In-depth Exploration of ABS Flame Retardant Technology: Flame Retardant Selection And Application Strategies

In-depth Exploration of ABS Flame Retardant Technology: Flame Retardant Selection and Application Strategies

ABS resin, a polymer material made from the copolymerization of three monomers: acrylonitrile (A), butadiene (B) and styrene (S), is a thermoplastic polymer between general-purpose plastics and engineering plastics. Its unique properties, such as excellent impact resistance, heat resistance, low-temperature resistance, chemical resistance, as well as easy processing and molding and excellent surface gloss, make ABS resin has a wide range of applications in automotive manufacturing, electronics and electrical appliances, textiles, household goods, and construction materials, and many other fields. As the application of ABS resin continues to expand, the requirements for its flame retardant properties are also increasing.

In this context, in-depth discussion of the importance of ABS flame retardant technology, to understand the effective way to improve the flame retardant properties of ABS, as well as screening the appropriate type of flame retardant, has become the focus of attention of the industry. This article will provide you with a detailed explanation of the core points of ABS flame retardant technology.

The urgent need for ABS flame retardant technology

In modern life and industrial production, polymer materials are favored for their unique properties. However, with the expansion of the scope of application of polymer materials, the importance of their flame retardant properties is also increasingly prominent. In China, the requirement for flame retardancy of polymer materials has become more and more urgent.

ABS resin, as a combustible material, has an oxygen index of only 22%, and burns quickly and with a large amount of smoke. This not only poses a threat to personnel safety, but also may cause pollution to the environment. Therefore, improving the flame retardancy of ABS resin has become an important research task. However, when ABS resin is used alone, its flame retardant properties are poor and cannot meet the needs in practical applications. In order to improve the flame retardant effect of ABS, it is usually necessary to add flame retardants. However, it is worth noting that the addition of flame retardants tends to negatively affect the physical and mechanical properties of ABS, especially the impact properties of the products will be significantly reduced. At the same time, the price of flame retardants is usually two to three times the price of ABS, which undoubtedly increases the cost of products.

Strategies to improve the flame retardant properties of ABS

In response to the challenges of ABS flame retardancy, researchers and engineers have proposed a variety of strategies to improve it. These strategies mainly include changing the components of ABS copolymer, mixing high flame retardant resins, adding inorganic flame retardants and organic flame retardants.

1. Changing the components of ABS copolymer: one method is to add transbutylene diene or tribromostyrene as the fourth monomer, and copolymerize with styrene, butadiene, and acrylonitrile to obtain a four-component flame retardant copolymer. This method has the advantage of good flame retardancy and durability, but it needs to be added in the process of ABS polymerization, the process is complex and high cost, so it is less used in practical applications.

2. Mixing high flame-retardant resins: Another method is to improve the flame-retardant property of ABS by mixing high flame-retardant resins (such as PVC, CPE, etc.). However, this method requires the addition of a large number of high flame retardant resins to be effective, which will have a greater impact on the inherent properties of ABS.

3. Add inorganic flame retardants: Inorganic flame retardants such as aluminum hydroxide (Al(OH)₃), magnesium hydroxide (Mg(OH)₂) and molybdenum trioxide (MoO₃) are also effective means to improve the flame retardant properties of ABS. However, these flame retardants need to be added in large quantities (usually more than 60 parts) to produce a significant flame retardant effect, which will lead to a significant decline in the mechanical properties of polymers and processing performance, thus losing value.

4. Add organic flame retardants: organic flame retardants such as halogen compounds and phosphorus flame retardants have the advantage of adding less, good flame retardant effect. However, these flame retardants also have poor weather resistance, expensive and black smoke when burning.

In order to balance the flame retardant effect and cost, most of the comprehensive after three additive flame retardant method, in order to prepare a better performance of the low smoke flame retardant ABS system. This approach through careful screening and proportioning of flame retardants, can ensure flame retardant properties at the same time, minimize the impact on the physical and mechanical properties of ABS, and control costs.

Selection and application of ABS flame retardants

In ABS flame retardant technology, the selection of flame retardants is crucial. According to the chemical composition and performance characteristics of flame retardants, they can be divided into two categories: halogenated flame retardants and non-halogenated flame retardants.

Halogenated flame retardants

Halogenated flame retardants mainly refer to bromine flame retardants, which have the advantages of high flame retardant efficiency, low dosage and moderate price. However, some brominated flame retardants do not comply with the RoHS ban and are non-environmentally friendly products, which have now been banned. The following is a detailed introduction to several common brominated flame retardants:

1. Polybrominated diphenyl ethers: Polybrominated diphenyl ether flame retardants include octabromodiphenyl ether and decabromodiphenyl ether. This type of flame retardant has high efficiency, low dosage, and the products have good mechanical properties. However, they are now banned because they do not comply with the RoHS ban.

2. Decabromodiphenyl ethane (DBDPE): DBDPE is a kind of bromine flame retardant without free bromine, and does not produce PBBs and PBDEs when burning, which are strictly prohibited by the RoHS ban. Its cost is comparable to that of decabromodiphenyl ether, and the safety assessment shows that DBDPE is a low-toxicity, non-irritating flame retardant with negative effects on numerous in vivo genes and low toxicity in repeated doses. Therefore, DBDPE can be used as an alternative to PBDEs in the flame retardant treatment of ABS.

3. Antimony flame retardant: Antimony flame retardant is an important flame retardant synergist, which can be used alone or in combination. Especially when used in conjunction with halogenated flame retardants, it can greatly improve the effectiveness of halogenated flame retardants. The main varieties are antimony oxide (Sb₂O₃), antimony pentoxide (Sb₂O₅) and sodium antimonate (NaSbO₃-1/4H₂O).

The antimony trioxide replacement agent T3 developed by YINSU Flame Retardant Company can also completely replace antimony trioxide and be applied in ABS. The added amount is 1.2 times of the original antimony trioxide.

4. Brominated epoxy resin: Brominated epoxy resin is an epoxy resin synthesized from tetrabromobisphenol A. It has excellent melt flowability, high flame retardant efficiency, excellent thermal stability and light stability. At the same time, it also has good physical and mechanical properties, is an ideal ABS flame retardant.

5. Bromotriazine: Bromotriazine is a new type of flame retardant with bromine/nitrogen synergy. It is mainly used for flame retardant ABS, PBT, PC/ABS, HIPS and other plastic products. Bromotriazine has good thermal stability and electrical properties, superior resistance to ultraviolet radiation and light resistance, good flame retardant effect, widely used.

Halogen-free flame retardant

With the improvement of environmental awareness and the implementation of RoHS ban, halogen-free flame retardants are gradually receiving attention.

1. Aluminum hydroxide and magnesium hydroxide: These two inorganic filler materials are favored as flame retardants for their halogen-free, non-toxic, smoke reduction and cost-effectiveness.

Their flame retardant action principle is similar, mainly through the condensed phase flame retardant (in high temperature conditions, aluminum hydroxide in the ABS material surface to form a protective layer, isolation of oxygen, reduce the flammability of the material to reduce the release of combustible gases; magnesium hydroxide / ABS composite material in the combustion, the surface of the formation of a dense charcoal layer, isolation of heat and decomposition products of the diffusion of the heat and insulation effect, effectively reduce the rate of heat release, delaying the combustion of the material). It can effectively reduce the heat release rate of the material and slow down the combustion process) and cooling effect (flame retardants can reduce the temperature of the material surface and combustion area through heat-absorbing dehydration, phase change, decomposition and other heat-absorbing reactions, prevent thermal degradation, reduce the release of combustible gases, and destroy the conditions of sustained combustion).

However, when used alone, it requires a large amount of addition and may significantly affect the mechanical properties of the resin, so it is usually not used as the main flame retardant.

2. Red phosphorus flame retardant: This flame retardant contains only phosphorus, and its flame retardant efficiency is better than other phosphorus-containing flame retardants.

Its flame retardant effect is mainly realized through the condensed phase flame retardant, that is, a protective layer is formed on the surface of ABS at high temperature, which can isolate the oxygen, prevent the heat transfer, and reduce the release of combustible gases, so as to realize the flame retardant effect.

For example, the red phosphorus masterbatch, ABS-P-20M, specially developed by YINSU Flame Retardant Company for ABS, with an addition amount of about 20%, can achieve UL94-V0, high efficient halogen-free flame retardant effect. The total cost of flame retardant is much lower than the cost of halogen flame retardant.

3. Phosphorus and nitrogen composite flame retardants: Nitrogen-containing flame retardants are mainly used to dilute flammable gases or cover the surface of the material through the non-flammable gases such as nitrogen produced in the decomposition process to realize the flame retardant effect. Common nitrogen-containing flame retardants include melamine, melamine cyanurate (MCA), melamine pyrophosphate and so on.

Expansion-type flame retardants with phosphorus and nitrogen as the main components are outstanding in ABS halogen-free flame retardant. Phosphorus compounds and nitrogen compounds combine to form phosphorus-nitrogen flame retardants, which are not easy to burn due to the gases released by nitrogen compounds after being heated, such as N2, CO2, NH3, H2O and so on, and they block oxygen supply, so as to realize flame retardant synergistic and synergistic effects.

The future development direction of ABS flame retardants can be analyzed from the following perspectives:

1. Environmental protection and low toxicity: Although halogenated flame retardants are still the mainstream products in the market, considering that they may release toxic and corrosive substances during combustion, the market demand for halogen-free, environmentally friendly flame retardants is on the rise.

2. High efficiency and multifunctionality: Research and development of highly efficient and multifunctional flame retardants is an important trend in the industry. These flame retardants can reduce environmental pollution and cost without sacrificing the physical and mechanical properties of the substrate.

3. Nanotechnology and microencapsulation: With the advancement of nanotechnology and microencapsulation technology, surface modification and ultrafine treatment of inorganic flame retardants have become possible. These technologies help to improve the flame retardant properties of inorganic flame retardants, reduce their additive amount, and enhance their performance through ultrafine, surface modification, macromolecular bonding and other methods.

4. Compounding technology: In some products, volume expansion flame retardant effect is realized by using phosphorus elements instead of halogens. Such composites, with the addition of specific flame retardants, are able to form a stable carbonized layer on the surface, which insulates, reduces oxygen ingress, prevents dripping of molten polymers, and at the same time reduces the emission of fumes and organic substances, providing protection to the material. In addition, the masterbatch offers good high-temperature stability, ease of processing and coloring properties.

With the rapid growth of the home appliance and automotive industries, China's demand for ABS resins continues to rise, and so do the requirements for environmentally friendly and flame-retardant properties of ABS. Therefore, the development of new flame retardants with excellent performance is not only a key task in the research of flame retardant materials, but also an important development direction for the ABS industry.