|Infobox on Matches|
|Example of Matches|
|Stowage factor (in m3/t)||3,96 m3/t (cases)|
|Humidity / moisture||To be kept in a dry place|
|Risk factors||See text|
Description / Application
A match is a tool for starting a fire under controlled conditions. A typical modern match is made of a small wooden stick or stiff paper. One end is coated with a material that can be ignited by frictional heat generated by striking the match against a suitable surface. Matches are usually sold in quantity; wooden ones are packaged in boxes, and paper matches are clustered in rows stapled into matchbooks. They are commonly sold by tobacconists and many other kinds of shops. The coated end of a match, known as the match "head," contains either phosphorus or phosphorus sesquisulfide as the active ingredient and gelatin as a binder. There are two main types of matches: safety matches, which can be struck only against a specially prepared surface, and strike-anywhere matches, for which any suitably frictional surface can be used. Some match-like compositions, known as electric matches, are ignited electrically and do not make use of heat from friction.
The strike-anywhere match
Early friction matches made with white phosphorus as well as those made from phosphorus sesquisulfide could be struck on any suitable surface. They were particularly popular in the United States even when safety matches had become common in Europe. They are still popular in many third world countries. Strike-anywhere matches are banned on both passenger aircraft and cargo-only aircraft flight under 'dangerous goods' classification., U.N. 1331, Matches, strike-anywhere.
The safety match
The dangers of white phosphorus in the manufacture of matches led to the development of the "hygienic" or safety match. The major innovation in its development was the use of red phosphorus, not on the head of the match but instead on a specially designed striking surface.
The safety of true "safety matches" is derived from the separation of the reactive ingredients between a match head on the end of a paraffin-impregnated splint and the special striking surface (in addition to the safety aspect of replacing the white phosphorus with red phosphorus). The idea for separating the chemicals had been introduced in 1859 in the form of two-headed matches known in France as Alumettes Androgynes. These were sticks with one end made of potassium chlorate and the other of red phosphorus. They had to be broken and the heads rubbed together. There was however a risk of the heads rubbing each other accidentally in their box. Such dangers were removed when the striking surface was moved to the outside of the box. The striking surface on modern matchboxes is typically composed of 25% powdered glass or other abrasive material, 50% red phosphorus, 5% neutralizer, 4% Carbon Black and 16% binder; and the match head is typically composed of 45–55% potassium chlorate, with a little sulfur and starch, a neutralizer (ZnO or CaCO3), 20–40% of siliceous filler, diatomite and glue. Some heads contain antimony(III) sulfide to make them burn more vigorously. Safety matches ignite due to the extreme reactivity of phosphorus with the potassium chlorate in the match head. When the match is struck the phosphorus and chlorate mix in a small amount which ignites due to the friction.
Extra-long matches, which provide additional safety when used to light a fireplace
Storm matches, also known as lifeboat matches or flare matches, are often included in survival kits. They have a strikable tip similar to a normal match, but much of the stick is coated or impregnated with a combustible compound and waterproofed with wax, and will burn even in a strong wind. This match was used in the first mass-produced Molotov cocktails.
Woods used to make matchsticks must be porous enough to absorb various chemicals, and rigid enough to withstand the bending forces encountered when the match is struck. They should also be straight-grained and easy to work, so that they may be readily cut into sticks. White pine and aspen are two common woods used for this purpose. Once the matchsticks are formed, they are soaked in ammonium phosphate, which is a fire retardant. This prevents the stick from smoldering after the match has gone out. During manufacture, the striking ends of the matchsticks are dipped in hot Paraffin Wax. This provides a small amount of fuel to transfer the flame from the burning chemicals on the tip to the matchstick itself. Once the paraffin burns off, the ammonium phosphate in the matchstick prevents any further combustion. The heads of strike-anywhere matches are composed of two parts, the tip and the base. The tip contains a mixture of phosphorus sesquisulfide and potassium chlorate. Phosphorus sesquisulfide is a highly reactive, non-toxic chemical used in place of white phosphorus. It is easily ignited by the heat of friction against a rough surface. The potassium chlorate supplies the oxygen needed for combustion. The tip also contains powdered glass and other inert filler material to increase the friction and control the burning rate. Animal glue is used to bind the chemicals together, and a small amount of zinc oxide may be added to the tip to give it a whitish color. The base contains many of the same materials as the tip, but has a smaller amount of phosphorus sesquisulfide. It also contains sulfur, rosin, and a small amount of paraffin wax to sustain combustion. A water-soluble dye may be added to give the base a colour such as red or blue. The heads of safety matches are composed of a single part. They contain antimony trisulfide, potassium chlorate, sulfur, powdered glass, inert fillers, and animal glue. They may also include a water-soluble dye. Antimony trisulfide cannot be ignited by the heat of friction, even in the presence of an oxidizing agent like potassium chlorate, and it requires another source of ignition to start the combustion. That source of ignition comes from the striking surface, which is deposited on the side of the matchbox or on the back cover of the matchbook. The striking surface contains red phosphorus, powdered glass, and an adhesive such as gum Arabic or urea formaldehyde. When a safety match is rubbed against the striking surface, the friction generates enough heat to convert a trace of the red phosphorus into white phosphorus. This immediately reacts with the potassium chlorate in the match head to produce enough heat to ignite the antimony trisulfide and start the combustion. Match boxes and match books are made from cardboard. The finned strips of cardboard used to make the matches in match books are called a comb.
