When it comes to flame retardancy, one may think of high temperature resistant materials, so what is the difference between the two?

 

Flame retardant and high temperature resistance

Simply put, high temperature resistant materials can still maintain their original properties under high temperature conditions, such as wear resistance, sealing and so on.

That is to say, under high temperature conditions, its chemical properties basically do not change, and at the same time try to ensure that the physical properties do not change.

 

Flame retardant materials usually have the characteristics that they do not burn in the presence of flames, or are not easy to burn, and are quickly extinguished after leaving the flame.

For example, some polymer materials containing bromine and phosphorus elements can hinder the chain reaction by absorbing free radicals generated by combustion during combustion.

 

 

So is flame retardant fabric a non-flammable fabric?

 In fact, the flame retardant fabric is not inflammable, it is after the fabric is processed,

It can achieve the performance of preventing the spread of the flame and automatically extinguishing it within a certain period of time.

 

Therefore, the flame retardant properties of fabrics are usually judged from the burning rate, burning time (afterburning time and smoldering time) of the fabric.

And the damage length is carried out, that is, the shorter the time of flame burning and flameless burning, the lower the degree of damage,

The better the flame retardant performance of the fabric; on the contrary, it means that the flame retardant performance of the fabric is not good.

 

related terms

Afterburning time: Under the specified test conditions, the material continues to burn with flame after the ignition source is removed.


Smoldering time: Under the specified test conditions, when the flaming combustion is terminated, or if it is a flameless combustion,

The time the material continues to burn without flame after the ignition source is removed.


Damaged length: The maximum length of the damaged part of the material in the specified direction under specified test conditions.

We all know that textile fabrics are flammable items, and some work clothes for special types of work

It is necessary to achieve the effect of flame retardant, such as fire suits, welding suits, etc.

 

So how does flame retardant fabric achieve the "flame retardant" effect?

01 Flame retardant fabric

Flame retardant fabrics refer to fabrics that can be automatically extinguished within 2 s of leaving the open flame even if ignited by an open flame.

That is, it will burn when it encounters fire, and it will die when it is removed from the fire, blocking combustion and preventing secondary damage. Flame retardant fabrics can be divided into post finishing flame retardant fabrics and fiber flame retardant fabrics.

 

Flame retardant fabrics can be divided into 4 categories from the number of times of washing: permanent flame retardant fabrics, washing resistance (more than 50 times) flame retardant fabrics,

Semi-washable flame retardant fabric, disposable flame retardant fabric.

 

Finished flame retardant fabrics are produced by coating and auxiliaries during dyeing and finishing, and are generally used to produce things that are not washed frequently.

 

Fiber flame retardant fabric has permanent flame retardant and good thermal stability. For example, acrylic vinyl is a modified acrylic fiber,

It is a copolymer of acrylonitrile monomer and a vinyl compound containing flame retardant elements. It has a wool-like feel and high flame retardancy, as well as acid and chemical resistance.

 

 

Because of the high cost of flame retardant fibers, there are many post-finishing methods for domestic flame retardant fabrics.

 

 

02 The principle of flame retardant

 The basic principles of flame retardant fabrics include surface coverage flame retardant, endothermic flame retardant, condensed phase flame retardant, gas phase flame retardant and droplet effect.

 

1. The surface is covered with flame retardant

Some substances that melt when heated and can form a protective film on the fiber surface after cooling,

Or when heated, non-combustible gas can be generated to isolate the air on the surface of the fiber, hinder the supply of oxygen, and then achieve the flame retardant effect.

 

2. Endothermic flame retardant

Through the endothermic reaction of the flame retardant during combustion, more heat is absorbed, the temperature of the combustion area is reduced, and the purpose of flame retardant is achieved.

 

3. Condensed phase flame retardant

The use of flame retardants affects the decomposition process of fibers and reduces the generation of combustible gases. This method is especially suitable for cellulose fibers.

 

4. Gas phase flame retardant

During the combustion process, a large number of free radicals are generated, and the addition of inhibitors can prevent the flame propagation by free radicals.

 

5. Droplet effect

Chemical fibers such as nylon and polyester will melt and shrink when heated, reducing the surface area, or dripping away from the fire source, hindering combustion.

 

03 Flame Retardant Application

 

Due to its unique properties, flame retardant fibers have broad application prospects in civil, military and industrial fields.

It can be used not only for flame retardant textiles for automobiles, trains and aircrafts, but also for aerospace flame retardant composite materials.

Decorative textiles in hotels, restaurants and other public places, hospitals, military, forest firefighting protective clothing and home textile products, etc.

 

The use of flame retardants is to make cotton and wool fibers have flame retardant properties after flame retardant finishing, while polyester,

Synthetic fibers such as aramid have flame retardant properties through fiber modification. Aramid flame retardant fiber products have a soft feel,

Good bulkiness, drape, moisture absorption and breathability and high strength, abrasion resistance, drape,

Good cloth surface finish, color fastness, and non-melting droplets in case of fire carbonization, so as to meet the requirements of high-grade flame retardant clothing,

Quality requirements for decorative fabrics.

 

How to know if the fabric has flame retardant properties?

 04 Flame retardant performance test

 

1. GB 8965.1-2009 "Protective Clothing - Flame Retardant Protection - Part 1: Flame Retardant Clothing" specifies the flame retardant properties of flame retardant fabrics

In fact, it is only one of the requirements for protective clothing. It is suitable for the user to engage in open flames, emitting sparks,

Flame retardant clothing for operating near molten metal and places with flammable substances and danger of fire, and is not suitable for flame retardant protective clothing used in fire rescue.

 

At present, the test of the flame retardant performance of textiles in my country mainly adopts GB/T 5455-2014 "Vertical Method of Textile Combustion Performance Test".

The principle is to use the flame generated by the specified igniter to ignite the center of the bottom edge of the sample in the vertical direction, and after the specified ignition time,

Measure the afterburning time, smoldering time and damage length of the sample. This method can be used for consumption, decoration,

Determination of flame retardant properties of various fabrics and their products such as traffic interiors.

 

 2. GB/T 14644-2014 is required in GB 31701-2015 "Technical Specification for Safety of Textile Products for Infants and Children"

"Textiles - Determination of Burning Performance in 45° Direction Burning Rate" to test the burning performance of infant and children's clothing,

The principle is that under the specified conditions, ignite the surface of the sample placed at an angle of 45°, and evaluate the burning rate of the sample according to the flame spread time.

For suede samples, the ignition of the base fabric is used as an additional indicator of the intensity of combustion. This standard also applies to all kinds of fabrics and their products.

 

To sum up, the market demand for flame retardant fibers is increasing day by day, and chemical fiber enterprises should not only increase their efforts to develop new flame retardant fibers,

It is also necessary to improve technology and equipment, improve the comprehensive quality of existing flame retardant fibers, and meet the requirements of high-end flame retardant textiles for civilian, military and industrial use.