Application of Halogen-Free Flame Retardant in Rubber Industry

Application of Halogen-Free Flame Retardant in Rubber Industry

When fire occurs, halogen-containing flame retardant materials will produce a large amount of smoke and toxic corrosive hydrogen halide gases during the flame retardant process, resulting in secondary hazards.In February 2003, the European Union promulgated two directives, RoHS and WEEE, the former is about restricting and prohibiting the use of certain toxic and hazardous substances and elements in electrical and electronic equipment, and the latter is a directive on the recycling of waste electrical and electronic equipment.

The WEEE Directive came into effect in August 2005 and the RoHS Directive came into effect in July 2006. The European Union in the building materials and other industries to implement the new flame retardant classification methods and test standards, China has also been reported for approval of building materials and products combustion performance level of the national standard, this standard and the above new EU standards have common characteristics, that is, in the evaluation of flame retardant materials, emphasizing the rate of heat release, the rate of development of the fire, the smoke and corrosive and toxicity of the products of combustion, etc., in order to pass such new standards, the traditional halogenated flame retardant materials will not be able to help, people will not be able to help, people will be able to help.

In order to pass these new standards, the traditional halogenated flame retardant materials will be unable to help, people will turn to the use of halogen-free environmentally friendly flame retardant materials, which is also in line with the RoHS directive on the restriction of hazardous substances and the prohibition of the use of the requirements.

I. Traditional flame retardant materials are widely used as flame retardant mixtures made of halogen-containing polymers or combinations of halogen-containing flame retardants.

The advantages of halogenated flame retardants are low dosage, high flame retardant efficiency and wide adaptability, but their disadvantage is that they generate a lot of smoke and toxic and corrosive gases during combustion, which is very harmful. Once a fire occurs, due to thermal decomposition and combustion, a large amount of smoke and toxic corrosive gases will be generated, thus hindering fire fighting and evacuation, corrosion of instruments and equipment. In particular, it has been found that more than 80% of deaths in fires are caused by smoke and toxic gases produced by the material. Therefore, the research and development of halogen-free flame retardants is bound to attract attention.

II. New flame retardant system, small amount of smoke when burning, does not produce toxic, harmful and corrosive gases.

Halogen-free flame retardants are mainly based on phosphorus compounds and metal hydroxides. These two types of compounds, combustion is not volatile, does not produce corrosive gases, known as environmentally friendly flame retardants, in addition to silicone flame retardants and nitrogen flame retardants and other new types of halogen-free flame retardants. These new halogen-free flame retardants have become new products in line with the development trend of international standards.

III. Phosphorus-based halogen-free flame retardants are also getting more and more attention.

Their polyphenol hydroxyl or polyamino derivatives can be used as curing agents for polymers, and the performance of the epoxy resin cured by them is very different from that of brominated epoxy resin, especially in the flame retardant, thermal stability, the difference is obvious. Nowadays, the research and development of organophosphorus compounds is developing rapidly from chain structure to cyclic structure, among which phosphine-phenanthrene compounds - DOPO and its derivatives are attracting much attention because of their unique molecular structure (coexistence of biphenyl and phenanthrene rings) and the many excellent performances they have shown. It can be said that DOPO derivatives are making their mark in environmental protection and flame retardant applications. They are suitable for use as a substrate for circuit boards because they do not drip or produce black smoke when burned.

IV. Phosphorus and nitrogen-based halogen-free flame retardants also include intumescent halogen-free flame retardants, which function mainly through the condensed phase. 

