The use of synthetic binders and sealants is the largest in wood processing, construction and light industry. Although the amount of rubber used in automobiles has increased significantly with the improvement of the manufacturing process level, even in countries with developed automobile manufacturing industries, the amount of rubber used in automobile production accounts for only 3% of the total output of adhesives and sealants. 5%. The history of the use of adhesives and sealants in automobile production began in the 1930s with the use of bonding methods in automotive production to install sealing strips such as doors and to bond the lining material of the ceiling.
Although adhesives and sealants are only auxiliary materials in the automobile manufacturing process, the application of such materials can simplify the production process, save the use of materials, and increase the strength of components. Especially in the anti-vibration, heat insulation, anti-corrosion, anti-rust, anti-loose, leak-proof, reduce noise, reduce weight, improve car comfort and safety and other aspects have a special role. Adhesives and sealants have become indispensable materials in the production of modern automotive industry.
With the improvement of the level of automobile manufacturing technology, the adoption of new materials and new technologies, and the improvement of customers' requirements for economy and comfort of automobiles, new varieties of adhesives and sealants and new processes are increasingly used in automobiles. . There are dozens of varieties, and the amount of rubber used in bicycles can reach 20-40Kg.


Automotive adhesive sealants can be classified according to the automobile manufacturing process:
1. Automotive body adhesive sealant
(1) Adhesive sealant for body welding, including spot weld adhesive, hemming adhesive, reinforced anti-vibration adhesive, and finger pressure sealant.
(2) Adhesive sealant for body coating line, including weld sealant, stone-resistant, heat-insulating damping coating.
(3) Anti-vibration and heat-insulating damping rubber sheets.

2. Adhesive sealant for automotive interiors
(1) Adhesives for door ceilings, doors and trunk lids.
(2) Adhesive for door waterproofing membrane.
(3) Adhesives and sealants for window glass.
(4) Adhesives and sealants for car floor.
(5) Adhesives and sealants for plastic body.

3. Binder sealant for engine and chassis assembly
(1) Various types of liquid sealant
(2) Anaerobic sealant

4. Adhesive sealant for other parts of automobiles
(1) Adhesive for brake pads and clutch plates.
(2) Adhesive sealant for automotive lighting.
(3) Adhesive sealant for automotive filters.
(4) Sealant for automobile fuel tank.
(5) Impregnation plugging agent.
(6) Adhesives and tapes for nameplates and decorative strips.
(7) Adhesives for parts such as car horns.
(8) Adhesive for the inner door of the car door.
(9) Adhesive for rubber-metal composite parts.
(10) Adhesive for the sealing strip manufacturing process.

5. Adhesive sealant for automobile manufacturing process
(1) Pressure-sensitive adhesive tape for painting protection and assembly.
(2) Adhesives for molds and tools.
(3) Casting resin.
(4) Other process adhesives.
(5) Repair adhesive.

The application of adhesives in the domestic automotive industry started in the 1950s. In 1956, when China's own production of the Jiefang brand car was born, only two kinds of adhesives and sealants were used. One is the 4010 glue produced by the former Soviet Union. Its main component is recycled rubber, which is used to bond the door and windshield seals. The other is the AK-20 glue produced by the former Soviet Union, namely nitro glue, mainly used for paper. The nameplate is bonded, and the flanged paper pad is sealed with a part of the through-hole bolt. In the early 1960s, domestic neoprene appeared on the market, gradually replacing 4010 glue and being widely used in automobile production. Subsequently, neoprene is widely used as a "universal glue" in automobile production due to its excellent bonding property. Such as ceiling lining, rear wall, door inner panel, door sealing strip, venting holes and windshield sealing strips.

In order to solve the problem of “three leaks” (ie oil leakage, water leakage and air leakage) of automobiles, in the late 1970s, China's automobile manufacturing industry began to gradually adopt various liquid sealants and anaerobic sealants.

In the early 1980s, cooperation with foreign automakers, joint ventures, introduction of technology and production processes began, and China's automobile manufacturing level has been greatly improved. People have come into contact with many new adhesives and sealants for automotive production. The localization of the imported model materials further promotes the development of automotive adhesives and sealant enterprises and the improvement of application technology. At present, the varieties of rubber used in China's automobile manufacturing industry and the amount of rubber used in bicycles are close to the world's advanced level. Among them, the amount of rubber used for bicycles is about 20Kg, that of light and medium-duty trucks is 16Kg, and that of heavy-duty trucks is 22Kg.

