CircleBlend: ® Launch a new product with excellent environmental protection, fla


PC materials

What type of flame retardant is used?


With the development of technology, the application of recycled plastics has become increasingly widespread. The flammability of recycled plastics used under certain special conditions has become a key indicator for measuring product safety. At the same time, with the continuous introduction of safety regulations, how to reduce or even solve the flammability of organic polymer materials in daily life has become an industry challenge. We are also constantly committed to exploring and solving this difficult problem.


What is flame retardant?

Why is plastic flame retardant?


It can be seen that special usage conditions and solving safety accidents caused by the combustion of recycled plastics are the main reasons for the need for flame retardancy of recycled materials. The most direct solution is to add flame retardants to recycled plastics, but this often affects the relevant performance. Therefore, it is necessary to conduct testing and analysis on recycled PC based on different types of flame retardants in order to adopt the most suitable flame retardant. As a result, flame retardants have rapidly grown and become a key foundational material widely used in the recycling industry.


As the material with the best high-temperature resistance among the five major engineering plastics, what type of flame retardant is most suitable for recycled PC materials?


There is really no definite answer to this. The material sources, process production, product quality, and product performance of different recycled PCs. Only based on specific material properties can an accurate answer be obtained.


The goal of measuring the flammability of plastics is the oxygen index, abbreviated as OI, which refers to the lower oxygen content required for plastic specimens to persist in combustion in the air. The lower the oxygen index of recycled plastics, the lower the oxygen concentration required for their continuous combustion. This indicates that they have good combustibility and can continue to burn when there is little oxygen. In other words, the lower the oxygen index of recycled materials, the easier they are to burn, and vice versa.


Commonly used flame retardants




Flame retardant


At present, there are six commonly used types of flame retardants:


  1. Halogenated flame retardants

Advantages: High flame retardant efficiency, low dosage, moderate price, and minimal impact on material performance;

Disadvantages: large combustion smoke, release toxic and corrosive gas, poor environmental protection performance;


  1. Phosphorus based flame retardant

It is divided into two types: organic phosphorus based flame retardants and inorganic phosphorus based flame retardants, with main characteristics of low toxicity, low smoke, low halogen or even zero halogen, high efficiency, and low dosage.


Organic phosphorus flame retardant:

Advantages: The products of thermal decomposition have a strong dehydration effect, which can carbonize the surface of the covered polymer, form a carbon film, isolate air, and achieve flame retardant effect.

Disadvantages: Poor heat resistance, high volatility, and deterioration of the plastic‘s thermal deformation temperature.

Inorganic phosphorus based flame retardants:

APP is applicable to intumescent flame retardant systems, mainly used for polyolefin, polyurethane foam, coatings and other flame retardants.


  1. Metal hydroxide

Mainly Aluminium hydroxide and Magnesium hydroxide, it is a flame retardant with three functions of flame retardancy, smoke suppression and filling. Main features: non-toxic, non corrosive, good stability, no generation of toxic gases, smoke suppression, etc.

Aluminium hydroxide:

Advantages: Flame retardant, smoke suppressant, and filling function, non-toxic, low-cost, and is the most important type of inorganic flame retardant. ATH begins to dehydrate and absorb heat at around 250 ℃, and generates alumina on the surface of the material, inhibiting its combustion. It can be used for elastomers, thermosetting resins, and thermoplastic plastics.

Magnesium hydroxide

Advantages: Low smoke and non-toxic, able to neutralize acidic and corrosive gases during combustion. The decomposition temperature of Magnesium hydroxide is 350~400 ℃ higher than that of ATH, which is suitable for engineering plastics with higher processing temperature.

Disadvantages: It catalyzes resin decomposition and is generally not suitable for thermoplastic polyester resins. Inorganic hydroxides have low flame retardant efficiency, with a general addition amount of up to 50%~70%, which affects material performance.

  1. Zinc borate

Advantages: It has multiple functions such as flame retardancy, smoke suppression, carbonization, smoldering suppression, and prevention of droplet formation. It is inexpensive, non-toxic and non irritating, and does not affect the strength, elongation, and thermal aging of the material. Zinc borate can be used alone or in combination with Halocarbon and Antimony trioxide, with better flame retardancy.

