Textile product with backcoating comprising smoke suppressant and/or flame retardant intumescent particles

A textile product with enhanced flame and/or smoke retardant properties and a method of forming the same is disclosed. The textile product is comprised of a textile material and a backcoating comprised of a polymer matrix and inorganic smoke suppressant and/or flame retardant intumescent particles. The backcoating may also contain an inorganic filler that further enhances the flame retardancy and low smoke properties of the textile product. The methods of forming this textile product include mixing the smoke suppressant and/or flame retardant intumescent particles with the backcoating prior to its application to the textile material or the simultaneous spreading of the particles on the textile material with the polymer backcoating in order to form a layer of the particles directly adjacent to the textile material.

FIELD AND BACKGROUND OF THE INVENTION 
This invention relates to a textile product and to the use of a backcoating 
on the textile product that includes intumescent particles which provide 
enhanced flame and/or smoke retardant properties to the textile product. 
Many commercial textile products are required by law to have smoke 
suppressant and flame retardant properties in order to help prevent smoke 
generation and flame spread in the event of a fire. In order to meet the 
safety standards required by law, it is fairly common for textile products 
to be comprised of fibers having flame retardant or smoke suppressant 
properties. See generally U.S. Pat. No. 4,012,546 to Schwartz et al which 
discloses a carpet containing flame retardant fibers. Alternatively, many 
textile products consist of at least two distinct components where a 
textile material is used in conjunction with various additional backing 
layers or blocking sheets that impart smoke suppressant and flame 
retardant properties to a given textile product. For instance, much 
transportation upholstery material is used in conjunction with separate 
fire blocking sheet layers. As a further example, many carpets include 
secondary or tertiary backing layers that have smoke suppressant and flame 
retardant properties. For instance, it is known in the art to incorporate 
polybrominated biphenyl oxides, for instance decabromobiphenyl oxide 
("decabrome"), or antimony oxide in these additional backing layers of 
textile products generally, but decabrome is very expensive and antimony 
oxide may pose toxicity problems. 
The present practice of including fire block sheets and separate backing 
layers to increase smoke suppression and flame retardancy is expensive and 
is often difficult to incorporate in the manufacturing process of textile 
products. The present invention, however, solves these problems by 
incorporating commercially available smoke suppressant-flame retardant 
intumescent particles in the backcoating of textile products to not only 
reduce the cost of textile products having enhanced flame retardancy 
and/or smoke suppression, but also to improve the potential for smoke and 
flame suppression. 
SUMMARY OF THE INVENTION 
The textile product of the present invention includes a textile material 
that constitutes a primary backing of, for instance, a pile carpet or 
plush material, or constitutes the entire textile portion of the textile 
product. The textile product of the present invention further includes a 
backcoating comprised of a polymer matrix containing inorganic smoke 
suppressant and/or flame retardant intumescent particles. The inorganic 
smoke suppressant and/or flame retardant particles are comprised of a 
commercially available mixture of soluble silicates, at least one oxy 
boron compound selected from the group consisting of boric acid and borate 
salts of Group I and II elements and water. (One known commercially 
available product is available from 3M and is sold under the trademark 
Expantrol.TM..) When exposed to heat, these particles and the layer 
comprised of these particles will swell and form an insulating char, thus 
choking off flames and reducing smoke. In addition, water bound with the 
soluble silicates is released, thus aiding dissipation of the heat and 
enhancing flame retardancy. Further, the polymer matrix may also include 
an inorganic filler, such as aluminum trihydrate, that further enhances 
the flame retardancy and low smoke properties of the backcoating layer. 
The inorganic smoke suppressant and/or flame retardant intumescent 
particles may be mixed with the backcoating prior to its application to 
the textile material or they may be applied simultaneously with the 
polymer backcoating. By spreading the particles on the textile material 
simultaneously as the polymer backcoating is applied, the particles form a 
layer directly adjacent to the textile material thereby enhancing the 
smoke suppressant and/or flame retardant properties of the textile 
material.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention will now be described more fully hereinafter with 
reference to the drawings, in which preferred embodiments of the invention 
are shown. This invention can, however, be embodied in many different 
forms and should not be construed as limited to the embodiments set forth 
herein; rather applicant provides these embodiments so that this 
disclosure will be thorough and complete and will fully convey the scope 
of the invention to those skilled in the art. 
