Alkoxylated Mannich condensates having fire retardancy properties and manufacture of rigid polyurethane foam therewith
BACKGROUND OF THE INVENTION 
     1. Technical Field of the Invention 
     This invention relates to Mannich condensates useful in the manufacture of rigid polyurethane foam. More particularly, this invention relates to modified Mannich condensates, to the manufacture from their propoxylation products, and to the synthesis therefrom of rigid polyurethane foams having improved fire retardancy properties. The invention is based upon the discovery that unique polyols are provided when melamine is reacted with formaldehyde in the presence of a particular class of Mannich condensates to provide a reaction product that is then alkoxylated with propylene oxide. 
     2. Prior Art 
     Johnson U.S. Pat. No. 4,369,258 is directed to polyurethane foams prepared by reacting a polyisocyanate with a mixture of a melamine polyol with a polyol derived from a polyester or a polyether polyol. 
     Yukuta et al. U.S. Pat. No. 4,221,875 is directed to rigid polyurethane foams having flame resistance which are prepared from a mixture comprising a polyhydroxy compound such as an ethylene oxide adduct of a material containing a plurality of hydroxyl groups such as sucrose or sorbitol, an organic polyisocyanate, a blowing agent and powdered melamine. From 20 to 60 parts by weight of powdered melamine per 100 parts of polyhydroxy compound are recommended. 
     Pcolinsky, Jr. U.S. Pat. No. 4,317,889 and the numerous U.S. patents cited therein disclose the use of melamine derivatives such as hydroxymethyl melamines, melamine phosphate, hexaalkoxymethylmelamine, etc. as a component for use in the manufacture of flexible polyurethane foams. 
     Edwards et al. U.S. Pat. No. 3,297,597 is directed to Mannich condensates of a phenolic compound, formaldehyde, and an alkanolamine which are then alkoxylated, preferably with propylene oxide, to provide polyols useful in the manufacture of rigid polyurethane foams. 
     Edwards et al. U.S. Pat. No. 4,137,265 is similarly directed to Mannich condensates prepared by reacting phenol with formaldehyde and diethanolamine which are then propoxylated and used in the manufacture of rigid polyurethane foam. 
     SUMMARY OF THE INVENTION 
     In one aspect, the present invention is directed to polyols prepared by alkoxylating a reaction product prepared by reacting melamine with formaldehyde in admixture with a particular class of Mannich condensates prepared from a phenol, formaldehyde and diethanolamine. 
     In another aspect of the present invention, a modified polyol based upon a Mannich condensate, as just described, is reacted with an organic polyisocyanate in the presence of a blowing agent, a catalyst, and other appropriate components, in order to manufacture a rigid polyurethane foam having improved fire retardancy properties. 
    
    
     DETAILED DESCRIPTION 
     The Modified Polyol 
     The principal components of the present invention are melamine, formaldehyde, a Mannich condensate of a phenol, formaldehyde and diethanolamine and propylene oxide. A minor amount of ethylene oxide may also be used, if desired. 
     The phenolic compound to be employed in accordance with the present invention is a phenol having a hydrogen atom on one or more of the ring positions ortho and para to the hydroxyl group and which is otherwise unsubstituted or substituted with a C1-C2 straight chain or branched chain alkyl group. Representative compounds include phenol, methylphenol, ethylphenol, propylphenyl, hexylphenol, nonylphenol, dodecylphenol, etc. 
     The phenolic compound is reacted with formaldehyde and diethanolamine to form a Mannich condensate. Formaldehyde may be employed in its conventional form, as an aqueous formalin solution, in &#34;inhibited&#34; methanol solution, as paraformaldehyde, or as trioxane. 
     For example, the Mannich reaction is conducted by premixing the phenolic compound with a desired amount of the diethanolamine and then slowly adding formaldehyde to the mixture at a temperature below the temperature of Novolak formation (a temperature that will vary with the phenolic compound employed and is a temperature of less than about 45° C. when phenol itself is employed). 
     At the end of the reaction, water is stripped from the reaction mixture to provide thereby a crude Mannich reaction product. Although it is within the scope of the present invention to separate the crude reaction product by conventional means into specific components or fractions, it is a feature of the present invention that the entire crude Mannich reaction product may be used as such without isolation of individual components thereof. In accordance with the preferred embodiment of the present invention, the entire crude Mannich reaction product is used. 
