Note: Descriptions are shown in the official language in which they were submitted.
CO~TING COMPOSITION AND PROCESS
This invention relates to a coating and impregnation
composition, especially for treating fabrics to render them flame
retardant.
Cotton fabrics can be rendered flame retardant by incorporation
therein of a wide variety of chemicals, which can provide durable or
non-durable flame retardance. Among these chemicals are antimony
compounds, organo halogen compounds and organic or non-organic
phosphorus compounds such as water insoluble and soluble ammonium
polyphosphates, which can be cured into the fabric by heating (eg
~~ee GB-P-1504507). In the treatment of many fabrics, especially for
upholstery uses, it is essential that the look and handle of the
fabric be substantially unaffected by any fire retardant treatment.
For this reason many upholstery fabrics are fire retarded by back
coating especially with a resin composition containing antimony
oxide and an organo bromine compounds. Such compositions are
undesirable for environmental reasons and secondly are only suitable
for low fabric weight fabrics.
We have discovered a back coating composition, which is
; suitable for a wide range of fabric weights and is more acceptable
to the environment.
The present invention provides a composition for flame
retarding fabrics which comprises (i) an at least partly water
insoluble ammonium polyphosphate, (ii) a surfactant, (iii) a heat
curable resin and (iv) water. Preferably the composition contains
(v) a water soluble ammonium polyphosphate and/or (vi) a carbamic
acid derivative. There is also provided a method of flame retarding
a fabric substrate which comprises impregnating the fabric with a
composition comprising components (i) to (iv), and preferably also
(v) and (vi), and then heat curing the impregnated fabric.
The invention also provides a fabric which as been flame
retarded by impregnation with a composition comprising components i)
`- to iv) and preferably also (v) and (vi) and curing the impregnated
fabric.
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The at least partly water insoluble (hereinafter referred to as
insoluble) ammonium polyphosphate (i) usually has a water solubility
of less than 10 g/100g water, at 20C especially less than 7 or 5
g/lOOg, such as 0.1-5, 0.5-3 or 1.5-7g/lOOg water, wherein the
solubility is as measured by the Manders test, as defined by the
Manders paint company for ammonium polyphosphates used in paints and
as hereinafter described. It may be considered as comprising a
mixture of truly soluble and insoluble components, the soluble
components of which can leach out on addition of or to water to
produce an insoluble fraction o~ very high surface area to volume
~~atio, e.g. as a very fine powder and/or a honeycomb structure. It
may be made by heating, eg at 200-400C, mono or di ammonium
polyphosphate alone or mixed with phosphorus pentoxide or ammonia.
The phosphorus pentoxide may be replaced at least in part by
phosphoric acid and the source of ammonia may be urea (see eg BP
1103772, 1184878, 1309873 and EP 49763). The insoluble
polyphosphate may have a straight or branched chain structure and
may be of general formula (NH4)a Hb-a+2 Pb3b+1' where b has
average value of greater than 10, a/b is between 0.7-1.1 and the
maximum value of a is b+2. The molecular weight of the lnsoluble
polyphosphate is usually greater than 10,000, eg 10,000 to 2
million, such as 10,000 to 1,000,000 or 200,000 to 1.5 million. The
water insoluble ammonium polyphosphate usually has a mean particle
size of less than 50 microns, preferably less than 30 microns, such
as 1-50, 5-50 or io-30 microns. Preferably at least 60% of the
particles are of less than 30 microns and especially at least 40%
less than 10 microns. The polyphosphate usually contains 20-35% P,
such as 23-32%P, preferably 25-32%P.
Examples of suitable insoluble polyphosphates are those sold by
Albright & Wilson Limited under the Trade Marks AMGARD MC and AMGARD
PI. The composition usually contains (based on the weignt of
components (;-vi)) 15-30%, eg 10-25% or 19-23%, of the water
insoluble ammonium polyphosphate, while containing 15-30%, such as
20-28 or 21-25, and especially 24-27%, of the polyphosphate (based
on the weight of components (i-iv)).
The surfactant (ii) is usually a poor wetting agent. It
preferably compr;ses a strong foaming agent, espec;ally one
which can stabilise oil in water emulsions, with an hydrophilic
lipophilic balance (HLB) figure of greater than 12, eg 12-20,
especially 12-16, but may alternatively be suitable for stabilizing
water in oil emulsions, with an HLB of figure less than 12, eg 1-8,
especially 3-7. The composition may comprise a mixture of
surfactants, eg an emulsifier for the resin and a strong foaming
agent.
- The surfactant may comprise at least one anionic, non-ionic,
cationic, amphoteric and/or semi-polar component.
Surfactants for use in our invention typically contain
hydrophobic groups such as alkenyl, cycloalkenyl, alkyl, cycloalkyl,
aryl, alkyl/aryl or more complex aryl (as in petroleum sulphonates)
moieties having from 8 to 22, preferably 10 to 20, typically 12 to
18, carbon atoms and a hydrophilic moiety. Other hydrophobic groups
included in the invention are polysiloxane groups.
