CA1304891C - Flame retardant treatment - Google Patents

Abstract

Inventor: PATRICK D. BUMPUS
Title: FLAME RETARDANT TREATMENT
Abstract of the Disclosure A flame retardant or fire retardant preparation can be employed with fibrous material containing either cellulosic fibers, non-absorbent fibers, or blends thereof, The preparation is formed of an aqueous solution of ammonium sulfate, a metasilicate salt serving as a binder, and ammonium phosphate (MAP or DAP). An ultraviolet inhibitor is preferably included in the solution.

Description

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F.lame Retardant Treatment Background of the Invention This invention relates to fire-retardant or flame-retardant preparations, and to articles treated with such preparations.
There is an increasi.ng need in industry, i.n pub.lic places, and in the home for treatment of f.lammable articles to render them fire resistant or flame resistant. This requirement applies to children's cl.othing, and al.so applies to drapes, car pets, and the like for hotels and motels, and to wa.l.l coverings for public p.laces. Flame proofing or flame retardancy is now being required even for displays and the like. Flame proofing and fire proofing is also desirable, if not required, for upholstered furni-ture, for vehicle interiors, and for i.ndustria.l gloves and outer cl.othi.ng. F.lame retardancy is also required in some situations for mattresses and is desirable for paper products, wall. hangings and other flammable i.tems.
The conventional method of treating these articles for fire or flame retardancy is to apply an aqueous solution of an inorganic sal.t having fire-retardant characteristics, and then to dry the article. ~owever, because these conventi.onal treatments involve a solub.~e inorganic salt, the durabil.ity of the treatment is quite limited, as the salt dissol.ves or leaches out in moisture and can be washed away by laundering or dry cleaning, or simply by perspiration or high humidity conditions.
Another problem of conventional treatmen-ts is that the inorganic salt employed as a fire-retardant can bring stiffness and/or ~Ç

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discoloration to the treated article. Fur-thermore, because the inorganic salt can be somewhat toxic, the amount that can be employed for a given area of fabric is somewhat limited.
It would be desirable to supply the trea-tment as a self-application kit, e.g. for use by schools, paren-t, theater ~roups, etc. This would provide a safe and simple means for those without special skills or training to apply the treatment. Such a self-application kit would, of course, facilitate the treatment in place of existing drapes, carpeting, etc., without requiring their removal and reinstallation. Elowever, to the best of applicant's knowledge no such kit has been made available.
Another problem with the previously-proposed flame-or fire-retardant treatments is their incompatibility with synthe-tic, high-polymer content fiber products. This is a problem derived from the need for wat:er soluble inorganic salts, which have little if any tendency to bond to the surfaces oE the synthetic organic polymer fibers.
Objects and Summary of the Invention It is an object of this invention to provide a fire- or flame-retardant treatment which avoids the drawbacks of the prior art, It is a more particular object of this invention to provide a fire- or flame-retardant treatment which can be applied to natural, i.e. celIulosic fiber products or to synthetic polymer fiber products, which is persistent and durable, which does not lose its flame- or fire-retardant properties if the treated ar-ticle is washed or laundered, and which does not adversely affect the texture or color of the treated articl.e.
It is yet another object of this invention to provide a flame- or fire-retardant treatment which can be applied to carpeting, drapery, or other instal.led articles while in place and which can be applied to articles formed of cel.lulosic fibers, of high-polymer absorbent fibers, or of b.lends of these.
According to an object of -this invention, a flame- or fire-retardant preparation is formed of an aqueous solution of ammonium sul.fate, a metasilicate salt, such as sodium metasilicate, serving as a binder, and an ammonium phosphate, such as monoammonium phosphate ~MAP) or diammonium phospha-te (D~P). In a typical preferred -treatment, the aqueous sol.ution consists essentially of about 0.9 parts sodium metasilicate, about 13.0 parts ammonium sulfate, abou-t 4.12 parts monoammonium phosphate, and sufficien-t water to make up 100 parts. To this an ultravio.l.et inhi.bitor can be added.
The dissolved ammonium sulfate penetrates into cellulosic fibers, such as cott.on, woo.l., cellulose, etc., and the sodium metasilicate assists ~he bonding of the ammonium su.lfate both to the cellulosic fibers and also to non-absorbent fibers, such as nylon, acetate, pol.yester, polypropylene, etc. Monoammonium phosphate covers and bonds to the surface of the non-absorben-t fibers, and the presence of the sodium metasilicate facilitates this.
The inclusion of the MAP or DAP cures one major defect in the prior-art treatment of these fibers. Synthetic polymer fibers have tended to defy conventional fire-retardant treatments, as ny.lon, acetate, polyethelene, polyester, polypropy.lene, po.l.yol.efin and the like, when heated, decompose and give off a fl.ammabl.e gas. An organic salt by i.tself does nothing to prevent this decomposi.tion or the combustion of the resulting gas, and wil.l not prevent flame spread in such materials. However, the monoammonium phosphate and diammonium phospha-te, when heated above about 260 degrees C, also decompose and give off a se.lf-extinguishing gas which starves the o~ygen from the fibers and from the decomposition gasses, thereby preventing fl.ame spread. In addition, the MAP or DAP, in combination with the other ingredients, increases durability of the fire retardancy.
Superior f.l.ame- or fire-retardant properties for cellulosic-fiber materials can be achieved with an aqueous solution of only the ammonium sulfate and the sodium metasil.ica-te. This solution also works we.ll for blends of cellulosic and non-absorbent fibers up to about 70% non-absorbent fibers. However, over that li.mit, monoammonium phosphate or diammonium phosphate is needed.
The above and many other objects, features, and advantages of this invention will be more fu.~ly understood from the ensuing detailed description of a preferred embodiment.
Detailed Description of a Preferred Embodiment In the preferred embodiment of this invention, the flame-or fire-retardant preparation is formed as an aqueous solution of ammonium sulfate, sodium metasilicate, and an ammonium phosphate, preferrabl.y monoammonium phosphate (MAP~. The ammonium sulfate, ``` ~3~4~

