PT814070E - FORMULATIONS FOR PHOSPHORUS CAKES - Google Patents

Abstract

Match head formulations suitable for the production of safety matches and matches that may be struck anywhere are described which include metal chelate complexes of iron, copper, chromium or vanadium and citric acid, lactic acid, tartaric acid and EDTA. The metal chelate complexes may be combined with conventional match head compositions in which chromium compounds, sesqui-based phosphorus compounds, sulphur compounds and oxides of zinc present or preferably combined with environmentally friendly compositions using either amorphous phosphorus or, optionally, 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

EPIREGUS DESCRIPTION: "FORMULATIONS FOR PHOSPHORUS CAKES " The present invention relates to phosphorus head formulations suitable for the production of safety matches, as well as for the production of matches that can be lit on any surface, and for phosphors produced by coating with said formulations.

For many years the phosphate formulations included compounds of chromium, phosphorus sesquisulfide, sulfur and / or sulfur compounds and zinc oxide. These compounds are currently considered to have undesirable environmental properties both in the manufacture of such formulations and in relation to their use, it being therefore the scope of the present invention to provide a phosphoric head formulation in which these compounds are essentially absent.

A commonly used type of phosphorus has a phosphor head formulation which is imbibed by abrasive contact with any suitable roughened surface. These are called "integral matches" (which light up scratching on any surface). A second type of commonly used phosphorus has a phosphor head formulation which is ignited by open contact with a surface containing a formulation which initiates inflammation of the phosphor head. These are called " safety matches ". UK-A-2252312 discloses compositions which include phosphorus or iron phosphorus and which exclude components harmful to the environment containing sulfur, chromium or zinc. Phosphorus compositions containing phosphorus are disclosed for both safety matches and full matches in which integral phosphor formulations comprise higher phosphorus moieties. The phosphors manufactured using these formulations have excellent environmentally friendly properties. The aim of this invention is to improve the control of the sensitivity properties while retaining the properties of the phosphorus head which respect the environment. Sensitivity control influences the force that the user must apply when scratching and igniting the phosphor head. If the force is excessive, you can split the phosphor head or alternatively splinter a splinter before the ignition occurs. In addition, if the force with which the phosphorus is scratched is too high, it may increase the risk of accidents caused by projected heads or splinters where the heads have been ignited. This also happens with conventional match compositions because matches can be very difficult to ignite. Alternatively, if the phosphor head easily ignites, this may lead to permenant ignition resulting in a fire hazard. It is possible to obtain phosphors with various properties, one of the problems being able to achieve the desired balance of the sensitivity of the ignition in a consistent and guaranteed way.

It is therefore a scope of the present invention to provide a phosphor head formulation having a sufficient sensitivity to ensure consistent ignition. It is also a scope of the present invention to achieve precise control of the sensitivity of the phosphor head so that the desired consistency of the sensitivity can be ensured. These objectives should be achieved without detriment to the other properties of the phosphorus head formulation and through the same manufacturing techniques and without significant cost increase.

According to a first aspect of the present invention there is provided a phosphor head formulation suitable for the production of integral phosphors or safety phosphors, wherein the phosphor head formulation contains a component which is a chelating agent such as EDTA (ethylenediaminetetraacetic acid), citric acid, lactic acid, tartaric acid, malic or gluconic acid or other alpha-hydroxycarboxylic acids, wherein said chelating agent is complexed with a metal selected from the following: manganese, iron, cobalt, nickel, chromium, copper or vanadium. The metal chelate is preferably iron citrate, which is preferred in the form of ferric ammonium citrate, which is soluble in water.

