US3895578A - Flare with adhesive liner - Google Patents

Abstract

An adhesive liner for bonding an illuminant candle of a flare to its case incorporates oxidizing materials and, optionally, material for coloring the light output thereof, whereby the formation of light-obscuring residue is not only prevented, but the brilliance and color of the flare may be enhanced.

Description

United States Patent [1 1 Shaw et a1.

[ FLARE WITH ADHESIVE LINER [75] lnventors: Graham C. Shaw, Garland; Russell Reed, Jr., Brigham City, both of Utah [73] Assignee: Thiokol Corporation, Bristol, Pa.

[22] Filed: Aug. 14, 1973 [21] Appl. No.: 388,317

Related US. Application Data [63] Continuation of Ser. No. 138,780, April 29, 1971,

abandoned.

[52] U.S. Cl. 102/373; 102/103; 149/15 [51] Int. Cl. C06D 1/10 [58] Field of Search 149/15; 102/103, 37.8

[4 1 July 22,1975

[56] References Cited UNITED STATES PATENTS 3,749,023 7/1973 Kawaguchi et a1. 102/103 X Primary ExamirterStephen .l. Lechert, Jr. Attorney, Agent, or FirmEdward E. McCullough; Stanley A. Marcus 13 Claims, No Drawings 1 FLARE WITH ADHESIVE LINER CROSS-REFERENCE TO RELATED APPLICATIONS This invention is related to that of a copending application titled Castable Illuminant Flare Composition, Ser. No. 144,679 filed Feb. 10, 1969 by V. T. Dinsdale et al. now US. Pat. No. 3,723,206.

BACKGROUND OF THE INVENTION This invention relates to flares; and, more specifically. to adhesive liners that bond the illuminant candles to the flare cases.

Although the present invention pertains to flares in general, it is particularly concerned with colored signal flares, wherein the combustible composition is diluted with coloring materials, and, hence, the combustion temperature is generally lower than that of illuminating flares. The particular type of flare case with which the present invention is concerned comprises an aluminum tube lined with a kraft paper tube in which the adhesive liner is applied. In colored signal flares, a persistent problem has been the formation of chimney-like residues around the burning illuminant candles, as a result of failure to burn the case and its adhesive liner completely. This residue tends to obscure the light output of the flare, effectively limiting the practical length thereof and, hence, the duration of its operational usefulness.

The liner is customarily an elastomeric hydrocarbon bonding material that is primarily used to achieve a good bond between the illuminant composition and the case of the flare, so that combustion will be confined to the exposed end of the flare candle and cannot progress down the sides thereof, which occurs when the liner is absent or too thermally conductive. The conventional liner composition, being primarily an adhesive and a thermal insulation, is ordinarily deficient in oxidizers, so that its combustion uses oxidizer from the flare candle, thereby further decreasing the light output of the flare.

SUMMARY OF THE INVENTION The present invention, which overcomes these disadvantages in prior art flares, is essentially an oxygenated adhesive liner composition for flare cases. This improved liner not only contains sufficient oxidizer to promote its own complete combustion and that of the case, so that light output of the flare is not obscured; but also enough to contribute to the brilliance of the flare.

The basic binder of the invention is an oxidizer-rich polymer, typically an elastomer similar to the binder of the illuminant composition. The added oxidizing coloring agent is chosen to be compatible with the color of the flare. For example, sodium nitrate is used for yellow flares, strontium chloride for red, and barium nitrate or chloride for green. Appropriate curing agents are used for polymerizing the binder. Additional oxidizer, such as potassium perchlorate, may be included if the remainder of the liner composition is deficient in oxidizers.

Objects of the invention are to provide an adhesive liner for flares that provides a good bond between a flare candle and its case, that will burn completely at substantially the same rate as the illuminant candle, and that will avoid the problems of side burning and chimney formation by burning the case at the same rate as the illuminant candle. An important feature of the invention is that it may contribute both color and light to the total output of the flare.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The typical flare construction to which the present invention applies is described more thoroughly in the application cited above, titled Castable Illuminant Flare Composition and Method for Making Flare Body Therewith, by V. T. Dinsdale et al. The flare case described therein comprises a kraft paper tube inside an aluminum tube and coated on the inside with an adhesive liner. The paper tube is filled with the illuminant and equipped with an igniter and deployment mechanisms.