Current status of domestic automotive adhesive sealant
China's automobile industry was still relatively backward in the 1980s, with low output and low technical level. The role of binders and sealants has not received widespread attention. The total amount of glue used is only about 1000t, which accounts for only about 0.3% of the total national adhesive production. However, with the further deepening of China's economic reforms and the gradual improvement of the introduction of technological content and the increasing number of joint-venture automobile manufacturers, the application level of adhesives and sealants in China's automobile manufacturing industry has reached a level, which has stimulated the binder. With the enthusiasm of the development and production of sealant, new manufacturers and new varieties of new brands continue to emerge. Now there are about 1,800 adhesive and sealant manufacturers in the country, with about 4,000 product grades and an annual output of 260×104t. Despite this, due to the special nature of automobile production, the domestic requirements for the localization of rubber for some imported models cannot be fully met at present, and some varieties and raw materials still need to be imported. Therefore, in order to fully meet the requirements of automobile production, the development and manufacture of adhesives and sealants need to be greatly strengthened.
1. Welding process glue
The adhesive sealants used here are mostly structural and semi-structural adhesives. It plays a role in reducing solder joints, replacing soldering, reinforcing structures, sealing rust and reducing vibration and noise. These adhesive sealants have good adhesion to oil-faced steel sheets. Usually, there is no need to set up special heat curing equipment (heat curing in electrophoresis and other paint drying ovens), and there is no bad treatment for cleaning, phosphating, electrophoresis, etc. influences. There are mainly folding edge glue, spot welding glue, vibration damping (expansion) glue and so on.

2. Coating process glue
The coating process in the automobile manufacturing process is very critical, although there are not many types of glue used in the process, but the amount of glue is currently the largest. It mainly includes weld sealant, stone-resistant paint and finger pressure sealant. The average bicycle usage is around 10Kg. Most of the currently used polyvinyl chloride (PVC) plastisol products. These products have good thixotropy, can be squeezed, can be sprayed, and will not cause discoloration after the application of the paint and topcoat.

Weld sealant can prevent air, rain and dust from entering the car, and plays an important role in sealing, rust prevention and leakage prevention. The anti-stone coating of the vehicle bottom can resist the impact of sand and stone on the floor of the car, improve the anti-corrosion ability, extend the life of the car body, and at the same time reduce the noise inside the car.

3. Interior glue
There are many types of adhesives for interior use, such as commonly used neoprene adhesives, acrylate pressure sensitive adhesives, and polyurethane adhesives. Mainly used for bonding and sealing of ceiling interior materials, door waterproofing membranes, door panel interior materials, etc.

Polyurethane glass binder is a new type of binder used in China's automobile manufacturing industry in the late 1980s. It is used for direct bonding and sealing of windshield, rear window glass, etc., eliminating the traditional assembly process and improving the safety factor of the whole vehicle. .

4. Engine and chassis assembly glue
The adhesive sealant for automobile engine, gearbox and chassis assembly is mainly used for sealing various planes, hole covers, pipe joints, bolts and shafts, and the like. Prevent oil, gas, water leakage and bolting. There are mainly anaerobic adhesives and silicone sealants and other liquid sealants. Among them, the anaerobic adhesive has good processability, fast curing rate and high strength, and can also be made into a microcapsule type for precoating. Silicone rubber has good elasticity, oil resistance and aging resistance.

5. Rubber for automotive parts
Adhesive sealant is also used in large quantities in the production of auto parts. For example, the shoe rubber for bonding the brake shoe and the friction plate; the adhesive for the vacuum absorption of the instrument panel and the door; the filter element for the filter; the adhesive for immersing and sealing, the adhesive for the lamp; Adhesives for interior materials and sound insulation materials.

Development trend of adhesive sealant for automobile
In recent years, with the continuous development of new materials and new processes in the automotive industry, automotive adhesive sealants have also been perfected and specialized.