As noted earlier, and as illustrated in FIGS. 1 and 2, the present 
invention is applicable to any textile product including conventional pile 
carpet (FIG. 1) and brushed woven material (FIG. 2). 
FIG. 1 illustrates a typical conventional pile carpet. Tufted pile yarns 10 
are looped through a primary backing 11, and extend upwardly therefrom. 
The backcoating 12 is an adhesive coating that fixes the pile yarns in 
place in the primary backing. Mixed in the backcoating are inorganic smoke 
suppressant-flame retardant intumescent particles 13. Finally, a secondary 
backing 14 is adhered to the backcoating. The primary backing 11 may be 
formed of natural fibers, such as jute, or of synthetic fibers such as 
polypropylene, polyethylene, or polyester, for example. The secondary 
backing 14 may also be formed of natural or synthetic fibers, or of a 
foamed or unfoamed polymer sheet, such as for example, PVC foam or 
ethylene vinyl acetate foam. As is conventional, the pile yarns 10 may be 
cut to form cut pile tufts as illustrated in FIG. 1, or may form loops 
(not illustrated). 
The backcoating may be comprised of any suitable polymer compound. 
Typically the backcoating is comprised of either a polymer latex or a 
polymer plastisol compound. The backcoating is cured on the textile 
material by heating or drying or in any way reacting the backcoating to 
harden it. An exemplary latex composition includes a polyvinylidene 
chloride copolymer with at least one acrylic monomer. Standard acrylic 
monomers include, for example, acrylic acid, methacrylic acid, esters of 
these acids, or acrylonitrile. Alternatively, the backcoating may comprise 
conventional thermoplastic polymers which are applied to the carpet by hot 
melt techniques known in the art. 
Also included in the backcoating are inorganic smoke suppressant and/or 
flame retardant intumescent particles. One particularly suitable class of 
smoke suppressant and/or flame retardant intumescent particles is 
commercially available and is comprised of hydrated alkali metal silicates 
and at least one oxy boron compound selected from the group consisting of 
boric acid and borate salts of Group I and II elements. Hydrated alkali 
metal silicates have been previously used as smoke suppressant and/or 
flame retardant additives in roofing materials, as described in U.S. Pat. 
Nos. 4,218,502 and 4,521,333. When subjected to the high temperatures 
existing in a fire, water of hydration in the intumescent compound is 
driven off causing the composition to puff and expand by some 7 to 30 
times its original volume. Sodium silicates are preferred because of their 
commercial availability and low cost, but silicates formed from other 
alkali metals may also be used including, for example, those formed from 
potassium and lithium. 
A borate compound is mixed with the soluble silicate to yield a composition 
with lower solubility and improved stability. Silicate based intumescent 
materials are subject to degradation and reduction of intumescent 
properties upon exposure to water or high relative humidity for extended 
periods of time. For the purposes of this invention, the term oxy boron or 
borate means any compound having a radical which contains boron and 
oxygen, such as the metaborate, tetraborate, perborate, or other 
polyborate radicals. Examples of suitable borates are: boric acid and oxy 
boron compound salts of Group I and Group II elements. This description 
includes naturally occurring borate compounds, such as borax and 
colemanite. By Group I and II elements, it is meant all elements of Groups 
IA, IB, IIA, and IIB of the Periodic Table of Elements. Some additional 
examples of suitable borates are calcium metaborate, magnesium borate, and 
zinc borate. 
Further protection of the soluble silicates may be obtained by coating the 
particles with a mixture of calcium hydroxide and a metal salt of a 
long-chain fatty acid (e.g., sodium stearate). Salts of other acids (e.g., 
oleic and palmitic acids) could be used. By protecting the soluble 
silicates with a borate compound or a coating, the particles are not as 
susceptible to degradation when the textile product is subjected to, for 
instance, repeated cleaning or high humidity. 
It may be desirable for the particles to be further comprised of additional 
inorganic compounds that raise the melting point of the particles. This 
prevents the premature destruction of the insulating char which is formed 
by puffing of the intumescent particles during a fire. Aluminum trihydrate 
powder is one such compound, but other commercially available and well 
known fillers may also be used. 
