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Патент USA US3075937

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United States atent O rice
3,075,927
Patented Jan. 29, 1963
2
3,075,927
,
_
,
FLAME-RESISTANT URETHANE FOAMS AND
_,
PROCESS FOR PREPARING SAME
William M. Lanham, Charleston, W. Va., assi'gilor to
Union Carbide Corporation, a corporation of New
York
No Drawing. Filed June 9, 1960, Ser. No. 34,872
9 Claims. (Cl. 260-25)
of dimensional stability, cell structure and product
strength. By means of the present invention ?ame
resistant polyurethane foams of widely varying and pre
selected properties are readily prepared which broadens
considerably their realm of practical utility.
The term “?ame-resistant” as employed herein is used
to characterize a material which does not burn readily.
The terms “burning,” “self-extinguishing” and “non-‘burn
ing” are ‘de?ned in accordance with the V“Tentative
This invention relates to ?ame-resistant polyurethane 10 Method of Test for Flammability of Plastic ‘Foams and
foams, and particularly to such compositions which are
Sheeting,” ASTM D—1692‘~59T. In this test the ?ame of
self-extinguishing and possess a high degree of ?ame
a Bunsen burner, having a blue cone ofabout 11/2 inches
resistance.
in height, is applied separately to the front edge of ten
Synthetic urethane foams derived from reactions in
foam specimens, 6”x2"x1/2", and allowed to remain
volving isocyanates with active hydrogen-containing
in contact therewith for a period of sixty seconds. The
polyethers are ?nding widespread utility in the ?eld of
extent of burning is considered the furthermost point
insulation, structural reinforcement, cushioning, elec
trical encapsulation and in domestic electrical equip
ment such as refrigerators, freezers and the like.
One
reached by the ?ame front whereas the burning rate in
inches per minute is a measure of the, time necessary
for the ?ame front to consume ?ve inches of the foam
formidable factor limiting the commercial utilization 20 specimen. A sample is judged “non-burning” if no
and growth potential of the foamed urethane products
evidence of ignition, such as ?ame or progressive glow,
is their risk of ?ammability in applications where high
is seen in each specimen after removal of the ?ame. If
temperatures and/ or exposure to ?re may be encountered.
Although various organic and inorganic compounds
the ?ame front of two or more specimens reaches the
?ve inch mark the sample is judged “burning.” A
have been recommended for the ?ameproofing of ?bers, 25 sample is judged “self-extinguishing? when ignition of
textiles, wood and plastics, including, for example,
the ten specimens gives an extent of burning less than
boron, phosphorus and chlorine-containing compounds,
?ve inches.
the oxides of zinc, bismuth, antimony and arsenic, as
In accordance with the invention polyurethane foams
well as mixtures thereof, the incorporation of such com
which are self-extinguishing and possess a high degree of
pounds in low density urethane foams having large 30 ?ame resistance are prepared by mixing together a poly
surface areas frequently results in a loss of desired
physical properties, e.g., tensile strength, compression
set, elongation and load bearing properties, which limit
the utility of the foam for its intended purpose.
For
example, the incorporation of a hygroscopic ?ame
proo?ng additive in a urethane foam may reduce ?am
mability tendencies but at the same time effect increase
moisture absorption, thus resulting in poor aging char
acteristics. Similarly the use of ?ameproo?ng additives
isocyanate and polyether derivative of a benzene com
pound having active hydrogens with about 0.5 to 5.0%
by weight antimony trioxide and about 1.0 to 10% by
weight of a vinyl halide resin, building up the urethane
polymer network and thereafter developing the foam
reaction. The vinyl halide resin and antimony oxide
?ameproo?ng ingredients can be added to the liquid
polyether, the isocyanate or the polyether-isocyanate re
action mixture. The mixture is then foamed in the
may upset the surface chemistry of the foaming system 40 presence of a catalyst by means of a blowing agent or
and lead to severe destruction of internal cell structures,
internal development of carbon dioxide. The network
formation of a coarse cell structure and/or collapse of
formation and building up of the foam can take place
the foam. The di?iculty in successful ?ameproo?ng
urethane foams as opposed to bulk materials is further
substantially simultaneously, as in the one-shot method,
or in more or less distinct steps as in the prepolymer and
complicated by the troublesome problems of proper addi 45 'semiprepolymer techniques, more fully described here
inafter.
The maximum weight percentages of antimony tri
oxide and vinyl halide resin based on the weight of the
efficient ?ameproo?ng of a urethane foam is not merely a
polyether-isocyanate reaction mixtureare of consider
simple function of incorporating various ?ameproo?ng 50 able technical importance in obtaining urethane foams
agents.
