Polychlorinated ester materials are more and more widely used in the automobile industry, which has become one of the most widely used plastics in the automobile industry. The global automobile manufacturing industry uses more than 1 million tons of polyurethane every year. In 2006, the annual output of China's automobile industry exceeded 7.2 million vehicles, and the total consumption of polyurethane will reach over 100000 tons. Polyurethane generally accounts for 15% of automotive plastics. The average usage of each vehicle is 15 kg, most of which are MDI series products.
According to the difference of automobile components, polyurethane is adapted to different requirements with different forms and properties such as foam plastics, elastomers and adhesives. For example, polyurethane foam has the characteristics of light weight, heat insulation, good resilience, good comfort, low temperature performance, durability, safety and high absorbers.
Recycling of waste foam plastics for automobiles and household electrical appliances has attracted more and more attention. Recently, foreign automobile manufacturers have been able to recycle 30% of the waste foam plastics. The production process is to wash, crush and dry the waste foamed plastics. Finally, they can be glued together with adhesive to produce carpet backing and other cushion materials.
(1) Epidermis material
At present, the automobile manufacturers pursue to further improve the comfort, safety and beauty of the interior space of the car. It can be said that the automobile interior is more and more advanced. This kind of high-level is first reflected in the use of a variety of materials with different properties (fiber fabric, real leather, hair planting), so that all surfaces in the car are soft decorated and strive to beautify (deep and thick pattern, wood grain, color matching). The soft decoration surface material, internal sound absorption, vibration absorption material and framework material are combined to form the interior ceiling, luxury instrument panel, steering wheel, seat, etc. In fact, this kind of development contradicts with material recycling and cost reduction. Therefore, it is an urgent task to develop new materials for interior decoration that can not only meet the requirements of advanced, soft and personalized interior decoration, but also meet the requirements of lightweight, low cost and material recycling.
BASF company has developed a polyurethane elastomer skin material (TPU) elastoskin for automobile interior decoration, which is used for the surface layer of instrument panel and door panel interior decoration. Its performance is superior to PVC and other skin materials currently used, and its cost is lower than PVC and other skin materials, so it is an ideal alternative to PVC. The material has excellent mechanical properties, very good leather grain sense, flexibility and luxury sense, which can be used in two-color products; excellent durability (weather resistance, high and low temperature resistance, abrasion resistance) makes it the first choice of high-quality interior decoration materials of C-class and above cars. This material has been used in the instrument panel and door inner panel of bujck Park Avenue, oilsmobiie Aurora, Cadillac CTS and other cars, and will also be used in new models such as Cadillac Seville and Cadillac DeVille. In short, the application of this material in automobile interior parts is just beginning. The greater significance of using polyurethane polyurethane to spray the skin is to provide an effective way for producing polyurethane integrated (polychlorinated spray coating + low density polyurethane foam foam + polyurethane short cut fiber skeleton) recyclable dashboard.
In addition, Bayer's thermoplastic polyurethane uses blow molding technology for automobile dashboard and door panel. It is said that the process can save 70% of the time compared with pouring molding.
(2) Dashboard buffer
The outer skin of the dashboard is vacuum formed and filled with semi rigid polyurethane foam, and fixed with metal or plastic skeleton. Semi rigid polyurethane foam is characterized by high compression load and outstanding vibration absorption performance. It is very suitable for making protective cushion materials for automobile dashboard, handrails and door posts.
(3) Skeleton material
A polychlorinated ester structure reaction molding (srlm) technology has been widely used in Europe and America, which can effectively reduce the quality of parts. The process is as follows: the skin is pre formed, the glass fiber mat is put into the mold, and then the polychloromethane resin is injected, and the curing is formed (micro foaming). This technology can be used to produce a variety of automotive accessories, such as door interior panel, coat rack, instrument panel framework and ceiling framework. The advantage of SRIM is that it can flexibly design wall thickness, radian or stiffener according to different mechanical properties of parts. Compared with injection molding and other products, SRIM has a lower interior noise and can improve the physical properties of the products, such as lower density, higher elongation, less odor and mildew, etc., which can create a comfortable interior environment.