In a preferred embodiment of this first aspect of the present invention, the density of the formulation, when in the form of a wet composition, is between 1.1 and 1.4 g / cm 3. Preferably the composition includes potassium chlorate present in a concentration between 40 and 60 weight percent dry mass, while the amorphous red phosphorus is present in a proportion of at most 9 weight percent dry mass for full matches and in the maximum 2 percent by weight dry mass for safety matches. The gelatin may provide a suitable binder if it is present in proportions between 3 and 18 weight percent dry mass or, alternatively, the binder may be an animal glue. The thickener is preferably a starch present in proportions up to a maximum of 5 weight percent dry mass, while feldspar or other siliceous minerals may be chosen for filler material. The formulation may also include an ash improving agent, a pigment and a bleaching agent. A blowing agent may be Arylan PWS, an amine salt of 3

an alkylarylsulfonic acid present in proportions up to a maximum of 0.2 weight percent dry mass. The formulation may also include an ash enhancing agent, such as diatomaceous earth, in proportions up to a maximum of 6 weight percent dry mass, or a cellulose meal such as olive stone meal, in proportions to a maximum of 7 weight percent dry mass, and a pigment such as iron oxide in proportions between 3 and 10 weight percent dry mass. The composition may also include ferro-phosphorus (a mixture of iron phosphides containing usually between 18 and 25 percent phosphorus).

In a preferred embodiment of the invention the iron citrate is provided in the form of ferric ammonium citrate. Alternatively, iron citrate is provided in the form of iron (III) citrate. Alternatively, iron citrate is provided in the form of ferrous citrate monohydrate.

In a preferred embodiment of the invention the proportion of iron citrate in the phosphorus head composition is from 0.01% to 2.14% by weight dry mass. In another preferred embodiment of the invention, the proportion of iron citrate in the phosphorus head composition is from 0.15% to 1.5% by weight dry mass. In yet another preferred embodiment of the invention, the proportion of iron citrate in the phosphorus head composition is 0.4% to 0.9% by weight dry mass.

In a further preferred embodiment of the invention, the proportion of phosphorus in the phosphorus head composition has a value of from 0.01% to 9% by weight of dry mass.

Some examples of the present invention are now described, which relate to formulations suitable for the production of safety matches and of integral matches. 4

Earlier formulations of phosphorus heads suitable for the production of full matches included, as the active ingredient, phosphorus sesquissuride compounds. Alternatively, the phosphorus sesquisulfide may be replaced by amorphous red phosphorus.

Example 1

A phosphorus head formulation suitable for the production of integral phosphors was prepared in which 48.34 weight percent dry mass of potassium chlorate was mixed with 12.43 weight percent gelatine dry mass, 2.76 percent by weight dry starch mass, 20.72 weight percent feldspar dry mass, 0.35 weight percent dry mass of Eosin, 2.76 weight percent dry weight of titanium dioxide , 6.90 weight percent dry limestone mass and 0.21 weight percent dry sodium dithionite mass, ensuring good humidification and dispersion of all ingredients before adding 5 weight percent dry mass of red amorphous phosphorus in the form of an aqueous slurry and 0.57 weight percent dry mass of ferric ammonium citrate. The foregoing formulation associates a satisfactory sensitivity and burning rate and has no tendency to produce inflamed fragments or to drop hot ashes. The formulation also offers cost benefits compared to other existing formulations. The sensitivity is substantially improved when compared to formulations which do not contain iron citrate. The water content of the above formulation may be in the range 40-50g per 100g solids, but it is common to have a solids content of 45.6g / 100g. The density of the formulation, when in the form of a wet composition, may range from 1.1 to 1.4 g / cm 3, but it is common to have a value between 1.2 and 1.35 g / cm 3. This value is lower than the usual value for phosphorus head formulations of this type because the formulation is more porous contributing to a higher sensitivity and a higher drying rate. Therefore, the formulation can dry even in high atmospheric humidity climatic conditions.

The proportions of potassium chlorate present may be in the range of 40-60 weight percent dry mass, while amorphous red phosphorus may be present in proportions up to a maximum of 9 and a minimum of 1 weight percent dry mass , for the formulation to maintain satisfactory performance. Iron citrate may be present in proportions between 0.01% and 2.5% by weight of dry mass. The following table shows the sensitivity variation, measured in grams, as a function of the increase in the amount of iron citrate:

Table 1: Composition of inorganic phosphates with 5% of red phosphorus of Iron Citrate 0.00 0.15 0.43 0.87 1.43 2.14 Sensitivity of (g) 212 197 160 164 153 163