of optimum ?ame resistance which suffer no major ef
The discovery has now been made that flame-resistant
fects on desired properties. For example, with antimony
polyurethane foams possessing desirable physical proper
trioxide alone desirable effects on physical properties
ties can be readily prepared from polyether derivatives
of dimensional stability and cell structure are obtained
of benzene compounds which have incorporated therein 55 with low concentrations ranging from 0.5 to 5% by
a limited proportion of ?ameproo?ng additives consist
weight and preferably about 2%. However, in order to
ing of a vinyl halide resin and antimony trioxide. It
render the foam self-extinguishing and non-dripping high
tive distribution at gas-solid interfacial surfaces due to
the inherent physical movement of the composition dur
ing the foaming operation. As can be appreciated, the
has been found that the amount of ?ameproo?ng addi
tives and the polyether structure are highly signi?cant
factors in preparing ?ame-resistant polyurethane foams 60
loss of desired physical properties. Urethane foams
prepared from polyether derivatives of benzene com
without incurring deleterious effects or an appreciable
pounds can be rendered ?ame-resistant at lower additive
er concentrations on the order of 10 to 15% by weight
antimony trioxide are needed. The increased concentra'
tion of oxide is accompanied by correspondingly more
severe undesirable effects on mechanical properties of
tensile, shear and compression strengths. In order to
obtain improved physical properties resulting from low
antimony oxide concentrations as well as optimum
levels than comparable urethane formulations derived, 65 ?ameproo?ng without encountering undesirable effects
for example, from aliphatic-based polyethers. The
produced by high antimony oxide concentrations, the
achievement of ?ame resistance at a low additive level
thus means that in a broad spectrum of polyether-based
urethane foams classi?ed as either self-extinguishing or
vinyl halide resins are used in amounts ranging from 1
to.10% by weight. Higher concentrations, i.e., greater
than 10% vinyl halide resin, result in signi?cantly re
non-burning by the ASTM D~1692 ?ammability test, 70 duced tensile and compressive strengths. Based on the
the ?ame-resistant urethane compositions of the inven
‘tion possess better mechanical and physical properties
polyether - isocyanate reaction mixture the preferred
amount of vinyl halide ‘resin and antimony oxide used for
amass?
Santicizer 3=N-ethyl-p-toluene sulfonamide
Santicizer IH=Cyclohexyl-p-toluene sulfonamide
purposes of the invention ranges from 2 to 4% and 3
to 7% by weight, respectively, of antimony trioxide and
vinyl halide resin.
The preferred plasticizers are the non-combustible
The vinyl halide resins used for purposes of the inven
plasticizers such as tricresyl phosphate, tri-(Z-ethylhexyl)
tion are characterized as having a reduced viscosity of
phosphate, tri-(Z-chloroethyl) phosphate, and tri-(dichlo
0.1 and lower to about 10.0 and higher in the best sol
ropropyl) phosphate. These plasticizers as well as others
vent available for a particular resin. The preferred range
mentioned above can be employed in resin to plasticizer
in this invention is 0.1 to 4.0. Reduced viscosity may ' weight ratios in the range of about 5:1 to 1:2 and pref
be determined with the Ubbelohde, Ostwald or equiva
erably 4:1 to 1:1.
lent viscometer in the temperature range between 20°
The polyethers used in preparing the ?ame-resistant
C. and 30° C. using a resin concentration in solution
polyurethane foams include a wide variety of polyether
su?iciently low to produce an approximate linear rela
derivatives of benzene compounds. The designated poly
tionship between reduced viscosity and polymer concen
‘ ethers contain at least one benzene nucleus and are fur
tration between in?nite dilution and the concentration
ther characterized as having a molecular weight of at
at which the reduced viscosity is determined. Reduced 15 least about 200, a plurality of ether oxygens and at least
viscosity is de?ned as:
two ‘active hydrogens as measured and determined by
the Zerewitino? method, J.A.C.S., vol. 49, p. 3181
‘
(1927). Since the preparation of flame-resistant poly
’ (TO)(C)
urethane foams according to the invention is dependent
in which T is the time required for a low concentrate 20 upon the use of polyethers which contain a benzene
resin solution to pass through a standardized Ubbelohde
nucleus, the useful polyethers can be derived from
viscometer; To is the time for the pure solvent to pass
polyhydroxybenzene such as catechol or from complex
through the viscometer; and C is the concentration of
polymeric materials such as the novolaks ‘and resoles.
the solution.
The selection of a particular polyether compound is
Representative vinyl halide resins include homopoly
governed by the properties desired in the ?nal urethane
composition and by practical considerations such as cost
and commercial availability.
Illustrative polyethers include those prepared by react
ing a 1,2-alkylene oxide such as ethylene oxide, propyl
25
mers such as poly(vinyl chloride) and poly(vinylidene
chloride) as well as copolymers of vinyl chloride with
a vinyl ester of a lower alkanoic acid or other polym—
erizable ole?nically unsaturated compound such as, for
example, vinyl acetate, vinyl propionate, vinyl hexoate,
methyl acrylate, butyl acrylate, methyl methacrylate,
butyl methacrylate, methyl chloroacrylate, acrylonitrile,
ene oxide, butylene oxide or mixtures thereof with mono
nuclear polyhydroxybenzenes such as resorcinol, pyrogal
lol, phloroglucinol, hydroquinone, 4,6-di-t-butylcatechol,
catechol, orcinol, methylphoroglucinol, 2,5,6-trimethyl
vinylidene chloride, dibutyl maleate, and the like. Also
included are copolymers of a vinyl halide and vinyl
resorcinol, 4-ethyl-5,?-dimethylresorcinol, n-hexylresor
ester of a lower alkanoic acid, e.g., vinyl chloride and 35 cinol, 4-chloro-S-methylresorcinol, and the like; poly
vinyl acetate, which have been partially hydrolyzed and
ethers prepared by reacting 1,2-alkylene oxides or mix
contain reactive hydroxyl groups. The hydroxyl-contain
ing resins advantageously provide a means whereby the
tures thereof with fused ring systems such as 3-hydroxy
2-naphthol, 6,7-dihydroxy-1-naphthol, Z-hydroxy-l-naph
thol, 2,5-dihydroxy-l-naphthol, 9,10-dihydroxyanthacene,
halide can be chemically combined in the urethane
molecule by reaction with isocyanate group (--NCO) 40 2,3-dihydroxyphenanthrene, etc.
to become an integral part of the ?nal form. Carboxylic
_‘
Other polyethers which can be employed are those
acid-containing resins, such as a copolymer of vinyl
obtained by reacting 1,2-alkylene oxides or mixtures
chloride and monobutyl maleate, are also useful in this
thereof with polynuclear hydroxybenzenes such as the
invention since the carboxylic acid group can be chemi
various di-, tri- and tetra-phenylol compounds in which
cally combined in the urethane molecule.
