Modification of polyurethanes with alkyl halide resins, inorganic salts, and encapsulated volatile and reactive halogen for fuel fire contro

Parker, J. A.

Riccitiello, S. R.

English

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https://ntrs.nasa.gov/search.jsp?R=19710015263 2020-03-17T02:58:13+00:00Z
J. A. PARKER AL 3,5493 
MODIFIED POLYURETHANE FOAMS FOR FUEL-FIRG 
Filed Feb. 5, 1968 
120 240 360 480 600 720 840 0' 
T I M E ,  SECONDS 
IN L'CNTORS 
BY 
~ , ~ ~ ~ , 5 6 ~  
Patented Dec. 22, 1970 
1 2 
5 
i n  
foam of a certain type as described hereinafter. In this 
foam, during or prior to forming the foam, there may he 
added three types 01 combination of types, of modifying 
agents. These include (1) a certain class of alkyl halide 
resins, (2) a certain class of inorganic salts and (3 )  en- 
capsulated halogen bearing volatile molecules. New and 
improved materials are provided by the use of ( 1 ) alone 
in the polyurethane but it is preferred to  use all three 
classes of additives. 
The preferred polyurethane foam is formed by reacting 
3,549,564 
MODIFIED POLYURETHANE FOAMS 
FOR FUEL-FWE 
John A. Parker, Los Altos, and Salvatore R. Riccitiello, 
San Jose, Calif., assignors bo the United States of Amer- 
ica as represented by the Administrator of the Na- 
tional Aeronautics and Space Administration 
Filed Feb. 5, 1968, Ser. No. 702,967 
Bnt. C1. CO8g 22/44 
8 Claims 
-" 
U.S. CI. 260-2.5 
a polycyclic ar&& polyisocyanate, drawn -from the 
class of isocyanates represented by the general structural 
formula as follows: ABSTRACT OF THE DISCLOSURE 
The invention relates to flame retardant and flame sup- N=C=O 
pressant materials. The main structure of the material is l5  
a highly rigid branched or semi-rigid structure, polyurethane in which foam, are incorporated preferably of one a #+]. or more materials to impart special properties. One of tbe added materials is an alkyl halide resin such as poly- 
vinyl chloride which is capable of splitting off HC1 and 2o 
forming a polyene on heating. Other materials which may 
be, and preferably are, added are cetain inorganic salts 
(e.g., potassium fluoborate) an encapsulated volatile halo- 
gen compounds such as trifluorotrichloroethane. 
I 
where n varies from 2 to 10, with a multifunctional 
polyol, performed from the reaction of propylene oxide 
with a multifunctional polyol, with a hydroxyl function- 
ality greater than four, of the general structure 
0-R 
I 
25 
HOR'O-C-H 
HOR'O-C-H 
E O  R'O-C-H H-r_ I 
H-C-0 
I 
The invention described herein was made by employ- 
ees of the United States Government and may be manu- 
factured and used by or for the Government for govern- 30 
mental purposes without the payment of any royalties 
thereon or therefor. 
This invention relates to the modification of closed cell 
rieid and semi-rieid oolvurethane foams in the densitv &C-OR'OH 
I .~ 
range from 0.50 to 50 pounds per cubic foot. Specifically, 35 
it relate to the modification of certain classes of poly- 
urethanes with alkyl halide resins, inorganic salts, and 
I1 
where R may be methyl as in the case of methyl glucoside 
and R a propylene 
encapsulated volatile and reactive halogen bearing mole- Both the polycyclic aromatic character of the isocyan- 
cules. These modifcations can be made without unduly ate and the highly branched functionality of the poly01 
affecting the desirable mechanical, physical, and thermal 40 are pre-requisite for obtaining the desired high char yield 
insulating qualities of the polyurethane foam. and integrity as well as low molecular weight non-com- 
The modified foams herein described are useful in Pro- bustible species. However, the particular polycyclic aro- 
viding effective protection for thermally sensitive strue- matic polyisocyanate I and polyol 11 need not be used. 
tures against the destructive action of fuel-fires. For this For example other ring systems may be used instead of 
reason these foams may find broad application in both 45 the benzene ring in I (e.g., naphthlene and heterocyclic 
military and commercial fields. rings) and the aromatic ring may be substituted as hy 
Conventional polyurethane foams are flammable, form- methyl and chloro substituents. 
ing little char residue and producing large volumes of In II the base, so to speak, is indicated as a hexose 
combustible noxious gases. Improvements in Conventional derivative which may be referred to as a glycoside. In the 
foams to make them more resistant to burning have been 50 selected glycoside, R may be methyl or other alkyl or 
made by the addition of phosphates, chlorowax and the an aryl group, or it may be another saccharide unit (e.g., 
like for application as insulation and structural members. as in sucrose); or the glycoside base may be replaced by 
State of the art modifications have improved the non- oxidation products (e.g., gluconic acid) or reduction prod- 
burning characteristics of foams but this has not im- ucts (e.g., sorbitol); or the poly01 base may be any suit- 
proved the ability of these materials to withstand the ac- 55 able halogen substituted (chlorendic acid) or unsubsti. 