The production technology of the existing door panel in China is to lay glass fiber in the mold in advance, then inject the composite material, and then mold the required interior parts such as the dashboard, door panel, air conditioning cover after closing the mold. Another technology is short cut fiberglass spray molding.
Rim and RRIM polyurethane products are mainly used in steering wheel, bumper, body panel, hood, trunk lid, radiator grille, fender, spoiler, etc. The quality of RRIM products is only 55% of that of steel, but the surface quality and dimensional stability of parts need to be further improved, and the consumption is not large.
Cushions, backrest and headrest are very large parts of polyurethane foam used in automobiles. They are also the most sensitive places for people to ride comfortableness, so their performance requirements are also very strict. At present, the polychlorinated foam cushion used for automobiles in China is mostly the uniform density of cold curing products. In recent years, a new type of automobile seat cushion developed is double hardness or multi hardness foam. The production of the double hardness seat cushion can be realized by injection of polyether polyols and isocyanates through a double head or multi head mixing head. The whole MDI cold molding process can also be used. The hardness of different parts of the cushion can be accurately controlled by changing the isocyanate index. The middle part of the cushion is soft. , hard on both sides. Soft foam gives comfort to people. The hard part on both sides provides support performance. When the car is running or turning at high speed, it helps to maintain the stability of the driver and passengers and improve the safety of the ride. FAW Group's FAO company has produced 3 hardness and multi hardness foam technology by using the technology of mixture of components, and technology occupies the leading position in China.
The armrest is constructed with a middle steel skeleton and a door plate fixed, and the outer layer is covered with self adhesive semi rigid polyurethane foam plastic, with decorative decorative patterns on the surface, which makes people feel comfortable and safe when riding. On the left and right doors of the car, there are also handles on the guard board. The material is made of semi-rigid polyurethane foam with self crust and plastic foam. The material used in this part shall be sweat resistant, odorless, hardness index, high and low temperature performance, etc.
The steering wheel of passenger cars in our country is basically made of semi hard self wound polyurethane foam plastic as the outer covering layer, and the internal steel skeleton is welded. Now it has gradually turned to the die casting of Al Mg alloy. The hardness of the covering layer is generally in shore a60-80.
(1) Car ceiling and door inner panel
The interior ceiling is a composite product of various materials, which requires a variety of functions such as heat insulation, sound absorption, sound insulation and vibration absorption. The soft ceiling is made of polyurethane foam composite fiber fabric, non-woven fabric and artificial leather. The hard ceiling is made of fabric fiber, glass fiber, cardboard and polyurethane foam by laminating.
There are also many areas of polyurethane foam sheet used in cars, for example, the fabric of seats is mostly woven +PU+ knitted synthetic fiber. After PVC film + PU composite is used for the interior decoration of the top, holes are punched on the surface, and then the adhesive is pasted on the top of the cab.
PP and PPO are often used as the materials of door column decorative board. Considering the cost of materials, PP materials with high fluidity, high rigidity and good impact resistance will have certain advantages in the future. The surface color of the decorative plate of the door pillar must match the overall color of the car. It is required to be antistatic, scratch resistant and beautiful. Therefore, the development of the production technology of the integral vacuum forming or hot pressing forming of the propylene plate and the surface decorative material can meet the demand of the production of the car which is not very large in batch.
(2) polyurethane foam for sealing purposes
There are some rectangular soft polyurethane foam blocks in the heating, air conditioning, dashboard, electrical parts or other parts of the car. The A and B columns of the car body are filled with cavity foam, some of them are used to reduce the vibration and noise of the body.
Microcellular polyurethane foam is expected to replace rubber material as a damping pad for most of the vehicle bodies. The North American automobile manufacturer is making efforts to make cars more quiet and comfortable. The damping pad is installed on the chassis of the vehicle to isolate the vehicle body and frame, so as to improve the riding and driving quality. Microporous polyurethane is a unique innovative material for sound insulation and vibration attenuation (NVH).
Microcellular polychlorinated ester is a competitive price substitute for rubber car body assembly. It can effectively improve the damping performance, prolong the holding time of material performance, reduce the mass, and improve the assembly process. Another advantage of using microcellular polyurethane is that by changing the density of the material, it is convenient to optimize the vibration proof rubber pad of the vehicle body chassis, instead of the traditional process that must be adjusted by changing the material production formula or product geometry. The latter requires prototyping, which is costly and time-consuming.
