What Is an Acetal Resin?
Acetal resin is a synthetic material blended with polyacetal (POM) resin and graphite. POM resin, a plastic material, is known for its high mechanical strength, wear resistance, and chemical resistance. Graphite enhances these properties by improving friction and heat resistance.
Uses of Acetal Resins
POM is employed in applications that demand wear resistance and self-lubrication, such as industrial machine parts, gears, screws, and sliding components. Its heat resistance ensures that its mechanical strength remains stable even in environments exceeding 100°C. POM is often used as a metal substitute, offering benefits in lightweight design, workability, and productivity. However, its flame resistance, weather resistance, and adhesiveness are low, necessitating careful material selection based on the intended environment. POM is flammable, and it should be noted that plating processes can be challenging with this material.
Principle of Acetal Resins
First, let us explain the manufacturing process of DURACON, a typical example of acetal resin is a copolymer and is synthesized from methanol as a starting point. Formaldehyde synthesized from the oxidation reaction of methanol is trimerized, followed by the polymerization of trioxane.
The trioxane is polymerized with a small number of comonomers as the main monomer to produce crude POM copolymer, which is then shipped with stabilizers, glass fibers, and reinforcing agents added to the crude polymer. Homopolymers, on the other hand, consist of polyoxyethylene chains produced by formaldehyde bonding. Note that homopolymers and copolymers have different properties.
1. Homopolymer POM
Homopolymers are polymers composed entirely of the same monomer unit, with the main chain consisting solely of carbon and oxygen atom bonds.
2. Copolymer POM
Copolymer POM, such as DURACON, comprises two different monomer units. It offers higher thermal stability than homopolymers, making it suitable for more demanding environments. Although acetal resin has excellent oil and alkali resistance, its rigidity and mechanical strength are marginally lower.
Types of Acetal Resin
1. Standard Acetal Resin
Standard acetal resin is the most common type of acetal resin and is composed of pure polyacetal resin. It has high heat and abrasion resistance and stable mechanical properties. It also has excellent dimensional stability, making it suitable for the manufacture of precision mechanical parts.
This type of acetal resin is a widely used product in the automotive industry for components such as gears, bearings, plugs, and valves.
2. Heat-Resistant Acetal Resin
Heat-resistant acetal resin offers improved heat resistance compared to standard types. It withstands high temperatures without deformation or deterioration, making it ideal for automotive parts, electronic devices, and home appliances. This resin type also demonstrates superior chemical resistance, maintaining stable performance against various chemicals. Additionally, its enhanced flame resistance is advantageous for applications where fire safety is a concern, such as in electronic equipment and automobile engine compartments.
3. Low-Friction Acetal Resin
Low-friction acetal resin, a variant of standard acetal resin, includes a friction-reducing agent to enhance its sliding properties. Characterized by a low coefficient of friction, it is particularly effective in applications like sliding parts, bearings, and gears where reduced friction loss is crucial. This improvement not only enhances the energy efficiency of machines but also minimizes wear risks.