Match head formulations

Abstract: Match head formulations suitable for the production of safety matches and matches that may be struck anywhere are described in which chromium compounds, sesqui-based phosphorus compounds, sulphur compounds and oxides of zinc are absent. In their place is described the use of either amorphous phosphorus or, in the case of match head formulations suitable for the production of safety matches, an iron phosphide known as ferrophosphorus. These formulations are environmentally friendly both in manufacture and use. Environmentally friendly match head formulations which may be brightly coloured are also described.

Description: The present invention relates to match head formulations suitable for the production of matches that may be struck anywhere and to matches when coated with the said formulations. For many years match head formulations have contained chromium compounds, phosphorus sesquisulphide, sulphur and/or sulphur compounds and zinc oxide. These compounds are now widely recognised as having undesirable environmental properties both in relation to the manufacture of such formulations and in relation to their use and it is therefore an object of the present invention to provide a match head formulation in which these compounds are substantially absent. One type of match in common use has a match head formulation which is ignited by an abrasive contact with any suitable roughened surface. These are referred to as 'strike anywhere' matches. A second type of match in common use has a match head formulation which is ignited by an abrasive contact with a surface containing a formulation for initiating ignition of the match head. These are referred to as 'safety matches'. According to the present invention there is provided a strike anywhere match head formulation suitable for the production of strike anywhere matches containing potassium chlorate and red amorphous phosphorus, the balance comprising a binder, a thickener, a filler, and a foaming agent to the exclusion of phosphorus sesquisulphide and sulphur, said formulation being dispersed in water, before drying, characterised in that the amount of amorphous red phosphorus is approximately 5.52% by dry weight and when in the form of the wet composition the formulation has a density of approximately 1.25 g/cm 3 . Preferably the proportion of potassium chlorate present is in the range from 40 to 60 percent dry weight. Gelatine may provide a suitable binder if present in proportions ranging from 8 to 18 percent dry weight or alternatively the binder may be in the form of animal glue. The thickener is preferably a starch present in proportions of up to 4 percent dry weight while feldspar or other siliceous minerals may be chosen as the filler. The formulation may also include an ash improver, a pigment and a bleaching agent. An example of the present invention will now be described with reference to formulations suitable for the production strike anywhere matches. Strike Anywhere Matches In the past match head formulations suitable for the production of strike anywhere matches have contained phosphorus sesquisulphide compounds as the active ingredient. In the first example phosphorus sesquisulphide is no longer present in the formulation and is replaced by red amorphous phosphorus. Example A match head formulation suitable for the production of strike anywhere matches is prepared in which 48.34 percent dry weight of potassium chlorate is mixed with 12.43 percent dry weight of gelatine, 2.76 percent dry weight of starch, 20.72 percent dry weight of feldspar, 0.35 percent dry weight of Eosin, 2.76 percent dry weight of titanium dioxide, 6.90 percent dry weight of limestone, and 0.21 percent dry weight of sodium dithionite ensuring good wetting and dispersion of all the ingredients before adding 5.52 percent dry weight of red amorphous phosphorus as an aqueous slurry. The above formulation combines a satisfactory sensitivity and burn rate and has no propensity to produce burning fragments or dropping of hot ash. The formulation also provides cost benefits over other existing formulations. The water content of the above formulation may be in the range from 40 to 50g per 100g of solids but is typically 45.6g/100g solids. The density of the formulation when in the form of a wet composition is typically 1.25 g/cm 3 . This figure is lower than is usual for match head formulations of this type as a result of being more highly aerated and contributes towards an improved sensitivity and a faster drying rate. The formulation is thus able to dry even during freak spells of high atmospheric humidity. The proportions of potassium chlorate present may range from 40 to 60 percent dry weight while the red amorphous phosphorus may be present in proportions of up to 7 percent dry weight for the formulation to maintain a satisfactory performance. The gelatine is present as a binder. The binder content of the formulation is lower than is usual and consequently improves the sensitivity of the formulation as well as the drying rate. The gelatine may be present in proportions ranging from 8 to 18 percent dry weight without adversely affecting the sensitivity. In place of gelatine animal glue may provide a satisfactory binding agent. Starch is present as a thickener to improve the head formulation during drying and may be present in proportions ranging from l to 4 percent dry weight and still serve its function satisfactorily. The presence of amorphous phosphorus makes it difficult to achieve the clear bright colours characteristic of match head formulations based on phosphorus sesquisulphide. The muddy colour of amorphous phosphorus in the above formulation is particularly difficult to mask in the orange/yellow spectral region and consequently a pigment such as Eosin may be required to be present in proportions of up to 7 percent dry weight. An alternative pigment to produce a match head formulation in the blue/red spectral region such as Rhodamine may not need to be present to such an extent. To assist the colouring of the formulation sodium dithionite may be used to bleach the gelatine while titanium dioxide may be employed as a masking agent. The titanium dioxide may be present in proportions of up to 7 percent dry weight. Limestone may be present in proportions ranging from 3 to 14 percent dry weight to control the pH of the formulation while felspar is used as a filler and serves to make up the balance of the formulation. It is to be noted that the above formulation is free of phosphorus sesquisulphide, zinc oxide and dichromates. The absence of sulphur from the formulation reduces the smell produced on striking a match coated with the formulation. The absence of phosphorus sesquisulphide is advantageous because it is difficult to handle during manufacture. It is to be noted that the above formulation is free of potassium dichromate, sulphur and zinc oxide. The absence of sulphur from the formulation reduces the smell produced on striking a match coated with the formulation. The absence of potassium dichromate is advantageous because potassium dichromate is difficult to handle during manufacture.

Claims: A strike anywhere match head formulation suitable for the production of strike anywhere matches containing potassium chlorate and red amorphous phosphorus, the balance being made up of a binder, a thickener, a filler, and a foaming agent to the exclusion of phosphorous sesquisulphide, said formulation being dispersed in water before drying, characterised in that the amount of red amorphous phosphorus is approximately 5.52% by dry weight and when in the form of the wet composition the formulation has a density of approximately 1.25 g/cm 3 . A match head formulation in accordance with claim 1 or claim 2 wherein the proportion of potassium chlorate present is in the range from 40 to 60 percent dry weight. A match head formulation in accordance with any preceding claim wherein the binder is gelatine and is present in proportions ranging from 8 to 18 percent dry weight. A match head formulation in accordance with claim 1 or claim 2 wherein the binder is animal glue. A match head formulation in accordance with any preceding claim wherein the thickener is a starch and is present in proportions of up to 4 percent dry weight. A match head formulation in accordance with any preceding claim wherein the filler is felspar or another siliceous mineral. A match head formulation in accordance with any preceding claim wherein the formulation also contains an ash improver. A match head formulation in accordance with any preceding claim wherein the formulation also contains a pigment. A match head formulation in accordance with any preceding claim wherein the formulation also contains a dithionite as a bleaching agent. A match suitable for striking anywhere having a head coated in a formulation in accordance with any of claims 1 to 9.

Inventors: COX MICHAEL GRAHAM CAREY, COX, MICHAEL GRAHAM CAREY
Applicants: BRYANT & MAY LTD, BRYANT & MAY LIMITED
Application year: 1991
Main classification: C06F3
IPC codes: C06F3, C06B39, C06C9