Hot melt adhesive is the most environmentally friendly and suitable for high-speed automatic assembly line operation. Nowadays, the automobile industry is developing rapidly, especially in China. With the improvement of the automation level of automobile production, the automobile industry needs a large number of adhesives that can be quickly bonded, adapt to high-speed automated production and are environmentally friendly. Hot melt adhesives can just meet all the above requirements, so hot melt adhesives are more and more widely used in the automobile industry, and their usage is increasing year by year, which has become an irreplaceable adhesive in the automobile industry. The reason why there is such a trend is determined by the characteristics of hot melt adhesive itself.

Hot melt adhesive features:

1, the curing speed is fast, and it is suitable for modern high-speed assembly line operation. 2. There are a wide range of bonding materials, and automobiles are mainly composed of a large number of metal and nonmetal parts. Hot melt adhesives are just suitable for bonding such products. Such as ABS, PP, PE, felt and so on, which are widely used in automobiles. 3. The construction is convenient. Hot melt adhesive can be applied in many ways, such as spraying, roller coating, scraping and so on.

4. Hot melt adhesive is 100% solid content, which is convenient to store, energy-saving, environmentally friendly, non-toxic and will not cause secondary pollution to the environment.

5. Nowadays, the world is short of resources, and many auto companies have considered recycling the resources after scrapping their cars when producing them. Hot melt adhesive has the characteristics of melting when heated, and it has more advantages when recycling and disassembling cars.

Types of hot melt adhesives for automobiles:

Most hot melt adhesives are used in automobiles, but different parts and uses will choose different kinds of hot melt adhesives. According to its function, it can be divided into two categories: adhesive type and sealing type. The sealing type mainly uses butyl glue, which is not discussed here. According to the purpose and construction temperature, it can be divided into ordinary type and heat-resistant type. Cars are mainly driven outdoors, and hot melt adhesives are generally required to have certain heat-resistant performance. According to the classification of materials, there are EVA, rubber, APAO, PUR, PA, PES, etc., and the shapes are block, film, rod, particle and powder.

Application of hot melt adhesive in automobile;

A car is made up of thousands of parts, and there are many parts involving the use of hot melt adhesive. Here are some common parts that are used in large quantities:

1. Headlights, the traditional method is to use rubber sealing strips with holes, which are tightly sealed by screws. After using hot melt adhesive, they can be quickly bonded and play a sealing role, which not only reduces the cost but also facilitates automatic production. The main types of hot melt adhesives are rubber type, APAO type and PUR type, which require good temperature resistance, high bonding glass strength and vibration resistance. At present, two-component adhesives are also available. License plate lights also use heat-resistant hot melt adhesive sticks to fix wire harnesses and electronic components.

2. In the past, the dashboard, ventilation duct, interior fixing buckle, etc. on the bridge were all fixed by mechanical methods, which was not only time-consuming and laborious, but also inefficient and had poor sealing performance. After using hot melt adhesive, the production efficiency and product quality are greatly improved. We mainly use heat-resistant hot melt adhesive sticks, and the base materials are EVA and polyolefin.

3, car roof, car roof is a composite of plastic plates, the types of hot melt adhesives are mainly adhesive film and rubber powder, and the base materials are PE and EVA.

4, car door panels, car door panels assembly needs to use hot melt adhesive bonding. There are PP pieces bonded, sound and wire harness fixed. APAO and heat-resistant glue sticks are mainly used.

5, car carpets and floor insulation pads, luggage buttons, etc., this is the place where cars use hot melt adhesives the most. The types of hot melt adhesives are glue blocks, glue particles and glue sticks. There are pressure-sensitive adhesives, EVA colloidal particles, glue sticks and APAO. It requires long opening time, convenient assembly and bonding of large pieces, good heat resistance and less odor.

6, automotive wiring harness fixed, there are a lot of wires inside the car, so many wire harnesses can't be fixed with conduit like our home decoration, fixing with hot melt adhesive is a time-saving and efficient method, and hot melt adhesive has a certain elasticity, it won't fall off during driving bumps, and it is easy to disassemble when it needs maintenance. Glue sticks and APAO-type hot melt adhesives are mainly used.

Examples of hot melt adhesive in automobile application are given, such as hot pressing and welding.

1 PVC ceiling and insulation layer, etc.

Most of PVC ceilings are bonded with solvent-based adhesives, which are used in a large amount. However, the use of this adhesive requires ventilation to dry the solvent, and the operating conditions are poor, and it is very environmentally friendly, which affects the health of workers. Therefore, this year, polyamide hot melt adhesive is used to replace the above adhesive. In addition, other thermal insulation layers of automobile roof and body can be hot-pressed in the following order (hot-pressing temperature is 150℃). 1. Water-resistant corrugated material 2. Polyamide hot melt adhesive 3. Polyurethane foam 4. Polyurethane adhesive 5. pvc plate

Another kind of polypropylene honeycomb insulation partition made by vacuum forming has the following structural sequence: 1. Polypropylene honeycomb core material 2. Polyamide hot melt adhesive 3. Polypropylene film 4. Polyurethane adhesive 5. pvc plate. After the bonding is completed, the shell with proper curvature can be made by vacuum forming method, which can be used as the parts of the roof or other parts of the car body.

2. Bonding of automobile interior decoration

There are many kinds of interior decorations in automobiles. As far as materials are concerned, most of them belong to non-metallic materials such as PVC or ABS films, sheets, plates, foam plastic plates, carpets and wood grain decorative plates. Adhesive such as epoxy resin is generally used for decorative boards with large stress, while hot-melt adhesive, acrylate emulsion adhesive or solvent-based adhesive is generally used for decorative boards with small stress. For example, when the edges of doors and decorative lining boards are wrapped with plastic sheets, hot-melt crimping adhesive can be used to position them.

Generally, the roof line, noise-deadening gasket and rubber rain belt in the car are fixed in the car or in the door slot with neoprene or SBR solvent adhesive. Carpets and floors are generally adhered with PA hot-melt adhesive.

3 Welding seal of automobile body panel

When sealing the car body, the whole car has been in the later stage of installation, so the construction quality is high, especially in some parts outside the car body, and the glue joint is required to be as small and smooth as possible to ensure the beauty of the car body. In order to ensure the construction quality and sealing, two-component rubber adhesive is generally used to make the adhesive solution have higher initial bonding strength and faster bonding speed. However, because the two components need to be prepared temporarily during construction, which is more troublesome, hot melt adhesive can be used instead. Hot melt adhesive is usually coated by a pressure spray gun with a heating device.

In addition to the above-mentioned hot melt adhesives, there are also some accessories, such as batteries, sun visors and so on.