The surfactant may for example consist substantially of an at
least sparingly water-soluble salt of sulphonic or mono esterified
sulphuric acids, e.g. an alkylbenzene sulphonate, alkyl sulphate,
alkyl ether sulphate, olefin sulphonate, alkane sulphonate,
alkylphenol sulphate, alkylphenol ether sulphate, alkylethanolamide
sulphate, alkylethanolamide ether sulphate, or alpha sulpho fatty
acid or its esters each having at least one alkyl or alkenyl group
with from 8 to 22, more usually 10 to 20, aliphatic carbon atoms.
The expression "ether" hereinbefore refers to compounds
containing one or more glyceryl groups and/or an oxyalkylene or
polyoxyalkylene group especially a group containing from 1 to 20
oxyethylene and/or oxypropylene units. One or more oxybutylene
units may additionally or alternatively be present~
.~ .
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For example, the sulphonated or sulphated surfactant may be sodium
dodecyl benzene sulphonate, potassium hexadecyl benzene sulphonate,
sodium dodecyl dimethyl benzene sulphonate, sodium lauryl sulphate,
sodium tallow sulphate, potassium oleyl sulphate, ammonium lauryl
monoethoxy sulphate, or monoethanolamine cetyl 10 mole ethoxylate
sulphate.
Other anionic surfactants useful according to the present
invention include alkyl sulphosuccinates, such as sodium di-2-
ethylhexylsulphosuccinate and sodium dihexylsulphosuccinate, alkyl
ether sulphosuccinates, alkyl sulphosuccinamates, alkyl ether
sulphosuccinamates, acyl sarcosinates, acyl taurides, isethionates,
soaps such as stearates, palmitates, resinates, oleates or
linoleates, and alkyl ether carboxylates. Anionic phosphate esters,
alkyl phosphonate and alkyl amino and imino methylene phosphonates
may also be used. In each case the anionic surfactant typically
contains at least one aliphatic hydrocarbon chain having from 8 to
22, preferably 10 to 20 carbon atoms, and, in the case of ethers,
one or more glyceryl and/or from 1 to 20 oxyethylene and/or
oxypropylene and/or oxybutylene groups.
Preferred anionic surfactants are sodium salts. Other salts of
commercial interest include those of potassium, lithium, ammonium,
monoethanolamine, diethanolamine, triethanolamine and alkyl amines
containing up to seven aliphatic carbon atoms.
The surfactant may optionally contain or consist of nonionic
componen~s. The nonionic surfactant may be, e.g. a C10 22
alkanolamide of a mono or di- lower alkanolamine, such as coconut
monoethanolamide. Other nonionic surfactants, which may optionally
be present, include tertiary acetylenic glycols, polyethoxylated
alcohols, polyethoxylated mercaptans, polyethoxylated carboxylic
acids, polyethoxylated amines, polyethoxylated alkylolamides,
polyethoxylated alkylphenols, polyethoxylated glyceryl esters,
polyethoxylated sorbitan esters, polyethoxylated phosphate esters,
. : . ' ' '"' '
- 5 - ~t~
and the propoxylated or ethoxylated and propoxylated analogues of
all the aforesaid ethoxylated nonionics, all having a C8 22 alkyl or
alkenyl group and up to 20 ethyleneoxy and/or propyleneoxy groups.
Also included are polyoxypropylene/polyethylene oxide copolymers,
polyoxybutylene/polyoxyethylene copolymers and polyoxybutylene/
polyoxypropylene copolymers. The polyethoxy, polyoxypropylene and
: polyoxybutylene compounds may optionally be end-capped with, e.g.
benzyl groups to reduce their foaming tendency.
Compositions o~ our invention preferably contain at least one
~~amphoteric surfactant.
The amphoteric surfactant may for example be a betaine, e.g. a
betaine of the formula:- R3N+CH2COO-, wherein each R is an alkyl,
cycloalkyl, alkenyl or alkaryl group and preferably at leasf one,
and most preferably not more than one R, has an average of from 8 to
20, e.g. 10 to 18, aliphatic carbon atoms and each other R has an
average of from 1 to 4 carbon atoms. Particularly preferred are the
quaternary imidazoline betaines of the formula:
CH2 CH2
N +N CH2COO
Rl
R
wherein R and R1 are alkyl, alkenyl, cycloalkyl, alkaryl or
hydroxyalkyl groups having an average of from 1 to 20 aliphatic
carbon atoms. R preferably has an average of from 8 to 20, e.g. 10
to 18, aliphatic carbon atoms and Rl preferably has 1 to 4 carbon
atoms. Other amphoteric surfactants for use according to our
invention include alkyl amine ether sulphates, sulphobetaines and
other quaternary amines or quaternised imidazoline sulphonic acids
and their salts, other quaternary amine or quaternised imidazoline
: .
