US2128368A - Method of making waterproof igniting compositions - Google Patents

Description

Patented Aug. 30, 1938 UNITED STATES PATENT OFFiCE METHOD OF MAKING WATERPROOF IGNITING COMPOSITIONS Sweden No Drawing. Original application November 20,

1933, Serial No. 698,94 plication May 15, 193

2. Divided and this ap- 6. Serial No. 80,022. In

Sweden November 28, 1932 3 Claims.

This application is-a division of Serial No. 693,942, filed November 20, 1933.

In countries with a very humid climate the usual safety match has proved insufliciently resistive to the influence of the moist air, and the reasons for this fact are among other things the following. As the heads of the matches, as a rule, are porous, the moist air can easily penetrate even into the interior parts of the heads, thereby subjecting the whole igniting mass to the influence of the humidity. As the greater part of the head consists of salts soluble in water, these salts will disappear partially due to the influence oi the humidity, and-as the binding l agent is capable of absorbing considerable amounts of water, it will lose its rigidity and be loosened from the match splint, when the latter is rubbed against an igniting surface.

Because of the absence of an oxidizing agent which is insoluble in water as substitution for the chlorate usually employed, experiments with moisture-proof igniting composition, have only had for their object, as a rule, to flnd an insoluble binding agent. Many proposals with this object in view have also been made, but they have always proved to suiler from drawbacks, which have rendered them less flt for commercial use.

Thus, for instance, an admixture of linseed oil or latex to the composition has been made. These substances, however, render the igniting mass less ignitable so that only up to 6-7 per cent could be used with advantage, whereas considerably larger amounts are required in order to reliably imbed the chlorate in the binding agent to afford protection against moisture. It is thus evident that in this way there will be obtained no essential improvement, but on the contrary an impairment, in as much as the moisture that enters can only be caused to disappear with great diiliculty, whereas igniting compositions containing a water soluble binding agent may, as a rule, again be fit for use after having been dried for a little while.

Furthermore, proposals have also been made to use some easily combustible substances dlssolved in organic solvents, as nitro-cellulose in amyl acetate and resin in spirits, but in case of the admixture of a suflicient quantity of chlorate to permit ignition of the composition against a striking surface, there will occur a very violent combustion of very short duration, rendering the transfer of the flame to the splint diflicult.

Another proposal involves the employment of a product of condensation, in which case the igniting composition has been prepared by mixing the requisite chemicals with water, phenol, aldehyde, and a catalyst. This method, however, sufiers from considerable inconveniences due to the fact that the igniting mass, even after drying, still contains large amounts of water which cannot be removed. The product of condensation produced is by itself incombustible and cannot, as a result, aid in the development of power during the combustion, but on the other hand 10 large amounts of heat are required to vaporize the water included. The combustion will, consequently, take place at a low temperature, and this circumstance together with the smothering eifect of the water vapors results, as a rule, in a suppression of the flame so that the igniting mass may only glow. From manufacturing point of view still another drawback arises, namely, that the binding agent under consideration may only for a very short while maintain a consistency suitable for the dipping action.

It is an object of this invention to overcome all these drawbacks by a new method of producing a moisture-proof initial igniting body which consists in mixing in an organic solvent, to form a pasty mixture, an artificial resin, as a binding agent a chlorate of alkali, and combustible and filling materials, said artificial resin amounting to at least 15 per cent by weight and said chlorate of alkali amounting to at least 50 per cent by weight of the dry ingredients, and forming such mixture into an igniting body, whereupon the solvent is caused to evaporate.

By the use of such a high amount of chlorate of alkali the sensibility of the mass to ignition will still be sufiiciently high, even when such a large amount of binding agent as 20-30 per cent is used, which still, in turn, affords a reliable protection of the imbedded chlorate grains against moisture. As, on the other hand, the binding agent may by itself burn at a very low speed of combustion, a reduction of the speed of combustion of the igniting mass will consequently result, so that the combustible substance of the match splint (as wood, cardboard, stearin and so on) may have sufilcient time to be ignited.

The artificial resin most suitable as binding agent is an intermediate product in the preparation of resite known as resol. A product especially fit for the purpose may be prepared, for instance, as follows: 100 parts phenol, 100 parts formaline, and 5 parts ammonia are heated to about 100 C., until a heavy muddiness appears as result of the precipitated resol, which is al lowed to settle to the bottom and then can be easily separated. This product is insoluble in water but easily soluble in alcohol, acetone and other usual solvents. The preparation of the igniting mass can either be effected by first dissolving the resol in alcohol and then admixing the other substances to be included in the mass, or by grinding the resol together with one or more of the substances not developing oxygen, and then moistening the mixture with alcohol and admixing the remaining chemicals. Such an igniting mass'may be of the following composition:

Potassium chlorate 59 parts Potassium bichromate 1 part Manganese dioxide 3 parts Sulphur 6 parts Powdered glass 6 parts Resol 25 parts-i-alcohol 17.5 P rts 100 parts The igniting mass thus produced will not solidify so rapidly as the well-known product of condensation above referred to, but can be maintained at a pasty consistency for a long while.

The igniting mass of the above stated composition is fit for use as paste in the heading of matches which may be dried in the usual way after the heads have been put on. If it is desired toimpart to the match heads an especially high degree of hardness this may be effected by hardening at a temperature of 100-150 C. Ac cording to the time and temperature of the hardening process the resol will then be converted, less or more, into the final product, resite, which is non-burning. Moreover, the hardening process may be accelerated or carried out at lower temperature if a small quantity of, for instance, hexamethylene tetramine is added. Because of the heat required for the hardening process it is advisable, to parafiine the matches after the hardening instead of before the dipping, as is amasce otherwise usual, as in other case the paramne will melt and flow away. Since the hardening process has the efiect of reducing the speed of combustion of the igniting composition, it is possible, by moderating the degree of hardening, to regulate the speed of combustion within wide limits.

Artificial resins may also be employed for the igniting composition of igniting rods, and the desired speed of combustion may be obtained by accordingly regulating the degree of hardening.

What I claim is:-

1. A method of manufacturing a moistureproof initial igniting body which consists in mixing in an organic solvent, to form a pasty mixture, resol, a chlorate of alkali, and combustible and filling materials, said resol amounting to between 15 and 30 per cent and said chlorate of alkali amounting'to at least per cent by weight of the dry ingredients, forming such mixture into an igniting body, and evaporating the solvent.

2. A method of manufacturing a moistureproof initial igniting body which consists in mixing in an organic solvent, to form a pasty mixture, resol and a chlorate of alkali, and combustible and filling materials, said resol amounting to between 15 and 30 per cent and said chlorate of alkali amounting to at least 50 per cent by weight of the dry ingredients, forming such mixture into an igniting body, evaporating the solvent, and converting the resol into resite by heat treatment.

3. A method of manufacturing a moistureproof initial igniting body which consists in mixing in an organic solvent, to form a pasty mix ture, a resol, a chlorate of alkali, and combustible and filling materials, said resole amounting to between 15 and 30 per cent and said chlorate of alkali amounting to at least 50 per cent by weight of the dry ingredients, applying such mixture to match splints, evaporating the solvent, converting the resol into resite by heat treatment, and afterwards paraifining the matches.

LARS ERIK LARSSON.