     In accordance with the present invention, from about 3 to about 10% by weight of melamine is mixed with a Mannich condensate as just described and then from about 1 to about 6 mols of formaldehyde, based on the melamine are reacted with this mixture at a temperature of about 80° to about 150° C. for about 1 to 5 hours to form a modified reaction product. This reaction product is then alkoxylated with propylene oxide or with propylene oxide and ethylene oxide. The alkylene oxide component may suitably comprise 100% to about 90% propylene oxide and 0 to about 20 wt.% ethylene oxide and may comprise about 20% to about 50% of the alkoxylation product. 
     The alkoxylation with propylene oxide is simply carried out by introducing the propylene oxide, preferably under pressure, into a vessel containing the modified Mannich reaction product. No added catalyst is needed since the basic nitrogen in this product provides sufficient catalytic activity to promote the reaction. Temperatures between about 30° C. and about 200° C. may be employed but the preferred temperatures are in the range of about 90° to 120° C. Under these conditions the phenolic hydroxyl group and the alkanol amino hydroxyls are reactive to form hydroxypropyl groups. The final condensation products are separated from unreacted and partially reacted materials by vacuum stripping and are obtained as clear amber to brown liquids having hydroxyl numbers in the range of 400 to 550 and viscosities between about 10,000 and 45,000 centipoises at 25° C. 
     The final condensation product is cooled and, if necessary, filtered to remove excess undissolved melamine. 
     MANUFACTURE OF RIGID POLYURETHANE FOAM 
     The physical components utilized for the manufacture of a rigid polyurethane foam are the polyols, an organic polyisocyanate, a blowing agent, a surfactant, a catalyst and suitable fire retardants and other additives. 
     The polyol component in the present invention comprises a modified propoxylated Mannich condensate as just described used alone or in admixture with from about 10 to about 60 parts by weight of a polyoxypropylene polyol having hydroxyl number between 200 and 800, preferably, between 300 and 700 and more preferably between about 400 and about 600, and a functionality of 2 to 6, and preferably from about 3 to 6. 
     Normally, propylene oxide will constitute from about 15 to about 95 wt.% of the total polyol composition, up to about 10 wt.% of ethylene oxide may be utilized if desired, based on the weight of the propylene oxide. 
     A wide variety of initiators may be alkoxylated to form useful polyoxypropylene polyols. Thus, for example, polyfunctional amines and alcohols of the following type may be alkoxylated: monoethanolamine, diethanolamine, triethanolamine, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, glycerine, sorbitol, and trimethylolpropane. 
     Such above amines or alcohols may be reacted with an alkylene oxide such as ethylene oxide, propylene oxide, or mixed ethylene oxide and propylene oxide using techniques known to those skilled in the art. Thus, for example, the reaction of alkylene oxides with initiators of this type is set forth in U.S. Pat. Nos. 2,948,757 and 3,000,963. Essentially such alkoxylations are carried out in the presence of a basic catalyst at a temperature sufficient to sustain the reaction. The hydroxyl number which is desired for the finished polyol will determine the amount of alkylene oxide used to react with the initiator. The oxypropylene polyol may be prepared by reacting the initiator with propylene oxide or ethylene oxide, or by reacting the initiator first with propylene oxide followed by ethylene oxide or vice versa in one or more sequences to give a so-called block polymer chain or by reacting the initiator with a mixture of propylene oxide and ethylene oxide to achieve a random distribution of such alkylene oxides. As noted above, the polyoxypropylene polyols useful here have a hydroxyl number ranging from about 200 to about 800. The reaction mixture is then neutralized and water and excess reactants are stripped from the polyol. 
     Any aromatic polyisocyanate may be used in the practice of the instant invention. Typical aromatic polyisocyanates include m-phenylene diisocyanate, p-phenylene diisocyanate, polymethylene polyphenylisocyanate, 2,4-toluene diisocyanate, 2,6-tolylene diisocyanate, dianisidine diisocyanate, bitolylene diisocyanate, naphthalene-1,4-diisocyanate, diphenylene-4,4&#39;-diisocyanate, aliphatic-aromatic diisocyanates, such as xylylene-1,4-diisocyanate, xylylene-1,2-diisocyanate, xylylene-1,3-diisocyanate, bis(4-isocyanatophenyl) methane, bis(3-methyl-4-isocyanatophenyl) methane, and 4,4&#39;-diphenylpropane diisocyanate. 
