Flame retardant method

Mixtures comprising compounds of the formula ##STR1## wherein A is either NH.sub.2 or N=P(NH.sub.2).sub.3, provided at least one A is N=P(NH.sub.2).sub.3, have been found to be good flame-retardants for material made from cotton or polyester-cotton having about 30 to 70% by weight cotton. Conveniently the material can be treated with an aqueous solution containing a sufficient amount of said mixtures and the material dried to make the material self extinguishing. Then the treated and dried material is cured at a sufficient temperature to bond said compounds to the material. Alternatively and usually preferably the drying and curing can be accomplished as a single operation. The treatment solution can additionally contain auxiliary treatment agents to make the material more durable to washing.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
Fireproofing. 
2. Description of the Prior Art 
One of the older patents in this art is U.S. Pat. No. 2,782,133 teaching 
aminocyclophosphazene as a fireproofing agent for cellulosic fibers such 
as cotton. A recent patent is U.S. Pat. No. 3,711,542 teaching certain new 
N-methylol phosphazene compounds as flame retardants on cotton, and this 
patent under Background of the Invention contains a summary of certain 
phosphazene prior art on flameproofing. 
SUMMARY OF THE INVENTION 
Mixtures comprising compounds of the formula 
##STR2## 
wherein A is either NH.sub.2 or N=P(NH.sub.2).sub.3, provided at least one 
A is N=P(NH.sub.2).sub.3, have been found to be good flameretardants for 
material made from cotton or polyester-cotton having about 30 to 70% by 
weight cotton. Conveniently the material can be treated with an aqueous 
solution containing a sufficient amount of said mixtures and the material 
dried to make the material self extinguishing. Then the treated and dried 
material is cured at a sufficient temperature to bond said compounds to 
the materials. Alternatively and usually preferably the drying and curing 
can be accomplished as a single operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Preparation of the Flame-Proofing Reagents 
Melamine and phosphorus pentachloride were allowed to react in molar ratios 
of 1/3; 1/2; 1/1. After reaction with ammonia, three materials were 
obtained having different solubilities, although their infrared spectra 
were quite similar. Elemental analyses showed that these materials were 
not pure compounds nor were they the simple materials expected by the 
reaction of the trihalophosphazenes with excess ammonia. 
##STR3## 
A reference to the tris-trichlorophosphazene was found in the literature 
(1. Derkash, USSR 168,693, C.A. 63, 1700g; C.A. 69, 36082s); however, no 
reference to any of the ammoniated compounds from melamine +PCl.sub.3 + NH 
has been found. All of the ammoniated products were water soluble and 
contained chlorine. Recrystallization from water resulted in losses of 
chlorine and significant changes in the phosphorus analyses. These 
products flame retarded cotton and 65/35 polyester-cotton. 
The reaction of 3 moles of phosphorus pentachloride and a mole of melamine 
will be used to represent all of the reactions between these two reagents 
in varying stoichiometries. 
##STR4## 
A mixture of 30.0 g (0.24 m) of melamine (MCB) and 177.5 g (0.85 m) of 
PCl.sub.5 with 200 ml of CHCl.sub.3 was heated at gentle reflux with 
stirring, until the evolution of HCl had ceased (44 hours). The top of the 
condenser was protected by a Drierite tube. The mixture was allowed to 
cool, and the solvent and trapped HCl were removed on a rotary evaporator 
leaving 190.7 g of a white solid which smelled of CHCl.sub.3. The solid 
was reactive to water but was not as reactive as PCl.sub.5. 
The solid was placed in a 3-liter flask with 500 ml of toluene. Eight 
hundred ml of liquid ammonia was added in portions. A Dry Ice condenser 
was used to contain the ammonia. This mixture was stirred overnight. The 
copious white solid that had formed was filtered to remove the toluene. 
Twelve hundred ml of ammonia was poured cautiously over the filter cake. 
The solid left on the filter and the solid left after evaporation of the 
ammonia from the filtrate had identical infrared spectra indicating the 
presence of both product and ammonium chloride and that the product was 
soluble in ammonia. The residue from evaporation of the ammonia filtrate 
was added to the filter cake giving a combined weight of product of 230 g. 