Likewise, the proportion of red phosphorus can be altered in order to obtain the optimum level for the amount of iron citrate. 6

Table 2: Composition of integral phosphors with 0.6% iron citrate% Phosphorus 0.00 1.0 2.0 3.0 4.0 Red Sensitivity (g) Does not light Does not light 272 201 163

In the above experiments, iron citrate is provided in the form of ferric ammonium citrate. Altematively, iron citrate may be provided in the form of ferric citrate or ferrous citrate monohydrate. The term iron citrate will be used as a general term throughout this specification to describe iron and citrate-containing chelating complexes which may not have a defined composition. The iron content can vary widely from 15% to 28% depending on the form in which the iron citrate is used. Water-soluble complexes, for example, also contain ammonia. The efficacy of a particular complex depends, and is proportional, to the iron content. The same is true if different metals are used. The iron citrate complex may also be formed "in situ" by addition of any citrate, such as potassium citrate, to the composition, and an iron salt, for example iron (III) sulphate. These two compounds react with one another to form the soluble iron citrate complex. Many other alternative compounds could be used, the corresponding reactions producing the desired complex. This also happens for the other complexes contemplated by the invention and formed from any of the metals, namely manganese, cobalt, nickel, chromium, copper or vanadium with the chelating agents; lactic acid, tartaric acid, malic acid, gluconic acid or other alpha-hydroxycarboxylic acids or EDTA. 7 1 ---

Gelatin is present as a binder. The binder content of the formulation is less than the usual value and hence improves the sensitivity of the formulation as well as the drying rate. The gelatin may be present in proportions between 8 and 18 weight percent dry mass. Instead of gelatin, the animal glue can provide a satisfactory binder. Starch is present as a thickener to improve the formulation of the head during immersion and may be present in proportions between 1 and 4 weight percent dry mass and still perform its function satisfactorily. The use of amorphous phosphorus makes it difficult to obtain the pure and vivid colors characteristic of phosphorus sesquissulfide based phosphate formulations. The muddy color of the amorphous phosphorus of the above formulation is particularly difficult to disguise in the orange / yellow region of the spectrum, and accordingly, the presence of a dye such as Eosin, in amounts up to a maximum of 7 weight percent of dry mass. An alternative dye for producing a phosphor head formulation in the blue / red region of the spectrum, such as Rhodamine dye, may not be necessary in such proportions. To aid the coloring of the formulation, sodium dithionite may be used to bleach the gelatin, while titanium dioxide may be used as a masking agent. The titanium dioxide may be present in proportions up to a maximum of 7 weight percent dry mass. The limestone may be present in proportions between 3 and 14 weight percent dry mass to control the pH of the formulation, while feldspar is used as the filler and serves to complete the mass balance of the formulation.

It should be noted that the above formulation is free of phosphorus sesquisulfide, zinc oxide and dichromate. The absence of sulfur in the formulation reduces the odor produced upon igniting a phosphor coated with the formulation. The absence of phosphorus sesquisulfide is advantageous because it is difficult to handle during manufacture. These components may be included in the formulation in proportions less than those conventionally used by the inclusion of iron citrate in proportions of from 0.01% to 2.5%, to improve and control the sensitivity.

Earlier phosphate formulations suitable for the production of safety matches included compounds of chromium, sulfur compounds and zinc oxide, and in particular included potassium dichromate, sulfur powder and zinc oxide. In the second example all these compounds are absent in the formulation and have been substituted in the formulations of the present invention by amorphous red phosphorus and iron citrate.

The experiments were repeated using various combinations of metal chelate complexes, as well as the above-mentioned iron citrate, citric acid, lactic acid, tartaric acid, malic acid or EDTA (ethylenediaminetetraacetic acid), as well as gluconic acid (also suitable other alpha-hydroxycarboxylic acids) complexed with manganese, iron, cobalt, nickel, chromium, copper and vanadium and similar results were obtained.