tion of a sustained fuel-lire. Conventional foams are un- tuted polyhydric alcohol having a sufficient number (e.g., 
satisfactory in providing the desired protection for such 4 or more) available hydroxyl groups. Also, the isopro- 
things as military aircraft when penetrated by incendiary pylene entity 
bullets in areas external to fuel tanks. 
a new class of foam plastic materials which provide ther- 
-CH-CHr It is an objective of the present invention to provide 60 
bH3 
mal protection because of their excellent insulation prop- may be replaced with other groups, e.g., the ethylene 
erties and also function as a fire-suppressant system. entity, A H A H - .  Also R may be hydrogen. 
Another objective of the present invention is to pro- Suitable commercially available isocyanates such as 
vide low density foam plastics which can function as 65 Mondur MR in which n is greater than 2, with an iso- 
ablative heat shield materials for low heating environ- cyanate content of 32%, may be reacted with a commer- 
ments. cially available polyol, such as Pluracol 201, the oxy-pro- 
Other objectives of the invention will be apparent from pylene derivative of methyl glucoside. Pluracol 201 is the 
the ensuing description and the appended claims. trade name of Wyandotte Chemicals for plyoxypropyl- 
In accordance with the present invention a closed cell, 70 ene derivatives of methyl glucoside corresponding to 
rigid or semi-rigid polyurethane foam is employed as a Formula I1 above. Pluracol 230 may also be used which 
basic foam forming matrix, although preferably it is a employs sucrose in place of methyl glucoside. Mondw 
3,549,564 
3 4 
M R  is the trade name of Mobay Chemicals for a poly- action product is highly branched and cioss-linked. When 
cyclic aromatic polyisocyanate corresponding to Formu- heated, volatile material is expelled and there is further 
la I above. cross-linking and Condensation of rings. This cross-linking 
The preferred alkyl halide resin (1) is polyvinyl chlo- and ring condensation is catalyzed by the hydrogen halide 
ride (or a copolymer of vinyl chloride with a non-halo- which is split off from the halogenated polymer. The halo- 
gen bearing monomer such as vinyl acetate and/or other genated polymer also gives rise to a conjugated polyene 
monomers such as a maleic anhydride) in the form of a which enters into condensation reactions and contributes 
particulate dispersion. The preferred resin is VMCH, to the yield and stability of the char. The potassium fluo- 
which is a tercopolymer of vinyl chloride, vinyl acetate borate decomposes into potassium fluoride and boron tri- 
and maleic anhydride. (VMCH is a trademark of Car- fluoride and the latter decomposes into elemental boron 
bide Chemical Corp.) Other halogen bearing polymers and fluorine. The boron enters into the char structure and 
may be used which like the polyvinyl chloride polymers stabilizes it. The fluorine has the desirable effect of re- 
and copolymers are capable, upon heating at tempera- acting with free radicals such as hydroxy1 radicals which 
tures in the range of 100 to 300" C., of splitting o f f  hy- are chain carriers and which act to sustain and propagate 
drogen chloride and producing a reactive polyene. Poly- 15 combustion. The reaction of fluorine with these chain car- 
vinylidene chloride and neoprene may also be used. rier free radicals suppresses combustion. 
As stated, the foam also preferably contains an inor- The following specific examples will illustrate further 
ganic salt (2) as another discontinuous phase. The pre- the practice and advantages of the invention: 
ferred salt is potassium fluoborate (KBF4), but other 
salts which dissociate such as ammonium bicarbonate, am- 20 
monium chloride, potassium silicofluoride, ammonium 
fluoborate, sodium chloride and sodium bicarbonate can Parts by weight 
be used. Mondur MR1 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _  150 
As stated, the foam may also contain (3) encapsulated 
volatile halogen containing molecules in addition to the 25 
aforementioned components. This modification of the 
closed cell, rigid or semi-rigid foam is prefared for those 
applications in which fuel-fire quenching or highly active 
suppression is more desirable than sustained fire protec- 
tion. The preferred encapsulants are Freon 113 (trifluo- BO 
rotrichloroethane) and the bromofluoro alkanes. (Freon 
is a trade name of Du Pont.) Encapsulation is achieved 
by coascervation with gelatin, polyvinyl alcohol, or other 
suitable film-former as carried out by National Cash 
Register Company. See for example Green, US. Pat. 35 
2,800,457. 