An illuminant composition for red flares that is bonded to the flare case by the adhesive liner of the present invention typically contains an elastomeric polymer for its binder, together with a suitable curing agent, ammonium perchlorate as an oxidizer, aluminum and/or magnesium as high-temperature fuels, and chromium octoate, strontium nitrate, and strontium chloride as coloring and oxidizing agents. Such compositions and their preparations are more thoroughly described in the cited, related application titled Illuminant Compositions for Colored Flares by G. C. Shaw et al.

A preferred formulation for an adhesive liner useful for bonding red-flare, illuminant candles to their cases is, in approximate parts by weight:

A preferred embodiment for an adhesive liner to be installed in yellow flares is, in approximate parts by weight:

WITCO Formrez F-17-8O (carboxylterminated polyester) 72.7 25.0 74.0 ERLA-OS l0 (triglycidyl ether of paraamino phenol) 15.0 5.0 18.0 chromium octoate 0.3 0.02 1.0 potassium perchlorate or sodium nitrate 12.0 8.0 70.0

A preferred embodiment for an adhesive liner to be installed in green flares is, in approximate parts by weight.

Carboxyl-terminated diethylene glycol succinate 34.9 Triglycidyl ether of trimethylol propane 13.0 Chromium octoate 0.4 Fused silicon dioxide 1.7 Barium nitrate 35.0 Perchloropentacyclo (5.2.1.0 0. '.0"")

decane 15.0

In general, the binder of the present invention is a polymer that forms a good bond with both the illuminant candle and the flare case and has a high oxidizer content. Typical binders of this nature are carboxyl or hydroxyl terminated polyesters and polyethers. Added oxidizers may be any of those commonly used in pyrotechnic materials and solid propellants, such as potassium pe chlorate, sodium nitrate. or ammonium perchlorate.

The binder of the present invention is itself rich in oxidizer. This not only promotes more efficient burning of the binder, but also it inhibits the formation of water in the combustion products, which tends to lower the flame temperature of the flare by dissociation. A preferred binder, sold under the trademark, WITCO Formrez F-17-80, is a carboxyl-terminated polyester derived from the esteriflcation of succinic acid and triethylene glycol. It is cured with the trifunctional epoxy sold under the trademark, ERLA-OS 10, (the triglycidyl ether of trimethylolpropane) is also catalyzed with chromium octoate. The triglycidyl ether of trimethylolpropane is also catalyzed with chromium octoate. The triglycidyl ether of trimethylolpropane is also useful as a curing agent.

The liquid polymeric binder material used in practicing the invention perferably is a mixture of liquid saturated polyester polymer and liquid epoxy resin. Preferably, the liquid saturated polyester polymer is a carboxyl-terminated polyester polymer such as a carboxylcontaining, low molecular weight, aliphatically saturated, substantially completely condensed, polymeric polyester of a saturated aliphatic diol, a dicarboxylic acid and a polyfunctional compound containing an average functionality greater than two groups selected from the group consisting of polyols, polycarboxylic acids and polycarboxylic acid anahydrides, said polymeric polyester being liquid at a temperature between about 25 and about 50C., having an acid content between about 0.1 and about 1.5 milliequivalents per gram, an average of between about 2.5 and about carboxylic groups per molecule, and average molecular weight between about 700 to about 10,000 and free from hydroxyl groups. Such polymers are known and are taught, for example, in US. Pat. No. 3,182,041. Preferred liquid saturated polyester polymers are those having a high oxygen content combined with the carbon and hydrogen content of the polymer. Especially preferred are liquid saturated polyester polymers having a carbon to hydrogen to oxygen ratio of about 2 to 2.55 to 1 and a viscosity at 25C. of 480 to 520 poise. Polyesters prepared from saturated diacids, e.g. saturated fatty acids, such as succinic and glutaric acids and their anhydrides, are especially preferred.