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~ ~ J ~ 3 ~
carboxylic acids and their salts and Zwitterionic surfactan~s, e.g.
N-alkyl taurines, carboxylated amido amines such as
RcoNH(cH2)2N+(cH2cH2cH3)2cH2co2-~ and amino acids having, in each
case, hydrocarbon groups capable of conferring surfactant properties
(e.g. alkyl, cycloalkyl, alkenyl or alkaryl groups having from 8 to
20 aliphatic carbon atoms). Typical examples include 2-tallow
alkyl l-tallow amido alkyl l-carboxymethyl imidazoline and 2-coconut
alkyl N-carboxymethyl 2-(hydroxyalkyl) imidazoline. Generally
speaking any water soluble amphoteric or Zwitterionic surfactant
compound which comprises a hydrophobic portion including a C8 20
~~alkyl or alkenyl group and a hydrophilic portion containing an amine
or quaternary ammonium group and a carboxylate, sulphate or
sulphonic acid group may be used in our invention.
Compositions of our invention may also include cationic
surfactants.
The cationic surfactant may for example be an alkylammonium
salt hav;ng a total of at least 8, usually 10 to 30, e.g. 12 to 24,
aliphatic carbon atoms, especially a tr; or tetra-alkylammonium
salt. Typically alkylammonium surfactants for use according to our
invention have one, or at most two, relatively long aliphatic chains
per molecule (e.g. chains having an average of 8 to 20 carbon atoms
each, usually 12 to 18 carbon atoms) and two or three relatively
short chain alkyl groups having 1 to 4 carbon atoms each, e.g.
methyl or ethyl groups, preferably methyl groups. Typical examples
include dodecyl trimethyl ammonium salts. Benzalkonium salts having
one C8 20 alkyl group, two C1 4 groups and a benzyl group are also
useful.
Another class of cationic surfactants useful according to our
invention are N-alkyl pyridinium salts wherein the alkyl group has
an average of from 8 to 22, preferably 10 to 20 carbon atoms. Other
similarly alkylated heterocyclic salts, such as N-alkyl
isoquinolinium salts, may also be used.
. . .
, . ` ' , ' '
- 7 ~ ,J3
:,
Alkylaryl dialkylammonium salts, having an average of from 10
to 30 aliphatic carbon atoms are useful, e.g. those in which the
alkylaryl group is an alkyl benzene group having an average of from
8 to 22, preferably 10 to 20, aliphatic carbon atoms and the other
two alkyl groups usually have from 1 to 4 carbon atoms, e.g. methyl
groups.
Other classes of cationic surfactant which are of use in our
invention include alkyl imidazoline or quaternised imidazoline salts
having at least one alkyl group in the molecule with an average of
~~from 8 to 22, preferably 10 to 20, carbon atoms. Typical examples
include alkyl methyl hydroxyethyl imidazolinium salts, alkyl benzyl
hydroxyethyl imidazolinium salts, and 2-alkyl-1-alkylamidoethyl
imidazoline salts.
Another class of cationic surfactant for use according to our
invention comprises the amido amines such as those formed by
reacting a fatty acid having 8 to 22 carbon atoms or an ester,
glyceride or similar amide forming derivative thereof, with a di or
poly amine, sùch as, for example, ethylene diamine or diethylene
triamine, in such a proportion as to leave at least one free amine
group. Quaternised amido amines may similarly be employed.
Typically the cationic surfactant may be any water soluble
compound having a positively ionised group, usually comprising a
nitrogen atom, and either one or two alkyl groups each having an
average of from 8 to 22 carbon atoms.
The anionic portion of the cationic surfactant may be any anion
which confers water solubility, such as formate, acetate, lactate,
tartrate, citrate, chloride, nitrate, sulphate or an alkylsulphate
ion having up to 4 carbon atoms, such as a methanesulphonate. It is
preferably not a surface active anion, such as a higher alkyl
sulphate or organic sulphonate.
:
:
Polyfluorinated anionic, nonionic or cationic surfactants may
also be useful in the compositions of our invention. Examples of
such surfactants are polyfluorinated alkyl sulphates and
polyfluorinated quaternary ammonium compounds.
Compositions of our invention may contain a semi-polar
surfactant, such as an amine oxide, e.g. an amine oxide containing
one or two (preferably one) C8 22 alkyl groups, the remaining
substituent or substituents being preferably lower alkyl, e.g. C1 4
alkyl, groups or benzyl groups.
Mixtures of two or more of the foregoing surfactants may be
used. In particular mixtures of non-ionic surfactants with cationic
and/or amphoteric and/or semi polar surfactants or with anionic
surfactants may be used.