     Preferred aromatic polyisocyanates used in the practice of the invention are methylene-bridged polyphenyl polyisocyanate mixtures which have a functionality of from about 2 to about 4. These latter isocyanate compounds are generally produced by the phosgenation of corresponding methylene bridged polyphenyl polyamines, which are conventionally produced by the reaction of formaldehyde and primary aromatic amines, such as aniline, in the presence of hydrochloric acid and/or other acidic catalysts. Known processes for preparing the methylene-bridged polyphenyl polyamines and corresponding methylene-bridged polyphenyl polyisocyanates therefrom are described in the literature and in many patents, for example, U.S. Pat. Nos. 2,683,730; 2,950,263; 3,012,008; 3,344,162; and 3,362,979. 
     The more preferred methylene-bridged polyphenyl polyisocyanate mixtures used here contain from about 20 to about 100 wt.% methylene diphenyl diisocyanate isomers with the remainder being polymethylene polyphenyl diisocyanates having higher functionalities and higher molecular weights. Typical of these are polyphenyl polyisocyanate mixtures containing about 20 to 100 wt.% methylene diphenyl diisocyanate isomers, of which 20 to about 95 wt.% thereof is the 4,4&#39;-isomer with the remainder being polymethylene polyphenyl polyisocyanates of higher molecular weight and functionality that have an average functionality of from about 2.1 to about 3.5. The isocyanate mixtures are known materials and can be prepared, for example, by the process described in U.S. Pat. No. 3,362,979, issued Jan. 9, 1968 to Floyd E. Bentley. 
     In the production of rigid polyurethane foams in the practice of the invention, other known additives are necessary. One such constituent is the blowing agent. Some examples of such materials are trichloromonofluoromethane, dichlorodifluoromethane, dichloromonofluoromethane, 1,1-dichloro-1-fluoromethane, 1,1-difluoro-1,2,2-trichloroethane, chloropentafluoroethane, and the like. Other useful blowing agents including low-boiling hydrocarbons such as butane, pentane, hexane, cyclohexane, and the like. See U.S. Pat. No. 3,072,582, for example. 
     The catalysts which may be used to make the foams are well known. There are two general types of catalyst, tertiary amines and organo-metallic compounds. Examples of suitable tertiary amines, used either individually or in mixture, are the N-alkylmorpholines, N-alkylalkanolamines, N,N-dialkylcyclohexylamines and alkylamines where the alkyl groups are methyl, ethyl, propyl, butyl, etc. Examples of specific tertiary amine catalysts useful in my invention are triethylenediamine, tetramethylethylenediamine, triethylamine, tripropylamine, tributylamine, triamylamine, pyridine, quinoline, dimethylpiperazine, dimethylhexahydroaniline, dimethylpiperazine, N-ethylmorpholine, dimethylaniline, nicotine, dimethylaminoethanol, tetramethylpropanediamine, and methyltriethylenediamine. Organo-metallic compounds useful as catalysts include those of bismuth, lead, tin, titanium, iron, antimony, uranium, cadmium, cobalt, thorium, aluminum, mercury, zinc, nickel, cerium, molybdenum, vanadium, copper, manganese, zirconium, etc. Some examples of these metal catalysts include bismuth nitrate, lead 2-ethylhexoate, lead benzoate, lead oleate, dibutyltin dilaurate, tributyltin, butyltin trichloride, stannic chloride, stannous octoate, stannous oleate, dibutyltin di(2-ethylhexoate), ferric chloride, antimony trichloride, antimony glycolate, tin glycolates, etc. Selection of the individual catalysts and proportions to use in the polyurethane reaction are well within the knowledge of those skilled in the art, and an amine and organo-metallic compound are often used together in the polyurethane reaction. 
     Conventional formulation ingredients are also employed, such as, for example, foam stabilizers also known as silicone oils or emulsifiers. The foam stabilizer may be an organic silane or siloxane. For example, compounds may be used having the formula: 
     
         RSi[O--(RSiO).sub.n --(oxyalkylene).sub.m R].sub.3 
    
     wherein R is an alkyl group containing from 1 to 4 carbon atoms; n is an integer of from 4 to 8; m is an integer of 20 to 40; and the oxyalkylene groups are derived from propylene oxide and ethylene oxide. See, for example, U.S. Pat. No. 3,194,773. 