a fire-retardant soluble inorganic salt, penetrates into the -fibers of the absorbent or "cellulosic" fibrous materials, and the metasilicate salt serves as a binder for the ammonium sulfate. The MAP attaches to the non-absorbent synthe-tic fibers, such as polyesters, polypropylenes, nylons or polyamides, acetates or polyacetates, polyolefins, polyethelenes, and the like. The metasilicate salt affects the surface characteristics of the materials, and also affects some bonding o~ the ammonium sulfate to the non-absorbent fibers. MAP or DAP, in -the presence of eLevated temperatures, serves as an oxygen-starving agent. The MAP or DAP breaks down chemically at temperatures above about 260 degrees C, and the breakdown products starve oxygen from the ~aseous flammable gases that emanate from heat decomposition of the non-absorbent fibers.
This has proved an effective way oE preventing spread of fire and flame in synthetic polymer materials. By contrast, conventional inorganic salts that are often used for flame- or fire-retardant treatment will not prevent flame spread in these synthetic materials.
The preferred preparation is formed of 0.9 parts of sodium metasilicate, 13.0 parts of ammonium sulfate, 4.12 parts of MAP, and sufficient water to make up 100 parts. These parts are by weight. This blend represents the maximum amount of the chemicals that can be dissolved in water and remain in solution.
~ever-theless, there is some trade off be-tween the ammonium sul~ate and the MAP, that is, if a greater amount of one of these chemicals is desired, the solution can accommodate it by ~L3~

using less of ~he other. Curren~ experiments seem to indicate that the ~wo t.oge~her can constit.ut.e up to about ~went.y percent of the solution. Accordi.ngl.y, the blend of ingredients can be tailored to suit a specific fabric, if the amount and types of fibers are known. Any combination of MAP or DAP with Ammonium Sulfate (up to this ~.o~.al of about twenty percen~) will have good fire retardancy, but ~he opt.imum protection seems to be with the above mentioned blend. The amount of sodium metasilicate used in this examp~e is sufEicient for adequate bonding of the ammonium sul.fate. It is desired to limit the amount of this ingredient, however, to keep the toxicity of the preparation to a minimum, and to Xeep the alkalinity low. A weak acid can be added to the solution, in dilute amounts, if it is feared the rather high pH
of tlle sodium metasilicate would affect the fibers. However, thi~ is virtual.ly never necessary.
Pre~erably, an ul.traviolet inhibitor is incorporated into the solution, and this should be a water so1uble UV inhibitor that does not react with the other chemicals, and does not di.minish the amount that can be dissolved. It has been found that two parts per hundred of UVIN~L MS-40 water sol.uble UV
inhibitor provides satisfactory results. UVINUL MS-40 is a trademark of BASF Wyandotte Chemica.l. Co.
The ammonium sulfate, MAP, and DAP are white to light grayish in color, and so constitute a general.l.y colorless treatment. The treatment does not affect the color or texture of the fabric or other ~ibrous material that is treated, nor is there noticeabl.e sti~fening of the treated material, as is often ~l3~