The compositions usually contain 0.1-5%, eg 1.0-3.5%, of the
surfactant (or surfactant mixture) especially with 0.2-1.5%, eg
0.4-1%, added surfactant in addition to any emulsifier present in
the resin dispersion, which may be in amount of 0.2-3.~%, such as
0.5-2.5%, of components (i-vi). Added surfactant may be 0.5-0.9%
based on components (i-iv). The emulsifier in the resin dispersion
is preferably non ionic or anonic, eg an alkyl sulphate or alkyl
ether sulphate, while the added surfactant is preferably a betaine.
Examples of suitable surfactants are the alkyl dimethyl betaine
surfactants, sold by Albright & Wilson Limited, Birmingham, England
under the Trade Mark EMPIGEN BB, those sold by Texchem UK
Manchester, England under the Trade Name TEXFIN TA, which are
believed to have a high HLB and the amphoteric surfactant OSCOL 459
sold by Oils and Soaps Ltd, Lancs, England.
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J,,
The resin (iii~ is derived from at least one ethylenically
unsaturated monomer and may be a homopolymer, but is preferably is a
copolymer. Exa~ples of suitable monomers are ethylene and mono
substituted ethylenes, eg vinyl carboxylate esters, eg o~ 4-8
carbons, such as vinyl acetate, mono and di carboxy substituted
ethylenes and esters thereof, such as acrylic acid, methacrylic
acid, maleic acid and their esters, such as ethyl acrylate,
chloroethylenes, such as vinyl chloride and cyanoethylenes, such as
acrylonitile. Preferred resins are copolymers comprising acrylic
monomer units with each other or acrylonitrile or vinyl chloride, or
--vinyl acetate/ethylene copolymers. Examples of suitable resins are
those sold under the trade marks REVACRYL 274 by Harlow Chemical Co,
England, VINAMUL 3306 ~y Vinamul Ltd, Surrey, England and LUTOFAN
LA560S, LUTOFAN 300D and ACRONAL DS 2272 by BASF, West Germany. The
resin is usually commercially available as an aqueous dispersion or
emulsion with an emulsifier, which may be anionic such as an alkyl
sulphate and/or alkyl ether sulphate, a mixture of which is present
in the case of the REVACRYL 274 resin, or non-ionic as in the case
of the ethylene/vinyl acetate copolymer sold as VINAMUL 3306. The
d;spersions usually contain 40-55% solids content of the resin.
While the emulsifier added with the resin may be sufficient to
provide the sole surfactant for use in the compositions of this
invention (as in the case of the vinyl chloride acrylic copolymer
sold as LUTOFAN 560S), preferably a separate surfactant, which is
preferably a foaming agent, is added as well. The resins are
usually ones with TG of less than 30C, eg -40 to +30~C, especially
O to - 30C. The resins are self curable by heat, eg at 80-180C,
especially 120-170C. The compositions of the invention usually
contain 10-30% or 15-30%, such as 20-25%, 21-24% or 21.5-23.5% resin
(expressed as resin solids on the total weight of the components
(i-vi)), or 10-30%, eg 14-23%, such as 17-21% or 14-18% (based on
the weight of a composition containing components (i-iv) but not (v)
or (vi)).
The compositions also contains as component (iv) water in
weight amount usually of 40-51%, such as 42-50 or 44-49% (based on
the weight of componénts (i-vi) or 50-60%, such as 56-58% (based on
the weight o~ components (i-iv) in the absence of (v) and (vi)).
- ~ 10 - ~ r~
These figures include any water added with the other components such
as resin or sur~actant, as well as water added separa~ely.
The water soluble ammonium polyphosphate (v), which is
preferably present in the compositions of the invention, is usually
made by reaction of a condensed phosphoric acid with ammonia or an
organic amine or quaternary ammonium hydroxide to give a water
soluble product. The condensed phosphoric acid usually has a mean
degree of condensation of more than 3, e.g. 3-30, and has a linear,
branched or cyclic structure. Preferably the salts contain nitrogen
~ and phosphorus in an atomic ratio of 0.5-2:1, especially about 1:1.
The polyphosphate salt is preferably a mixture of the ammonium salts
of a plurality of polyphosphoric acids, which mixture has been
produced by a process of reacting an aqueous solution of phosphoric
acids containing 80-86% by weight of phosphorus pentoxide with
ammonia or a basic derivative thereof at a temperature of 15-70C,
e.g. 15-40C, and at a pH of 4-12, e.g. 5-12, such as 5-9, 6-~ or
6.5-7.5. Ammonium polyphosphate mixtures which may be used are
described in BP 1504507 and may be made as described therein. This
added ammonium polyphosphate usually has a (true) water solubility
of at least 50 g/l, e.g. at least 100g/1, in water at 20GC.
Examples of suitable soluble polyphosphates are these mixed with
urea and sold by Albright & Wilson Ltd under the Trade Mark AMGARD
LR2. The composition usually contains 0-10%, such as 2-8%, eg 4-6%,
of the water soluble ammonium polyphosphate.