In the practice of the present invention, conventional 
methods of frothing, spraying, and pour in place to form 
foams are used. Also conventional blowing agents such 
as Freon 11, catalysts such as triethylene diamine, in the 40 
form of Dabco 33-LV, and surfactants such as DC-195 
silicone lubricants are used. (Dabco is a trade name of 
Houndry Chemical Company.) Various methods of in- 
EXAMPLE SYSTEM 
Formulation 
Part A: 
---. n _  rut D. 
Pluracol 2019 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _  65 
Freon11 (CC1,F) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _  37 
Surfactant DC 195 (a silicone lubricant) _ _ _ _ _  0.9 
Catalyst Dabco 33LV (triethylene diamine) _ _ _  1.4 
Procedure: Pluracol, surfactant, catalyst and Freon 11 
are weighed into a steel vessel and mixed with a stirrer at 
7OC-900 r.p.m. until blended, about 30 sec. The pre- 
weighed Mondur MR is added to the vessel and stirred 
an additional 20 sec. to insure complete blending. The 
mixture is transported to a suitable container and let rise. 
The foam is tack free in 3 to 5 minutes. Let stand for 
16 hours before testing. 
EXAMPLE 2.-URETHANE SYSTEM 5-D 
Formulation 
Part A: Mondur MR-100parts by weight 
Part B: AS in Example 1 plus 16.5 parts VMCH (a vinyl 
resin having an approximate composition of 86% vinyl 
chloride, 13% vinyl acetate, and 1% maleic anhydride). 
Procedure: Same as Example 1. 
corporating these modifying agents will be apparent to 
and may he employed by one skilled in the polyurethane 45 
art. The preferred method of this invention is to add 
all of the modifying agents to the polyol. In the case where 
the dispersing system used employs gear pump metering, 
the component should he added at the mix- 
ing head. This is the preferred order of mixing for all 50 
applications. 
It has also been found that the desired characteristics 
of the product are substantially improved if a skin is 
present on the surface of the product, for example, on the 
outer exposed surface. Such a skin can be conveniently 55 PartA: Mondur MR-lOO parts by weight 
formed by restraining the expanding foam in a mold 
whereby the cells at the interface of the foam and the 
restraining wall of the mold will collapse the foam cells 
and form such a skin. However, a skin may be applied 
after the foam has been formed, for example by the appli- GO 
cation of unblown compositions as described herein. A 
skin has the desirable effect of distributing heat evenly Part A: Mondur MR-lOO pars by weight 
hecause, highly porous body Part B: As in Example 3 PIUS 16.5 Parts Freon 113 micro- 
of foam, fie skin is a better heat conductor, therefore spheres prepared by method of U S  Pat. 2,800457; 
conducts heat rapidly from local hot spots to cooler areas. 65 encapsulahg made from arabic and gelatin; The skin also to the evolution of gases particle size 100-300 microns; encapsulated material= 
which are formed during charring of the foam. The even 85% of weight of capsules; walls cured with glutaralde- 
distribution of the gases evolved during charring is also hyde' 
advantageous because it sweeps away oncoming hot Procedure: Same as Example 1. 
molecules and absorbs oncoming thermal energy uni- 70 
formly, thereby preventing or lessening the probability of 
localized overheating and tunneling which weakens the 
structure and distorts the foam shape. 
It is our belief that the mechanism of charring pro- 
ceeds as follows: The preferred polyurethane-polyol re- 75 Parts B: As in Example 4 plus 16.5 parts Fyrol 6 trade. 
EXAMPLE 3.-URETHANE SYSTEM 5-1 
Formulation 
Part B: As in "" parts KBF4' 
Procedure: Same as Example 1. 
EXAMPLE 4.-URETHANE SYSTEM 5-AF 
Formulation 
to the much 
EXAMPLE 5.-URETHANE SYSTEM 5-AH 
Formulation 
Part A: Mondur MR-100parts by weight 
3,549,564 
5 
mark of StanlTer Chemical Co., Victor Division, for the 
Procedure: Same as Example 1. 
Samples of the foam of each of these examples were 
subjected to identical tests as follows: A 4" x 4" x 1%" 
slab of foam is adhered to a 0.060 inch steel plate 4" x 4" 
in area. A wing tip Bunsen burner was used at a flow rate 
of 3 cc. natural gas/miuute. The slab was held i%" 
from the burner. The rise of temperature of the back 
side of the steel plate was noted. The results are set forth 
in the table below. 
COmPoUd (CaHsO)aP(O)CH2N(CH2CH~OH)a. 
5 
10 
6 
(c) a dissociable inorganic salt selected from the group 
consisting of potassium fluohorate, ammonium bicar- 
bonate, ammonium chloride, potassium silicofluoride, 
ammonium fluoborate, sodium chloride, and sodium 
bicarbonate. 
