Fire Principle of Safety Match

The safety match must be rubbed on the matchbox to burn, even if the match head is hit with a hammer, it will not catch fire. The earliest matches easily caught fire. Friction with any rough surface can make them on fire. Even if a mouse bites the head of the match, it will be on fire; if it is hit with a hammer, it will explode.

The ignition principle of a safety match is that a chemical substance on the match reacts with a chemical substance on the matchbox. The heat generated by rubbing matches triggers this chemical reaction. If the match head is not in contact with the friction surface, the match will not burn.

The ancestor of modern matches was a British pharmacist. In 1827, he made instant matches, but they were not very reliable.

In 1830, Sorrier in France invented the use of yellow phosphorus as a match head to make better matches. This kind of match is called a friction match and it has been used until the end of the 19th century.

Friction matches are very reliable and easy to store. But one of the biggest drawbacks is that it is fatal. Yellow phosphorus emits toxic smoke when it burns. Long-term exposure can cause a disease called phosphorus-toxic osteonecrosis of the jaw. The patient's jaws rot and eventually die. Match factory workers are the most affected. Yellow phosphorus was banned in the manufacture of matches at the end of the last century and was replaced by tetraphosphorus trisulfide.

In the mid-1850s, the Swedish manufacturer Lundstrom separated phosphorus from other flammable ingredients to create a safety match. He applied non-toxic red phosphorus to the friction surface of the matchbox, and other ingredients were hidden in the matchbox.

Now, matches are made with automated machines. The production capacity reaches 2 million per hour, and matches are packed into boxes for later use.

The production of standard matches is to first cut the logs into small wooden sticks, each about 2.5 mm thick, then cut the small wooden sticks into match sticks, and dip them in ammonium carbonate, this is to ensure that the match sticks do not smoulder.

The match stick is inserted by a machine into a long steel strip with holes that moves continuously, and the end is immersed in hot paraffin; the paraffin penetrates into the fibers of the wood to help the flame burn from the outer layer of the match head to the top of the match stick. Then, the match is immersed in the mixture for making the match head.

After the match head dried, the match stick was shot down and fell into the inner box of the matchbox on the conveyor belt.

The ingredients in safety matches are: the match head is mainly composed of oxidizer (KCIO3), flammable substances (such as sulfur) and adhesives. The side of the matchbox is mainly composed of red phosphorus, antimony trisulfide and adhesive. When a match is struck, the match head and the side of the matchbox rub against and generate heat. The heat released decomposes KCIO3, produces a small amount of oxygen, and ignites the red phosphorus, causing the combustibles (such as sulfur) on the match head to burn, and the match is on fire. 

The advantage of the safety match is that it separates the red phosphorus from the oxidant, which is not only safer, but also the chemicals used are non-toxic. So it is also called a safety match.

The outer box of the matchbox is on another parallel conveyor belt. The two conveyor belts stop every few seconds, and the inner box is pushed into the outer box. Add scratch paper coated with red phosphorus on both sides of the box, causing the surface to be rubbed. In the case of a match that is burned immediately, the friction surface is made of glass sandpaper or sand-containing resin.

Yellow phosphorus is a colorless wax-like crystal with a garlic-like smell. Molecular formula P4. The molecular weight is 124.08. The relative density is 1.82 (20°C). Melting point 44.1C. Boiling point is 280C. The relative vapor density is 4.3. Insoluble in water, soluble in organic solvents such as fat and carbon disulfide. At room temperature, it can ignite spontaneously in the air and is easily oxidized into phosphorus trioxide and phosphorus pentoxide, so it is often stored in water. Yellow phosphorus vapor can be oxidized to hypophosphorous acid and phosphoric acid when exposed to humid air. Light green fluorescence can be seen in the dark. Yellow phosphorus is highly toxic. About 5% of liquid yellow phosphorus burns can be fatal. After entering the body, most of it exists in the elemental state, and is gradually stored in the liver and bone tissues, and finally is slowly excreted from urine, feces, and sweat in the form of phosphate. Elemental phosphorus may be present in exhalation, blood and feces. Yellow phosphorus increases the amount of phosphoric acid in the body, accelerates the excretion of calcium, and causes bone decalcification. And can inhibit the body's oxidation process, causing protein and fat metabolism disorders. The amount of amino acids, fatty acids and total nitrogen in urine increases, and the excretion of lactic acid and phosphate increases. The liver glycogen is reduced, the blood sugar is lowered, and the blood lactic acid is increased. The central nervous system has a bit of hemorrhage, pericardium and endocardium hemorrhage, skin, conjunctiva, serous membrane, muscle, digestive tract and solid organs may have varying degrees of bleeding. There are fat deposits or necrosis and dystrophic changes in nerve cells, myocardium and liver.

Tetraphosphorus trisulfide, also known as phosphorus trisulfide, with molecular formula P4S3. 

Appearance and properties:

Yellow-green needle-like crystals. 

It starts to oxidize and phosphorescence in the air at 40-60°C. 

It burns at 100°C. 

Molecular weight is 220.1. 

Boiling point is 407.5C. 

Melting point is 172.5°C. 

Insoluble in cold water, hydrochloric acid and sulfuric acid, soluble in nitric acid, benzene and carbon disulfide. 

Relative density (water=1) 2.03 stable flammable solid. 

Mainly used to make matches and also to make the friction surface of match boxes.