The product was soluble in water. The mixture was also soluble in methanol 
and ethanol and formed a salt with acetic acid. There was no apparent 
solubility in acetone, acetonitrile, THF, benzene, toluene, chloroform or 
methylene chloride. 
The 230 g of solids product was slurried in 1200 ml of chloroform and 315 
ml (3 m) of diethylamine. The mixture was heated slowly to reflux. (This 
method, see below, affords a chloroform soluble amine hydrochloride from 
the ammonium chloride, thus enabling separation of the phosphazene.) 
EQU (C.sub.2 H.sub.5).sub.2 NH + NH.sub.4 Cl .fwdarw. (C.sub.2 H.sub.5).sub.2 
NH.sub.2 Cl + NH.sub.3 
the ammonia was detected at the top of the condenser. The mixture was 
refluxed overnight. The cooled solution was filtered to remove the red 
chloroform solution of the amine hydrochloride. The filter cake product 
was washed with chloroform and air dried, wt. 89.9 g. The infrared 
spectrum of this product showed no ammonium chloride. An aqueous solution 
of the product was neutral; however, there was a slight indication of 
chloride ion using a silver nitrate test. 
When heated in a capillary tube, gas was evolved at 113.degree. C to form a 
foam; at 260.degree. C, more expansion occurred and at 280.degree. 
-300.degree. C, the material softened to a thick syrup with more gas 
evolution. A thermogravimetric analysis on this material in air from room 
temperature to 980.degree. C left 18% residue. At 300.degree. C, only 20% 
of the material had decomposed. Another 30% was lost between 300.degree. 
and 500.degree. C. There was slightly less weight loss in helium. An 
elemental analysis of the product was as follows: 
______________________________________ 
% Found 
______________________________________ 
C 10.17 
H 5.61 
N 41.04 
P 19.06 
Cl 1.70 
______________________________________ 
Treatment of Fabrics 
A solution containing the desired weight percent of the flameproofing 
reagent in sufficient water to just saturate the cloth was poured on a 
weighed piece of cloth lying flat in a plastic bag. The solution was 
worked over the surface of the cloth, until it was uniformly wet. After 
standing for about fifteen minutes, the cloth was placed in an oven at the 
desired temperature and cured. After curing and drying, the cloth was 
allowed to equilibrate before being weighed. 
Cure Conditions 
Cure was effected at 140.degree. C or as shown in the following table using 
the one operation to also dry the wet sample. Formaldehyde or 
trimethylolmelamine and quarternary base, sodium hydroxide or magnesium 
chloride were included as auxiliary treatments in some instances 
attempting to make the material more durable to washing, and these 
auxiliary agents are present in the same aqueous solution as the primary 
reagent when it is applied to the material. 
Flammability Tests 
Samples of cloth 10 in. .times. 31/2 in. were clamped in a metal stand and 
tested according to AATCC Test Method 34-1969 using a propane torch in 
place of the special gas mixture. This flammability test is described in 
J. Amer. Assoc. Text. Chem. and Colorists 2 (3), 49/19 (1970). 
Tabulation of Data 
The test data are tabulated in the following table. The table is divided 
into three main sections: Fabric Treatment, Flammability Tests and 
Miscellaneous Conditions. The following column headings are used. The 
added notes are for explanation of their meanings where not self 
explanatory. 
______________________________________ 
Column Heading Explanation 
______________________________________ 
1 Cloth Type 
2 Reagent * - Melamine/PCl + NH.sub.3 product 
3 Auxiliary material used to bind to 
cloth such as formaldehyde 
and catalyst; QB = quarternary 
base, TMM = trimethylolmelamine 
4 % Final Add-On 
weight percent of product added 
to the cloth after all processes 
including laundering if indicated 
in column 9 
5 Distance this represents the length of 
Burned, in. the sample that was burned 
out, charred or scorched from 
the ignited edge 
6 Time, Sec time from ignition to removal 
of flame even though self 
extinguishment had already 
occurred 
7 (SE) answers question --Did the 
Self Extinguish 
fire self extinguish before 
burning the entire sample 
length Y = yes; N = no 
8 Cure Temperature 
temperature at which the 
wet cloth was dried and cured 
in a single operation 
9 Post Treatment 
indicates treatment of sample 
after curing but before 
flammability test. L = laundered, 
detergent wash and dried; 
NL = Not Laundered 
______________________________________ 
__________________________________________________________________________ 
Miscellaneous 
Fabric Treatment Flammability Test 
Conditions 
% Distance Cure 
Final 
Burned, 
Time, Temp. 