.~ The flame retardant composition of the invention usually also
contains a carbamic acid derivative (vi) having 2 amino groups per
molecule in a weight percentage (expressed as urea) to the ammonium
polyphosphate (expressed by weight as ammonium polyphosphate itself)
: of 0.5%-300%, such as 0.5-50%, eg 5-30%, such as 7-20% or 10-20%.
However 50-300%, e.g. 50-200%, and especially 75-125% are preferred.
The carbamic acid der;vative may be guanidine or dicyandiamide, but
is preferably urea The weights are expressed as urea but equivalent
weights of the other carbamic acid derivative can be used.
- 1 1 -
The presence of the carbamic acid derivative reduces any tendency to
discoloration of the fabric after heat curing. The composition
usually contains 0-10%, such as 2-8%, eg 4-6%, of the carbamic acid
derivative (expressed as urea).
The compositions of the invention are usually thixotropic
pastes, which are pourable when freshly made, form a gel on
standing, but are converted to a pourable emulsion on shearing. The
stable emulsions may be water in oil emulsions, but are preferably
oll in water emulsions. On contact with a cotton fabric under the
-influence of gravity only, the compositions tend not to pass through
the fabric nor to lose water rapidly into the fabric. On shearing
the composition in contact with the fabric, eg under the pressure of
a knife edge, it is believed that the compositions shear allowing
them to penetrate the fabric, wherein they regel rapidly, but do not
pass through the fabric and exude from the opposite side. The
compositions may be made by mixing the components in any order, but
usually in order of resin first, then insoluble ammonium
polyphosphate, followed preferably by soluble ammonium polyphosphate
and carbamic acid derivative, then water and finally any extra
surfactant. The mixing is usually done with a high speed stirrer.
The compositions of the invention containing components (i) -
(iv) usually contain these in weight proportions of 20-28 : 0.1-5 :
14-30 : 50-60. The compositions of the invention containing
components (i-vi) usually contain these in weight proportions of
15-30 : 0.1-5 : 15-30 : 40-51 : 2-8 : 2-8.
The substrates to which the composition is applied may be woven
or non woven. They are usually cellulosic based substrates, e.g.
textile fabrics, such as cotton, linen, jute or hessian or
regenerated cellulosic materials, such as rayon or viscose, alone
or with other fibres coblendable or mixable therewith, e.g.
polyester, nylon, acrylics, acetate, polypropylene, silk or wool.
These blends or mixtures of fibres may contain at least 10%, or at
least 20%, such as 15-100% or 30-90%, but pre~erably at least 40%,
such as 40-75%, of the cellulosic material.
;
.
Preferred are fabrics from intimate blends or non-blended
m;xtures of cellulo~ic material, eg cotton, and synthetic polymer,
eg polyester, nylon or acrylics. The fibres used to form at least
part of the fabrics may if desired be of core sheath construction
but are preferably not so. The fabrics may be of union
construction, for example with at least one of the weft and
especially the warp being predominantly (eg 50-100%), especially
essentially completely, of synthetic polymer fibres. Those with a
warp predominantly of polyester or nylon and a cotton weft,
especially with embossed cotton designs and/or colour woven cotton
--are preferred. The flame retardant compositions of the invention
and the method of the invention enables one more uniformly to flame
retard, at least semidurably, such union fabrics, preferably
embossed ones, but especially ones with non uniform distribution of
synthetic polymer and cellulosic material on a surface thereof
(hereinafter called "differential surface fabrics"). Particularly
important differential surface fabrics are ones with a front side
with a different (usually lower) proportion of the cellulosic
material to synthetic material from that on the back side, as well
usually as having a face or front side having significant areas of
predominantly ~eg 50-100%) fibres of synthetic polymer on the
surface, as well usually as significant areas of predominantly (eg
50-100%) fibres of the cellulosic material. Examples of such
differential surface fabrics are ones with a polyester warp and dyed
cotton weft, especially with more than one differently coloured
cotton weft, with the fabrics woven with front designs of such dyed
cotton on a background of the polyester warp and a nondesigned back
with a substantial cotton surface. Such differential surface fabrics
may be used as upholstery fabrics. Other useful fabrics are pile
fabrics, especially with a cotton base fabric back and an acrylic
pile face. In the cases of the union fabrics and pile fabrics each
having a face and a back, the compositions are applied to the back
of the fabrics.
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- - 13 -
In add;tion to upholstery fabrics, the flame retardant
composition can be applied to other furnishing fabrics, such as
curtains, wh;ch are not subjected to frequent washing, and wh;ch are
for use in, for example, domestic, office, institutional or public
buildings. The ability to treat different types of fabric makes it
useful w~lere various fabrics bear ~he same, or similar, designs for
use in situations which have "colour-coordinated" decor.
Fabric weights can be 0.050-1.0kg/m2, e.g. 0.080-0.700kg/m2, or
0 400-0.700 kg/m2, typically 0.200-0.400 kg/m2, especially with
~~fabrics containing at least 30% of non cellulosic fibres. Each of
the components of the fabric may be plain or undyed or may be dyed,
especially with white or pastel shades. The fabric before
impregnation is usually free of dirt, sizes, natural waxes and
applied finishes though it may contain an optical brightening agent.