2. The material of claim 1 wherein the alkylene oxide is 
propylene oxide. 
3. The material of claim 1 wherein the lower alkyl 
glycoside is methyl glycoside. 
4. The material of claim 1 wherein the dissociahle inor- 
ganic salt is potassium fluoborate. 
Back side 
temperature Weight 
time to ioss, Dimension 
Slab material Density 120° C., see sams loss, inch Remarks 
Eaamplle: 
1. 5-0 .......... 2.1 125 LO ?4 Poor char. 
2.5-D .......... 2.2 375 6.0 x very good char. 
4. 5-AF 2.2 525 11.0 
6. 5-AH ........ 2.2 600 15.5 
3.5-1 ........... 2.5 540 7.0 jj Do. 
?2 2: ......... 
In each of the foregoing examples, 100 parts of polyiso- 
cyanate and 65 parts of polyol were used resulting in ap- 
proximately 165 parts of polyurethane foam; and each of 
the additives (alkyl halide resin, inorganic salt and en- 
capsulated halogen hearing material) was added in the " polymer is poly(viny1 chloride). 
amount of 10% of the combined weight of polyisocyanate 
and polyol, or approximately 10% of the weight of poly- 
urethane foam. Each of the proportions may be varied 
considerably. In the following table are set forth various 
proportions that may be used, parts being by weight. 
5. The material of claim 1 wherein the halogenated 
polymer is a copolymer of vinyl chloride, vinyl acetate, 
and maleic anhydride. 
6. The material of claim 1 wherein the halogenated 
7. The material of claim 1 wherein the foam includes 
a substantial amount of an encapsulated, halogenated, 
volatilizable fire suppressant material. 
8. The material of claim 1 wherein the foam is an 
addition product of a polymeric polyaryl polyisocyanate 
having 31.5-32% active -NCO groups and a viscosity 
Partshy Preferred Broad of about 200 cps. at 25" C. and a polyol formed by the 
reaction of methyl glycoside and propylene oxide; the Mntedal weight range range 
Foam ................................... 100 100 &I 35 halogenated polymer is polyvinyl chloride; wherein said 
Alkyl halide resio. ..................... 10 1&20 
Inorganic salt. ......................... 10 IWO 6 66 foam also includes uniformly dispersed therein potassium 
EnOapSUlatedmate rial................. 10 10-70 5-70 fluoborate and microcapsules of a highly halogenated low 
molecular weight alkane; the combined proportions of 
The inorganic salt and/or encapsulated materid may be polyvinyl chloride, potassium flnoborate and microcap- 
omitted altogether as in certain of the examples but it is 40 sules not exceeding about 70% of the weight of the foam 
prefened to have at least one of them and most advan- and the proportion of each being not less than about 10% 
tageously both of them present. 
It will therefore be apparent that a novel and very 
useful, polyurethane foam-hased heat insulating, fire re- 
sistant and suppressant material has been provided. 
We claim: 
1. A heat insulating and fire retardant and suppressant 
of the weight of the foam. 
References Cited 
UNITED STATES PATENTS 4B 
2,800,457 7/1957 Green et al. _ _ _ _ _ _ _ _ _  252-316 
material in the form of a semi-rigid or rigid polyurethane 3,075,928 1/1g63 Laham _ _ _ _ _ _ _ _ _ _ _ _  260-2.5 
foam which comprises, 3,239,482 3/1966 Rapp _ _ _ _ _ _ _ _ _ _ _ _ _ _ _  2 6 0 4 1  
(a) the reaction product of a polymeric polyaryl poly- 
isocvanate and a nolvol ether having a hvdroxvl 50 FOREIGN PATENTS 
~ ~ ~ ~ ~ ~ ~ ~ l ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ r ~ ~ o ~ ~ ~ ~  
selected from the group consisting of lower alkyl 
glycoside, aryl glycoside, hexose glycoside, gluconic 55 
acid, sorbitol, sucrose, and glucose; 
(b) a halogenated polymer uniformly dispersed in said 
foam, said polymer being selected from the group 
consisting of poly(viny1 chloride), poly(viny1 d o -  E. TAYLOR, Examiner 
ride-vinyl acetate), poly(vinylidene chloride), poly 
(vinyl chloride-vinyl acetate-maleic anyhydride), and 
neoprene; and 
1,177,816 9/1964 Germany _ _ _ _ _ _ _ _ _ _ _  260-2.5 
1,490,316 6/1967 France _____________ 260-2.5 
OTHER REFERENCES 
The Condensed Chemical Dictionary, 5th edition (1956), 
page 502 cited. 
M. J. WELSH, Assistant Examiner 


Modified polyurethane foams for fuel-fire Patent

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