Note: Descriptions are shown in the official language in which they were submitted.
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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
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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,
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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
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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
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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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