1. Light body adhesive sealant
In order to reduce the weight of the car body, reduce fuel consumption, and improve the economy of the vehicle, various light body adhesives have been widely adopted by some automobile manufacturers. Such as low-density PVC weld sealant, low-density PVC anti-stone coating. The density of ordinary PVC sealing materials is 1.40g/cm3, while the density of low-density PVC sealing materials can reach 0.9-1.0 g/cm3, which can reduce the amount of use (mass) when using the same thickness (volume) sealing material. ~35%.

2. Application of green environmentally friendly adhesive sealant
Protecting the environment and providing a good working environment for operators is one of the goals pursued by today's automakers. To this end, the use of water-based materials is on the agenda. Due to the strict requirements of foreign environmental regulations, water-based coatings have begun to appear and replace oil-based bonding and sealing products. If water-based paint is used instead of the currently widely used PVC plastisol, it will replace the asphalt-based damper plate used in the car. Since the water-based material can be self-drying or drying type, the damping coefficient is higher than that of PVC and asphalt materials, and the environmental pollution is small, and the application prospect is good. In addition, green PVC sealant and underbody anti-stone coatings are also used in the automotive manufacturing process.

3. Development of wet-on-wet PVC sealing material
Many new automakers' painting workshops do not have a PVC pre-drying furnace to increase production efficiency and save energy. This process requires PVC sealing materials (sealing adhesive, car bottom stone-resistant coating, skirt anti-stone protection coating) products to have good compatibility with medium coatings. The so-called wet-on-wet process means that the PVC sealing material is not subjected to the pre-gelling (pre-gel) process, but is directly applied to the surface of the wet PVC material, and the PVC material is to be coated in the middle coating drying oven. The layers are dried together. This requires good adaptability of the PVC material and the intermediate paint, and does not cause problems such as blooming, sag, keyhole, pinhole, etc.

4. Sheet reinforcement
As the car develops toward lighter weight, the thickness of the steel plates used to make the body is getting thinner and thinner, but some parts (such as door handle holes) require higher lightness. The application of thin sheet reinforcement can solve this problem. Commonly used thin plate reinforcement materials are mainly composed of epoxy resin modified materials. There are preforms and liquid sprayable materials. The reinforcing material is solidified in the drying process of the paint and pasted on the steel plate, which not only plays a role of local reinforcement, but also reduces the vibration of the steel plate and eliminates noise.

5. Clean coating workshop concept
The cleanliness of the paint shop is directly related to the quality and manufacturing costs of automotive painting. The concept of a clean coating shop is to advance the construction of materials not directly related to painting from the coating shop to the welding shop or to the assembly shop to reduce the impact on the cleanliness of the paint shop and avoid cleanliness. Low coating quality problems, reduced rework, rework, and reduced manufacturing costs.

6. Spray-type vibration-damping and sound-insulating material replaces asphalt damping plate
Because the shape of the asphalt damping plate used in automobile manufacturing is different, it requires a lot of storage space, wastes manpower during construction, and brings in a large amount of dust, which affects the environment of the painting workshop. The use of spray-type vibration-damping insulation materials allows automated construction by robots while reducing manufacturing costs. Spray-type vibration-damping and sound-insulating materials mainly include PVC plastisol type and water-based acrylate type.

7. New polyurethane glass adhesive
The appearance of the aluminum body and the application of the glass built-in antenna require the use of a glass adhesive having a high electrical resistivity (low electrical conductivity) to prevent corrosion of the introduced vehicle body and adverse effects on the antenna receiving effect. At the same time, the use of high modulus glass adhesive can improve the rigidity of the car body, improve the resistance to twisting, and ensure the safety of members. The new polyurethane glass binders are low-conductivity, high-modulus, high-modulus, low-conductivity, High-tack, and fast-curing.

8. Universal application of induction curing devices
For the curing of the hemming glue, the induction curing equipment is generally used to solidify the workpiece (such as the door, the hood, the trunk lid, etc.) to improve the production efficiency and speed.

9. Widely used adhesive and sealant automated construction systems
In foreign automobile manufacturers, automatic coating equipment for adhesives and sealants can be seen everywhere. From the folding equipment in the welding shop, the damping rubber, the paint on the floor of the paint shop, the glass adhesive in the assembly shop, and the adhesive for the ceiling interior. Due to the precise construction of the automation equipment, the quality of the material can be reduced while reducing the consumption of materials.