Application of Polycarbonate Flame Retardant

This article will introduce the main types and application areas of PC flame retardants, as well as how to balance flame retardant performance and transparency. We will explore different types of flame retardants such as organosilicon flame retardants and sulfonate flame retardants, and provide you with suggestions for selecting suitable flame retardants.

Polycarbonate (PC) is a high-performance and widely used engineering plastic. It has extremely high transparency and a light transmittance of up to 89%, making it suitable for many scenes that require high optical and color requirements. In addition, PC itself has a certain flame retardant effect, which can reach V-2 level flame retardant and belongs to self extinguishing engineering plastics.
However, in certain application scenarios, it is necessary to achieve a V-0 flame retardant rating of 1.6mm or even 0.8mm, such as in the fields of phone cases and other electronic products, PC films, PC boards, etc. At the same time, it is necessary to maintain the transparency of the PC, which poses certain challenges.
At present, the main flame retardants used for flame retardant PC include the following categories:
 

1. Phosphate ester flame retardants (such as BDP, RDP): These flame retardants require a large amount of addition and are prone to dripping. To solve the drip problem, it is necessary to add anti drip agents, but this will seriously affect the transparency of PC.
 

2. Organosilicon flame retardants: mainly including polysiloxanes and their derivatives. Organosilicon flame retardants can maintain high transparency of PC and have good flame retardant effects. The addition amount is usually 1.5% to 4%, which can achieve UL 94 V-0 level (1.0-1.5 mm) for PC while maintaining a transmittance of about 87%.
 

3. Sulfonate flame retardants: Sulfonate flame retardants belong to alkaline earth metal salts and have a high flame retardant efficiency for PC products. Common varieties include sodium 2,4,5-trichlorobenzenesulfonate (STB), potassium benzenesulfonate (KSS), and potassium perfluorobutylsulfonate (PFBS). Among them, STB is mostly used in non transparent PC systems, while KSS and PFBS are more widely used in transparent PCs.
 

The following mainly introduces PC flame retardants,
Sulfonate flame retardants:
1. Sodium 2,4,5-trichlorobenzenesulfonate (STB): commonly used in non transparent PC systems.
2. Potassium benzenesulfonate (KSS): widely used, with an addition of 0.05% -0.1%, can increase the oxygen index of PC from 27% to 37% without affecting transparency. It is usually compounded with polysiloxane or added with a small amount of fluoropolymer to improve flame retardancy.
3. Potassium perfluorobutylsulfonate (PFBS): Adding 0.06% -0.1% can achieve UL94 V-0 level (3.2mm) for PC, but achieving V-0 level of 1.6mm or 0.8mm still poses challenges. Note that PFBS dosage exceeding 0.1% will affect transparency.
Organosilicon flame retardants:
1. Polysiloxane and its derivatives: The flame retardant mechanism includes the formation of insulation and flame retardant structures, adsorption of smoke and toxic gases, and promotion of carbonization. The addition amount is 1.5% -4wt%, which can make PC reach UL94 V-0 level (1.0-1.5mm) and the transmittance is about 87%. Silicon copolymer PC also has fluidity and low-temperature toughness.

Application of PC flame retardant
1. Electronic and electrical industry:
Phone case, TV case, computer case: These products need to meet flame retardant performance while maintaining transparency. Therefore, organosilicon flame retardants such as polysiloxane and its derivatives are commonly used.
Electronic components, sockets, switches, etc.: These components need to have flame retardant properties to ensure the safety of electrical appliances. Sulfonate flame retardants (such as STB, KSS) also have certain applications in these applications.
2. Automotive industry:
Car lampshade, dashboard, and interior parts: These components need to meet flame retardant performance and high transparency. Organic silicon flame retardants and sulfonate flame retardants are both applied in the automotive industry.
Electric vehicle battery box and charging station housing: These components require flame retardant performance to ensure the safety of the battery.
3. In the field of optics:
Glasses, camera lenses, optical instruments: These products require high transparency, so organic silicon flame retardants are usually used.
4. Construction and Home Furnishings:
Sunrooms, sunshades, and daylighting panels: These building materials need to have flame retardant properties to prevent fires. Organic silicon flame retardants and sulfonate flame retardants have applications in these fields.
Household and kitchen utensils: They need to meet flame retardant performance to ensure safe use.

In summary, PC flame retardants are an important component of ensuring product safety, with a wide variety and continuous development. In the future, they will be dominated by more environmentally friendly and efficient new flame retardants, providing safer and more reliable materials for various industries.