The composite structure of low foaming PVC material + PU foaming material + porous material is mostly used in light buses. The low foaming PVC material is shaped after vacuum molding, filled with foaming PU material locally, and pasted with porous material locally on the back. The structure is not only elastic and firm, but also has good foot sensibility, sound insulation and heat insulation performance.
In order to effectively ensure the sound insulation and heat insulation of the interior of the car body, besides the rigid polyurethane foam used in the insulation layer in the middle of the refrigerated vehicle, the van also uses the way of field spraying to expand the application of rigid polyurethane foam. The rigid polyurethane foam plastics are sprayed on the top and sides of the vehicle body, and are bonded with the inner and outer skin of the vehicle body. Machine as a whole. So as to effectively improve the heat insulation, heat preservation and sealing performance of the car body, prevent the corrosion of the car body, reduce the vibration of the car body and reduce the noise in the car. The estimated consumption of each vehicle is about 20 kg.
The thermal insulation cover made of rigid polyurethane foam is made of polyurethane foam, glass fiber felt, nylon fabric layer or aluminum film, and has the characteristics of light weight and good heat insulation.
The application of glass fiber reinforced polyurethane foam in automobile parts is also gradually expanding. For example, the automobile interior top parts are made of textile and glass fiber reinforced PU. For example, the wheel cover fender and oil pan fender are light, thin and complex in shape, which require high technology, stone splash proof, impact resistance and high and low temperature performance.
Recently, many automotive interior parts show the development trend of polyolefin (PO) foamed plastics instead of polyurethane (PUR) materials. Several kinds of polyolefin foam plastics are constantly challenging the application of polyurethane foam in many aspects, including surface decoration, foam, coated fiber, fabric and sound insulation system. The driving force of foaming polyolefin instead of polyurethane foam is the cost of products, as well as the recovery of products and whether it can reduce the emission of toxic gases, because toxic gas will be generated in the process of PUR foam laminated fabric.
Automobile dashboard has many functions, many parts and complex structure. The recycling of automobile interior materials should first consider the dashboard. At present, the dashboard is mostly composed of PVC skin + semi-rigid foaming Pu + skeleton, so it is very difficult to recycle the materials. The development trend of the instrument panel is that it is easy to disassemble and assemble in the design, the material meets the design requirements and the possibility of recycling is considered, so as to make it as beautiful and low-cost as possible. It is possible to promote the development of thermoplastic instrument panel and single type of plastic instrument panel, but it should meet the requirements of safety and beauty.
The car interior ceiling is usually made of glass fiber + foam polychlorinated ester + surface decoration fabric, etc. the truck generally adopts the foam sheet pasting ceiling with artificial leather or fiber fabric on the surface. Considering the requirements of function and recycling, the development trend in the future is that the skeleton, sound absorption, heat insulation and skin materials should be the same as possible, or the reinforced composite materials which can be recycled directly and without separation should be used.
PU leather gradually replaced PVC artificial leather. As the first generation of artificial leather products, PVC artificial leather has a considerable scale since the 1970s, because of its similar natural leather, bright appearance, soft texture, wear resistance, folding resistance, acid and alkali resistance. However, due to the poor permeability and hygroscopicity, the development in recent years has been limited. At present, Pu can be used as a substitute for PVC. Pu is not only excellent in high strength and toughness, but also resistant to aging, air permeability, moisture permeability, water and oil. It is a mature environmental protection material.
FAW fuojiangsen Co., Ltd. is the backbone factory of automobile interior decoration products industry, which consumes more than 10000 tons of polyurethane raw materials for softened products such as seats and dashboard every year, and 4000 tons for Changchun alone. More than 100 kinds of softened products such as seats and dashboard are supplied for Jetta, Audi, Mazda and Jiefang automobile, which consume more than 3000 tons of polyurethane raw materials every year.
The main technical problems of polychlorinated foam and products include storage stability of MDI, TDI and additive mixture, moisture and heat resistance of products, vacuoles and cracking caused by unstable foaming process.
The development needs of polyurethane foam and products include light weight, multi hardness, low odor, low haze, aging resistance, storage stability and environmental protection, such as the replacement of foaming agents.
