CA1109600A - Production of polyurethane foam of reduced tendency to form embers when burned - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Flexible polyurethane foam having reduced tendency to form burning embers when it is ignited and burned is provided by incorporating into the reaction mixture before foaming a derivative of melamine wherein one or more hydrogens have been replaced by hydroxymethyl and/or lower alkoxymethyl groups.
In one embodiment, flexible polyurethane foams of increased flame retardance are also provided, by also incorporating a halogenated phosphorus ester into the reaction mixture before foaming.

Description

- 1 11~96?Q~) 1 ¦ BACKGROUND OF THE INVENTION

2 1 Flexible, resilient,polyurethane foams can be made by reacting a

3 polyol and a polyisocyanate in the presence of a blowing agent. The foams

4 can be used for a wide variety of purposes, such as carpet underlay, textile innerlining,furniture padding, crash pads in automobiles, mattresses, 6 pillows and insulation. Polyurethane foams can burn readily when ignited.
7 ¦ The present invention provides a method whereby there can be manufactured 8 1 a flexible, resilient, polyurethane foam of reduced tendency to produce 9 ¦ burning embers when burned. This is an important advantage, inasmuch as the spreading of the fire is reduced.
11 . .
12 SUMMARY OF T~E INVENTION

14 This invention provides a flexible, resilient, polyurethane foam of reduced tendency to form burning embers when burned.
16 The invention is provided by incorporatin~ lnto the reaction 17 mixture before foaming a hydroxymethyl or lower alkoxymethyl derivative of 18 melamine, for example, tris-(hydroxymethyl) melamine or hexa-(methoxymethyl) 19 melamine.
In a more limited aspect, the invention also provides a flexible, 21 ¦ resilient, polyurethane foam of increased flame retardance. This is 22 1 accomplished by also incorporating into the reaction mixture to be foamed 23 ~ a halogenated phosphorus ester.
24 ;¦ In contrast to prior art processes, such as that disclosed by 2~ ~ Nyquist et al in U.S. 3,l35,707? which incorporate certain partially alkylatedll 26 li polymethylolmelamines or other similar thermosetting resin precursors into 27 ,`1 polyurethane foam reaction mixtures for the purpose of increasing the 28 I rigidity and/or load-bearing capacity of the resultant foam by causing 29 I resinification of the resin precursor during manufacture, the process of ', the present invention has as an objective the manufacture of flexible ~ . 11096~0 1 ¦ polyurethane foam which has a reduced propensity to form incendiary embers 2 ¦ when burned. In this process, resinification of the melamine during 3 1 manufacture of the foam is avoided.
4 ¦ The novel products of this invention, rather than being stiff ¦ and rigid, retain substantially the flexibility, resilience, cell structure, 6 ¦ permeability, and hand of conventional flexible polyurethane foams which 7 ¦ do not contain the melamine derivatives employed in the present process.
8 ¦ As a consequence, the foams of this invention can be used in most or all of 9 1 the applications where conventional flexible foams have heretofore been lo ¦ used. These novel foams can, if desired, be peeled, split, or sliced 11 1 into sheets of any desired thickness using techniques well-known in the 2 ¦ art, and the fl OE ible sheets also can be rolled up for convenient storage 13 1 and transportation. Like conventional flexible polyurethane foams, the 14 ¦ products of the present process can be laminated to textiles or plastic 15 ¦ substrates by conventional methods, such a~ flame-lamination or by means 16 of adhesives.
17 ¦ Although the foams of this invention have the appearance and 18 l flexibility of conventional foams, once they are ignited they have a greatly 19 ¦ reduced tendency to form burning embers. As is well known, one of the ¦ dlsadvantages of conventional polyurethane foams and other synthetic 21 1 polymers is the fact that when they are ignited they tend to melt and form 1 22 burning embers which can drip and cause the spread of flames to other 23 1 nearby materials. Even when such materials contain flame-retardants they 24 ! can still produce smoldering, dripping embers which can ignite nearby 1 materials which are not f1ame-retardant. While we are not bound by any 26 , particular mechanism to xplain the re & ction in the tendency to form 27 burning embers, one such mechanism may be the resinification of the melamine 28 derivative under the influence of the heat of combustion to form a thermoset 29 '1 material within the foam structure which results in a lesser tendency to '1 melt and drip.
I .

, I

In a more limited embodiment of the present invention, the reaction mixture to be foamed can also comprise one or more known flame retardants such as halogenated phosphorus esters. When such flame retardants are used, the finished foams support combustion for a shorter period of time after ignition, in addition to having a reduced tendency to produce burning embers during the time combustion does occur.
DETAILED DESCRIPTION OF THE INVENTIO`N
According to the present invention, there is provided a process for the manufacture of a flexible, resilient, polyurethane foam by the steps of (1) forming a reaction mixture comprising at least one polyol, at least one organic polyisocyanate, at least one catalyst, and a blowing agent, the amount of said polyisocyanate being at least one equivalent per equivalent of the total of said polyol and said blowing agent, by introducing into a mixing chamber said polyol maintained at a temperature between about 19C and about 30C said polyisocyanate maintained at a temperature between about 18C and 27C, said catalyst maintained at a temperature between a~out 15~C ~ about 50C
and said blowing agent maintained at a temperature between about 15C and about 50C, (2) blending said reaction mixture until it is uniform, and (3) discharg-ing said reaction mixture onto a casting surface, characterized by incorporat-ing into said reaction mixture at least one compound of the formula A \ N G

N - C ~ C - N
B /
N N
\ C ~
N \
D E
in said formula A, B, D, E, F, and G being selected from the group consisting of hydrogen, methylolJ and ROCH2- wherein R is an alkyl radical containing from one to four carbon atoms, with the proviso that in said formula at least one of A, B, D, E, F and G is methylol or ROCH2-, the amount of said compound being from one to about 20 percent by weight based on the weight of said l~

$~`~0 polyol, and the temperature of said compound being maintained at between about 15C and 50C while being introduced into said mixing chamber, whereby a polyurethane foam having a reduced tendency to form incendiary embers when the foam is burned is obtained.
The mixture to be foamed will also include a polyol, an organic polyisocyanate and a blowing agent. The polyol can be one or more polyether polyols, one or more polyester polyols, or a mixture of one or - 4a -B

1 1~09~

¦ more polyether polyols and polyester polyols.
2 ¦ The polyols suitable for use in the present invention can be 3 ¦ polyether polyols, such as those made by the addition of an excess of ; 4 ¦ propylene-1,2-oxide to hexane triol, trimethylolpropane, glycerol, S ¦ triethanolamine or a polyethylene glycol. Also, the polyols suitable for 6 I use in this invention can be polyester polyols or a mixture of polyester 7 ¦ polyols and polyether polyols. The polyester polyol can be prepared, 8 ¦ for example, by reacting a dicarboxylic acid, such as adipic acid, with a I I mixture of a diol, such as diethylene glycol, and a triol, such as glycerol.
o ¦ The polyether polyol can also be selected from any of the wide variety of polyhydric polyether compounds avallable and conventionally 12 l used by the art for the preparation of flexible polyether-type polyurethanes.
13 I The most common polyether polyol compounds, the polyoxyalkylene polyether 14 ¦ polyols, are generally prepared by the reaction of an alkylene oxide, such i 15 1 as propylene-1,2-oxide, with a polyhydric initiator or starter. The 16 I polyhydric initiator or starter can be, for example, glycerol, trimethylol-17 I ethane, trimethylolpropane, triethanolamine or a polyethylene glycol.
18 ~ The alkylene oxides used in preparing the polyethers preferably 19 are those which contain from two to four carbon atoms, for example, I ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide, trimethylene 21 1 oxide and tetramethylene oxide. Also useful are the poly(aralkylene ether~
22 I polyols which are derived from the corresponding aralkylene oxides such 23 ¦ as, for example, styrene oxide, alone or mixed with an alkylene oxide.24 ~¦ Generally, propylene oxide, i.e., the 1,2-propylene oxide, and mixtures of '¦ 1,2-propylene oxide with ethylene oxide, are preferred for the preparing 26 of the polyether polyol reactant.
27 1 The polyethers for use in the present invention preferably have 28 ,1 a molecular weight of from about 500 to about 6500 a~d optimally of from 29 il about 2800 to about 4600 and an average hydroxy functionality of at least ¦ 2.5 to about 3.1.

1109~

1 ¦ The polyester polyol reactants useful in the present invention 2 ¦ include any conventionally used in the preparation of flexible and3 1 semi-flexible urethane polymer foams The polyhydric polyester reactant 4 ¦ usually has a molecular weight of at least about 400 and optimally between ¦ about 500 and about 5000. The hydroxyl number of the compound is 6 ¦ correspondingly in the range of from about 15 to about 300. The preferred 7 ¦ average hydroxyl functlonality for the polyester resins is from about 8 1 2.2 to 2.8.
I The range of polyester polyol compounds useful for preparing lo l the flexible polyurethane foams in the present invention is well known to 1 ¦ the art, and the polyester polyol compounds can be prepared by, for 12 ¦ example, the reaction of a polyhydric alcohol with a polycarboxylic acid 13 ¦ compound, each containing from two to about 36 or more carbon atoms in 14 ¦ the molecule, The polycarboxylic acid includes such acid precursors as the corresponding acid anhydrides or acid halides or even, for example, 16 alkyl esters, The preferred acids are the dicarboxylic acids containing 17 ¦ from 4 to 36 carbon atoms in the molecule, Examples of such preferred 18 ¦ carboxylic acid compounds which can be used include, for example, aromatic 19 acids, such as phthalic acid, terephthalic acid, isophthalic acid,tetrachlorophthalic acid, cycloaliphatic acids such as dimerized linoleic 21 acid, maleated and fumarated resin acids, and cyclohexane-1,4-diacetic acid, 22 but especially the aliphatic acids such as itaconic, oxydipropionic, 23 ¦ succinic, glutaric, adipic, azelaic, suberic and sebacic acids, or24 ¦ combinations or such acids. The polyester polyols can also be prepared ,I from the corresponding lactones, such as gamma-butyrolactone or epsilon-26 1l caprolactone, for example, by self-condensation on a diol-triol initiator.
27 il The polyhydric alcohol used in the preparation of the polyester 28 , polyol is generally a mixture of a dihydric and a trihydric alcohol.
29 ,¦ Preferably, a mixture of polyols, the major portion having a functionality I of two and the minor a functionality of three, is used. This mixture of .
i -6--9~

1 j di- and tri-functional polyols is utilized to give an average functionality 2 1 of between two and three. A functionality of greater than two is desirable 3 ~ to provide cross-linking in the reaction between the polyester polyol and 4 the polyisocyanate to form a flexible, but strong foam. It has been found to be preferable to obtain this additional functionality by using trihydric 6 or higher polyols in a minor amount when forming the polyester polyol.
It is recognized that certain compounds which are considered by 8 those skilled in the art as polyester resins also contain ether linkages, 9 e.g., esters prepared from dipropylene glycol. However, the primary character of such resins is considered to be that of an ester.
l1 The organic polyisocyanates useful in the present invention are 12 also conventional. They contain at least two isocyanate groups per molecule.
13 Preferably, the isocyanate mixture selected has an isocyanate functionality 14 of from 2.0 to 3Ø The useful isocyanates are the aromatic polyisocyanates, alone or admixed with aliphatic, cycloaliphatic or heterocyclic polyisocyanates 16 The aromatic dilsocyanates are generally the least expensive and 17 most suitable polyisocyanates available~ The aromatic diisocyanates, 18 especially the toluene diisocyanate isomers, are used commercially in the 19 preparation of foam by the one-shot, continuous slab-stock process. However, for certain purposes, other polyisocyanates, especially the aliphatic, 21 aralkyl and cycloalkyl polyisocyanates,have valuable properties and can be 22 used, if desired, in admixture with, e.g. toluene diisocyanates. The 23 aralkyl, aliphatic and cycloaliphatic polyisocyanates are especially useful 24 11 when resistance against degradation and discoloration due to oxidation or ! light is needed. The non-aryl polyisocyanates are generally not useful 26 1 alone, but can be used in combination with the other types for special 27 purposes.
28 il Suitable organic polyisocyanates include, for example, n-butylene 29 1l diisocyanate, methylene diisocyanate, m-xylyl diisocyanate, p-xylyl 1¦ diisocyanate, cyclohexyl-l, 4-diisocyanate, dicyclohexyl~ethane-4, . ' . .
" _7_ 11()9600 .

1 ¦ 4'-diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 2 ¦ 3-(alphalsocyanatoethyl)-phenyl isocyanate, 2,6-diethylbenzene-1, 3 ¦ 4-diisocyanate, diphenyldimethylme$hane-4, 4'-diisocyanate, ethylidene ¦ diisocyanate, propylene-1,2-diisocyanate, cyclohexylene-l, 2~diisocyanate, S ¦ 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 3,3'-dimethyl-4'-; 6 ¦ biphenylene diisocyanate, 3,3'-dimethoxyl-4,4'-biphenylene diisocyanate, 7 ¦ 3,3-diphenyl-4,4'-biphenylene diisocyanate, 4,4-biphenylene diisocyanate, 8 j 3,3'-dichloro-4,4'-biphenylene diisocyanate, 1,5-naphthalene diisocyanate, g ¦ isophorone diisocyanate, m-xylylene diisocyanate, triazine triisocyanate, lo l triketotrihydrotris(isocyanatophenyl) triazine and tris(isocyanatephenyl) ll I methane.
12 ¦ Generally, in carrying out the urethane polymerization reactions, the only significant groups in the reactant compounds are the isocyanate r 14 groups ~ and active hydrogen groups which are reactive therewlth. Acyclic, alicyclic, 16 ar atic and heterocyclic radicals are all possible substituents on the 17 active hydrogen and polyisocyanate reactants.
18 The preferred blowing agent for general use in the production 19 of the flexible polyurethane foam is water. The advantages of using water 20 1 are low cost and the stability which the use of water adds to the foam-making.
21 ~ The water-isocyanate reaction gives not only gas for blowing, but also 22 produces urea-containing polymer very quickly, contributing materially to 23 early polymer strength needed to hold the gas inside, to form foam.
24 ~ Generally, when water is used, it is present in proportions of from about 2s ' Q~5 to about 6 weight percent of water based on the total weight of the ,1, 1 26 ,I reacting polyols. Blowing agents which do not react with the isocyanate 27 ~ can be used as an adjunct with water or as a total replacement of water.
28 I These include c pounds which are vaporized at the temperatures produced 29 by the exotherm of the isocyanate-reactive hydrogen reaction. The various , blowing agents are well known in the art and constitute no part of the ., ill~96110 I
I

1 present invention. Other blowing agents that are preferably used by the art include certain halogen-substituted aliphatic or cyclo-aliphatic 3 ¦ hydrocarbons having boiling points between about -40C. and +70C., 4 including methylene chloride; the volatile fluorocarbons, such as trichloromonofluoromethane, dichlorodifluoromethane, and 1-chloro-2-6 fluoroethane; low boiling hydrocarbons such as n-propane, cyclopropane, 7 butane, isobutane, pentane, hexane, cyclohexane and their mixtures and 8 the like.
9 In accordance with the present invention, there can also be lo produced a flexible polyurethane foam of increased flame retardant properties by including in the reaction mlxture to be foamed one or more 12 halogenated phosphorus esters, for example, tris(l,3-dichloropropyl) 13 phosphate, trls(2,3-dlbromopropyl) phosphate, dichloromethylene-bis[di~2-14 chloroethyl) phGsphate~, tris-(2-chloroethyl) phosphate, and tris-(2-chloropropyl) phosphate. The amount of flame retardant used will 16 generally be up to about 30 percent by weight, and preferably from four to 17 20 percent by welght, based upon the welght of the polyol present in the 18 reaction mixture to be foamed.
19 The followlng Examples lllustrate the invention or provide comparisons with respect thereto, and are to be considered not limitative 1 21 ¦ of the invention.
22 ¦ Examples 1 to 4 23 These four examples represent the preparation of hand batch 24 ` formulations using the one shot technique.
, In each example 100 grams of a polyol which was a glycol adipate 26 li having a molecular weight of 3000 was weighed out in a cup. An activator 27 comprising of the following ingredients was then added: water, 3.7 grams;
28 ,~ proprietary hot amine coupler, 2.0 grams; and N-ethyl morpholine, 1.5 29 ~ grams. Amine catalyst, 0.3 grams; black paste (carbon black in ~ tricresylphosphate~, 7.5 grams; catalyst(N-cocomorpholine), 0.8 grams;

_g_ ~,~g6~0 1 ~1 mineral oil, 0.2 grams; flame ~etardants and stannous actoate catalys t, 2 1 0.2 grams, were added in that order.
3 ,¦ In Example l the flame retardant was composed of 13.3 grams of 4 1~ Fyrol CEF [tris-(2-chloroethyl) phosphate] and 6.7 grams of tris(hydroxymethyl) !I melamine. In Example 2 the flame retardant was composed of 20.0 grams of 'I the same halogenated phosphate. In Example 3 the flame retardant was 7 I composed of 20.0 grams of tris-(hydroxymethyl) melamine, and in Example 4 8 1¦ no flame retardant was used. ~;
9 1¦ The premixes prepared as described were each combined with !1 49.8 grams of toluene diisocyanate (65/35) (index lll) and after about five 11 1 seconds of mixing were poured into an 8 inch by 8 inch mold. The rise times 12 1 were about 60 seconds and each foam had a density of about two pounds per 13 cubic foot.
14 1 When the four cured and condltioned foams were ignited by the ; same standardized test procedure (ASTM 1692-68), the following results .o were obtained:
17 ¦ TABLE I
18 1 Example 1 2 3 4 19 1 Time to loss of 32 28 No loss of ~lame l flame (secs) ! Extent of burn 21 ¦I damage (inches~ l.l l.l 5.0 5.0 22 1 Drlpping embers , during burning None Many NoneMany 23 ;1 glowing glowing ~ I Examples 5 to 32 26 ' A series of foams were prepared as in Examples l to 4, but 27 ~j containing various flame retardants, alone and in combination with either 28 I the melamine derivatives of this invention or commercially available 29 I products recommended as intumescent agents. All cured foams were ignited ~1 under two standardized sets of conditions: by ASTM 1692-68; and, after * Trade Mark -10-- ~ ~

B
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11096~0 1 ~ being aged, by a modification of UL 94. The latter test allows for a better 2 ¦ observation of dripping ember formation. The modification of UL 94 was in 3 , the measurement of flame time. The standard test calls for starting to 4 ¦ count flame time 60 seconds after ignition, whereas in the procedure used ¦ flame time was counted from the start of ignition.
6 fi t TABLE II
7 ¦ Ex. Foam 8 No. Additives, Phr Ignition Test Results ¦ ASTM 1692-68 UL 94 I Secs. Time to Inches Secs.
lo ¦ flame extin- Burn Flame Ins. Flaming ¦ guishment Extent Time Damage Embers 12 l 5 None (control) Sample consumed Sample consumed Yes 13 ¦ Single Additives -; 14 l 6 CEF, 20 (A~ 67 2.08 50 1.42 Yes l 7 FR 2, 20 (B) 29 2.38 50 1.75 Yes l 8 TM 101, 20 (C) 52 1.71 40 1.12 Yes l 9 2XC-20,20 (D) 62 2.46 44 1.38 Yes 16 ¦ lQ Dibutyl ; I Chloroendate, 17 ¦ 10 ~E~ Sample consumed Sample consumed Yes 11 Melamine, lQ t~) Sample consumed SampIe consumed Yes 18 l 12 Tris(hydroxy-methyl~ melamine, 19 10 (G2 Sample consumed Sample consumed No 13 Tris(hydroxy-methyl)-tris (methoxymethyl) 21 l melamine 12.5 (H) Sample consumed 63 2.54 No 14 Hexa(methoxy-22 methyl) melamine (I) Sample consumed 66 1.96 No 23 1 Double Additives 24 1l 15 A,20; F,10 50 1.13 42 1.08 Yes ;l 16 A,20; E,10 60 1.17 50 1.46 Yes 17 A,20; H,12.5 34 1.08 32 1.12 No l 18 A,20; I,10 50 1.17 36 1.04 No 26 j 19 B,20; G,10 42 0.96 48 1.04 No ! 20 B,20; H,12.5 28 0.96 32 1.00 No 27 1 21 B,20; I,10 40 1.29 41 1.50 No l 22 B,20; F,10 52 1.5 45 1.38 Yes28 23 B,15.2; H,18.5 35 0.96 35 1.08 No f ~ 24 B,10, I,20 52 1.71 41 1.25 No 29 ~, 25 C,20; E,10 42 1.21 44 1.08 Yes Ij 26 C,20; G,10 42 0.75 41 0.79 No .1 27 C,20; H,12.5 37 0.96 31 0.96 No ~1096~0 1 1 TABLE II (continued) 2 ~ Ex. Foam 3 ¦ No Additives, phr I~nition Test Results 4 ¦ ASTM 1692-68 UL 94 l Secs. Time to Inches Secs.
1 5 1 flame extin- Burn Flame Ins. Flaming 6 ¦ guishment Extent Time Dama~e Embers ; 7 ~ 28 C,2Q; I,10 46 1.04 32 0:.71 No l 29 D,20; G,10 35 0.88 41 1.04 No 8 1 30 D,20; H,12.5 29 0.88 29 0.96 No l 31 D,20; I,10 34 0.88 35 0.96 No 9 ¦ 32 D,20; E,10 42 1.42 44 1.43 Yes "' 10 I
11 1 In Table II and wherever else used in this disclosure, phr means I parts by weight per 100 parts by weight of polyol present in the mixture to be13 l foamed. CEF is a proprietary tris-(2-chloroethyl) phosphate and is I ~_.. ..
14 1 designated in Table II by the letter A. FR-2 is a proprietary tris-(1,3-l dichloropropyl) phosphate ant is designated in Table II by the letter B.
16 l TM 101 is a proprietary bis-~(chloroalkyl)phosphate] and is designated in 17 1 Table II by the letter C. 2XC-20 is a proprietary dichloromethylene-bis 18 l [di(2-chloroethyl) phosphate] and is designated in Table II by the letter D.
19 l Further, in Table II dibutyl chlorendate, melamine, tris(hytroxymethyl) ¦ tris-tmethoxymethyl) melamine and hexa-(methoxymethyl) melamine are 21 ¦ designated, respectively, by the letters E,F,G,~ and I.
22 1 Examples 33 and 34 23 1 A commercially available flame retardant is claimed by its 24 I manufacturer to be a cross-linked condensate of hexa-(methoxymethyl) melamine and tris(2,3-dibromopropyl) phosphate. This flame retardant is 26 1 a clear, strongly acidic liquid containing ionic halide. Attempts to il neutralize the acidity (for improved foam-making) by cautious addition of 28 I bases gave useless precipitates.
29 ¦ Following essentially the procedure of Example 1, a lab foam 30 ji was made using 13.3 phr of tris(2,3-dibromopropyl) phosphate and 6.7 phr : .

96~0 1 ¦ of hexa-(methoxymethyl) melamine. The foam was somewhat darker in shade ¦ than the foam of Example 1, and slightly less open. When ignited according to the procedure of AST~ 1692-74, the initial flame burnt itself out within 4 ¦ 21 seconds of the ignition, and the foam showed no dripping ember formation ¦ during the time of burning.
¦ Exactly the same foam-making procedure was tried several times 7 ¦ in which the combination of the dibromopropyl phosphate and the melamine-¦ formaldehyde derivative was replaced by the liquid condensate of the second 9 ¦ preceding paragraph at 5-20 phr levels. In each attempt, no foam was obtained, even when excess amine catalyst was used to neutralize the added ll acidity. An attempt was made to concentrate the condensate and volatilize 12 acidic components by holding the condensate under vacuum at ambient 13 temperature. The resultant discolored sludge was still acidic, and failed 14 to permit foam-making when used at a 5 or 10 phr level.
Examples 35 and 36 16 A commercially available black polyester-based polyurethane foam 17 (Example 35) advertised as being "permanently flame retardant" is used 18 extensively in sound-adsorption requirements in such mechanical applications 19 as computer building and motor vehicle interiors. A commercial sample of this black foam was compared by the following tests with a plant-made foam 21 (Example 36) having a formulation essentially as follows:
22 Polyester prepared from 100 parts by weight diethylene glycol 23 ~ trimethylolethane 24 and adipic acid 2s 1 65/35 TDI (111 index) 50.1 !! Water 2.5 26 l ll 12 percent by weight 7.45 27 ; dispersion of carbon I black in cresyl diphenyl 28 1 phosphate 29 ', Stannous Octoate (1:1 by 0.78 il weight mixture in cresyl diphenyl phosphate , 1109~0 ¦ N- cocomorpholine (4:1 by 1.0 2 l weight in mineral oil) l Distilled dimethylhexade- 0.2 3 j cylamine 4 ¦ N-ethyl~morpholine 0.5 ¦ Non-silicon cell 1.5 6 ¦ control agent l Tris(hydroxymethyl)- 6 ¦ tris(methoxymethyl) melamine 8 l Tris(1,3-dichloropropyl) 9 ¦ phosphate 15 10 ¦ Foam 36 was comparable in color, cell uniformity, and physical 11 ¦ properties to Foam 35, but had a pleasanter, less haræh, hand. Both showed 12 ¦ comparable standing wave sound adsorption curves at equal thicknesses, and 13 l both satisfied the requirements for HF-l ~no drip) classification of the 14 ¦ UL 94 ignition test, as freshly tested.
15 ¦ A. Laminatability I

16 ¦ Occasionally the use of either foam in sound adsorbency 17 1 necessitates a pre-lamination of the foam to te~ctile or plastic. Both 18 l Foams 35 and 36 appear to be equally laminatable to both fibrous webs and 19 ¦ thermoplastic (PVC~ sheets by aqueous and non-aqueous adhesives, although,in general, Foam 35 give~ a slightly poorer bond than Foam 36. However, in 21 ¦ laboratory trials, Foam 36 could be readily flame laminated to cellulosic 22 1 fiber, while Foam 35 could not be.
23 ~ Test B. Permanency of Flame Retardancy 24 I The two foams were ignited by the procedure of UL 94, and the , results noted in Table III. Fresh samples of both foams were simultaneously 26 `~ immersed in separate beakers of boiling water for 10 minutes and for 30 27 ¦ minutes, and were dried by air at the same controlled temperatures and 28 1~ hum-dities for 48 hours before being retested by the procedure of UL 94.

30 .!
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11096~0 I .. ..
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1 i TABLE III
2 1 Foam 35 Foam 36 Original Materials 4 UL 94 Buxn Distance, inches 1.02 1.02 UL 94 Burn Time, secs. 29.3 29.2 Embers Dripping None None Cotton Ignition from Embers No No 6 UL 94 Classification 94HF-1 94HF-l 7 Material after l0 Minutes in Boiling Water UL 94 Burn Distance, inches 5.0 1.29 UL 94 Burn Time, secs. 98.5 28.8 9 Embers Dripping Yes None Cotton Ignition from Embers Yes No UL 94 Classification - Failed ll Classification 94HF-l 12 Material after 30 Minutes in Boilin~ Water UL 94 Burning Distance, inches 5.0 1.38 13 UL 94 Burning Time, secs. 96.5 27.5 Dripping Embers Yes None 14 Ignition of Cotton from Embers Yes No UL 94 Classification Failed Classification 94HF-l 17 From the above Table III, it can be seen that the commercially 18 available "permanently flame retardant" Foam 35 loses its retardancy by 19 contact with boiling water (extraction), which does not affect Foam 36 of this invention.
21 ¦ Test C. Shelf Storage Stability 22 ¦ One criterion for shelf storage stability is the ability to 23 resist the degradative effects of the nitrogen oxide~ generated by commonly 24 1 used space heaters. The test most frPquently used is the AATCC Fume ~ Chamber Test No. 23-1962 which had the results shown in Table IV.
26 ,, TABLE IV
27 ~I Foam 35 Foam 36 28 i, Original Material 29 Tensile strength, psi 22 16 i UL 94 Burn Distance, inches 1.02 1.02 ;l UL 94 Burn Times, secs. 29.3 29.2 Dripping Embers, Cotton Ignition No, None No, None ., ~ . . .

096~0 1 TABLE IV (continued) 2 ~ Foam 35 Foam 36 3 Material After Fume Chamber 4 1 Tensile Strength, psi 7 11 UL 94 Burn Distance, inches 2.1 1.1

5 I UL 94 Burn Time, secs. 43 30 ¦ Dripping Embers, Cotton Ignition A few,infrequent No, None

6 1

7 ¦ Thus, it can be seen that the ni~rogen oxides encountered in

8 ¦ storage ~re more damaging to Foam 35 than they are to Foam 36.

9 ¦ Examples 37 to 39 lo ¦ It is well-known that ether-based foams are more difficult to 11 1 make flame-retardant than ester-based foams, and more difficult to make 12 l dripless if a high-resilient ether formulation is used. As a test of the ; 13 ¦ invention, high-resilient slabstock foams were made with and without the 14 I additives of this invention and tested for flammability. Table V shows the ¦ three formulations in parts by weight.

17 Foam 37 18 (Control~ Foam 38 Foam 39 19 4000 mol. wt. polyol 800 800 800 ¦ Proprietary Isocyanate 431.2 431.2 502.8 1 Proprietary Cross-Linker 40 40 40 I TriethanolamIne 40 40 40 21 1 Mixture of triethylene l diamine in dipropylene I n l glycol (33:67 weight ratio) 3.2 3.2 3.2 ; Tris (1,3-Dichloropropyl) 23 phosphate 160 61.5 92.3 Tris-(hydroxymethyl)-tris 24 l (methoxymethyl)-melamine 0 98.5 147.7 l Foam Density, pounds per ~ cubic foot 3.4 3.2 2.4 il Foam Permeahility (Dow), 26 'I cubic feet per minute 2.8 3.1 3.8 l~ Foam Appearance Punky celled Uniform Uniform 27 ¦ ASTM 1692-68 Ignition:
~¦ Burn time, secs. 18 21.2 28.7 28 ¦ Burn extent, inches 0.67 0.42 0.92 i Dripping embers Many, burning NoneNone . . ~

11091i~0 . . .

1 Examples 40 to 42 In Example 40, a foam was made using 200 grams of a proprietary 3 ~ ether polyol having an average molecular weight of 6000, 93.4 grams of a 4 ! proprietary polyisocyanate (TDI index of 104), 15 grams of tris-(1,3-8 dichloropropyl) phosphate, 30 grams of hexa-(methoxymethyl) melamine, 6 5.35 grams of water and 20 grams of bis-(hydroxyethyl) dimethylhydantoin.
7 In Example 41, the procedure of Example ~ was repeated, but using 20 grams of tris-(1,3-dichloropropyl) phosphate and 40 grams of hexa-(methoxymethyl) melamine.
The foams of Examples 40 and 41 each had a cream time of 10 11 seconds, and densities of 2.82 and 2.9 pounds per cubic foot, air 12 permeabilities (Dow) of 3.5 and 3.3 cubic feet per minute, and ASTM 1692-68 3 burn times of 61.9 and 67.1 seconds and burn extents of 2.7 and 3.0 inches~
14 respectively. The foam of Example 40 dripped few burning embers, while the ~ foam of Example 41 dripped very few burnlng embers.
16 Control foam Example 42 was made similarly to that of Example 40, 17 but using 99.7 grams of the polyisocyanate, 20 grams of tris-(1,3-18 l dichloropropyl) phosphate and no hexa-(methoxymethyl) melamine. The control 19 foam had a cream time of 10 seconds, a rise time of 60 seconds, a density 1 of 2.62 pounds per cubic foot, an air permeability (Dow) of 3.2 cubic 21 ¦ feet per minute~ and an ASTM 1692-68 burn time of 20.9 seconds and burn n ! extent of 0.92 inch. The control foam dripped many burning embers, once 23 ignited.
24 ; Examples 43 and 44 1 Small amounts of the additives of this invention serve to give 26 ~ more reproducible flame-retardant results even at concentrations where full 27 char formation does not occur, tending to minimize the deleterious effects 28 l of inconsistent flame retardant concentrations and erratically spotty 29 , increases in cell permeability~ such as is experienced in measuring the ' top, the middle, and the bottom of a bread slice. Pilot line buns of the ' ' I
l . 1~9~ .. , . . .
I

1 following formulations were prepared, the amounts being in parts by weight:
2 j 43 44 3 ¦ Ester Resin prepared from diethylene 100 100 I glycol, trimethylolethane and adipic 4 ~ acid l 65/35 TDI 50.1 50.1 ¦ Stannous Octoate (1:1 by weight i in cresyl diphenyl phosphate) 0.4 0.4 6 1 Water 3-7 3-7 i Non-Silicon Surfactant - 1.5 1.5 7 ¦ Pigment, Black Dispersion 7.45 7.45 N-Ethyl morpholine 0.5 0.5 Dimethyl hexadecyl amine 0.5 0.5 I N-cocomorpholine (4:1 by weight 9 1 in mineral oil) 1.0 1.0 i ¦ Tris(1,3-Dichloropropyl) phosphate 20.0 20.0

10 1 Tris(Methoxymethyl)-tris(Hydroxymethyl) Melamine ---- 5.0 Foam Density, pounds per cubic foot 2.26 2.02 I Bread slices of each foam were cut in sufflcient number so that U ¦ 10 UL 94 test samples each could be cut from identical places in the top, I
14 1 middle, and bottom thirds of each slice. Permeabilities were determined t5 ¦ on each sample~ and then half the number of sample3 from each location were 16 ¦ sub~ected to UL 94 before, and the other half after storage at 70C.
; 17 ¦ for a week. The UL 94 results below in Table VI are therefore averages I
18 ¦ of 5 samples each, for each test.
19 ~ TABLE VI
1 Origin81 Material Foam 43 Foam 44 21 ~ Permeability:

i cubic feet per minute 2z 1 Top (T) 2.14 1.98 Middle (M~ 2.13 2.00 23 ~I Bottom (B) 2.21 2.03 24 !1 T M B T _ B

Ignition Test: ¦
Burn time, secs. 53.5 49.7 45;3 44.0 41.5 45.3l 26 ; Burn extent, inches 2.30 2.12 1.7 1.59 1.30 1.19¦
i Dripping Embers Yes Yes Yes No No No l~
27 ~ Embers Ignite Cotton No No No No No No j jl Sa~ple Burn Failures 3Of5 lof5 0Of5 0Of5 0Of5 0Of5 28 ~1 ¦ Aged Material 29 ~j ' Ignition Burn Time, secs.53.4 43.7 44.0 45.5 44.6 44.7 30 I Burn extent, inches 2.23 1.87 1.59 1.36 1.31 1.27 .

~ ~096~

TABL~ Vl (cantlnued) 2 Foam 43 Foam 44 T M B T M B
4 1 Dripping Embers Yes Yes Yes No No No l Embers Ignite Cotton No No No No No No 1 Sample Burn Failures 2Of5 lof5 0Of50Of5 0Of5 0Of5 6 ¦ From Table VI, it can be seen that the additive of this invention not only 7 1 improves flame retardancy, but makes the foam more uniform, from top to 8 ¦ bottom, in both permeability and flame retardancy.
9 ¦ Examples 45 to 47 ¦ While the instant invention shows to excellent advantage in

11 1 flame retardancy, another desirable use is to control the stiffness, or

12 hand, of the foam, at will.

13 Three highly open, primarily ester-resin-based foams are made

14 essentially according to the procedure of U.S. Patent No. 3,884,848, issued ¦ May 20, 1975, naming Ricciardi, Cordora and Smudin as inventors, using 16 the following formulations:

19 Foam Foam Foam 21 Ester resin derived from diethylene90 pbw 90 pbw 90 pbw glycol, trimethylol propane and 22 ! adipic acid Propoxylated glycerol l0 l0 l0 23 'j Toluene Diisocyanate (80/20) 45.1 48.1 49.1 1 Silicon Surfactant 3.2 3.2 3.2 24 ! Stannous Octoate (l:l by weight 0.45 0.45 0.45 l1 in cresyl diphenyl phosphate `! Pigment Black Dispersion 3.0 3.0 3.0 - il N-ethyl morpholine 0.l 0.l 0.l 26 `I Triethylenediamine (33 percent Il by weight in dipropylene glycol) 0.4 0.4 0.4 27 ,I Water 3.58 3.58 3.58 ! Octadecyl methacrylate 3.0 3.0 3.0 28 Tris(hydroxymethyl~ melamine ----- l0.0 l0.0 Benzophenone Tetracarboxylic ----- ----- 3.0 29 j Dianhydride .i 1 , --1 q-- ~

~' 1109~0 1 ~ All three foams are essentially equal in physical properties, 2 ¦ including hand, density and appearance, of quality and appearance most useful 3 ¦ in making textile linings of uniformly delustered grey attractiveness. In ¦ the laboratory, the three are essentially equal in flame laminatability, ¦ but with Foam 47 giving a slightly crisper hand (as desired in U.S. trade) 6 ¦ than Foams 45 and 46. When the laminates are heat-cured, as on heated rolls or in ovens for less than 5 minutes at or above 300F., then the Foam 46 laminate becomes crisper than the Foam 45 laminate, and the Foa~ 47 becomes I
9 1 sturdy in hand.
¦ Examples 48 to 50 ¦ Three industrial grade lab foams are made using the following 12 ¦ ingredients in parts by weight:
13 1 Parts ~4 ¦ Polyester derived from diethylene glycol, 85.0 I trimethylolpropane, and adiplc acid:
j 15 1 mol. wt. 2000, hydroxyl no. 52 I l Propoxylated glycerol: mol. wt. 3500, 7.0 16 ¦ hydroxyl no. 48 Tolylene diisocyanate (80/20)* 49.4 17 1 Ethoxypropoxylated polysiloxane 3.5 Polydimethylsiloxane (viscosity 50cs) 0.6 ~8 l Water 3-5 Stannous octoate solution, 50% in tricresyl 0.2 19 1 phosphate I N-ethylmorpholine O.l 1 Triethylenediamine solution, 33% in dipropylene glycol 0-~5 21 ~ Brown pigment dispersion in tricresyl phosphate3.0 l Tribromoneopentyl alcohol solution, 60% in 2t 1 3000 mol. wt. propoxylated glycerol 20.0 23 *80/20 weight ratio of 2,4- and 2,6-tolylene diisocyanate.
24 ,I Foams 49 and 50 also contained in the following additional ingredients in , parts by weight:
26 , Foam 49 Foam 50 27 i Tris(hydroxymethyl) melamine lS 15 28 , Hydroxylated epoxy resin 0 5 29 ~ All three foams before oven cured are essentially equally firm, 1 30 ¦ but after being oven cured (200 degrees F., one-half hour) Foam 49 is .

11~96~0 1 slightly and Foam 50 somewhat less limp, in thin sections, than is Foam 48.2 1 Oven curing each foam at 300 degrees F. for three minutes accentuates the 3 firmness differences, with Foam 50 alone becoming self-standing in one inch4 thicknesses. All three foams with or without added heat treatment show essentially equal dust filtration capacities. In UL 94-type ignition 6 tests, Foam 48 shows about the same time and extent of burn as does Foams 49 and 50, but 11ke those tto, dr1ps bur=1ng c~bers t~at lgnlte cotton.

i ; ~6~)0 1~ ' ~ !¦ Although the novel polyurethane foams of the present invention 2 ~I can-be made by any of the batch-type and continuous-type processes known 3 in the art, it is preferred to use the one-shot process and to prepare the 4 I foams continuously in the form of large buns having a circular or nearly S ¦ circular, or a rectangular or nearly rectangular, cross section.
6 I Typically, the one-shot process comprises the steps of: (1) 7 combining separate streams of (a) one, or a mixture of two or more, polyols 8 ¦ maintained at a temperature of between about 19C and 30C and preferably 9 between 21C and 24~C, (b~ an organic polyisocyanate, or a mixture of two or more organic polyisocyanates, maintained at a temperature of between 1l about 18C and 27C, preferably between 21C and 24~C, and (c~ a mixture l2 of one or more amine catalysts and blowing agent, in a mixing chamber;
13 (2) forming a uniform mixture from the separate streams; and (3~ discharging ~14 ¦ the mi`xture into a mpld or onto a casting surface where the foaming re-15 ¦ action commences and the foam rises. When additional components of a .
16 foam-forming reaction mixture are used, these can be supplied to the mixing 17 chamber as additional separate streams or can be combined with other streams, 1~ depending on the characteristics of the components and on the number of 19 inlets to-the mixing chamber of the apparatus being used Thus~ separate -¦ streams can be used for flame retardants, pigment or colorant dispersions, 21 I and tin catalyst (when used). Although surfactants and dispersing agents 22 1I can be introduced as a separate stream, it is convenient to add them to~ li .
23 ' gether with amine catalyst (or catalysts) and water (blowing agent) in the form of a pre-blend or activator. If additional water is used to alter I the density of the foam, it ca~ be introduced as a separate stream if de-26 sired. In~ the practice of the present invention it is preferred to add 27 ~I the compound of the formula Il .

6'~

A N G
~_ C ~ C_ N /

~ C
6 ¦ D E

8 as a separate stream, although it can be combined with another stream if 9 jdesired provided that it ls compatible with and unaffected by the other lo ¦components of the stream. The streams other than the polyol and the iso-ll ¦cyanate streams are less critical with respect.to temperature and can be 12 ¦maintained be.tween about 15C and 50C, but preferably between about 20C
13 ¦and 30C. I
14 I A representative apparatus for continuous production of polyurethane ¦foam in the form of slabs or buns can comprise accurate mete~ring or pumping16 unlts far each stream (with means for accurate temperature control where 17 necessary), an efficient mixing head capable of handling three or more 18 streams of components and rapidly forming a uniform blend thereof, outlet 19 means for del~vering the blend of reactants onto a casting surface at a deposit station and a continuously-moving conveyor to carry the reaction 21 mixture on the casting surface away from the outlet means and through 22 , shaping means to form the rising foam into a desired cross-sectional con-23 ~ figuration. Examples of suitable apparatus for making buns of a generally 24 circular cross-section include those disclosed by Buff et al in U. S. Patent 2i 1 3,296,658, and by Ferstenberg in U.S. Patent 3,659,981. Any other suitable 26 ~ apparatus known in the art may also be employed. The apparatus used to 27 1 make the novel polyurethane foam of this invention does not, per-se, 28 1l constitute a part of the invention.
29 il Of the preceding examples, Examples 36, 44, 46, and 47 were made ¦¦ by the one-shot process using metering and mixing equipment as described It .
1`! -23-6~
:: i 1 in the preceding paragraph, and an apparatus for forming a continuous bun ~a~- 2 1~with an essentially circular cross section as disclosed in P.S, Paten~
¦ 33,296,658. By way of further ~llustraeion, in Example 36 the separate 4Istreams fed into the mixing head were (a2 polyester, (b2 65!35 TDI, (c2 carbon black dispersion, (d~ stannous octoate, (e) tris (hydroxymethyl) -6 tris (methoxymethyl) melamine, (f) tris (1,3-dichloropropyl) phosphate, and (g~ an activator comprising a blend of water, N-cocomorpholine, 8 1dimethylhexadecylamine, N-ethylmorpholine, and non-silicon cell control 9 agent. ~hile being fed into the mixing head, the polyester was maintainedto~ at a temperature of between 21C and 24Ç, and the TDI was maintained at 11 Ithe same temperature. The other components fed into the mixing head were U ¦at ambient te=p ~ature. ,~

t9 : 27 30 ~ ~

I!

Claims (18)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the manufacture of a flexible, resilient, poly-urethane foam by the steps of (1) forming a reaction mixture comprising at least one polyol, at least one organic polyisocyanate, at least one catalyst, and a blowing agent, the amount of said polyisocyanate being at least one equivalent per equivalent of the total of said polyol and said blowing agent, by introducing into a mixing chamber said polyol maintained at a temperature between about 19°C and about 30°C said polyisocyanate maintained at a temperature between about 18°C and 27°C, said catalyst maintained at a temperature between about 15°C and about 50°C, and said blowing agent main-tained at a temperature between about 15°C and about 50°C, (2) blending said reaction mixture until it is uniform, and (3) discharging said reaction mixture onto a casting surface, characterized by incorporating into said reaction mixture at least one compound of the formula in said formula A, B, D, E, F, and G being selected from the group consisting of hydrogen, methylol, and ROCH2- wherein R is an alkyl radical containing from one to four carbon atoms, with the proviso that in said formula at least one of A, B, D, E, F and G is methylol or ROCH2-, the amount of said compound being from one to about 20 percent by weight based on the weight of said polyol, and the temperature of said compound being maintained at between about 15°C and 50°C while being introduced into said mixing chamber, whereby a polyurethane foam having a reduced tendency to form incendiary embers when the foam is burned is obtained.

2. The process of claim 1 wherein said compound is tris-(hydroxymethyl) melamine.

3. The process of claim 1 wherein said compound is tris-(hydroxymethyl)-tris-(methoxymethyl) melamine.

4. The process of claim 1 wherein said compound is hexa-(methoxymethyl) melamine.

5. The process of claim 1 wherein the reaction mixture also comprises at least one halogenated phosphorus ester in amount sufficient to increase the flame retardant properties of the foam, the temperature of said phosphorus ester being maintained at between about 15° and 50°C while being introduced into said mixing chamber.

6. The process of claim 5 wherein the amount of said halogenated phosphorus ester is from four to twenty percent by weight, based upon the weight of the polyol.

7. The process of claim 5 wherein said halogenated phosphorus ester is tris-(2-chloroethyl) phosphate.

8. The process of claim 5 wherein said halogenated phosphorus ester is tris-(1,3-dichloropropyl) phosphate.

9. The product of the process of claim 1.

10. The product of the process of claim 2.

11. The product of the process of claim 3.

12. The product of the process of claim 4.

13. The product of the process of claim 5.

14. The product of the process of claim 6.

15. The product of the process of claim 7.

16. The product of the process of claim 8.

17. The process of claim 1 wherein the following are introduced into said mixing chamber: said polyol maintained at a temperature between 21°C
and 24°C, said polyisocyanate maintained at a temperature between 21°C and 24°C, said catalyst maintained at a temperature between 20°C and 30°C, and said blowing agent maintained at a temperature between 20°C and 30°C, the temperature of said compound being maintained at between about 20°C and 30°C
while being introduced into said mixing chamber.

18. The process of claim 5 wherein the temperature of said phosphorus ester is maintained at between about 15°C and 50°C while being introduced into said mixing chamber.