Example 2

A phosphorus head formulation suitable for the production of safety matches was prepared in which 54.18 weight percent dry mass of potassium chlorate was mixed with 4.06 weight percent gelatine dry mass, 6 percent by weight dry starch mass, 20.32 percent by weight feldspar dry mass, 2.71 percent by dry weight diatomaceous earth mass, 6.77 percent by dry weight mass of iron oxide, 0.09 by 9 weight percent Arylan PWS dry matter and 6.77 weight percent dry limestone mass, ensuring good humidification and dispersion of all ingredients before adding 0.5 per by weight dry mass of amorphous phosphorus in the form of an aqueous slurry and 0.5 weight percent dry mass of iron (III) citrate in the form of ferric ammonium citrate. The water content of the above formulation may be between 40 and 55g per 100g of solids, but it is common to have a value of 48.8g / 100g solids. The density of the formulation, when in the form of a wet composition, may range from 1.0 to 1.4 g / cm 3, but is usually 1.15 g / cm 3. As in Example 1, this value is lower than the usual value for matchhead formulations of this type because the formulation is more porous contributing to a greater sensitivity and a higher drying rate.

It has been found that the proportion of potassium chlorate present may range from 40 to 60 weight percent dry mass and the proportion of amorphous phosphorus may range from 0.01 to 2.0 weight percent dry mass, maintain satisfactory performance. The proportion of iron citrate may have a value of from 0.01% to 2.5% by weight of dry mass.

Example 3

A phosphorus head formulation suitable for the production of safety matches was prepared in which 57.98 weight percent dry mass of potassium chlorate was blended with 9.28 weight percent dry mass of glue, 97 weight percent dry mass of a non-colored premixture of inert materials including silica, aluminosilicates and alkaline earth carbonates, 0.09 weight percent dry mass of Arylan PWS and 0.14 weight percent of dry matter of Eosin dye, before adding 1.1 weight percent dry mass of amorphous phosphorus and 0.43 weight percent dry mass of ferric ammonium citrate. This example originates matches of red security.

Example 4

A phosphorus head formulation suitable for the production of safety matches was prepared in which 55.93 weight percent dry mass of potassium chlorate was mixed with 8.95 weight percent dry mass of glue, 56 percent by weight of a brown premix of inert materials including silica, aluminosilicates, alkaline earth carbonates and iron oxides (where the iron oxides provide the brown color of the phosphorus head), 0.08 percent by weight weight of dry matter of Arylan PWS before adding 1.06 weight percent dry mass of amorphous phosphorus and 0.42 weight percent dry mass of ferric ammonium citrate. This example yields brown colored safety matches. The following table shows the sensitivity variation, measured in grams, as a function of the increase in the amount of iron citrate:

Table 3: Safety Composition with 0.86% Red Phosphorus% Citrate 0.00 0.15 0.43 0.87 1.43 2.14 Iron Sensitivity (9) 134 117 99 84 104 94

Likewise, the proportion of red phosphorus can be altered in order to obtain the optimum level for the amount of iron citrate. 11

Table 4: Safety Composition with 0.6% Iron Citrate Red Phosphorus% 0.00 0.29 0.86 Sensitivity (g) 416 135 86

In the above tests the iron citrate is provided in the form of ferrous citrate monohydrate. Alternatively, iron citrate may be provided in the form of iron (III) citrate or ferric ammonium citrate. Gelatin is present as a binder. As in Example 1 the binder content is lower than the usual value and, accordingly, improves the sensitivity of the formulation as well as the drying rate. The gelatin may be present in proportions ranging from 3 to 12 weight percent dry mass. Instead of gelatin, the animal glue can provide a satisfactory binder.

Again, the presence of amorphous phosphorus makes it difficult to obtain pure and living colors, but does not hinder the production of brown standard formulations. To this end, the iron oxide is used as pigment and may be present in ratios ranging from 3 to 10 weight percent dry mass.

It should be noted that the above formulation is free of potassium dichromate, sulfur and zinc oxide. The absence of sulfur in the formulation reduces the odor produced by igniting a phosphor coated with the formulation. The absence of potassium dichromate is advantageous because potassium dichromate is difficult to handle during manufacture.