     The flame retardancy of the polyurethane composition can be enhanced by using known fire retardants. Examples of suitable flame retardants are: tris(1,3-dichloropropyl)phosphate, tris(2,3-dibromopropyl)phosphate, 2,2-bis(chloromethyl)-1,3 propylene bis[-di(2-chloroethyl)phosphate], tris(2-chloroethyl)phosphate, tris(2-chloropropyl)phosphate, bis(dichloropropyl)tribromopentyl phosphate, tetrakis(2-chloroethyl)ethylene diphosphate (sold by Olin Chemicals as THERMOLIN®101), FYROL®EFF (oligomeric chloroalkyl phosphate, sold by Stauffer Chemical Co.), tricresyl phosphate, cresyl diphenyl phosphate, chlorinated paraffin, and brominated paraffin. Halogenated phosphates are preferred flame retardants in the practice of this invention, especially tris(1,3-dichloropropyl)phosphate, tris(2-chloroethyl)phosphate, FYROL®EFF, and tetrakis(2-chloroethyl)ethylene disphosphate. Although a single flame retardant is preferred from the standpoint of simplicity of formulation, mixtures of two or more of the same type or of different types may be found to give improved performance in some cases, and such mixtures are included in the scope of this invention. The amount of flame retardant can be varied over a wide range of from about 20 to about 60 parts by weight per 100 parts by weight of polyol in the reaction mixture. It is preferred to use from about 20 to about 40 parts by weight. 
     The rigid polyurethane foams prepared here can be made in one step by reacting all the ingredients together at once (one-shot process) or the rigid foams can be made by the so-called &#34;quasi-prepolymer method&#34;. In accordance with this method, a portion of the polyol component is reacted in the absence of a catalyst with the polyisocyanate component in proportion so as to provide from about 20 percent to about 40 percent of free isocyanato groups in the reaction product, based on the polyol. To prepare foam, the remaining portion of the polyol is added and the two components are allowed to react in the presence of a catalyst and other appropriate additives such as blowing agents, foam stabilizing agents, fire retardants, etc. The blowing agent, the foam stabilizing agent, the fire retardant, etc., may be added to either the prepolymer or remaining polyol, or both, prior to the mixing of the component, whereby at the end of the reaction a rigid polyurethane foam is provided. 
     SPECIFIC EXAMPLES 
     Example A 
     A. Incorporation of Soluble Polymethylol Melamine into Aromatic Amino Polyol Mannich Condensates (5474-09) 
     A 1-liter three-neck round bottom flask, equipped with a mechanical stirrer, thermometer and condenser, was charged with 500.0 g R-350-X (5031-72-13B or -12B; equimolar phenol (formaldehyde/diethanolamine, water stripped, no propylene oxide) or R-650-X (5327-12-4; 1:2:2 mols monononylphenol (formaldehyde/diethanolamine, water stripped, no propylene oxide ) Mannich condensates and 27.0 g (0.2140 mol) melamine. To this well stirred slurry, there was rapidly added 37% formalin to correspond to one to six mols inclusive of formaldehyde per mol of melamine (range, 17.4 g to 104.2 g 37% formalin). The whole was then heated to 100° C. and held for 3.0 hrs. Some solids still remained at this point. Water was stripped at aspirator pressure (˜25 mm) and 150° C. maximum and then liquid product recovered by hot filtration to remove solids. Product analyses follow: 
     
         __________________________________________________________________________
             R-350-X                                                      
NB           Cond.                                                        
                  5474-51                                                 
16                                                                        
09                                                                        
26                                                                        
52                                                                        
53                                                                        
mols CH.sub.2 O/mol melamine                                              
             0    1   2  3   4   5   6                                    
__________________________________________________________________________
OH No.       539  817 796                                                 
                         828 808 821 804                                  
Total amine, meq/g                                                        
             --   4.69                                                    
                      4.62                                                
                         4.65                                             
                             4.69                                         
                                 4.90                                     
                                     4.73                                 
% Nitrogen   6.52 7.42                                                    
                      7.37                                                
                         8.43                                             
                             8.58                                         
                                 9.20                                     
                                     9.26                                 
% Water      --   0.35                                                    
                      0.17                                                
                         0.57                                             
                             0.08                                         
                                 0.10                                     
                                     0.11                                 
Viscosity (210° F.), cs                                            
             --   70.6                                                    
                      128                                                 
                         6359                                             
                             734 2039                                     
                                     2241                                 
pH [10/l(MeOH/H.sub.2 O)]                                                 
             --    9.8                                                    
                      9.7                                                 
                         9.6 9.6 9.8 9.6                                  
__________________________________________________________________________
NB           Cond.                                                        
                  5474-57                                                 
18                                                                        
12                                                                        
28                                                                        
58                                                                        
59                                                                        
mols CH.sub.2 O/mol melamine                                              
             0    1   2  3   4   5   6                                    
__________________________________________________________________________
OH No.       456  563 544                                                 
                         527 529 518 527                                  
Total amine, meq/g                                                        
             --   4.16                                                    
