According to statistics, currently in China, each car uses about 20kg of rubber, medium-sized cars use about 16kg, and heavy-duty cars use about 22kg. It is expected that by 2020, the total demand for various types of adhesives and sealants in China's automotive industry will reach 300000 tons. This article systematically introduces the bonding parts and characteristics of automobile body, operating system, power system, and maintenance, as well as the types and main properties of adhesives used in automobiles. It also elaborates on the development status of adhesive varieties in recent years.
According to statistics, the adhesive used for car interiors in China currently weighs about 20kg per sedan, 16kg per medium-sized car, and 22kg per heavy-duty car. It is expected that by 2020, the total demand for various types of adhesives and sealants in China's automotive industry will reach 300000 tons. This article systematically introduces the bonding parts and characteristics of automobile body, operating system, power system, and maintenance, as well as the types and main properties of adhesives used in automobiles. It also elaborates on the development status of adhesive varieties in recent years.
Adhesive for Automotive Interior Decoration
Chloroprene rubber is the earliest developed synthetic rubber, which has reversible crystallinity, high adhesive strength, high tensile strength and elongation, excellent weather resistance and heat resistance. The adhesive prepared can be cold cured at room temperature and has the characteristics of high adhesive strength, high initial adhesion, good medium resistance, and wide bonding range. However, long-term storage of chloroprene rubber will release hydrogen chloride, promote its hydrolysis, and corrode metals. Therefore, magnesium oxide and lightweight zinc chloride need to be added. To prevent adhesive aging, anti-aging agents can also be added.
Adhesive for automotive ceiling lighting fixtures
The currently most widely used hot melt adhesive. EVA resin is used as the base material, with rosin glycerides and polymerized rosin as thickeners, and polymer paraffin as plasticizers.
Sealing adhesive for automobile body structure
PU adhesive is an adhesive containing amino ester groups (NHCOO) and/or isocyanate groups (NCO) in the base material molecules. It is the most commonly used sealant, with good wear resistance, adjustable performance, wide application range, high mechanical strength, low tenderness and softness, excellent recovery, and can be used for sealing dynamic joints. But there are also drawbacks, such as inability to withstand heat for a long time, susceptibility to UV aging, and the need for a primer in many situations. The application of polyurethane sealant in automobiles includes the assembly and sealing of car windows (windshields), as well as the assembly of car bodies and other components. In recent years, the annual demand for polyurethane adhesives in China has grown at an average rate of 30%. In addition, there are rubber type sealing adhesives and polysulfide sealing adhesives.
Adhesive for Automotive Operating Systems
The bonding of automotive operating systems mainly includes the bonding of friction plates and clutch plates. This type of adhesive requires high bonding strength, excellent heat resistance, and a certain degree of toughness, as well as low cost and good processability
The adhesive used for automotive operating systems is mainly modified phenolic resin adhesive for brake pad bonding. Drum brake pad adhesive is used to bond the manufactured brake pads and steel backing together, usually using nitrile rubber modified phenolic resin adhesive. Disc brake pad adhesive is a type of adhesive that compresses brake pad powder into a cold embryo and coats it with adhesive. It is then positioned at high temperature for a short period of time with the coated backing, and subjected to post-treatment at high temperature without pressure. Currently, in China, disc brake pad adhesive is prepared using calcium oxide as a catalyst. In addition to the above adhesives, silicone modified phenolic resin can also be used for bonding clutch adhesives.
Adhesive for Automotive Power Systems
The bonding parts of the automotive power system mainly include the fastening and sealing of screws and bolts, the sealing of cylinder gaskets. Anaerobic adhesives are more commonly used in the automotive manufacturing industry for thread fastening and locking, fixing of mating parts, flat bonding, sealing of pipelines and flanges, and pinhole sealing, which can solve problems such as anti loosening and leak prevention and simplify assembly processes.
The sand holes generated during the casting of the engine in the automotive power system, the fastening of various bolts, the sealing of pipelines, and the sealing of flat surfaces mainly use various types of anaerobic adhesives. The sand holes generated during engine casting are poorly sealed by water glass infiltration, while good sealing effect can be achieved by using high-temperature resistant anaerobic adhesive infiltration. High strength anaerobic adhesive can be used for holding and sealing engine cylinder heads and transmission double headed bolts, as well as bolts that are not often disassembled, collective process bodies, cylindrical bowl shaped plug drive axle differential housing connection bolts, circular shaft gears and differential fixing bolts, etc. In addition, automotive gaskets cannot guarantee sealing performance and geometric accuracy of connecting components, while using anaerobic adhesive for planar sealing can solve these problems. Components that are easy to disassemble can use low-strength anaerobic adhesive.