The inorganic smoke suppressant-flame retardant particles may comprise 25% 
to 70% by weight (dry basis) of the backcoating layer. These particles may 
be an admixture of approximately 50% inorganic filler particles such as 
aluminum trihydrate and 50% intumescent particles. This composition of 
filler and intumescent compound has unusually and unexpectedly favorable 
results. The thickened layer of intumescent foam and filler that forms 
when the composition is subjected to high heats enhances the smoke 
suppressant and/or flame retardant properties of the mixture as a whole 
for a relatively longer period than without the filler because the filler 
maintains the integrity of the insulating char at relatively higher heats. 
FIG. 2 illustrates a typical woven material 15' having a backcoating 12' 
similar to that discussed in connection with FIG. 1. The woven material 
15' is comprised of any natural or synthetic fiber yarns. The woven 
material 15' illustrated in FIG. 2 has been brushed so that the material 
has a softer and more plush feel. This invention also applies to actual 
velvet plush materials that are commercially manufactured that are 
structurally similar to the pile carpet of FIG. 1 where there is a primary 
woven backing with plush fibers looped through the backing and extending 
outwardly therefrom. This invention further applies to any nonwoven 
material or any other fabric formed of interengaged yarns that may have 
various commercial applications including, for example, textile liners 
like trunk liners. In any event, the backcoating comprises a polymer 
matrix containing inorganic smoke suppressant and/or flame retardant 
particles 13' as illustrated in FIG. 2 that are identical to those 
discussed with respect to FIG. 1. 
The inorganic smoke suppressant and/or flame retardant particles may be 
incorporated into the polymer matrix backcoating by mixing them therein 
prior to the coating being gelled or fused to a textile product. 
Alternatively, the particles may be spread or sprinkled on simultaneously 
with the combining of a textile web and the polymer backcoating. By 
simultaneously sprinkling the particles onto the textile web at the time 
the polymer backcoating is added, the particles form a layer directly 
adjacent to and substantially in contact with the textile material being 
treated thus enhancing the smoke suppressant and/or flame retardant 
properties directly adjacent to the textile material. 
EXAMPLE 
A latex emulsion may be prepared of a commercially available copolymer of 
polyvinylidene chloride and 2-ethylhexyl acrylate (T.sub.g of -10.degree. 
C.) by slowly adding to a mix tank, with agitation, the following: 
______________________________________ 
Parts by Weight 
______________________________________ 
PVDC-acrylate copolymer (47% solids) 
51.3 
Defoamer .13 
Antifoam Surfactant (Ethylene oxide- 
.33 
propylene oxide block copolymer) 
Ammonia 28% .13 
______________________________________ 
The pH of the mix is tested and adjusted to between 8.5 and 9.5 by addition 
of ammonia. Then 20.0 parts by weight aluminum trihydrate and 20.0 parts 
by weight Expantrol.TM. 4, smoke suppressant-flame retardant intumescent 
particles produced by 3M Company, and comprised of 65-75 wt. % sodium 
silicate, 13-17 wt. % zinc borate, and 9-18 wt. % water, with a bulk 
density of about 0.5-0.9 g/cc are slowly added with mixing and mixing is 
continued for 20 minutes. Then up to about 2.5 parts by weight of a sodium 
polyacrylate thickener is added to adjust the viscosity of the mix to 
between 5000 to 5500 cps. 
A carpet is prepared on a commercially available tufting machine, and the 
yarns are tufted into a polypropylene woven primary backing to form a 
carpet. After tufting, the carpet is conveyed to a coating application 
station where the above polyvinylidene chloride latex emulsion coating is 
applied to the back side of the primary backing at a rate of about 18-24 
ounces per square yard. The coating is then dried at the drying station at 
a temperature of 280.degree. F. for about 7 minutes, after which the 
carpet is allowed to cool and is formed into a roll. In a subsequent 
operation, the carpet is unrolled and the latex-coated rear surface of the 
primary backing is heated under infrared heat lamps to a temperature of 
from 350.degree. to 400.degree. F. to activate the thermoplastic adhesive 
properties of the coating. An ethylene vinyl acetate foam sheet (34 ounces 
per square yard) is brought into contact with the heated carpet and 
laminated thereto by the polyvinylidene chloride adhesive coating. 
In the drawings and specification, there have been disclosed typical 
preferred embodiments of the invention and, although specific terms are 
employed, they are used in a generic and descriptive sense only and not 
for purposes of limitation, the scope of the invention being set forth in 
the following claims. It is contemplated that the appended claims cover 
any such modifications as incorporate those features which constitute the 
central features of these improvements within the true spirit and scope of 
the invention.