  1. Triazine flame retardant

Advantages: Excellent thermal stability, good flame retardant effect, multiple reaction functions, good compatibility with polymers, etc;

Disadvantage: The scope of application is relatively narrow, mainly used for intumescent flame retardant nylon.

  1. Intumescent flame retardant

Phosphorus nitrogen based intumescent flame retardant:

Advantages: Flame retardants mainly composed of phosphorus and nitrogen have good flame retardancy, low smoke generation, and low toxic gas generation. Phosphorus nitrogen based flame retardants form a porous layer when heated, which can insulate from heat and oxygen. The released water vapor and ammonia can foam the carbon layer, which is beneficial for flame retardancy.

Application scope: The most widely used in melamine, APP, PER systems.

Expandable graphite:

Advantages: The volume of expandable graphite expands hundreds of times with the increase of temperature, forms a carbon layer on the surface of polymer, isolates heat source, absorbs a lot of heat during expansion, releases acid radical ions in interlayer, promotes dehydration and carbonization, and inhibits Chain reaction in combination with free radicals generated by combustion. It can be used in combination with phosphorus compounds and metal oxides to produce synergistic effects. Adding a small amount can achieve flame retardancy.


The above are the most commonly used flame retardants, what are the flame retardants suitable for PC?

Flame retardants commonly used in PC

Based on the current application of flame retardants on PC, we can know that the flame retardants suitable for PC and PC alloys mainly include: phosphorus based flame retardants are easy to corrode molds, reduce the processing performance of PC, and are generally used for PC alloys, rarely used alone for PC; Silicon based flame retardants have attracted increasing attention due to their excellent comprehensive flame retardancy on PC, becoming the focus of the current flame retardant family.

In addition, flame retardants that have not been widely used in PC mainly include: emerging nano flame retardants can only reduce the heat release rate, but cannot reduce the heat release amount. They are rarely used alone for flame retardancy and are often used in combination with other flame retardants; Aromatic sulfonate flame retardants are one of the most efficient flame retardants, but they are expensive and have not been widely used.

Looking at the research and development status of flame retardants in recent years, it can be seen that their development trend is towards environmental protection, low toxicity, high efficiency, multifunctional, nanoparticle, microencapsulation, and the application of composite technology. How to develop new flame retardants with excellent performance through compounding technology is an important topic in flame retardant research and should also be a very important direction for the development of flame retardants.

CircleBlend® Through continuous experimentation and exploration of the material properties of recycled PC, R&D personnel have tested and optimized the active composite flame retardant system to achieve rPCBlend ™ Better environmentally friendly flame retardant performance and testing performance, while being smokeless, non-toxic, and harmless, taking into account the most balanced and optimized comprehensive performance of the material.



This is for CircleBlend® rPCBlend ™ In terms of product characteristics, rPCBlend™ By using modified granulation equipment to produce recycled polycarbonate particles after consumption, we can provide enhanced, flame-retardant, color matching and other modified recycled polycarbonate products. We can provide customized services for material performance and system solutions according to customer requirements. The products are suitable for direct extrusion and injection molding, and can be used for various injection molded parts such as power supply shells, electrical instrument shells, television shells, etc.


Not only that, CircleBlend® rPCBlend ™ The product can achieve full life cycle traceability and Carbon footprint. Halogen Free environmental protection conforms to ROHS/REACH standards, and has passed GRS/UL2809/TUV PCR/ITE/"zero" carbon certification, using rPCBlend ™ Can achieve dual environmental protection of "zero" carbon and flame retardancy, and through  CircleBlend® Driven by innovation in research and development capabilities, we aim to truly achieve green and low-carbon usage scenarios for our products while minimizing their impact on environmental pollution.





If you see the above identification

Please remember that they are all our logos


See All

World Oceanic Day Guard the ocean health Topcentral®Drop of a new
June 8th is the 14th "World Ocean Day" and the 15th "National Ocean Propaganda Day"……

See All


See All

World Environment Day Special Event Topcentral®
On the eve of the arrival of the World Environment Day, the World Environment Day event specially planned by the Green Cycle Environmental……

See All


See All

Drive the future with green, help "Green Intelligent Manufacturing" To
Green and low carbon, not only in the mountains and rivers, but also in every detail and every aspect of production and life……

See All


See All

Science and technology resistance Topcentral®
In spring, it should have been a good season, and the bright and bright season……

See All


See All

See All