic used in cars in Germany is 300 kg. The average amount of plastic used in cars in China is 80~100 kg/car, and the amount used in Audi A2 cars is 220 kg. The PU body is a carbon fiber reinforced microporous PU elastomer composite material.
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TPU and its composite materials are one of the important raw materials for the plasticization of automobiles
At present, the plastic parts materials used in cars are mainly PP (polypropylene), PVC (polyvinyl chloride), PU and PA (nylon) four kinds of materials. The development direction of automotive plastic parts is to continue to introduce excellent cost performance and recyclable materials. TPU has been used in a variety of automotive body components, including TPU plastic alloy, such as TPU and PP, PVC, PA and other plastics to form cost-effective composite materials, can play a significant role in the automotive industry. have important uses.
(1) TPU/PP (polypropylene) plastic alloy
Currently, domestic and foreign TPU-PP glass fiber (including long and short fibers) is being developed for automotive reinforced rubber-plastic composite structure materials, such materials have the advantages of light weight, excellent cost performance, recyclable, etc., can be expected to be widely used in automotive interior and exterior parts, such as bumpers and their brackets, a variety of brackets and structural frames, etc., once the development is successful, the application of TPU in the car will be significantly increased.
(2) TPU/PC (polycarbonate) plastic alloy
TPU/PC co-mingled gold can improve the PC toughness, stress cracking, fracture sensitivity, solvent resistance, chemical resistance, while reducing the PC molding processing temperature, in the automotive industry to expand its application.
(3) TPU/PVC plastic alloy
TPU/PVC alloy can significantly improve the elongation of PVC (can replace the toxic DOP plasticizer) to expand the application of PVC. Recently, reactive blending technology has been reported for the preparation of TPU/PVC alloys. First dissolve PVC in TPU raw material diol, and then add isocyanate for in-situ polymerization to form TPU/PVC alloy, the performance is better than the general TPU/PVC co-blended gold, in the automotive field, expanding the scope of application.
(4) TPU/PA6 (nylon 6) plastic alloy
PA6 has high strength, corrosion resistance, oil resistance and excellent self-lubricating characteristics, but there are impact toughness is not high, moisture absorption is large shortcomings. TPU elastomer has high strength, high elasticity and high wear resistance, but has the disadvantage of low temperature resistance. The development of TPU/PA6 engineering plastics combines the advantages of the above two materials and overcomes their shortcomings, which will be a new type of high-performance composite materials. It has wide application value in automotive industry.
TPU plastic alloy and TPU rubber composite material both have the advantages of recycling, at present, there are more than 50 million scrap vehicles in China, and there will be 10 million old vehicles to be renovated and scrapped every year. Advanced countries in Europe and the United States on the automotive industry plastic parts clearly put forward the recyclable rate indicators and utilization rate, requiring automotive plastic recyclable rate of 95% or more, the utilization rate of 90% or more. China’s Development and Reform Commission, the Ministry of Science and Technology, the Environmental Protection Bureau jointly developed a technical policy on the recycling of automotive parts “by 2017, China’s automotive recycling rate is required to reach more than 95%, the utilization rate of 85%”. TPU is a recyclable thermoplastic elastomer, but the current annual consumption of TPU in China’s automotive industry is only 3 About 10,000t, TPU plastic alloy and other composite materials undoubtedly to the new TPU elastomer materials in the automotive application provides a new huge market opportunities.
Fourth, PU green materials is an inevitable trend in the development of automotive materials
(A) the development of low VOC PU foam
(1) VOC (volatile organic compounds) content in the car has become an important evaluation indicator of consumer awareness of its products.
(2) VOC volatiles in PU foam materials, PU adhesives, PU coatings, PU synthetic leather, etc. in the car is the main factor affecting the air quality in the car.
(3) research and control of harmful gases and volatile problems in PU materials and effective preventive measures to improve the environment in the car, the development of China’s automotive industry are of great significance.
(4) the main sources of PU foam VOC for automotive interior parts: polyether polyol (mainly POP), catalysts, levelling agents (stabilizers), volatile organic compounds in isocyanates including aromatic compounds (toluene, styrene) and organic amine compounds, etc..
(5) Development of high-solid, low-volatility POP, organic amine reactive catalysts, low-volatility leveling agents, etc. Shanghai Institute of Applied Technology is working with Wuhan Xingqiao Polymer New Material Technology Company and other units to develop a vehicle VOC air purifier, which has obvious effect on improving the air quality in vehicles.
(B) actively develop biomass vegetable oil-based polyol green technology
Vegetable oil is a renewable resource, the use of such as soybean oil, castor oil, palm oil and other vegetable oils as raw materials, the corresponding vegetable oil polyol can be developed to replace the petrochemical route polyether polyol. Bio-based PU foam recycling rate, organic matter volatilization and CO2 emissions are better than petroleum-based PU foam, is a green and environmentally friendly raw materials. The United States focuses on developing soybean oil-based vegetable oil polyols, and Ford Motor Company has successfully developed into soybean oil-based PU foam for car seat cushions and seat backs. Malaysia, using local resources, has developed a series of palm oil polyols, which are widely used in the field of PU hard foam. Toyota Motor Corporation of Japan has successfully developed castor oil-based PU foam seat cushions.