                      4.36                                                
                         4.25                                             
                             4.25                                         
                                 4.10                                     
                                     4.05                                 
% Nitrogen   6.04 7.34                                                    
                      7.62                                                
                         6.61                                             
                             8.80                                         
                                 8.30                                     
                                     8.95                                 
% Water      --   0.06                                                    
                      0.06                                                
                         0.20                                             
                             0.27                                         
                                 0.92                                     
                                     1.07                                 
Viscosity (210° F.), cs                                            
             --   413 785                                                 
                         856 1107                                         
                                 858 1011                                 
pH [10/l(MeOH/H.sub.2 O)]                                                 
             --   9.8 9.7                                                 
                         9.7 9.5 9.4 9.5                                  
__________________________________________________________________________
 
    
     B. Propoxylation of Polymethylol Melamine Modified Mannich Condensates 
     The modified condensates prepared in Example A were propoxylated (82.5 g or 99.4 ml PO/g of R-350-X condensate and 51.2 g or 61.6 ml PO/g of R-650-X condensate) at 100°-105° C. in an uncatalyzed reaction by a standard procedure well known to those skilled in the art. The resulting polymethylol melamine modified aromatic amino polyols analyzed as follows: 
     
         __________________________________________________________________________
Precursor (Ex. A)                                                         
            --   5474-51                                                  
16                                                                        
09                                                                        
26                                                                        
52                                                                        
53                                                                        
Aromatic Amino Polyol                                                     
            R-350-X                                                       
                 5474-70-1                                                
42-5                                                                      
42-4                                                                      
42-6                                                                      
70-2                                                                      
70-3                                                                      
__________________________________________________________________________
OH No.      534  514  497 512  504 500  476                               
Total Amine, meq/g                                                        
            2.8  2.71 2.72                                                
                          2.72 2.76                                       
                                   2.55 1.63                              
% Nitrogen  3.92 4.20 4.27                                                
                          4.80 5.11                                       
                                   5.33 5.37                              
Viscosity (25° C.), cs                                             
            14,500                                                        
                 15,440                                                   
                      24,911                                              
                           19,906                                         
                               --  302  329                               
                          (100° F.)                                
                                   (210° F.)                       
                                        (210° F.)                  
% H.sub.2 O 0.02 0.01 0.01                                                
                          0.04 0.01                                       
                                   0.05 0.01                              
Gardner color                                                             
            --   12-13                                                    
                       11 10-11                                           
                               10-11                                      
                                   12   12-13                             
pH [10/l(MeOH/H.sub.2 O)]                                                 
            11.2 11.1 11.7                                                
                          11.7 11.8                                       
                                   11.6 11.7                              
__________________________________________________________________________
Precusor (Ex. A)                                                          
             --    5474-71-1                                              
18                                                                        
12                                                                        
28                                                                        
59                                                                        
Aromatic Amino Polyol                                                     
             R-650-X                                                      
                   5474-71-1                                              
63-5                                                                      
63-4                                                                      
63-6                                                                      
71-3                                                                      
__________________________________________________________________________
OH No.       455   403  373  392  376   409                               
Total Amine, meq/g                                                        
             3.00  2.87 2.79 3.22 2.84  2.91                              
% Nitrogen   4.20  4.94 5.53 6.20 6.03  6.09                              
Viscosity (25° C.), cs                                             
             28,000                                                       
                   61,788                                                 
                        94,189                                            
                             144,366                                      
                                  147,376                                 
                                        43,969                            
                                        (100° F.)                  
% H.sub.2 O  0.02  0.01 0.01 0.01 0.26  0.02                              
Gardner color                                                             
             --    13-14                                                  
                         16   15  16-17 &gt;18                               
pH [10/l(MeOH/H.sub.2 O)]                                                 
             10.6  11.1 11.2 11.5 11.1  11.1                              
__________________________________________________________________________
 
    
     C. Rigid Polyurethane Foams (5474-65) 
     Rigid polyurethane foams were prepared from R-350-X and R-650-X standards and selected polymethylol melamine modified aromatic amino polyols listed in Ex. B. The formulation components were mixed at 2700 rpm and poured into an 8&#34;×8&#34;×12&#34; open mold and allowed to rise. The resulting foams were allowed to stand at room temperature for 3 days before testing. Formulations and foam physical properties are listed below. 
     
         __________________________________________________________________________
                5474-                                                     
Formulation, pbw                                                          
                35-1                                                      
                    77-4                                                  
                        65-6                                              
                            66-1                                          
                                73-5                                      
                                    73-4                                  
                                        73-6                              
__________________________________________________________________________
R-350-X (OH = 534)                                                        
                36.0                                                      
                    --  --  --  --  --  --                                
5474-70-1 (OH = 514)                                                      
                --  36.8                                                  
                        --  --  --  --  --                                
42-5 (OH = 497) --  --  37.5                                              
                            --  --  --  --                                
R-650-X (OH = 455)                                                        
                --  --  --  39.4                                          
                                --  --  --                                
5474-63-5 (OH = 373)                                                      
                --  --  --  --  43.7                                      
                                    --  --                                
4 (OH = 392)    --  --  --  --  --  42.6                                  
                                        --                                
6 (OH = 376)    --  --  --  --  --  --  43.5                              
Silicone DC-183  0.5                                                      
                    →                                              
                        →                                          
                            →                                      
                                →                                  
                                    →                              
                                        →                          
Freon R-11B     13.0                                                      
                    →                                              
                        →                                          
                            →                                      
                                →                                  
                                    →                              
                                        →                          
Mondur MR (index = 1.10)                                                  
                50.5                                                      
                    49.7                                                  
                        49.0                                              
                            47.1                                          
                                42.8                                      
                                    43.9                                  
                                        43.0                              
Times (sec), Mixing                                                       
                 15 12  14  12   8   6   8                                
Cream            26 17  18  17  12   8  12                                
Gel             104 50  60  57  29  29  26                                
Tack Free       134 66  66  62  34  31  30                                
Rise            141 96  98  99  64  55  75                                
Initial Surface Friability                                                
                none                                                      
                    →                                              
                        →                                          
                            →                                      
                                →                                  
                                    →                              
                                        →                          
Foam Apprarance good                                                      
                    →                                              
                        →                                          
                            →                                      
                                →                                  
                                    →                              
                                        →                          
Physical Properties                                                       
Density, lbs/ft.sup.3                                                     
                2.05                                                      
                    1.94                                                  
                        2.05                                              
                            2.13                                          
                                2.29                                      
                                    2.23                                  
                                        2.33                              
K-Factor        0.122                                                     
                    0.111                                                 
                        0.112                                             
                            0.115                                         
                                0.123                                     
                                    0.116                                 
                                        0.121                             
Comp. Str. (psi), .sup.--w rise                                           
                48.89                                                     
                    47.77                                                 
                        51.48                                             
                            47.86                                         
                                28.78                                     
                                    38.44                                 
                                        41.48                             
-x rise         16.17                                                     
                    19.22                                                 
                        20.79                                             
                            16.25                                         
                                24.83                                     
                                    24.23                                 
                                        23.31                             
% Closed Cells  92.3                                                      
                    94.4                                                  
                        92.9                                              
                            93.2                                          
                                91.8                                      
                                    93.7                                  
                                        92.2                              
Friability (% wt loss, 10 min)                                            
                 3.9                                                      
                     4.6                                                  
                         3.3                                              
                             3.5                                          
                                 8.5                                      
                                     3.9                                  
                                         5.4                              
Heat Distortion, °C.                                               
                171 170 147 155 168 168 163                               
ASTM 1692 Burn, in/min (BHA)                                              
                2.124                                                     
                    2.868                                                 
                        2.904                                             
                            2.970                                         
                                2.262                                     
                                    2.346                                 
                                        2.916                             
__________________________________________________________________________
 
    
     Polymethylol melamine modified R-350-X foams gave better K-factors and improved compressive strength. A faster reaction profile was also observed. 