The flame retardant finishing may also be used to treat
carpeting (by back coating), which can weigh up to 2kg/m2.
The flame retardant composition, usually at pH 2-8, e.g.
5.5-7.5, is applied to the fabric substrate by a back coating
procedure, such by spreading with a knife over a roller or air or,
preferably, by using a rotary screen, optionally in combination with
said knife, to give an application rate o~ 35-150% or 50-150% (on
weight of fabric), such as 60-80% on pile fabrics or 80-120% on
intimate blend or union fabrics. The minimum application rate
necessary to provide adequate flame retardant properties is
typically that required to saturate the fabric (especially the pores
of the fabric) or a minimum of 95%, whichever is the lesser.
If desired, after impregnation the substrate may be dried, e.g.
at 80-120C for 0.1 to 10 minutes. The drying may be performed in
any conventional drier, e.g. a forced air drier or stenter.
.
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- 14 - ~ J~
The impregnated substrate after drying, ;f desired, is then
heat cured, eg by heating at a temperature of at least 80C, such as
at least 120C, e.g. 120-170C preferably 140-170C or 140-165C,
e.g. for 6 to 0.5 minutes, the combination of longer times and
higher temperature preferably being avoided to decrease any tendency
to discoloration. Preferably the drying and curing steps are
combined.
The curing, which is usually continuous, may be performed by
radiant, e.g. infra red, heating but preferably the curing is by
~eating from impact of hot a;r on the surface of the substrate and
preferably on both surfaces to ensure uniformity of heating. Thus
preferably, the substrate is passed continuously on a stenter
through a thermostated oven in which heated air flows are passed on
to the top and bottom surfaces of the substrate. The stenter gives
the most uniform curing with minimum scorching. In the case of the
stenter oven, the cure temperature of the substrate is essentially
the same as that of the heated air flow. Usually at the end of the
curing the substrate is cooled rapidly by passing or drawing cool
air through it.
The cured fabric as finished usually has a solids content of
30-60%,`such as 35-45% for pile fabrics, or 50-60% for union or
other non pile fabrics~ and usually contains 3-10% P, preferably
5-8% P. The fabric as finished has a reduced flammability compared
to the untreated substrate and can pass the BS 5852 test with
ignition sources 0 and 1. The fabric after leaching once in hard
water at 40C according to BS 5651 without final ironing can pass
the flammability test of BS 5852 Part 1 with ignition sources 0 and
1. The reduced flammability finish can be durable for 1-3 washes in
soft water at 74C or to 10 dry cleaning operations depending
primarily on the nature of the resin. The fabric as finished
usually has a face handle not significantly changed from that of the
untreated fabric and shows no surface salt deposits or resin marks.
It usually has a colour not significantly changed from that of the
untreated fabric.
.' ~.
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The synergistic combination of the components (i)-(iv)
especially with components (v) and (vi), can give treated fabr;cs
with improved flame retardant propert;es and, particularly with
fabrics having a face and back, without salt or resin deposits on
the face, when the compos;tion is applied to the back. It is
believed that some of the water and any water soluble ammonium
polyphosphate, added as such or as part of the water insoluble
polyphosphate, migrates from the back towards the face but does not
reach the face.
~- In this specification all parts and percentages are by weight.
The invention is illustrated in the following Examples. In
Examples 1 to 23 the following fabrics were used:
Fabric A was an intimate blend fabric of 20% viscose, 40%
polyester, 20% acrylic and 20% polypropylene of 0.320 kg/m2 fabric
weight.
Fabric B was a 50:50 cotton polyester union fabric with cotton
weft and polyester warp of 0.240 kg/m2 weight.
Fabric C was a 100% viscose pigment print of 0.230 kg/m2
weight.
Fabric D was a 65:35 cotton polyester union fabric with cotton
weft and polyester warp of 0.470 kg/m2 weight.
Fabric E was a 50:50 cotton acrylic pile fabric with acrylic
pile and a cotton base, of 0.540 kg/m2 total fabric weight.
Fabric F was an intimate blend 40:60 cotton polyester fabric of
` 0.380 kg/m2 weight.
Fabric G was an intimate blend 65:35 viscose/polyester fabric
of 0.220 kg/m2 weight.
16 - ~f~ G'~
Fabric H was a 100% cotton vat printed fabric of 0.240 kg/m2
fabric weight.
Fabric I was a 50:50 cotton acrylic pile fabric with acrylic
pile and a cotton base of 0.320 kg/m2 total fabric weight.
In each case the composition of the invention was prepared and
applied to the fabric on a supporting surface with the aid of a
knife which spread the composition onto the fabric and forced it
i_to the fabric; in the cases of fabrics B, D, E and I the
~~composition was applied to the back of the fabric. The supporting
surface under the fabric became cool but not damp in this procedure,
showing that water did not exude from the underside of the fabric.