the case with conventional ~ire-retardant treatments. A.lso, the chemicals involved here are all considered safe and are not regarded as toxic. The sodium met~silicate, while quite alkaline, is considered safe when used in the dilute concentrati.on indicated here. The UV inhibitor employed is also safe and colorl.ess~
The treatment is preferably applied by spraying the aqueous solution onto the material, or by dipping the material into the solution. The water is then evaporated from the sprayed or dipped material. Evaporation of the water can be accel.erated by the application of heat or dry ai.r.
Because of the binding effect of the sodium metasil.icate and the natural bonding characteristics of -the MAP, the fire- or .
flame-retarding treatment of this inven-tion has been found to be exceptionally durable, and is not noticeably di.mi.nished, even by ten or more cycles of l.aundering or dry cleaning. Thus, the treatment is consi.dered permanent. Products treated with this preparation have been found to have a flame spread index of five, under the standard ASTM ~8~ Steinner Tunnel Test, and usually meet the requirements for class ~ fire retardancy, even after ten cycles o~ laundering or dry cleaning.
The preparation of this invention can be easily appl.ied to previousl.y installed carpeting, drapery, upholstery, etc., for retreatment thereof. Application involves simply spraying the prepara-tion onto the drapery, carpeting, or the like, and permitting the same to dry. This obviates the need to have carpeting removed and replaced with new, treated carpeting, simply in order to meet a chanye i.n fire code requirements.
The preparation of this invention naturally .lends itself to use in self-application kits, which include a contai.ner of the preparation and a sprayer device. By fol.l.owing a simple set of instructions relating to the simple steps mentioned previously, school custodial. personnel, parents, theater groups, or others without any special training can apply this fire- or flame-. retardant treatment to fabrics or other fibrous products.
~: The fire- or flame-retardank preparation of this inven-ti.on can be applied to carpets, furniture, draperies, curtains, pil.~ows, clothing, displ.ay items, paper items, wood, wallpaper, and building materia.l.s, or other products which are bodies of fibrous material.
It has been found that if the MAP or DAP ingredient is omitted from the preparation, blends of fibers of up to 70% :
pol.yester (e.g., at least 30% cotton or wool) wil.l. receive adequate protection. However, for fiber blends o~ more than 70 polyester, MAP or DAP is required.
In the above-described embodiment, water i9 employed as the solvent or vehicle for the other ingredients, and water has been selected as a safe, non-to~ic and non-f.l.ammable carrier.
However, ~or a controlled industrial application where high speed of drying is required, an organic solvent could be substituted as the vehicle or carrier. Such solvent should be inert as to the fibers or material. being treated.
Fabrics treated with the preparations described hereinabove have been found t.o pass all current flame spread tests, including ASTM E84 (Class A), Federal. Aviation Agency :
horizontal and vertical flame spread tests, and the NFPA-701 test; the treated materials were found to have indexes at least as good as these:
F.lame Spread Index - 5 Fuel Contributed - 10 Smoke Developed - 15 While a particular embodiment of this invention has been dsscribed in detail hereinabove, it should be recogni~ed that this invention is not limited to that embodiment, and that many modi~ications and variations thereof would present themselves to those of skill in the art without departing from the scope and spirit of this invention, as defined in the appended c.laims.

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Claims (22)

1. A flame-retardant or fire-retardant preparation consisting essentially of an aqueous solution of ammonium sulfate, a metasilicate salt serving as a binder, and ammonium phosphate, in relative amounts effective to impart flame-retardancy or fire-retardancy to articles to which said preparation is applied.

2. The preparation of claim 1 wherein said ammonium phosphate is monoammonium phosphate.

3. The preparation of claim 1 wherein said ammonium phosphate is diammonium phosphate.

4. The preparation of claim 1 wherein said metasilicate salt constitutes substantially 0.9% of the aqueous solution.

5. The preparation of claim 1 wherein said ammonium sulfate and said ammonium phosphate together constitute substantially about seventeen percent of the aqueous solution.

