What are the applications of high-performance nylon in the cooling pipeline of new energy vehicles?

What are the applications of high-performance nylon in the cooling pipeline of new energy vehicles?

With the promotion of national policies, the enhancement of people’s awareness of environmental protection and the advancement of technology, the popularity of new energy vehicles is gradually deepening. In the heat dissipation technology of new energy vehicles, the cooling system is particularly critical. The cooling system can be divided into air-cooled, liquid-cooled and phase change materials according to the cooling medium.

Liquid cooling is currently the main way of cooling new energy vehicles, including water cooling and oil cooling. As an important component of new energy vehicles, coolant pipelines need to meet various requirements such as hydrolysis resistance, oil resistance, high temperature resistance, and light weight. At present, the pipe materials used in automobiles can be divided into three categories, namely metal, rubber and nylon plastic.

Due to its light weight and simple processing technology, nylon pipe has gradually become the main material used in cooling and lubrication pipelines. Today we talk about the main development of nylon in the coolant pipeline of new energy vehicles.

Nylon (polyamide) plastic coolant lines

Nylon material for pipelines is mainly aliphatic and aromatic nylons used in coolant pipelines. Aliphatic groups are represented by PA11, PA12, PA612, and aromatics are represented by PA9T and PA11T.

PA12 structure

Since the polyamide material contains an amide group (-NHCO-), and the automotive coolant is composed of polyethylene glycol and water, in such a medium, the amide group will be alcohololyzed and hydrolyzed, and ordinary polyamide materials are not suitable for coolant media. In response to this problem, DuPont, EMS, Basf, Arkema and other well-known nylon companies have developed corresponding hydrolyzed polyamide materials, which are suitable for automotive coolant media environments.

2. Nylon coolant line application location

Nylon plastic pipelines can be used in the motor compartment, chassis, and battery pack, and the nylon material and structure type corresponding to the temperature resistance grade can be selected according to the different requirements of temperature, pressure and assembly in different positions. Nylon coolant pipelines will also be the most important product type of coolant pipelines on new energy vehicles in the future.

Structural perspective of new energy vehicles

3. Nylon coolant line type

According to the actual application needs, the morphology, assembly connection method and performance requirements of nylon tubes are different. There are two main forms of nylon tubes:(1) smooth pipe: suitable for most coolant lines; (2) bellows: mainly used in branch pipes in the battery pack to narrow the connection area.

Bellows

There are two main connection methods between nylon pipe and quick connector: 1) cold plug: the connection form with relatively low requirements for quick connector materials, suitable for most positions; (2) laser welding: the connection form with high requirements for quick connector materials, but the leakage of pipelines in some positions is very high, and the assembly space in the battery pack is very small, and the coolant pipeline assembly is more suitable for laser welding.

4. The main performance requirements of the coolant line

The coolant line has requirements for liquid leakage, acid resistance, and coolant dynamic fatigue resistance. Leakage requirements: Since the cooling part of new energy vehicles involves motors, batteries and other units, there are clear requirements for the leakage of water pipes in the motor, chassis and battery pack, and the requirements of each automobile factory are different. Acid-resistant medium requirements: In the pipeline in the battery pack, some automakers will have acid-resistant media requirements, need to choose acid-resistant media with good performance, generally use PA9T/PA12 structure pipeline, can meet acid resistance requirements. Dynamic fatigue performance requirements for coolant: simulates the temperature, pressure and vibration state of the whole vehicle, and the dynamic fatigue performance requirements are different in each position. Other performance requirements, such as burst pressure, blow-off pressure, static aging test, flame retardant test, etc., different automakers have different requirements.

Introduction to the nylon category

Nylon 46 (PA46)

Polyamide46 or Nylon46; Abbreviated as PA46. Nylon 46, also known as polyamide 46, that is, polyadipyl butyldiamine.

Its outstanding characteristics are high crystallinity, high temperature resistance, high rigidity, and high strength. Mainly used in automobile engine and peripheral parts, such as cylinder head, cylinder base, oil seal cap, transmission. In the electrical industry, it is used in contactors, sockets, coil frames, switches and other fields that require high heat resistance and fatigue strength.

Nylon 4T (PA4T)

English name: Polyamide4T or Nylon4T; Abbreviated as PA4T. Nylon 4T, PA4T is the first high-temperature nylon synthesized since entering the 21st century. It has been 10 years since it was born on September 27, 2007, and it is the first high-temperature nylon invented after 2000 in the polymer group.

The melting point of PA4T pure resin is very high, exceeding its decomposition temperature, and if it is not copolymerized modified to reduce its melting point, it cannot be commercialized, and it is difficult to promote. Therefore, PA4T is promoted in the market, generally requires copolymerization modification, and the common means is to copolymerize with PA66 and/or PA6 to reduce the melting point. After modification, the comprehensive mechanical properties are excellent, the fluidity is good, the electrical properties are excellent, the chemical corrosion resistance and the high temperature resistance are outstanding, which can meet the requirements of electronic and electrical, mobile terminals and other fields.

Nylon 56 (PA56)

 English name: Polyamide56 or Nylon56; Abbreviation: PA56. Nylon 56 is formed by polycondensation of pentanediamine and adipic acid, the extraction of which can come from natural organisms.

Eco-friendly, good performance, can improve the comfort of the end fabric. Its water absorption, glass transition temperature, strength, softness, moisture absorption, resilience are better than some products of nylon 6, nylon 66 and polyester.

Nylon 6 (PA6)

English name: Polyamide6 or Nylon6, abbreviated as PA6; Nylon 6, also known as polyamide 6, that is, polycaprolactam, obtained by caprolactam ring polycondensation, molecular structure:

It is a translucent or opaque opaque resin with superior mechanical properties, stiffness, toughness, wear resistance and mechanical shock absorption, good insulation and chemical resistance. Widely used in auto parts, electronic and electrical parts and other fields.