The Manufacturing Process
Matches are manufactured in several stages. In the case of wooden-stick matches, the matchsticks are first cut, prepared, and moved to a storage area. When the matchsticks are needed, they are inserted into holes in a long perforated belt. The belt carries them through the rest of the process, where they are dipped into several chemical tanks, dried, and packaged in boxes. Cardboard-stick matches used in match books are processed in a similar manner. Here is a typical sequence of operations for manufacturing wooden-stick matches:
Cutting the matchsticks
- 1 Logs of white pine or aspen are clamped in a debarking machine and slowly rotated while spinning blades cut away the outer bark of the tree.
- 2 The stripped logs are then cut into short lengths about 1.6 ft (0.5 m) long. Each length is placed in a peeler and rotated while a sharp, flat blade peels a long, thin sheet of wood from the outer surface of the log. This sheet is about 0.1 in (2.5 mm) thick and is called a veneer. The peeling blade moves inward toward the core of the rotating log until only a small, round post is left. This post is discarded and may be used for fuel or reduced to wood chips for use in making paper or chipboard. Stripped logs are placed in a peeler, which cuts a sheet about 0.1 in (2.5 mm) thick, called veneer, from the log. The veneer proceeds to the chopper, which cuts it into small sticks. The sticks are soaked in a dilute solution of ammonium phosphate and dried, removing splinters and crystallized solution. The matches are dumped into a feed hopper, which lines them up. A perforated conveyor belt holds them upside down while they are dipped in a series of three tanks. The matches are dried for 50-60 minutes before they are packaged.
- 3 The sheets of veneer are stacked and fed into a chopper. The chopper has many sharp blades that cut down through the stack to produce as many as 1,000 matchsticks in a single stroke.
Treating the matchsticks
- 4 The cut matchsticks are dumped into a large vat filled with a dilute solution of ammonium phosphate.
- 5 After they have soaked for several minutes, the matchsticks are removed from the vat and placed in a large, rotating drum, like a clothes dryer. The tumbling action inside the drum dries the sticks and acts to polish and clean them of any splinters or crystallized chemical.
- 6 The dried sticks are then dumped into a hopper and blown through a metal duct to the storage area. In some operations the sticks are blown directly into the matchmaking facility rather than going to storage.
Forming the match heads
- 7 The sticks are blown from the storage area to a conveyor belt that transfers them to be inserted into holes on a long, continuous, perforated steel belt. The sticks are dumped into several v-shaped feed hoppers that line them up with the holes in the perforated belt. Plungers push the matchsticks into the holes across the width of the slowly moving belt. A typical belt may have 50-100 holes spaced across its width. Any sticks that do not seat firmly into the holes fall to a catch area beneath the belt and are transferred back to the feed hoppers.
- 8 The perforated belt holds the matchsticks upside down and immerses the lower portion of the sticks in a bath of hot paraffin wax. After they emerge from the wax, the sticks are allowed to dry.
- 9 Further down the line, the matchsticks are positioned over a tray filled with a liquid solution of the match head chemicals. The tray is then momentarily raised to immerse the ends of the sticks in the solution. Several thousand sticks are coated at the same time. This cycle repeats itself when the next batch of sticks is in position. If the matches are the strike-anywhere kind, the sticks move on to another tray filled with a solution of the tip chemicals, and the match ends are immersed in that tray, only this time not quite as deeply. This gives strike-anywhere matches their characteristic two-toned appearance.
- 10 After the match heads are coated, the matches must be dried very slowly or they will not light properly. The belt loops up and down several times as the matches dry for 50-60 minutes.
Packaging the matches
- 11 The cardboard inner and outer portions of the match boxes are cut, printed, folded, and glued together in a separate area. If the box is to contain safety matches, the chemicals for the striking strip are mixed with an adhesive and are automatically applied to the outer portion of the box.
- 12 When the matches are dry, the belt moves them to the packaging area, where a multi-toothed wheel pushes the finished matches out of the holes in the belt. The matches fall into hoppers, which measure the proper amount of matches for each box. The matches are dumped from the hoppers into the inner portions of the cardboard match boxes, which are moving along a conveyor belt located below the hoppers. Ten or more boxes may be filled at the same time.
- 13 The outer portions of the match boxes move along another conveyor belt running parallel to the first belt. Both conveyors stop momentarily, and the filled inner portions are pushed into the outer portions. This cycle of filling the inner portions and pushing them into the outer portions is repeated at a rate of about once per second.
- 14 The filled match boxes are moved by conveyor belt to a machine, which groups them and places them in a corrugated cardboard box for shipping.
Shipment / Storage
Safety matches are classified as dangerous goods; to be stowed in a dry place, readily accessible. They are not universally forbidden on aircraft; however, they must be declared as dangerous goods and individual airlines and/or countries may impose tighter restrictions.
Match-sticks without sulphur heads including wood for the manufacture of match boxes, is frequently offered for shipment from ports in West Africa. The packing consists of a plastic inner packing wrapped in rush-mat, or of a rush-mat wrapping only.
<r> Although this cargo is not considered a dangerous product, it may be liable to self-heating and spontaneous ignition. The larger the block stowage, the lower is the critical temperature of the environment (i.e. the lowest environmental temperature, at which the material takes fire).
Combustible, may ignite from excessive heat, crushing, or dropping. Smoke from fire may be irritating to lungs and eyes. Contains oxidizers, which may increase the burning rate of combustible materials with flare-burning effect.
Consult the IMDG Code (International Maritime Dangerous Goods Code) and applicable MSDS sheet for (overseas) transport advice.