At a lower temperature, the acid source produces the acid that can esterify polyol (carbon source) and can be used as a dehydrating agent; at a slightly higher temperature, the acid and the polyol (carbon source) carry out the esterification reaction, and the amine in the system acts as a catalyst for the esterification reaction, accelerating the reaction; the system melts before the esterification reaction or in the process of esterification; the water vapor produced in the course of the reaction and the non-combustible gases produced by the gas source make the system that has already been in the molten state expand and foam, and at the same time, the system expands and foams, and is very suitable as a substrate for circuit boards. At the same time, the polyol and ester dehydration carbonization, the formation of inorganic substances and carbon residues, and the system further foaming; reaction is nearly complete, the system gelatinization and curing, and finally formed a porous foam carbon layer. Such as ammonium poly polyphosphate, melamine, expanded graphite, melamine phosphate, zinc borate, TGIC.

V. Aluminum hydroxide Al(OH)3.

Its dosage accounts for more than 40% of the total amount of flame retardants used. Aluminum hydroxide itself has three functions: flame retardant, smoke elimination and filler. Because it is non-volatile, non-toxic, and can produce synergistic flame retardant effects with a variety of substances, it is known as a harmless inorganic flame retardant. However, aluminum hydroxide has the disadvantage of adding a large amount of aluminum hydroxide, usually need to add more than 50% to have a good flame retardant effect. In order to overcome this drawback, granulation technology can be used to develop in the direction of ultrafine, which is a narrower particle size distribution; improve the wrapping technology in order to improve its dispersion in polymers; and treat it with macromolecular bonding. Magnesium hydroxide Mg(OH)2 is a fast developing additive flame retardant, low smoke, non-toxic, can neutralize the acidic and corrosive gases in the combustion process, so it is a kind of environmentally friendly green flame retardant. Its flame retardant mechanism is similar to that of Al(OH)3. Compared with Al(OH)3, the decomposition temperature of Mg(OH)2 is 100-150℃ higher than that of Al(OH)3, so it can be used for the flame retardancy of engineering plastics with the processing temperature higher than 250℃, and it also has the effect of promoting the polymer to form charcoal, but in order to achieve a certain flame retardant effect, the amount of additives needs to be over 50%, which has a great influence on the performance of the material. In order to reduce the amount of Mg(OH)2 added to the polymer, one way is to refine the Mg(OH)2 particles, and another way is to modify the surface of Mg(OH)2 by using the coating technology to improve its compatibility with the polymer.

VI. Red phosphorus is a flame retardant with excellent performance.

It has high efficiency, smoke suppression and low toxicity flame retardant effect, but it is easy to absorb moisture, oxidize, and release highly toxic gases, and the dust is easy to explode and show deep red color, so its use is greatly restricted. In order to solve some of the above shortcomings, surface treatment of red phosphorus is the main direction of research, of which microencapsulation is the most effective method. There are many types of microencapsulated red phosphorus products in the international market, and a lot of research has been carried out in China, generally using aluminum hydroxide, metal sulfate, synthetic resin as the wall material of the capsule, but not many of them have been pushed to the market. In the future, the development direction of red phosphorus surface treatment is as follows: firstly, to develop multi-functional microencapsulated red phosphorus flame retardant by modifying the capsule material of the capsule to make it both heat stabilized, plasticized and flame retardant at the same time; secondly, to study the effective compounding relationship between all kinds of flame retardant and red phosphorus flame retardant, and to make it microencapsulated, to increase the effect of flame retardant, and to improve the mechanical properties of the material; thirdly, as the red phosphorus has the effect of smoke suppression, it can be used to search for the suitable anti-smoke agent to compound with it, and to make it a fire retardant. Thirdly, red phosphorus has the effect of smoke suppression, so we can find suitable smoke suppressant to compound with it. Smoke suppression is more important than fire prevention in a fire, which promotes the development of smoke suppression technology.