Liquid epoxy resins and solutions thereof are also well known. The epoxy resins are formed by the reaction of a 1,2 epoxy compound and a dihydric phenol. The preferred 1,2-epoxy resins are prepared by the reaction of epichlorhydrin with bis-phenol-A (2,2-bis-(4- hydroxyphenylypropane) generally in alkaline solution. A number of compounds may be used, including polyglycidyl ethers of ethylene glycol, propylene glycol, trimethylene glycol, diethylene glycol, triethylene glycol, glycerol, dipropylene glycol, etc. Similarly, other dihydric phenols may be employed, including resorcinol, catechol, hydroquinone, 4,4'-dihydroxybenzophenone, l-lbis-(4-hydroxyphenyl)-butane. 1,5 dihydroxynaphthylene, para-aminophenal, trimethyol propane, etc. It is understood that the epoxy resins formed from the various reactants mentioned above are not necessarily equivalent and, further, that the exact composition of the epoxy resins are dependent upon the molecular proportions of the epoxy compound and dihydric phenol employed in its preparation. Preferred liquid epoxy resins are those having an epoxide equivalent (weight of resin in grams containing one gram of epoxy) of about to 210 and a viscosity of about 500 to 900 centipoises. When a solvent is used, organic solvents such as toluene, xylene and ketone, e.g., acetone, are preferably used. The liquid epoxy resin serves as a curing agent for the polyester polymer. Polyfunctional epoxy resin is especially preferred, particularly, a trifunctional epoxy resin wherein the functional group is hydroxyl or amino.

While the liquid epoxy resins are preferred as curing agents for the polyester polymer, other polyfunctional curing agents may also be used, for example, polyfunctional aziridines, e.g., trifunctional derivatives of ethylenimine and other alkylenimine derivatives, and other curing agents such as those taught in US. Pat. No. 3,182,041.

The binder material is accelerated in its curing by the addition of a small amount of catalyst for the curing agent. Preferably, the curing rate catalyst is a metal salt of a fatty acid, e.g., chromium octoate or iron linoleate. Such compounds are commonly referred to as metallic soaps. They are insoluble soaps of such fatty acids as stearic, naphthenic, octoic, or Z-ethylhexoic, rosin (resinates) or tall oil (tallates) with the heavier metals such as aluminum, calcium, cadmium, copper, iron, lead, tin or zinc. Sufficient catalyst is used to obtain a curing rate which will give a pot life of about 8 to 24 hours. The amount will usually be from about 0.5 to about 2.0 parts per 100 parts ofliquid saturated polyester polymer, but may be more or less as found desirable.

Generally, it is desirable that the amount of curing agent used be present in approximately stoichiometric mount relative to the polyester polymer, in order to provide complete cure of the polyester polymer. The amount of catalyst used then controls the rate at which the cure occurs.

According to the present invention, the adhesive liner for yellow flares contains potassium perchlorate or sodium nitrate, which oxidize the binder and yield, in the case of sodium nitrate, sodium species which emit light strongly in the yellow spectrum. The liner for red flares contains strontium chloride, which yields efficient red coloring material, and strontium nitrate, an oxidizing agent that yields strontium species that also emit light in the red spectral ranges. Barium nitrate and/or chloride is used as the oxidizing agents in liners for green flares.

EXAMPLE I A liner composition was prepared by mixing 72.7 parts by weight of carboxyl terminated diethylene glycol succinate prepolymer with 15 parts of p-N, N- dipropylene oxide phenyl glycidyl ether and 0.3 parts of chromium octoate. This mixture was stirred for about 15 minutes, after which 12 parts of 6 to 20 micron potassium perchlorate was gradually added as stirring continued. After this composition was thoroughly mixed, it was applied by brush to a kraft paper flare case to about a 30-mil thickness. it was then placed in .an oven and cured at 135F for about 3 days. The pyrotechnic composition for a red illuminant candle was then cast in the tube and cured at elevated temperature for an appropriate length of time. When ignited, the liner and flare case were observed to burn at approximately the same rate as the flare candle, with no observable obscuration of the light output or color thereof.

