Types and Advantages of Organophosphorus Flame Retardants

American legislation had updated the flame retardants in furniture and children’s products. The proposal prohibits or restricts the use of halogen flame retardants in children’s products or upholstered furniture.

Flame retardant is a basic requirement for the process of plastic production and use. Halogen flame retardant is the most widely used in many plastic flame retardants. But the shortcomings of halogen flame retardants and increasingly strict environmental regulations make the halogen flame retardant face more and more limitations. The market needs a more efficient and environmentally friendly flame retardant.

Organophosphorus flame retardants are the same as halogen flame retardant. It has many varieties and is widely used. The halogen flame retardant has many disadvantages, such as the poor anti-UV stability, the burning of more smoke, corrosive gases and toxic gases. Organic phosphorus flame retardants is a hotspot in the study of flame retardant, because of organophosphorus flame retardants also has the plasticizing, thermal stability, etc. It is very significant to improve the comprehensive performance of the molecular material.

Types of Organophosphorus Flame Retardants.

1. Phosphate Ester Flame Retardants

Phosphate ester flame retardant is the main flame retardant of organophosphorus, which can be used in polystyrene(PS), polyurethane(PU) foamed plastics, polyester(PET), polycarbonate(PC) and liquid crystal, etc.

The flame retardants of phosphate ester include phosphoric acid ester flame retardant, nitrogen phosphate flame retardant, and halogen phosphate flame retardant.

(1) Phosphate Ester Flame Retardants which Only Contains Phosphorus

Most of the flame retardants are phenolic phosphate ester. Some two substituted phosphate ester flame retardants can be used in the flame retardant of polycarbonate, and the following compounds are used in polycarbonate.

Some two substituted phosphate ester flame retardants can be used in the flame retardant of polycarbonate, and the following compounds are used in polycarbonate.

opfr structural formula 1
In addition, some sulfur-containing phosphate compounds can be used in the flame retardant of fiber, PU foam, PC and ABS materials.

(2) Nitrogen Phosphate Flame Retardants

The phosphoric acid ester containing nitrogen has two kinds of elements, including nitrogen and phosphorus. The effect should be better than phosphate ester flame retardants. Nitrogen phosphate flame retardants are mainly derived from amine, diamine, and melamine in compounds.

opfr structural formula 2
(3) Halogen Phosphate Ester Flame Retardants

The flame retardant can generate corrosive gas and carcinogen after being burn. So it has been out of the flame retardant market.

2. Phosphonic Acid Ester Flame Retardants

The phosphonic acid ester can also be widely used as a flame retardant. At present, the research of phosphonic acid ester flame retardants is mainly focused on the two aspects of nitrogen-containing phosphonic acid ester and reactiveness phosphonic acid ester flame retardant.

Cyanophosphate generated by phosphonic acid ester and cyanide has the effect of flame retardant and plasticizing.

3. Phosphorus Oxide Flame Retardants

The hydrolysis of phosphorus oxide is better than that of phosphate ester. Phosphorus oxide flame retardant is divided into additive type and reactive type. It can be used to make flame retardant polyester, polycarbonate, epoxy resin, and polyurethane.

4. Phosphinates Flame Retardants

As reactive flame retardants, phosphinates flame retardant has a stable effect and is widely used in polyester flame retardant treatment.

5. Organic Phosphorus Heterocyclic Compound Flame Retardants

Organophosphorus heterocyclic compounds are one of the most active fields in the recent study of flame retardants, and also a hotspot in the research of organophosphorus chemistry.

This is mainly because the structure and synthesis of organophosphorus heterocyclic compounds have very important, and its application scope is expanding. The flame retardant of the organophosphorus heterocyclic compound has five rings, six rings, and spiral ring compounds.

(1) Phosphorus Pentacyclic Compound

The five-element phosphorus heterocyclic flame retardant has fewer varieties, and the compound with the following structure is a good flame retardant. It can be used in the flame retardant of polyester, polyamide, and polyolefins.

opfr structural formula 3
(2) Phosphorus Hexacyclic Compound

Phosphor heterocyclic flame retardant is one of the main varieties, mainly phosphorus mixed oxide phosphorus, phosphate, cage phosphate ester, phosphonate, and phosphinate. They can be used for polyester, epoxy resin and polyurethane flame retardant treatment of a variety of materials, etc.

opfr sf 4
(3) Phosphorus Spiral Ring Flame Retardants

Phosphorus screw ring flame retardants are mostly was prepared from pentaerythritol reaction with phosphorus compounds. Molecules generally contain huge amounts of carbon which contains two phosphorus atoms. So it is high phosphorus content. The flame retardant effect is better, can be used as an expansion type flame retardant, widely used in various kinds of polymer materials, flame retardants, such as stability and plasticizing effect.

The phosphorus spiral ring flame retardant can be expressed as follows.

opfr sf 5
(4) Double Ring Cage Phosphate Ester

Due to its structural characteristics, it is used widely. Compounds with the following structures can be prepared by ester exchange for the flame retardant treatment of various polymers.
opfr sf6
(5) Seven-Element Phosphorus Mixed Ring Flame Retardants

As with the five-element phosphorus heterocyclic compound, there are also few varieties of seven-element phosphorus hybrid flame retardant. Its structure is as follows:
opfr sf 7

6. Phosphate Polymer Flame Retardants

Convergent phosphate ester flame retardant molecular contains some repeat unit, its molecular weight is large, low steam press, low toxicity, and mobility. It has very good durability, and have the function of flame retardant, antioxidant and plasticizing. It mainly includes the oligomer type and high polymer type. Organic phosphorus flame retardants in recent years are its another important development field.

(1) Oligomer Type Phosphate Ester Flame Retardants

Oligomer type phosphate ester is a compound with the following structure:

opfr sf 8
(2) High Polymer Type Phosphate Ester Flame Retardants

The molecular weight is larger than that of the oligomer type phosphate ester flame retardant. It can be divided into two types: main chain phosphorus and side chain phosphorous, which are widely used in the flame retardant of plastics, rubber, and fiber.

opfr sf 9

7. Organic Phosphate Flame Retardants

Zinc, magnesium, aluminum hydroxide and phosphate have a good flame retardant effect and to inhibit smoke. So the organic phosphate which contains zinc, magnesium, and aluminum has become more and more important. There are mainly phosphate, phosphonate, and phosphinates, etc.

opfr sf 10
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Types and Advantages of Organophosphorus Flame Retardants