It will be understood, however, that in accordance with the invention it is possible to include any of these components instead of the red phosphorus in minor proportions with the addition of iron citrate. This will reduce the adverse environmental effect 12 and also increase the sensitivity properties. A person skilled in the art will appreciate that the proportion of iron citrate used will vary according to the components used in the remainder of the composition and also according to the desired final cost of the composition.

Such safety match compositions may be formulated according to the guidelines of the above example so as to associate a satisfactory sensitivity and burning rate without the tendency to produce ignited fragments or to drop hot ashes. The formulation meets all the requirements of BS 3795 and provides cost benefits by comparison with other existing formulations.

Example 5

To achieve a more vivid color phosphor head formulation suitable for the production of safety matches and with properties similar to those described with respect to Example 2 above, 55.52 weight percent dry mass of potassium chlorate was mixed with 4 , 16 weight percent dry mass of gelatin, 4.16 weight percent starch dry mass, 13.88 weight percent feldspar dry mass, 5.55 weight percent dry mass of soil 0.09 weight percent dry matter of Arylan PWS, 6.94 weight percent dry limestone mass, 6.94 weight percent dry mass of olive stone flour, a maximum of 7.0 weight percent dry mass of a selected pigment and 1.39 weight percent dry weight of titanium dioxide ensuring good wetting and dispersion of all ingredients before adding 0.5 weight percent of dry mass of amorphous phosphorus in the form of an aqueous slurry and 0.5 percent by weight of dry mass of iron citrate in the form of ferric ammonium citrate. 13 The following table shows the sensitivity variation, measured in grams, as a function of the increase in the quantity of iron citrate:

Table 5: Safety phosphorus with 0.86% of: phosphorus Red% Iron Citrate 0.00 0.15 0.43 0.87 1.43 2.14 Sensitivity (g) 129 118 99 88 105 94

Likewise, the proportion of red phosphorus can be altered in order to obtain the optimum level for the amount of iron citrate.

Table 6: Safety phosphorus composition with 0.6% Iron Citrate Red Phosphorus% 0.00 0.29 0.86 Sensitivity (g) 416 135 86

In the above tests the iron citrate is provided in the form of ferrous citrate monohydrate. Alternatively, iron citrate may be provided in the form of iron (III) citrate or ferric ammonium citrate.

This formulation is similar to that described in Example 2 above and differs essentially only in that it can have a more vivid color. Accordingly, the proportions of chlorate, amorphous phosphorus, gelatin, starch, diatomaceous earth, Arylan PWS, limestone and feldspar may vary essentially within the same range of proportions indicated in Example 2. Of the constituents not found in that Example, the flour of olive pit acts as an ash enhancing agent and may be present in proportions up to a maximum of 7 weight percent dry mass while titanium dioxide may also be present in proportions up to a maximum of 7 percent in weight ratio of dry mass and acts as a masking agent as described in Example 1. The olive stone meal may be substituted for other cellulose flours.

Example 6 The amorphous phosphorus of the formulations described in Examples 2 and 3 may be substituted for iron phosphorus, a mixture of iron phosphides normally containing between 18 and 25 percent phosphorus. Iron-phosphorus is relatively inexpensive and easy to handle, but it is a dense black powder and therefore limits the range of colors that can be obtained.

A phosphorus head formulation of this type suitable for the production of safety matches is provided by mixing 52.63 weight percent dry mass of potassium chlorate with 3.95 weight percent dry mass of gelatin, 3 , 95 weight percent dry starch mass, 19.73 weight percent feldspar dry mass, 6.57 weight percent dry iron oxide mass and 12.66 weight percent dry mass of iron-phosphorus and 0.5 percent by weight of dry mass of iron citrate. The following table shows the sensitivity variation, measured in grams, as a function of the increase in the amount of iron citrate:

Table 7: Safety Composition with 12% Iron Phosphorus% Iron Citrate 0.00 0.15 0.43 0.87 1.43 2.14 Sensitivity (g) 128 115 97 84 101 93 15

In the tests indicated above the iron citrate is provided in the form of ferrous citrate monohydrate. Alternatively, iron citrate may be provided in the form of iron (III) citrate or ferric ammonium citrate.