EXAMPLE 11 A mixture was made of 64 parts by weight of carboxyl-terminated diethylene glycol succinate prepolymer, 21 parts of triglycidyl ether of trimethylopropane, one part of iron linoleate, and four parts of fused silicon dioxide of submicron particle size. When these ingredients were mixed thoroughly, 12 parts of 6 to 30 micron diameter potassium perchlorate was added gradually as stirring continued. The viscosity of the composition may be adjusted within limits by varying the quantity of silicon dioxide, to permit control of the tendency of the material to slump after it is applied to a surface. This composition was then diluted to a sprayable consistency by adding methylene chloride. Any of several other volatile solvents may be used for this purpose. It was then applied to a flare case to an 0.60 inch thickness. The solvent evaporated rapidly and the remaining liner was cured at 135F for 4 days.

EXAMPLE III A premix was made of 40.4 parts by weight of carboxyl-terminated diethylene glycol succinate prepolymer, 15.1 parts of triglycidyl ether of trimethylopropane, 0.5 parts of chromium octoate, and two parts of submicron fused silicon dioxide. When these ingredients were thoroughly mixed, 28 parts of strontium nitrate having 100 to 300 micron particle size and 14 parts of strontium chloride having to 100 particle size were added to the prepolymer composition as stirring continued. This material was then applied to a kraft paper flare case and was cured at 135F for 3 days. Pyrotechnic illuminant material for a red flare was then cast into the case and cured in the usual manner. When the resulting flare was ignited, the intensity of the red color was not diluted or washed out as is usual with small-diameter flares having liner thicknesses greater than 15 mils.

EXAMPLE IV A liner for green flares was prepared by mixing 34.9 parts by weight of carboxyl terminated diethylene glycol succinate, 13 parts of triglycidyl ether of trimethylol propane, 0.4 parts of chromium octoate and 1.7 parts of fused silicon dioxide. When these ingredients were thoroughly mixed, parts of barium nitrate and 15 parts of perchloropentacyclo (521.0 5.0 .0 decane were added while mixing continued. The resulting composition was applied, as in the above example, to a kraft paper flare case and was cured at 135F for 4 days. Green flare illuminant composition was then cast in the case and cured. Very satisfactory results were observed when the flare was burned.

We claim;

1. [n a flare having a tubular case and a colored illuminant composition in the case, the improvement comprising an adhesive liner on the inner surface of the case to provide a bond and thermal insulation between the case and the illuminant composition that will promote coextensive linear consumption of case, liner, and

illuminant, comprising a cured mixture of:

a saturated, carboxyl-containing polyester, liquid polymeric binder; and

5 an oxidizer/coloring agent selected from the group consisting of strontium nitrate, potassium perchlorate, sodium nitrate, and barium nitrate, the oxidizer being in stoichiometric deficiency and selected for color compatability with the illuminantthe color of the oxidizer/coloring agent being produced by the predominant flame spectra thereof.

2. The flare of claim 1 wherein the binder comprises carboxyl-containing, low molecular weight, aliphatically saturated, substantially completely condensed, polymeric polyester of a saturated aliphatic diol, a dicarboxylic acid, and a polyfunctional compound containing an average of three functional groups selected from polyols, polycarboxylic acids and polycarboxylic acid anhydrides, the polymeric polyester being liquid at a temperature between about 25 C and 50 C, having an acid content between about 0.1 and 1.5 milliequivalents per gram, an average of between about 700 and 10,000 and free of hydroxyl groups. I

3. The flare of claim 1 in which the binder include a curing agent selected from the group consisting of triglycidyl derivative of para-amino phenol and triglydidyl ether of trimethylolpropane.

4. The flare of claim 1 wherein the coloring agent of the liner comprises strontium nitrate.

5. The flare of claim 1 wherein the coloring agent of the liner comprises barium nitrate.

6. The flare of claim 5 further including perchloropentacyclo (5.2.1.0 ,6.0 .0 decane, as a color enhancer in the liner.

7. The flare of claim 1 wherein the oxidizer of the liner comprises potassium perchlorate.

8. The flare of claim 1 wherein the oxidizer of the liner comprises sodium nitrate.

40 9. The flare of claim 1 wherein the oxidizer of the liner comprises a mixture of strontium nitrate and strontium chloride.