6. The preparation of claim 1 wherein said aqueous solution consists essentially of about 0.9 parts sodium metasilicate, about 13.0 parts ammonium sulfate, about 4.12 parts monoammonium phosphate, and sufficient water to make up 100 parts.

7. A flame-retardant preparation consisting essentially of an aqueous solution of ammonium sulfate, a metasilicate salt serving as a binder, and ammonium phosphate, in relative amounts effective to impart flame-retardancy or fire-retardancy to articles to which said preparation is applied and an ultraviolet inhibitor in said aqueous solution with said ammonium sulfate, said metasilicate salt, and said ammonium phosphate.

8. The preparation of claim 7 wherein said ultraviolet inhibitor comprises 2-hydroxy-4-methoxy-benzophenone-5-sulfonic acid in an amount of 2 parts per 100.

9. The preparation of claim 7 wherein said ultraviolet inhibitor comprises a substituted benzophenone in an amount of 2 parts per 100.

10. A flame-retardant or fire-retardant preparation consisting essentially of an aqueous solution of ammonium sulfate and a metasilicate salt serving as a binder, in relative amounts effective to impart flame-retardancy or fire-retardancy to articles to which said preparation is applied.

11. The preparation of claim 9 which consists essentially of about 0.9 parts of sodium metasilicate, about 13 parts of said ammonium sulfate, and water sufficient to make up 100 parts.

12. A flame-retardant or fire-retardant preparation consisting essentially of a solution of ammonium sulfate, a metasilicate salt serving as a binder, and ammonium phosphate, in relative amounts effective to impart flame-retardancy or fire-retardancy to articles to which said preparation is applied, and an evaporable liquid vehicle carrying said ammonium sulfate, said metasilicate salt and said ammonium phosphate.

13. A flame-retardant or fire-retardant preparation consisting essentially of a solution of ammonium sulfate, and a metasilicate salt serving as a binder, in relative amounts effective to impart flame-retardancy or fire-retardancy to articles to which said preparation is applied, and an evaporable liquid vehicle carrying said ammonium sulfate and said metasilicate salt.

14. An article treated to be fire retardant or flame-retardant, said article comprising a mass of fibrous material including cellulosic fibers and containing from zero to no more than about 70% non-absorbent fibers, and an effective amount of a fire-retardant treatment consisting essentially of ammonium sulfate and a salt which serves as a binder to bind the ammonium sulfate to said fibers, said fire-retardant treatment having been applied to said fibers as a solution of ammonium sulfate and said salt and thereafter dried.

15. An article treated to be fire-retardant or flame-retardant, said article comprising a mass of fibrous material including non-absorbent fibers, and an effective amount of a fire-retardant treatment consisting essentially of ammonium sulfate, an ammonium phosphate, and a salt which serves as a binder to bind the ammonium sulfate and the ammonium phosphate to said non-absorbent fibers, said fire-retardant treatment having been applied to said fibers as a solution of ammonium sulfate, ammonium phosphate and said salt, and the mass of fibrous material having been thereafter dried.

16. An article as in claim 14, in which said non-absorbent fibers include synthetic polymer fibers.

17. An article as in claim 15, in which said synthetic polymer fibers are selected from the group consisting of polyamides, polyolefins, polyethylenes, polyacetates, polyesters, and polypropylenes.

18. An article as in claim 15 in which said article also comprises an ultraviolet inhibitor included in said solution and applied to said non-absorbent fibers with said ammonium sulfate, said ammonium phosphate, and said binder salt.

19. A process for treating a fibrous article containing from zero to no more than about 70% non-absorbent fibers, said process comprising wetting the article with a flame retardant or fire-retardant solution consisting essentially of an evaporable liquid vehicle, ammonium sulfate, and a metasilicate salt serving as a binder to bind said ammonium sulfate to fibers of said article, in relative amounts effective to impart flame-retardancy and fire-retardancy to said article, and evaporating the vehicle from the wetted article.

20. A process for treating a fibrous article comprising wetting the article with a flame-retardant or fire-retardant solution consisting essentially of an evaporable liquid vehicle, ammonium phosphate, ammonium sulfate, and a metasilicate salt serving as a binder to bind said ammonium sulfate and said ammonium phosphate to fibers of said article, in relative amounts effective to impart flame-retardancy and fire-retardancy to said article, and evaporating the vehicle from the wetted article.

21. The process of claim 19, wherein said wetting includes spraying the solution onto the article.

22. The process of claim 19, wherein said wetting includes dipping the article into said solution.