The assays were repeated using various combinations of metal chelate complexes of citric acid, lactic acid, tartaric acid, malic acid or EDTA (ethylenediaminetetraacetic acid), as well as gluconic acid (other alpha-hydroxycarboxylic acids) complexed with manganese , iron, cobalt, nickel, chromium, copper and vanadium, and similar results were obtained.

Preferably, the ferro-phosphorus is milled to a particle size of at most 100 μηπ. The preferred particle size for the formulation shown in Example 6 is less than 5 μηη. It should be noted that, having a particle size between 20 and 65 μητι, it is possible to produce a composition having a color other than black using colorants. It has been found that in this particle size range it is beneficial to use ferro-phosphorus for a range of pyrotechnic applications.

While it has been found that the proportion of potassium chlorate present may range from 40 to 60 weight percent dry mass, to maintain satisfactory performance, the iron phosphorus ratio should exceed 5 weight percent dry mass.

It was found that the proportion of gelatin present in the formulation could be in the range of 3 to 12 weight percent dry mass while the starch could be present in proportions up to a maximum of 10 weight percent dry mass. As in the previous examples, feldspar is used as a filler and serves to complete the mass balance of the formulation.

If, in spite of the nature of the iron-phosphorus, a more vibrant 16-color formulation is required, the iron oxide can be omitted and replaced with titanium oxide and a suitable pigment, each in proportions up to a maximum of 7 weight percent dry mass.

It will be understood that in all of the above examples it is possible to include larger amounts of iron citrate, or the relevant metal chelate complex, which can not increase sensitivity or adversely affect the properties of the composition in other ways, but which would unnecessarily increase the cost of formulating

Of all the metal chelate complexes it has been found that iron citrate is an effective controller of the sensitivity of the phosphorus head composition and is also the most economical and environmentally friendly.

Lisbon, 2 8 BEZ. 2001 the agent DMM Da prqpkiltmdí

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Claims (10)

A phosphorus head formulation suitable for the production of integral matches or safety matches in which the phosphorus head formulation comprises a component which is a chelating agent such as EDTA (ethylenediaminetetraacetic acid), citric acid, lactic acid , tartaric acid, malic acid, or gluconic or other alpha-hydroxycarboxylic acids, characterized in that said chelating agent is complexed with a metal selected from the following: manganese, iron, cobalt, nickel, chromium, copper or vanadium. A phosphorus head formulation as claimed in claim 1, characterized in that the metal chelate complex is iron citrate. A phosphorus head formulation as claimed in claim 1 or 2, characterized in that it comprises potassium chlorate and red amorphous phosphorus, the mass balance being completed by a binder, a thickener, a filler and an agent foaming with the exclusion of phosphorus sesquissulfide. A phosphorus head formulation as claimed in any one of claims 1 to 3, characterized in that the iron citrate is supplied in the form of ferrous citrate monohydrate. A phosphorus head formulation as claimed in any one of claims 1 to 3, characterized in that the iron citrate is provided in the form of iron (III) citrate. A phosphorus head formulation as claimed in any of the preceding claims 1 to 3, characterized in that the iron citrate is provided in the form of ferric ammonium citrate. 1 A phosphorus head formulation as claimed in any one of the preceding claims 1 to 5, characterized in that the metal chelate is formed "in situ" by the addition of a chelate compound, such as potassium citrate, to a metal salt, such as iron (III) sulfate, wherein said chelate compound and the metal salt react with one another when added to the composition to form the desired metal chelate. A phosphorus head formulation as claimed in claim 1, wherein the proportion of the metal complex of the phosphorus head composition is from 0.01% to 2.14% by weight of the dry mass. A phosphorus head formulation as claimed in claim 1, wherein the proportion of the metal complex of the phosphorus head composition is between 0.15% and 1.5% by weight dry mass. A phosphorus head formulation as claimed in claim 1, characterized in that the proportion of the metal complex of the phosphor head composition is between 0.4% and 0.9% by weight of the dry mass. Lisbon, ° 2 8 DEC. 2001 'U N' F °! 'CiAL LM PROPíÍÍÍADADI: IN; Λν. Ujque O- Ávila, 32, r-1000! i: UL: 54/763 / 315503