45 two to four hydroxybenzene groups are attached by
The preferred vinyl halide resins are poly(vinyl chlo
means of single bonds or by an aliphatic hydrocarbon
ride) and copolymers of vinyl chloride with vinyl ace
radical containing one to twelve carbon atoms. The
tate which contain from about 25 to 99% by weight
.term “polynuclear” as distinguished from “mononuclear”
vinyl chloride.
is used to designate at least two benzene nuclei in a
The vinyl halide resins above described also can be 50
compound.
used in the form of a plastisol, the term “plastisol” re
Exemplary diphenylol compounds include 2,2-bis(p
ferring to ?uid suspensions of ?nely divided vinyl halide
hydroxyphenyl)
propane; bis(p - hydroxyphenyl)methane
resins in liquid plasticizers. The plastisol technique of
and the various diphenols and diphenylol methanes dis
fers a distinct advantage in urethane applications by
providing a ?uid dispersion at room temperature which 55 closed in U.S. Patents 2,506,486 and 2,744,882, respec
can be easily pumped or used in spray techniques.
tively.
'
Exemplary triphenylol compounds which can be em
Representative liquid plasticizers which can be. em
ployed include the alpha, alpha, omega, tris(hydroxy
phenyl) alkanes such as 1,l,2-tris(hydroxyphenyl)ethanes;
ployed include non-polymerizable ester plasticizers such
as the alkyl and aryl phosphates, the alkyl phthalates,
1,1,3-tris(hydroxyphenyl)propanes; 1, l ,3-tris(hydroxy-3
adipates, sebacates, azelates and epoxidized vegetable oil. 60 methylphenyl)propanes;
1,1,3-tris(dihydroxy-3 - methyl
Among these can be mentioned tri—i(2-ethylhexyl) phos
phenyD-propanes; 1,1,3-tris(hydroxy-2,4-dimethylphenyl)-
phate, tricresyl phosphate, di-(Z-ethylhexyl) phthalate,
propane; l,1,S-tris(hydroxy-2,S-dimethylphenyl)propanes;
and di-(Z-ethylhexyl) adipate, etc. Other suitable plas
ticizers include triethylene glycol di-(Z-ethylhexoate),
polyethylene glycol di-(Z-ethylhexoate), ,2,2’-(2-ethyl
hexamido)-diethyl-di-(Z-ethylhexoate), tetrabutyl thiodi
LLB-tris(hydroxy - 2,6 - dimethylphenyDpropane; 1,1,4
tris(hydroxyphenyl)butanes; 1,1,4 - tris(hydroxyphenyl)65
Z-ethvlbutanes; 1,1,4-tris(dihydroxyphenyl)butanes; 1,1,,
5-tris(hydroxyphenyl)-3 - methylpentanes; 1,1,8 - tris(hy
succinate and the commercial plasticizers sold under the
droxyphenyl)octaues; 1,1,10<tris(hydroxyphenyl)decanes,
trademark “Santicizer” which include:
and the like.
Santicizer 8=A mixture of ortho and para toluene ethyl
Tetraphenylol compounds which can be reacted with
70 1,2-alkylene oxides include the alpha, alpha, omega,
sulfonamides
Santicizer 9=A mixture of ortho and para toluene sul
omega, tetrakis(hydroxyphenyl)alkanes such as 1,l,2,2
fonamides
‘
tetrakis(hydroxyphenyl)ethanes; 1,1,3,3-tetrakis(hydroxy
Santicizer 130=N-isopropyl benzene sulfonamide
B-methylphenyl)propanes;
Santicizer l31==Mixed N-isopropyl benzene sulfonamide
and N-isopropyl toluene sulfonamide
75
1,1,3,3-tetrakis(dihydroxy - 3.
methylphenyl) propanes; 1,1,4,4-te_trakis (hydroxyphenyl),-
3,075,927
butanes; '1,1,4,4-tetrakis(hydroxyphenyl)-2-ethylbutanes;
resoles. A resole ‘produced by the ‘condensation of phenol
1, 1 ,5 ,5 -tetrakis ( hydroxyphenyl) pentanes ; 1, 1 ,5 ,5 -tetrakis
with formaldehyde most likely proceeds through an in
(hydroxyphenyl)-3-methylpentanes; l,1,5,5-tetrakis(dihy
termediate having the following illustrated type of struc
droxyphenyl) pentanes;
l, 1,8,8-tetrakis (hydroxy-3 -butyl
ture:
phenyl)octanes; 1,1,8,8-tetrakis(dihydroxy-3 - butylphen
yl) octanes; 1,1, 8,8-tetrakis (hydr0xy-2,5-dimethylphenyl) -
HOCHr-
octanes; 1,l,10,10-tetrakis(hydroxyphenyl)decanes; and
the corresponding compounds which contain substituent
HO~
groups in the hydrocarbon chain such as l,l,6,6-tetrakis
(hydroxyphenyl) -2-hydroxyhexanes; l,1,6,6-tetrakis(hy
droxyphenyl)-2-hydroxy-S-methylhexanes; 1,1,7,7 - tetra
CH2——
10
=CH2OH
=OH
élHzOH
éHrOH
Other suitable polyethers include the 1,2-alkylene oxide
In a typical synthesis, resoles are prepared by heating
one mole of phenol with 1.5 moles of formaldehyde under
derivatives of mononuclear primary amines such as o—,
alkaline conditions. Then water and other volatiles are
m-xylene; 3,5-diamino-o-xylene; isohexyl-p-phenylenedi
The polyethers used in accordance with the inven
tion can be prepared by reacting the benzene compounds
above noted with a 1,2-alkylene oxide selected from the
kis(hydroxyphenyl)~3-hydroxyheptanes; and the like.
m-, and p-phenylenediamine; 2,4- and 2,6-diaminotoluene; 15 removed and condensation is completed at elevated tem
peratures under pressure.
2,6-diamino-p-xylene; 4,6-diarnino-m-xylene; 2,4-diamino
amine; 3,5-diaminotoluene; and the like; polynuclear
and fused aromatic polyamines such as 1,4-naphthylenedi
amine; 1,5-naphthylenediamine; 1,8-naphthylenediamine;
benzidine; tolidine; 4,4'-methylenedianiline; 3,3'-dimeth
20
group of ethylene oxide, propylene oxide, butylene oxide
oxy-4,4'-biphenyldiamine; 3,3'-dichloro-4,4’ - biphenyldi
and mixtures thereof. The reaction is conducted in the
presence of a catalyst, e.g., alkali metal catalysts such as
diam'line; 4,4'-ethyl.idenedianiline; l-?uorenamine; 2,5
the alkylene oxide to the starting material which is pref
sodium hydroxide and potassium t-butoxide, by adding
amine; 3,3'-dimethyl-4,4'~biphenyldiamine; 4,4'-ethylene
?uorenediamine; 2,7-?uorenediamine; 1,4~anthradiamine;
3,3'-biphenyldiamine; 3,4-biphenyldiamine; 9,10-diamino
25
phenanthrene; and 4,4’-diaminoazobenzene, etc.
Higher functional mono- and polynuclear polyamines
which also can be reacted with 1,2-alkylene oxides to
provide useful polyether start-ing materials include 2,4,6
catalyst employed generally ranges from about 0.002 to
30 2.0% by weight based on the total amount of reactants,
including the alkylene oxide or mixtures thereof appear
ing in the reaction product. To the extent required any
triaminotoluene; 2,3,5-triaminotoluene; 5,6-diaminoace
naphthene, 4,4',4” - methylidynetrianiline, 3,5 ¢ diamino
conventional heat transfer means can be used to remove
benzoic acid, triaminodiphenyl ethers and sul?des such
as 2,4,4’~triaminodiphenyl ether; 2,3',4r-triamino-4’-meth
the exothermic heat of reaction. The products of the
reaction are generally mixtures which can be used as such
yldiphenyl ether; 2,3‘,4 - triamino - 4’ - methoxydiphenyl
or further re?ned to provide a puri?ed product.
ether; and polyamines obtained by interaction of aromatic
monoamines with formaldehyde or other aldehydes, for
The average molecular weight and reactivity of the
alkylene oxide addition products can be determined read
example:
ily by analysis for hydroxyl content. The hydroxyl num~
I
3
erably stirred and in a molten state or slurried in an
inert solvent. The reaction is carried out in the absence
of water under atmospheric or superatmospheric pressure
at temperatures of about 110 to 170° C. The amount of
40 her is a measure of and is proportional to the hydroxyl
NH;
+ ZCHzO
concentration per unit weight. The hydroxyl number
is de?ned in terms of milligrams of KOH equivalent
per gram of alkylene oxide reaction product and is de
——>
45
R2
rm
termined by reacting acetic anhydride (in pyridine solu
tion) at re?uxing temperature with the hydroxyl groups
of the ‘reaction product. The unreacted anhydride and
acetic acid formed are titrated with aqueous sodium hy
droxide using phenolphthalein as ‘an indicator. The mo
lecular weight can be readily calculated from the hy
50
droxyl number by the formula:
___Functionality>< l000>< 56.1
M'W'__
I-Iydroxyl No.
wherein R2 is hydrogen or an alkyl group.
Other particularly useful polyethers which can be em
ployed are the ethylene oxide, propylene oxide and butyl
ene oxide adducts of phenolic and resole type resinous
materials.
The molecular weight of the polyethers used in pre
55
paring the ?ame-resistant‘polyurethane foams should
range from about 200 to about 7500 to obtain foams of
rigid and semi-rigid characteristics. Based on hydroxyl
numbers the preferred polyethers are those which have
hydroxyl numbers ranging from 56 to 540 as de?ned
compounds of the diphenylmethane type of structure, 60 herein.
such as 4,4'-dihydroxydiphenylmethane and 2,4'-dihy
A variety of isocyanates may be employed for reaction
droxydiphenylmethane formed by the Baeyer reaction of
with the polyethers above described to provide urethane
phenol and formaldehyde. In a typical synthesis, novo
foams which can be rendered ?ame-resistant according
laks are prepared by condensing one mole of phenolic
to the invention. Preferred isocyanates are polyisocy
compound, such as phenol or cresol, with 0.8 mole of
anates and polyisothiocyanates of the general formula:
an aldehyde, such as formaldehyde or furfural, under
Novolaks are believed to be mixtures of polynuclear
acid conditions at a temperature around 160° C. to 170°
C. The polynuclear products frequently contain 4 to 8
wherein G is oxygen or sulfur, x is an integer of two
or more and R is an alkylene, substituted alkylene, aryl
such, are non-curable, thermoplastic resins. Resoles, or 70 ene or substituted arylene radical, a hydrocarbon, or
Bakelite-type resins, are one-stage thermosetting resins
substituted hydrocarbon containing one or more aryl
produced by the condensation of phenols and aldehydes
--NCG bonds and one or more alkyl —NCG bond.
under alkaline conditions. It is believed that resoles dif
R can also include radicals such as —RZR- where Z
fer from novol-aks in that polynuclear methylol-substituted
phenols are formed as intermediates in the case of the 75 may be a divalent moiety such as -—O-—- '—O—'-R—O—‘,
units and may contain 12 or more units.
Novolaks, as
3,075,927
formation of the urethane linkage as well as the forma;
tion of isocyanate dimers and trimers. In addition, an
other reaction than can occur is the formation of allo
Examples of such compounds include hexamethylene di
isocyanate, l,8-diisocyanato-p-menthane, xylylene diiso
cyanates, (OCNCH2CH2CH2OCH2)2, 1-methyl-2,4-diiso~
cyanatocyclohexane, phenylene diisocyanates, tolylene di~
isocyanates, chlorophenylene diisocyanates, diphenyl
methane-4,4’-diisocyanate, naphthalene-l,S-diisocyanate,
phanate structures.
'
a
Preferred blowing agents are the ?uorocarbons such
as trichloromono?uoromethane; dichlorodi?uoromethane,
triphenylmethane-4,4’,4"-triisocyanate, xylene-a,a'-diiso
dichloro?uoromethane, 1,1-dichloro - l - ?uoroethane; 14
chloro-l,1-di?uoro, 2,2-dichloroethane; and 1,1,1-tri?uoro,
2-chloro-2-?uoro, 3,3-di?uoro, 4,4,4-tri?uorobutane. .The
thiocyanate, and isopropylbenzene-ot,4-diisocyanate.
Further included are dimers and trimers of isocyanates
and diisocyanates and polymeric diisocyanates of the gen 10 amount of blowing agent used will vary with density de
sired in the foamed product. In general it may be stated
eral formulae:
that for 100 grams of resin mix containing an average
NCO/OH ratio of 1 to 1, about 0.005 to 0.3 mole of gas
are used to provide densities ranging from 30 to 1 lbs.
per cubic foot. If desired, water may be used in con
in which x and y are two or more, as well as compounds
of the general formula:
junction with the blowing agent.
Organic tin catalysts that are suitable for accelerating
the polyether-isocyanate reaction are compounds having
the general formula:
in which x is two or more and M is a polyfunctional atom
or group.
Examples of this type include ethylphos
phonic diisocyanate, C2l-I5P(O) (NCO) 2; phenylphos
phonic diisocyanate; CGH5P(O)(NCO)2; and isocya
20 ('1)
nates derived from sulfonamides [R(SO2NC.O)X].
The preparation of polyether-based urethane foams can
be carried out by forming a prepolymer, i.e., prereacting
molar equivalents of the polyether and isocyanate in the
absence of water and thereafter producing a foam by
the addition of excess isocyanate, catalyst, water and sur
RgSnX or RrSn
(c)
(d)
RSHX;
RaSuY
(9)
RSnO O R’
(a)
R
factant; by the one-shoe method in which the polyether,
blowing agent, and isocyanate reactants are simultane—
Ilt.
R
alas.
it
ously mixed together and allowed to react in the presence
of a catalyst; or by the semiprepolymer technique wherein
the polyether reactant is partially extended with excess
isocyanate to provide a reaction product containing a
in which R represents hydrocarbon or substituted hy
drocarbon radicals such as alkyl, aralkyl, aryl, alkaryl,
(h)
R2311 (Y RX) 2
high percentage of free isocyanate groups (20-35%)
alkoxy, cycloalkyl, alkenyl, cycloalkenyl, and analogous
which is then foamed at a later stage by reaction with
substituted hydrocarbon radicals; the R’ represents hy
additional polyether, a blowing agent and catalyst.
drocarbon or substituted hydrocarbon radicals such as
those designated by the R or hydrogen or metal ions, the
The amount of isocyanate used in the preparation of
rigid or semirigid foams when external blowing agents are
employed can be such that there is approximately the
theoretical amount required to form a urethane linkage,
-NHCO—O, in the polymer resulting from reaction
of the isocyanate with the active hydrogens of the poly-v
ether. However, when the foaming is performed by
means of isocyanate and water to form carbon dioxide,
X represents hydrogen, halogen, hydroxyl, amino, alkoxy,
substituted alkoxy, acyloxy, substituted acyloxy, acyl
radicals or organic residues connected to tin through a
sul?de link; and the Y represents chalcogens including
oxygen and sulfur.
,
Among the compounds of group (a) that deserve
special mention are trimethyltin hydroxide, tributyltin
the amount of isocyanate employed is generally within
hydroxide, trimethyltin chloride, trimethyltin bromide,
1.2 to 3.0 equivalents, preferably 1.2 to 2.0 equivalents, 45 tributyltin chloride, trioctyltin chloride, triphenyltin chlo
per equivalent of polyether.
ride, tributyltin hydride, triphenyltin hydride, triallyltin
The reaction of excess diisocyanate with a polyether
chloride, tributyltin ?uoride, tributyltin acetate, and tetra
produces a polymer having terminal isocyanate groups.
butyltin, etc.
When it is desired to form a foam, the mixture of the is@
The compounds in group (b) that deserve particular
cyanate-rnodi?ed polyether reacts through the isocyanate
mention and are representative of the group include di
groups with a chain extending agent containing active
methyltin diacetate, diethyltin diacetate, dibutyltin diace
hydrogen, e.g., water, in the presence of a tertiary amine
or an organic tin catalyst. This involves several re
actions that proceed simultaneously including the reaction
tate, dioctyltin diacetate, dilauryltin diacetate, dibutyltin
dilaurate, dibutyltin maleate, dimethyltin dichloride, di
butylin dichloride, dioctyltin dichloride, diphenyltin di
chloride, diallyltin dibromide, diallyltin diiodide, bis
between the isocyanate groups and water to form urylene 55
links (-NHCONH-—) and carbon dioxide, as well as the
(carboethoxymethyl)-tin diiodide, dibutyltin dimethoxide,
reaction of the urylene links so formed with unreacted
dibutyltin dibutoxide,
isocyanate groups to form biuret cross links. Depending
upon the desired density of the urethane foam and the
amount of cross linking desired, the total -—NCO equiv 60
:(in which x is a positive integer), dibutyl-bis[O-acetyl
alent to total active hydrogen equivalent should be such
as to provide a ratio of 0.8 to 1.2 equivalents of —NCO
acetonyH-tin, di'outyltin-tbisv?thiododecoxide), and
per equivalent of active hydrogen and preferably a ratio
of about 0.9 to 1.1 equivalents.
The foaming operation also can be effected by means 65
of a blowing agent, such as a low boiling, high molec
all readily prepared by hydrolysis of the corresponding
ular weight gas, which vaporizes at or below the tem
perature of the foaming mass. In rigid foams intended
dihalides. Many commercially available compounds
mono?uoromethane, is used in blowing rigid foams, a
lower K-factor is obtained than in rigid foams of equal
(0) are butyltin trichloride, octyltin trichloride, butyltin
triacetate and octyltin tris(thiobutoxide).
used as stabilizers for vinyl resins are also included in
for use in the ?eld of insulation and structural rein
forcement the incorporation of a gas lowers its heat 70 this group.
Among the compounds that are representative of group
conductivity. If a ?uorocarbon gas such as trichloro
Typical among the compounds of group (d) are di
The reac
tions that occur during this type operation include 75 methyltin oxide, diethyltin oxide, dibutyltin oxide, dioctyl
density blown with air or carbon dioxide.
3,075,927
10'"
tin oxide, dilauryltin oxide, diallyltin oxide, diphenyltin
oxide, dibutyltin sul?de, [HOOC(CH2)5]2SnO,
and
(
The following examples illustrate the best mode now
contemplated for carrying out the invention.
EXAMPLE 1
) x_1CH2] 25110
5
[CH3OCH2 (CI-IZOCHZ ) XACHOK CH2 ) 5] 25110
Methylstannonic acid, ethylstannoni-c acid, butylstan
nonic acid, octylstannonic acid, HOOC(CH2)5-SnOO=I-l,
( CH3) 3N( CH2) sSnO OH
and
130 grams of a polyether blend prepared by the addition
of propylene oxide to 1,1,3-tris(hydroxyphenybpropane
(in which the x’s are positive integers).
(hydroxyl No. 268) and 96 grams of a semiprepolymer
prepared therefrom by reaction with tolylene diisocyanate'
(29.1% total free NCO) were mixed with 1.0 gram di
10 butyltin dilaurate, 1.0 gram of a silicone oil surfactant
(siloxane-oxyalkylene copolymer) and 39-41 grams of
CH3OCHz(CH2OCH2)x_1CH3SnOOH
trichloromono?uoromethane. As soon as the mixture be
gan to foam it was discharged into an open mold and
cured for 10 minutes at 70° C. The foamed product has
are examples of group (e) catalysts and group (1‘) 15 a density between 1.9 and 2.1 lbs./ cu. ft.
catalysts are represented by HOOSn(CH2)XSnOOH and
EXAMPLE 2
HOOSnC-H2-(CH2OCH2)xCH2SnOOH, the x’s being posi
tive integers.
Typical compounds in group (g) include compounds
100 grams of a propylene oxide addition product of
glycerol (hydroxyl No. 640‘) and 175 grams of a semipre
as poly(dialkyltin oxides) such as dibutyltin basic laurate 20 polymer prepared therefrom by reaction with tolylene di
and dibutyltin basic hexoxide.
isocyanate (29.9% total free NCO) were mixed with 1.2
Other compounds that are e?icient catalysts are those
grams of a silicone oil surfactant (siloxane-oxyalkylene
of group (h), of which the organo-tin compounds used as
copolymer), 0.8 gram dibutyltin dilaurate and 38-43
heat and light stabilizers for chlorinated polymers and
grams trichloromono?uoromethane. The foamed prod
available under the trade names Advastab 17-M 1 and 25 uct was cured for 10 minutes at 70° C. and has a density
between 1.8 and 2.0 lbs/cu. ft.
Advastab T-SO-LT 2, are typical, as well as many other
organo-tin compounds commercially available.
EXAMPLE “3
Other organic tin compounds which can be used in
clude the divalent tin compounds selected from the
180 grams of a polyether blend prepared by the addition
group consisting of stannous acylates and stannous alkox 30 of propylene oxide to a phenol-formaldehyde resin~con~
ides.
taining an average of four to ?ve phenolic rings per
molecule3 (hydroxyl No. 247) and 122.5 grams of a
Suitable stannous acylates are the divalent tin salts of
semiprepolymer prepared therefrom by reaction with
aliphatic mono- and polycarboxylic acids which contain
tolylene diisocyanate (28.8% total free NCO) were mixed
from 1 to 54 carbon atoms. The acids can be saturated,
such as acetic acid, 2-ethylhexanoic acid, etc.; unsaturated 35 with 1.2 grams of a silicone oil surfactant (siloxane
oxyalkylene copolymer), 0.5 gram dibutyltin dilaurate
such as oleic acid, linoleic acid, ricinoleic acid, and the
like; or they may be polymerized fatty acids derived from
and 46-48 grams trichloromono?uoromethane. The
foamed product, after curing for 10 minutes at 70° C., has
natural oils, e.g., linseed oil, tung oil, soybean oil, dehy
a density between 1.8 and 2.4 lbs/cu. ft.
drated castor oil, which have a molecular weight up to
about 500. Examples of speci?c acylates include: stan 40
EXAMPLE 4
nous acetate, stannous propionate, stannous oxalate, stan
80
grams
of
the
polyether
blend as prepared in Example
nous tartrate, stannous butyrate, stannous valerate, stan
1 (hydroxyl No. 268) and 80 grams of a polyether blend
nous caproa-te, stannous caprylate, stannous octoate, stan
prepared vby the addition of propylene oxide to 4,4'-di
nous laurate, stannous palmitate, stannous stearate, and
aminodiphenylmethane (hydroxyl No. 230) were mixed
stannous oleate. Of these materials the preferred cata
with 66 grams of tolylene diisocyanate, 1.2 grams of a
lysts are stannous acetate, stannous octoate and stannous
oleate.
silicone oil surfactant (siloxane-oxyalkylene copolymer),
0.4 gram dibutyltin dilaurate, 0.4 gram N,N,N',N'-tetra
methyl-1,3-butanediamine and 35-38 grams of trichloro
The stannous alkoxides which can be used may be rep
resented by the formula:
50 mono?uoromethane. The foamed product was cured at
Sn(OR)2
70° C. for 10 minutes and has a density between 2.0 and
2.8 lbs./ cu. ft.
in which R is a monovalent hydrocarbon radical, satu
The polyurethane foams prepared in Examples 1 to 4
rated or unsaturated, branched chain or straight chain,
were blended prior to foaming with varying amounts of
containing 1 to 18 carbon atoms, preferably 3 to‘12. 55 antimony trioxide and vinyl halide resin and tested for
Representative examples of stannous alkoxides include
stannous methoxide, stannous isopropoxide, stannous
butoxide, stannous t-butoxide, stannous 2-ethylhexoxide,
stannous tridecanoxide, stannous heptadecanoxide, stan
?ammability characteristics according to the ASTM D
1692-59T test procedure previously described. If the
foam burns (ASTM Class B) the rate of burning is re
ported in inches per minutes (i.p.m.). If the foam is self
nous phenoxide, and 0-, m- and p-stannous cresoxides, 60 extinguishing (ASTM Class S) or non-burning (ASTM
etc.
Class N) the extent of burning is reported in inches. In
Other catalysts which can be employed in combination
instances where ignition of ten specimens results in nine
with the tin catalysts above noted are amine catalysts such
specimens classi?ed as non-burning (N) and one specimen
as 2,2,1-diazabicyclooctane, trimethylamine, 1,2-dimethyl
imidazole, triethylamine, diethylcyclohexylamine, di
self-extinguishing (S), the ?ammability of the sample has
been judged inconclusive (I). The data tabulated in
methyl long-chain C12 to C18 amines, dimethylamino
Table I below illustrates that polyurethane foams prepared
ethanol, diethylaminoethanol, N-methylmorpholine, N
from polyether derivatives of benzene compounds can be
ethylmorpholine, triethanolamine and N,N,N’,N’-tetra
rendered ?ame-resistant (ASTM Class N) at lower addi
methyl-1,3-butanediamine.
tive levels than comparable polyurethane foams derived
70 from aliphatic-based polyethers. The percentages shown
are weight percentages based on the polyether-isocyanate
1 Alkyltln mercaptide. about 90-92% pure,_partial structure,
(C4H?)2S11(-OC8H17. C,H,0,S) ; percent C=a5. , percent H=v
reaction mixture.
9.1. percent $=8.5. percent Sn=15.6; probable structure:
(C4Hn) 2SI1 ( SCH2CO2C8H17) 2.