VII. Expandable graphite is a new type of non-halogen flame retardant.

It is made from natural graphite by acidification with concentrated sulfuric acid, then washed, filtered, dried and then expanded at 900-1000℃. Expandable graphite expansion of the initial temperature of 220 ℃ or so, generally in 220 ℃ began to expand slightly, 230-280 ℃ rapid expansion, after the volume can be up to more than 100 times the original, or even 280 times. Expandable graphite in the flame retardant process mainly plays the following roles: (1) in the polymer surface to form a tough carbon layer, the combustible material and heat source isolation; (2) in the expansion process of a large number of heat absorption, reducing the temperature of the system; (3) in the process of expansion to release the entrapped acid ions, promote dehydration carbonization, and can be combined with combustion of free radicals generated by the interruption of the chain reaction. Expandable graphite can produce a coordinated effect when used in combination with phosphorus compounds and metal oxides, and a small amount can be added to achieve the purpose of flame retardancy.

VIII. Organophosphorus flame retardant is one of the most important varieties of flame retardants.

With flame retardant and plasticizing double effect, can make the flame retardant completely halogen-free, improve the rubber, plastic molding in the liquidity performance, inhibit the residue after combustion, toxic gases and corrosive gases produced less than halogen flame retardants, the flame retardant mechanism is: on the one hand, the flame retardant heat decomposition produces phosphoric acid, metaphosphoric acid, polyphosphoric acid, these phosphoric acid has a strong dewatering, which can make the surface of the polymer dewatering charcoal, and These phosphoric acid-containing agents have strong dehydrating property, which can make the polymer surface dehydrated and carbonized, while the monomaterial carbon can not produce flame evaporation combustion and decomposition combustion, so it has a flame-retardant effect; on the other hand, the flame retardant produces PO-radicals by heat, and it can absorb a large number of H-HO-radicals to interrupt the combustion reaction. Organic phosphorus flame retardants mainly include phosphate ester, phosphonate ester, phosphine oxide and heterocyclic class.

IX. Yinsu Flame Retardant Company is specialized in R&D and production of flame retardants for new materials. After years of research and development by our expert team, we have developed a new series of rubber composite flame retardants with high efficiency and environmental protection: XJ-A2, XJ-85M, etc.

1. XJ flame retardant series flame retardant mechanism:

When heated, XJ flame retardant series decompose on the surface of the product to produce a layer of viscous crust isolation, isolate the diffusion of oxygen, heat and small molecules in the combustion process. In addition, the decomposition of free radicals and promote the combustion of H. and OH. reaction, the termination of the chain reaction of combustion, at the same time will release water and carbon dioxide, and efficiently absorb a large number of generated heat, play a role in suppressing the flame, so as to achieve the purpose of efficient flame retardant.

2. Advantages of XJ halogen-free flame retardant series:

As it does not contain PBB, PBDE, chlorine, fluorine, antimony trioxide and other halogenated flame retardants, it has high flame retardant efficiency, smoke elimination, non-toxic, halogen-free, and complies with the EU RoHS and WEEE environmental directives. Relative to the current market equivalent products with high flame retardant efficiency, excellent physical properties of the surface, relatively low density, easy molding and processing, is a halogen-free, efficient and environmentally friendly synergistic flame retardant. They are widely used in rail transportation components, electrical and electronic components, automobiles, petroleum and coal mining industries such as flame retardant rubber and plastics, cables and other flame retardant products.

3. The excellent performance of XJ series flame retardants in rubber

A. Highly efficient synergistic flame retardant, easily reach V0 level;

B. Halogen-free, in line with the increasing environmental requirements;

C. Comply with EU REACH, RoHS, WEEE environmental protection directives;

D. Extruded products are smooth, with good physical properties and low smoke;

E. Relatively low specific gravity.

4. The good performance of XJ series flame retardant in processability:

A. Good dispersion in the adhesive;

B. Good fluidity of rubber, easy to extrude, good dimensional stability;

C. Smaller energy consumption during mixing;

D. Reduced vulcanization time.

5. XJ halogen free series main characteristics:

A. Flaky structure;

B. Large specific surface area;

C. Small particle size and reasonable particle size distribution;

D. Low impurity content, non-toxic, odorless.

The above is the introduction of halogen-free rubber flame retardant. If you still need to know other related information, welcome to check the website, or contact us directly.