The impregnated fabric was then heated in a stenter at 150C for 90
secs to provide a combined drying and curing operation. The cured
fabric was then tested for flame retardancy as finished and after
one leach in hard water at 40C according to BS 5651 part l without
final iron;ng.
The solubility of the water insoluble ammonium polyphosphate as
used in the text and Examples is that determined by the Manders
test, in which 5g of solid is shaken with 50ml of water at ambient
temperature and then 10 ml of solution is removed, weighed and
evaporated to dryness to leave a residue. The solubility is given
as 10 times the weight in g of the residue.
~`
Example 1 - 5
A composition was made up by thoroughly mixing in the following
order the following ingredients : 50 parts of a 45.5% solids content
aqueous emulsion of a self cross linking heat curable acrylic
copolymer containing some acrylonitrile monomer units, whose TG was
-24C, sold as REVACRYL 274 by Harlow Chemical Co. England (an
emulsifier was also present in the emulsion), 21 parts of a water
insoluble ammonium polyphosphate of mean particle size 15 microns
with a particlc s;ze distribution of 98% less than 32 microns,
; , ,
,
,
- :
. :
- .
- 17 - ~'JPJ~.)'J 6~/f'J
90% less than 30, 75% less than 22, 50% less than 13, 25% less than
6 and 10% less than 1.6 microns and containing 30% P and a Manders
solubility of about 2g/100g water at 20C, 5.1 parts of urea and 5.1
parts of water soluble ammonium polyphosphate made according to the
process of BP 1504507, 8.8 parts of water, extra water as specified
below and various amounts of a 40% aqueous solution of an alkyl
dimethyl ammonium betaine amphoteric emulsifier sold, as a foaming
agent with some surface activity, as TEXFIN TA by Texchem Ltd
England. The insoluble polyphosphate was obtained by milling the
product sold by Albright & Wilson Limited under the trade mark
---AMGARD MC.
The composition was a pourable stable emulsion which on
standing th;ckened to a gel, which was reconverted to the emulsion
on shearing.
For fabrics A-D, F,G and H the composition was applied with an
application rate of 96%~ while for pile fabrics E and I the rate was
70%.
Details of the compositions and the fire retardant effect on
the various fabrics were as follows.
With compositions containing 1, 2, 3 and 4 parts of the extra
TEXFIN emulsifier solution and 9, 8, 7 and 6 parts respectively of
added water all the fabrics passed the BS 5852 ignition source O and
1 tests before and after the soaking, cured fabrics D and E
which had been treated by forcing into the back of the fabric
corresponding compositions containing no TEXFIN emulsifier but 10
extra parts of water also passed the FR tests. All the fabrics
passed the ignition source O tests.
In all cases the cured fabric showed no salt deposits or resin
; marks on their faces or on the surface opposed to that on which the
composition was applied. The face handle of the fabrics was
substantially unaffected by the treatment.
- 18 - ~J 3 r ~ J ~!~
Examples 6 and 7
The process of Examples 1-5 were repeated with different
amounts of added water. For fabrics A, B, C, D, F, G and H the
composition contained 2 parts of the TEXFIN emulsifier solution and
8.33 and 12.5 extra parts of water and was applied at a loading of
96% (on weight of fabric). For pile fabrics E and I the composition
contained 2 parts of the TEXFIN emulsifier solution and 11.43 and
17.14 extra parts of water and was applied at a loading of 70% to
the back of the fabric. In all cases (apart from Fabrics C and F
~~and 17.14 part water) the cured fabrics passed the BS 5852 ignition
source O and 1 tests before and after soaking. All the fabrics
passed the ignition source O test. Again there were no salt
deposits nor resin marks on the faces of the fabric and the facial
handles were substantially unaffected.
ExamPle 8-11
. The process of Ex 2 was repeated with equal weights of other
` self cross linking copolymer resin emulsions replacing the REVACRYL
274 resin emulsion. The resins were as follows; an aqueous
vinylacetate ethylene copolymer emalsion containing 50% solids of TG
-18C containing also a non ionic surfactant, sold under the trade
mark YINAMUL 3306 by Vinamul Ltd of Carshalton, Surrey, England; an
aqueous carboxylated vinyl chloride acrylic copolymer emulsion
containing 51% solids of TG -3C with a synthetic emulsifier, sold
under the trade mark LUTOFAN LA5605 by BASF A.G. of West Germany; an
aqueous vinyl chloride copolymer emulsion containing 50% solids of
TG +26C, sold under the trade mark LUTOFAN 300D by BASF; and an
aqueous ethyl acrylate copolymer emulsion contain;ng 45% solids,
sold under the trademark ACRONAL DS 2272 by BASF.
In each case the composition was a thixotropic paste shearable
; to a stable pourable emulsion. Each of the compositions as applied
to each of the fabrics as in Ex 2 and cured for 2 mins at 150C; in
all cases the cured fabrics passed the FR tests before and after one
soak in hard water.