10. The flare of claim 1 wherein the liner composition comprises, in approximate parts by weight:

LII

carboxyl-terminated diethylene 72.7 glycol succinate polymer p-N, N-dipropylene oxide phenyl glycidyl ether- 15.0 chronium octoate 0.3 potassium perchlorate 12.0.

11. The flare of claim 1 wherein the liner composition comprises, in approximate parts by weight:

carboxyl-terminated diethylene 64.0 glycol succinate polymer triglycidyl ether of trimethylolpropane 21.0 iron linoleate 1.0 fused silicon dioxide (submicron particles) 4.0 potassium perchlorate 12.0.

12. The flare of claim 1 wherein the liner composition comprises, in approximate parts by weight:

5 carboxyl-terminated diethylene 40.4

glycol succinate polymer triglycidyl ether of trimethylolpropane. 15.1 chromium octoate 0.5 fused silicon dioxide (submicron particles) 2.0

-Continued strontium nitrate strontium chloride 13. The flare of claim 1 wherein the liner composi- 5 tion comprises, in approximate parts by weight:

carboxyl-terminated diethylene

Claims (13)

1. IN A FLARE HAVING A TUBULAR CASE AND A COLORED ILLUMINANT COMPOSITION IN THE CASE, THE IMPROVEMENT COMPRISING AN ADHESIVE LINER ON THE INNER SURFACE OF THE CASE TO PROVIDE A BOND AND THERMAL INSULATOR BETWEEN THE CASE AND THE ILLUMINANT COMPOSITION THAT WILL PROMOTE COEXTENSIVE LINEAR CONSUMPTION OF CASE, LINER, AND ILLUMINANT, COMPRISING A CURED MIXTURE OF: A SATURATED, CARBOXYL-CONTAINING POLYESTER, LIQUID POLYMERIC BINDER, AND AN OXIDIZER/COLORING AGENT SELECTED FROM THE GROUP CONSISTING OF STRONTIUM NITRATE, POTASSIUM PERCHLORATE, SODIUM NITRATE, AND BARIUM NITRATE, THE OXIDIZER BEING IN STOICHIOMETRIC DEFICIENCY AND SELECTED FOR COLOR COMPATABILITY WITH THE ILLUMINANT- THE COLOR OF THE OXIDIZER/COLORING AGENT BEING PRODUCED BY THE PREDOMINANT FLAME SPECTRA THEREOF.

2. The flare of claim 1 wherein the binder comprises carboxyl-containing, low molecular weight, aliphatically saturated, substantially completely condensed, polymeric polyester of a saturated aliphatic diol, a dicarboxylic acid, and a polyfunctional compound containing an average of three functional groups selected from polyols, polycarboxylic acids and polycarboxylic acid anhydrides, the polymeric polyester being liquid at a temperature between about 25* C and 50* C, having an acid content between about 0.1 and 1.5 milliequivalents per gram, an average of between about 700 and 10,000 and free of hydroxyl groups.

3. The flare of claim 1 in which the binder includes a curing agent selected from the group consisting of triglycidyl derivative of para-amino phenol and triglydidyl ether of trimethylolpropane.

4. The flare of claim 1 wherein the coloring agent of the liner comprises strontium nitrate.

5. The flare of claim 1 wherein the coloring agent of the liner comprises barium nitrate.

6. The flare of claim 5 further including perchloropentacyclo (5.2.1.02,6.03,9.05,8) decane, as a color enhancer in the liner.

7. The flare of claim 1 wherein the oxidizer of the liner comprises potassium perchlorate.

8. The flare of claim 1 wherein the oxidizer of the liner comprises sodium nitrate.

9. The flare of claim 1 wherein the oxidizer of the liner comprises a mixture of strontium nitrate and strontium chloride.

10. The flare of claim 1 wherein the liner composition comprises, in approximate parts by weight:

11. The flare of claim 1 wherein the liner composition comprises, in approximate parts by weight:

12. The flare of claim 1 wherein the liner composition comprises, in approximate parts by weight:

13. The flare of claim 1 wherein the liner composition comprises, in approximate parts by weight: