Brief Description of Polypropylene Flame Retardant Modified Flame Retardants

Polypropylene (PP) has been applied in many industries due to its small density, good mechanical properties, chemical resistance, easy processing, good heat resistance, low cost, and simple production process. Flame retardant pp has become the most growth rate. Fast, widely used polymer flame retardant materials. In the automotive plastics, electrical accessories, electronic enclosures, household appliances, electrical equipment, home appliances and many other industries have flame retardant polypropylene applications.

Polypropylene modification includes: copolymerization modification, graft modification, chlorination modification, cross-linking modification and most widely used blend modification, such as: filling, toughening, reinforcement, flame retardant, and weather resistance. PP flame retardant modification is booming in recent years!


Polypropylene flame-retardant modification is generally modified by the use of flame retardant and polypropylene melt blended through a twin-screw extruder. The currently widely used flame retardants include: organic bromine, chlorine, such as octabromo ether, decabromodiphenyl ether, decabromodiphenyl ethane, octabromo S ether, clones, chlorinated paraffins, and the like. Inorganic flame retardants (often referred to as non-halogen flame retardants), such as: magnesium hydroxide, aluminum hydroxide, zinc borate, are sometimes also used, such as nitrogen, phosphorus, and their common composition of the intumescent flame retardant.

The brominated flame retardant has the best affinity with plastics. It has become the most widely used flame retardant for flame retardant polypropylene with excellent compatibility, reliable production process and mature technology reserves, and perfect price/performance ratio. Because of its high flame retardancy and low cost of use when used in flame-retardant polypropylene, it is often used by a modification plant.

Flame retardant Octabromo ether (BDDP)
Chemical name: 1.1'-(Methylhexyl)-bis[(3.5-dibromo)-4 (2.3-dibromopropyloxybenzene)
Molecular Formula: C21H20Br8O2
Molecular weight: 943.62
Structural formula:

Product quality indicators:
Appearance white powder melting point 107-120 °C
Volatile 0.3% max
Decomposition temperature 285°Cmin
Bromine content 67% min


Octabromoether as a halogen flame retardant and other halogen flame retardants have a common flame retardant principle - to control the decomposition products of plastics, combined with monomers, to effectively prevent the occurrence of combustion, flame retardant mainly for the gas phase and condensed phase. With octabromoether fire-retardant polypropylene plastics, it is necessary to mix with antimony trioxide which is not less than 1/3 of its own amount, and it will have better flame-retardant effect. In the laboratory, the UL94 3.2mm test piece V-2 passes only a flame retardant compound with a total amount of about 4% or less. Another advantage of the octabromoether flame retardant polypropylene is that the mechanical properties of the flame retardant material are excellent. Almost no effect.
However, in practical applications, octabromoether exhibits better flame-retardant effect on homopolymerized pp, and is often unsatisfactory for the copolymerization of polypropylene. Polypropylene octabromoether modified for toughening and weathering is usually also represented. For flame retardant fatigue. Also, affected by the dispersion and other issues, the actual production of the same flame retardant level, the proportion of octabromoether added is much higher than the proportion of 4% of the laboratory. The addition of octabromoether will reduce the melting point of the entire flame retardant system, This is a very unfortunate news for plastics such as auto parts that have special requirements for heat distortion temperature. Flame-retardant polypropylene will have different degrees of thermal deformation temperature drop, so it is difficult to achieve product performance requirements. In addition, the most unbearable is that octafluoroether flame-retardant pp plastic will generally appear the phenomenon of flame retardant precipitation, even if the concentration is very low. Especially for colored plastic products, the frost will greatly reduce the quality of the product. And after the flame retardant is precipitated, the flame retardant effect will be reduced. We have tried various techniques such as physics, chemistry, blending with other materials, and process improvement, and unfortunately have not fundamentally changed the state of precipitation. With the continuous improvement of environmental protection, the inevitably generated "non-friendly substances" such as polybrominated diphenyl ethers in the process of octabromoether synthesis have also become an obstacle to application.
However, octabromoether as a cheap and good pp flame retardant is still very useful in some occasions.

Decabromodiphenyl ether and decabromodiphenylethane

Flame retardant decabromodiphenyl ethane (TDE)
Product name Decabromodiphenylethane Molecular formula C14Br10H4
Molecular weight 971.27
Structural formula

Product Specifications Appearance white or light yellow powder Non-bromine content 82.3% (min)
Melting point 350°C
Specific gravity 3.25

The flame retardant effect of these two kinds of flame retardants is almost the same as the use process. In the tests, we found that it exhibits relatively excellent flame-retardant efficiency for polymers such as ABS and HIPS.

In the use of general-purpose plastics PP, PE, in addition to the need for a higher proportion of the added and the cost, it is not a small "damage" to the mechanical properties of the material. In addition, the processing fluidity of polypropylene added with a decabromodiphenylethane-added flame retardant was significantly deteriorated. In the production of spinning processes, dispersibility has become difficult to overcome.

However, as a simple, easy, familiar flame retardant, many engineering and technical personnel are still happy to choose.

Inorganic flame retardants Magnesium hydroxide Magnesium hydroxide has a higher flame retardant efficiency and a higher decomposition temperature than aluminum hydroxide. Magnesium hydroxide with a purity of 99.8 or higher can be completely used in pp flame retardant. Magnesium hydroxide is recognized as a halogen-free, environmentally friendly flame retardant. Two problems must be solved during use: First, the problem of dust pollution, this can be solved by the method of making flame-retardant masterbatch, there is with plastic The compatibility issue, to add a certain percentage of coupling agent to a certain extent, can solve such problems. But in no way can it be fundamentally changed, because inorganic materials and organics are naturally not "friendly!"
Magnesium hydroxide has lower flame retardant efficiency than brominated flame retardants, and the same flame retardant rating generally increases exponentially with the addition of halogen-based flame retardants, which inevitably results in the loss of mechanical properties of the material. In addition, like all flame-retardant products, magnesium hydroxide in the laboratory's flame-retardant test is often better than the actual application performance, subject to product processing characteristics, other additives, etc., not all processes can be used It achieves the desired flame retardant effect.
Intumescent Flame Retardant Expanded Flame Retardant In terms of flame retardant efficiency, expanded graphite can be described as “unsurpassed”. In combination with other phosphorus-based flame retardants, flame-retardant polyolefin plastics can easily achieve V0 flammability ratings. Moreover, the expanded graphite has a rich source and low price. The main problem lies in the fact that when the expanded graphite reaches a significant flame-retardant effect, a product with a size of about 80 mesh must be used, and the appearance of the obtained product is difficult to compliment.


Red phosphorus, commercialized mainly red phosphorus masterbatch. It is also commonly referred to as an environmentally friendly flame retardant. Halogen-based flame retardant flame retardant principle is completely different. There is a relatively good flame retardant effect on polyethylene. Also used in flame retardant nylon. However, the flame retardant efficiency of polypropylene with many side chains is very low. For the processing technology and the color of the product is more picky, the use of red phosphorus as a flame retardant is often a helpless choice. The advantage of red phosphorus is that it is less picky about other additives.


Flame retardant use process rules:
1. Any kind of flame retardant has certain requirements on the processing technology. Some flame retardants have better effects in the injection molding environment, while others are more suitable for spinning or extrusion processes.
2. Bromine- and nitrogen-based flame retardants may be “failed” by certain additives or processes. Carbon black, calcium carbonate, other fillers, certain pigments, zinc oxide, etc., which have a large specific surface area, may be fatal killers of halogen-based flame retardants! Mixing of different plastics due to the differences in the high and low melting point and decomposition temperature may cause the "wick" effect in the combustion process, thereby greatly reducing the flame retardant effect.
3. The dispersion of flame retardants in the resin is critical. Whether effective formation of "islands structure" or effective mutual solubility is critical to the flame retardant efficiency of flame retardants.


The basic starting point for the birth of fire-retardant masterbatch flame retardant masterbatch or flame retardant masterbatch is to solve problems such as: uneven dispersion, dust pollution, convenient processing, transportation, storage, and simple use. In the 1960s, Americans reportedly began using flame retardant masterbatches. The development of flame-retardant masterbatches, like other functional masterbatches, followed a series of processes. So far, the function of flame-retardant masterbatch has gone far beyond the initial requirements. As a relatively new product, with the increasing complexity of the process and the continuous application of new high-tech equipment, the function and performance of the flame-retardant masterbatch have been greatly improved, and now the high-performance fire-retardant masterbatch is in flame-retardant efficiency, dispersion effect, Many aspects such as compatibility are far from common flame retardants, and flame retardant masterbatch is likely to become the flame retardant raw material with the understanding of modified companies.