Post 
Cloth Type 
Reagent 
Auxiliary 
Add-On 
in. Sec. SE .degree. C 
Treatment 
__________________________________________________________________________ 
cotton -- 0.00 10 1 N -- NL 
65/35 
polyester/cotton 
-- 0.00 10 1 N -- NL 
cotton * -- 3.27 31/2 3,15 Y 120 NL 
cotton * -- 3.27 10 3 N 120 L 
65/35 * -- 13.2 4 3 Y 140 NL 
polyester/cotton 
65/35 * -- 13.2 10 3 N 140 L 
polyester/cotton 
cotton * -- 2.5 51/2 12 Y 150 NL 
cotton * -- 2.5 10 13 N 150 L 
65/35 * -- 9.3 6 15 Y 150 NL 
polyester/cotton 
65/35 * -- 9.3 10 15 N 150 L 
polyester/cotton 
65/35 * CH.sub.2 O 
4.45 10 8 N 120 L 
polyester/cotton 
cotton * CH.sub.2 O . Q.B..sup.1 
20.3 3 20 Y 130 NL 
cotton * CH.sub.2 O . Q.B. 
14.7 6 15 Y 130 L 
65/35 
polyester/cotton 
* CH.sub.2 O. Q.B. 
30.7 3 20 Y 130 NL 
65/35 
polyester/cotton 
* CH.sub.2 O . Q.B. 
0 10 15 N 130 L 
cotton * CH.sub.2 O . NaOH 
7.7 10 10 N 140 L 
65/35 * CH.sub.2 O . NaOH 
6.45 8 8 N 140 L 
polyester/cotton 
cotton * Q.B. 5.7 10 5 N 140 L 
65/35 * Q.B. 6.25 10 5 N 140 L 
polyester/cotton 
cotton * TMM.sup.2, Q.B. 
6.4 4 5-30 Y 140 L 
65/35 * TMM, Q.B. 
8.9 10 5 N 140 L 
polyester/cotton 
65/35 * TMM, Q.B. 
9.5 10 18 N 140 L 
polyester/cotton 
50/50 * TMM, Q.B. 
20.0 41/2 3 Y 140 NL 
polyester/cotton 
50/50 * TMM, Q.B. 
7.6 10 10 N 140 L 
polyester/cotton 
65/35 * CH.sub.2 O . Q.B. 
3.85 10 8 N 140 L 
polyester/cotton 
65/35 * TMM, Q.B. 
10.7 10 15 N 140 L 
polyester/cotton 
65/35 * CH.sub.2 O . MgCl.sub.2 
4.86 10 10 N 140 L 
polyester/cotton 
cotton * CH.sub.2 O . MgCl.sub.2 
7.1 10 10 N 140 L 
__________________________________________________________________________ 
*Melamine/PCl.sub.5 + NH.sub.3? 
SE = Self Extinguishing? 
Y = Yes 
NL = Not Laundered 
N = No 
L = Laundered 
.sup.1 Quarternary base 
.sup.2 Trimethylol melamine 
Note: 
Untreated cotton and polyester/cotton cloth are not self extinguishing in 
the flammability test and data for these materials are given for 
comparison purposes. 
Although the invention has been described in terms of specified embodiments 
which are set forth in considerable detail, it should be understood that 
this is by way of illustration only and that the invention is not 
necessarily limited thereto, since alternative embodiments and operating 
techniques will become apparent to those skilled in the art in view of the 
disclosure. For example, although mixtures of compounds of the invention 
were used for flameproofing, each individual compound is a flameproofing 
agent, i.e. each compound whether one, two or all three A's of the general 
formula is N=P(NH.sub.2). Accordingly, modifications are contemplated 
which can be made without departing from the spirit of the described 
invention.