(C) actively develop PU automotive green tire technology
At present, the vast majority of the global automobile tires using rubber tires. PU tires have excellent wear resistance (natural rubber 3 to 5 times, the actual application of up to about 10 times), does not contain carbon black and paraffin hydrocarbons harmful substances, used in urban transportation, will greatly improve urban air quality. PU tires than rubber tires also have the advantages of low energy consumption in processing, energy saving and long service life. The important raw material for rubber tires is natural rubber (NR), China’s tire industry needs 490 ~ 6 million t of NR each year, accounting for 50% of global production, while the self-sufficiency rate of only 13% ~ 16%, a large number of imported NR, the current price of NR has been as high as 40,000 yuan / t or more. Therefore, the active development of PU tires has become imperative, has been included in the Chinese PU Industry Association “Twelfth Five-Year Plan” during the key development objects.
South China University of Technology has successfully developed a PU-rubber compound tire using CPU technology, which is already in the industrialization stage. Shanghai Institute of Applied Technology is actively developing TPU tires, welcome the relevant units to participate in cooperation.
(D) the development of water-based PU adhesives for vehicles has broad prospects
With the sound environmental regulations and environmental awareness of the increasing, solvent-based automotive adhesives will gradually be replaced by environmentally friendly adhesives, such as water-based adhesives. In particular, the promotion and application of water-based automotive interior adhesives has become imperative. Water-based interior adhesive is mainly used to bond the car roof, floor, carpet, instrument panel, door panels and other interior parts. At present, Japan’s automotive interior adhesive all reach water-based, the United States for 60%, China is only 20%. In the water-based automotive interior adhesive, PU adhesive is the main species. China’s water-based PU interior adhesive technology has become increasingly mature, should be actively promoted in the field of automotive applications.
In addition, with the light weight of the car, the amount of plastic parts continue to increase, environmentally friendly solvent-free PU structural adhesive in the field of automotive applications have broad prospects for development, such as glass fiber reinforced plastic (FRP) and sheet molding compound (SMC) has been widely used in Europe and the United States, Japan, automotive body panels, roof, cockpit roof, etc. FRP and SMC can not use the traditional welding technology, and body frame assembly The bonding technology must be used. Solvent-free PU adhesive is one of the important varieties.
(E) The development of water-based PU coatings for vehicles has a bright future
Water-based PU flexible coating is a low VOC coating, more than 10 times lower than the traditional solvent-based coating VOC volatiles. With the light weight of the car, plastic parts applications continue to expand, environmentally friendly green water-based PU flexible material is the future direction of the development of automotive plastic parts coating.
(F) PU synthetic leather has a promising application in automobile interior trim
PU synthetic leather has the advantages of odorless, soft touch, good abrasion resistance, high tear strength and good color fastness compared with genuine leather, and overcomes the problem of increasing tension of genuine leather resources and serious environmental pollution, which meets the green environmental protection requirements of automobile interior parts. Especially, PU microfiber imitation deerskin velvet has the advantages of luxurious appearance, soft texture, elegant luster and good durability, which makes the car interior parts have a sense of living room and has been favored by car manufacturers and become an indispensable senior interior environmental protection material for high-grade cars.
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Five, PU material comfort and safety is its important development direction
(A) to improve the comfort of the car is an important development direction of PU automotive interior parts
Seat cushions, backrests and headrests are the parts of polyurethane foam that are used a lot in cars, and they are also the places where people are sensitive to riding comfort, so the performance requirements of the products are also very strict. At present, most of the polyurethane foam seat cushions for domestic automobiles are cold-ripened products of uniform density. The new type of car seat cushion developed in recent years adopts double hardness or multi-hardness foam, and the production of such double hardness seat cushion can be realized both by using polyether polyol and isocyanate through double or multi-head mixing head injection mold, and also by using full MDI cold molding process to accurately control the hardness of different parts of the seat cushion by changing the index of isocyanate – – The middle of the seat cushion is soft and the sides are hard. The soft foam gives a sense of comfort, while the hard part on both sides provides support performance, which helps to keep the driver and passenger’s body stable and improve the safety of the ride when the car is driving at high speed or turning. Wuhan Xingqiao Polymer Technology Co., Ltd. has adopted multi-component mixing technology to produce dual-hardness and multi-hardness foam, and the technical level is in the leading position in China.
(B) Microporous PU used as vibration damping pad for car floor
Microcellular polyurethane foam is expected to replace rubber materials in most car bodies as underbody vibration damping pads. North American automobile manufacturers are trying to make cars quieter and more comfortable. Vibration damping pads are installed on the chassis of a car to isolate the body from the frame to improve ride and driving quality. Microcellular polyurethane is a unique insulation