:
.: :
~ . .
In the case of the LUrOFAN LA560S resin, the corresponding
composition without the added TEXFIN emulsifier was also a
thixotropic paste shearable to a pourable emulsion. The composition
was applied and cured as in Ex 2; again all the FR tests were passed
and there were no salt or resin marks on the face nor any adverse
facial handl e .
ExamPles 12-16
_ In these examples only Fabric B, D, E, H and I were treated.
The compositions used for Fabrics B, D and H contained (for Ex 12)
50 parts of the REVACRYL 274 resin emulsion used in Ex 1, 2.08 parts
of the TEXFIN TA emulsifier solution, 25 parts of the insoluble
ammonium polyphosphate and 35.4 parts of extra water and in a second
Example (Ex 13) the amounts of the insoluble polyphosphate and extra
water were changed to 29.2 parts and 41.7 parts respectively. In
the compositions used for Fabrics E and I, the compositions were as
for Ex 12 but the amounts of insoluble polyphosphate and extra water
were changed to 34.3 parts and ~8.6 parts respectively in one case
(Ex 14) and to 40 parts and 57.1 parts respectively in another case
(Ex 15). All 4 compositions were stable thixotropic pastes
shearable to stable emulsions.
The compositions were otherwise applied and cured as in Example
1 to give cured fabrics wh;ch passed the FR tests as before.
In the case of Fabrics D and E compositions were also used(for
Ex 16) in which the amounts of insoluble polyphosphate and extra
water were 20.8 parts and 29.2 parts respectively. The compositions
were stable thixotropic pastes shearable to stable emulsions. They
were applied to Fabrics D and E as before and cured as in Ex 1 to
give cured fabrics which passed the FR tests as before, and showed
no salt or resin marks on the faces nor any adverse facial handle.
`:
4~ J i~ ~
.
Examples 17 and 18
Samples of fabric H were treated at an application rate of 96%
in a similar manner to that in Example 1 with a composition
consisting of:-
50 parts of Revacryl 274 resin emulsion;5.1 parts of the soluble ammonium phosphate;
5.1 parts of urea;
2_parts of a 30% aqueous solution of a C12 14 alkyl dimethyl
betaine, sold by Albright & Wilson Limited as under the Trade Mark
EMPIGEN BB;
: 16.8 parts of water; and
20 parts of an insoluble ammonium phosphate having the following
properties:-
Example %P Manders Particle Size
solubilitY
17 30.2 3.51 98% < 32um
18 31.8 0.5 95% < 10um
In each case the fabric passed the FR test and exhibited no ~
facial marks or adverse handle. -
Example 19
` Samples of fabric B were treated at an application rate of 96%
in a similar manner to that in Example 1 with a composition
consisting of:-
:~ 50 parts of Revacryl 274 resin emulsion;
4.8 parts of the soluble ammonium phosphate;
;~ 4.8 parts of urea;
.
,
; 21 ~ ~3~ 3 `~ ~
2 parts of a 30% aqueous solution of a C12 14 alkyl dime~hY
betaine, sold by Albright & Wilson Limited as EMPI~EN BB;
16.3 parts of water; and
20 parts of the insoluble ammonium phosphate of Example 1l.
In each case the fabric passed the FR test and exhibited no
facial marks or adverse handle.
Example 20-21
~~~ Samples of fabrics E and I were treated at application rates of
70% with the composition containing 2 parts of TEXFIN TA foaming
agent (as used in examples 1 to 5) with respectively 8.33 parts and
12.5 parts of added water.
In each case the fabric passed the FR test and exhibited no
facial marks or adverse handle.
` ExamDles 22-23
Samples of fabrics E and I were treated at application rates of 70%
as in Examples 12 and 13 but using 25 and 29.2 parts of added water
and 35.4 and 41.7 parts of insoluble phosphate respectively.
In each case the fabric passed the FR test and exhibited no
facial marks or adverse handle.
Examples 24-26
The following fabrics
i) 75/25 cotton/polyester union of 0.336kg/m2 fabric weight;
ii) 55/45 cotton/polyester union of 0.321 kg/m2 fabric weight; and
iii) 55/45 cotton/polyester union of 0.324 kg/m2 fabric weight;
~` were treated with a composition comprising:-
ï
,.
. ~, .
.. `' . ~ .
,: - - : . ' '
:
- 2Z -
51 parts of Revacryl 274 resin emulstions;
5 parts of soluble phosphate;
5 parts of urea;
1 parts of Texfin TA foaming agent;
13 parts of water; and
25 parts of insoluble phosphate.
The final applied solids levels were 30% for fabrics i) and iii) and
38Yo for fabric (ii).
-~Drying and curing were carried out as in previous Examples and all
treated fabrics passed the BS5852 test with ignition sources O and 1
following a water soak as specified in BS5651.
.