_
2Pure liquid (no additives), polymeric, partial structure,
éC4H§})22n(C|H,O) ; percent C=45.9, percent H=6.5, percent
65
3Prepared from a reaction mixture of phenol (100 parts),
formalin (56.5 parts) and lead acetate (.75 part heated at
about
100° C. for two hours then after partial ehydration
75 distillation,
heated at 150° C‘. to 158" C. for one hour.
11
l2
'
Example
Percent Polyols Used in-
Ex.l
Ex.2
Ex.3
’
Table I
Percent
Percent Vinyl Percent Density, AppearTDII Halide’ SbzOs
p.c.l.
ancei
ASTM
Class
Rate or
Extent
Ig/B l
Ex.4
mid“
mo‘
ocamrwiu
1 Mixture of 80% 2,4- and 20% ZFS-tolylene diisocyanate.
,
_
8 Copslymer of vinyl chloride and vinyl acetate having a reduced viscosity 0i 0.57 and containing 5.3 Wt. percent vinyl alcohol,
2 Po1y(vinyl chloride) having reduced viscosity of 1.42 used in Examples 5—40.
4.4 wt. percent vinyl acetate and 90.4 wt. percent vinyl chloride.
,
4 Ignition time in seeondslextingulshment time in seconds.
_
5 The appearance or the foam is rated by a three-letter code with the ?rst letter estimating average cell size, the second
letter uniformity of cell size and the third letter bulk ?aws (splits, ridges, burns, etc.) wherein
lst Letter
A=Fine.
26 Letter
36 Letter
Good.
None,
B=Medium.
Fair.
Minor.
C = Large.
Poor.
Severe.
The polyurethane foams tested for ?ammability characAs shown below the achievement of ?ame resistance at
teristics in Table I were also tested for compressive 50 low additive levels in polyurethane foams prepared from
strengths in adirection perpendicular (i) and parallel (If)
polyether derivatives of benzene compounds results in a
to the foam rise at 23° C. The loss in tensile strength
accompanying su?icient vinyl halide resin and antimony
trioxide to obtain a non-burning foam (ASTM Class N)
having a density of 2 lbs/cu. ft. is reported in Table II. 55
smaller and less appreciable loss of desired physical prop
erties, e.g., tensile strength, than in comparable foams de-'
rived from aliphatic-based polyethers (Examples 16 and
18).
Table II
Percent
Cone. of Addi
Strength
tlvcs, Wt.
Orien-
Lost in
percent
tation
Achieving
Tensile Strength, p.s.i.
Example
ASTM
Base Foam-Fire-Resistant=Lost
Class N
Vinyl SbzO;
Halide
8 _________ __ I1
.L
420
29. 0
27. 0
20.9
15.0
8.1
36>32
28
5.0
1.0
28 ________ -. II
.L
34. 4
as 9
27. 2
23.0
7. 2
10. 9
21>26
32
4. 0
1. U
6.0
5.0
16 ________ _-
I
1s ________ .. ll
39 ........ -- ll
.L
54. 5
28. 0
26.5
49>52
33. 3
15. 4
17. 9
5i
54. 5
2e. 8
24.1
45
7.0
9.1.0
27. 5
18. 3
33>“)
6.0
4. 0
as. 3
30. 5
1e. 2
1G. 0
17. 1
9. 2
l4. 5
51>48
48
.
13
3,075,927
What is claimed is:
1. A process for the preparation of ?ame-resistant poly
urethane foams which comprises catalytically reacting a
polyether having active hydrogens and a molecular weight
of at least 200 which is an alkylene oxide addition product
of a polyhydroxybenzene compound with an organic poly
isocyanate in the presence of a blowing agent, 0.5 to 5.0%
by weight antimony trioxide and 1.0 to 10% by weight of
a vinyl chloride resin having a reduced viscosity ranging
14
alkylene oxide addition product of a polyhydroxybenzene
compound with an organic diisocyanate in the presence of
a blowing agent, 0.5 to 5.0% by weight antimony trioxide
and 1.0 to 10% by weight of a vinyl chloride resin having
a reduced viscosity ranging from 0.1 to 10.0.
6. The process of claim 5 wherein the vinyl chloride
resin is a member selected from the group consisting of
poly(vinyl chloride) and copolymers of vinyl chloride
with vinyl acetate.
from 0.1 to 10.0.
7. The process of claim 6 wherein the polyether is an
10
2. The process of claim 1 wherein the polyether is an
alkylene oxide addition product of a 1,1,3—tris(hydroxy
alkylene oxide addition product of a polynuclear hydroxy
benzene.
phenyl) alkane.
8. The process of claim 7 wherein the alkane is 1,1,3
3. The process of claim 1 wherein the polyether is an
tris(hydroxyphenyl) propane.
alkylene oxide addition product of a novolak phenolic 15
9. The product produced according to the process of
resin.
claim 6.
4. The product produced according to the method of
claim 1.
References Cited in the ?le of this patent
5. A process for the preparation of ?ame-resistant poly
UNITED STATES PATENTS
urethane foams which comprises catalytically reacting a 20
2,634,244
Simon et al. ____ __. _____ __ ‘Apr. 7, 1953
polyether having at least two active hydrogens and a mo
2,843,568
Benning et al. ________ __ July 15, 1958
lecular weight ranging from 200 to ‘about 7500 which is an
2,888,408
Rogers et al ___________ __ May 26, 1959
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