     Modified R-650-X foams gave an increased heat distortion temperature and decreased tendency to burn. Reaction profiles were also faster. 
     EXAMPLE B 
     A. Incorporation of Soluble Polymethylol Melamine into Aromatic Amino Polyols (5474-11) 
     Preparation was identical to Example A employing 500.0 g THANOL®R-350-X (lot 1A-410, OH No.=534) or R-650-X (lot OV-408, OH No.=455), 27.0 g (0.2140 mol) melamine and 17.4 g to 104.2 g 37% formalin. Mol ratio of formaldehyde to melamine was 1-6. Homogeneous reaction products were obtained in all cases except the mol ratio 1 and 2 experiments. Product analyses follows: 
     
         __________________________________________________________________________
                  5474-                                                   
NB           R-350-X                                                      
                  54  17   11   27  55   56                               
mols CH.sub.2 O/mol melamine                                              
             0    1   2    3    4   5    6                                
__________________________________________________________________________
OH No.       534  516 496  502  498 482  498                              
Total Amine, meq/g                                                        
             2.8  3.00                                                    
                      3.05 3.11 3.10                                      
                                    3.02 3.07                             
% Nitrogen   3.92 5.73                                                    
                      6.83 7.11 7.00                                      
                                    6.98 7.14                             
% Water      0.02 0.10                                                    
                      0.33 0.25 0.02                                      
                                    0.94 0.57                             
Viscosity (25° C.), cs                                             
             14,500                                                       
                  32,071                                                  
                      52,792                                              
                           110,215                                        
                                74,526                                    
                                    82,471                                
                                         100,511 - Gardner                
                                         color -- 6-7 4-5 6-7 ˜4 4 4
                                         1                                
pH [10/l(MeOH/H.sub.2 O)]                                                 
             11.2 11.2                                                    
                      10.4 10.5 10.2                                      
                                    10.3 10.5                             
__________________________________________________________________________
                  5474-                                                   
NB           R-650-X                                                      
                  60  19   13   29  61   62                               
mols/CH.sub.2 O/mol melamine                                              
             0    1   2    3    4   5    6                                
__________________________________________________________________________
ON No.       455  444 432  428  420 440  414                              
Total Amine, meq/g                                                        
             3.00 3.13                                                    
                      3.24 3.22 3.24                                      
                                    3.22 3.28                             
% Nitrogen   4.20 6.17                                                    
                      7.37 7.43 7.24                                      
                                    7.30 7.24                             
% Water      0.02 0.25                                                    
                      0.01 0.09 0.11                                      
                                    0.10 1.13                             
Viscosity (25° C.), cs                                             
             28,000                                                       
                  61,907                                                  
                      183,788                                             
                           306,558                                        
                                --  495  492                              
                                    (210° F.)                      
                                         (210° F.)                 
Gardner color                                                             
             --   ˜15                                               
                      ˜15                                           
                           ˜16                                      
                                13-14                                     
                                    ˜13                             
                                         ˜14                        
pH [10/l(MeOH/H.sub.2 O)]                                                 
             10.6 9.9 10.0 10.1 9.9 9.7  9.8                              
__________________________________________________________________________
 
    
     B. Rigid Polyurethane Foams (5474-36) 
     Rigid polyurethane foams were prepared from R-350-X and R-650-X standards and selected polymethylol melamine modified aromatic amino polyols listed in Ex. B. The formulation components were mixed at 2700 rpm and poured into an 8&#34;×8&#34;×12&#34; open mold and allowed to rise. The resulting foams were allowed to stand at room temperature for 3 days before testing. Formulations and foam physical properties are listed below. 
     
         __________________________________________________________________________
                5474-                                                     
Formulation, pbw                                                          
                35-1                                                      
                    77-1                                                  
                        65-1                                              
                            66-1                                          
                                66-4                                      
                                    66-3                                  
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R-350-X (OH = 534)                                                        
                36.0                                                      
                    --  --  --  --  --                                    
5474-54 (OH = 516)                                                        
                --  36.7                                                  
                        --  --  --  --                                    
27 (OH = 498)   --  --  37.5                                              
                            --  --  --                                    
R-650-X (OH = 455)                                                        
                --  --  --  39.4                                          
                                --  --                                    
5474-19 (OH = 432)                                                        
                --  --  --  --  40.5                                      
                                    --                                    
13 (OH = 428)   --  --  --  --  --  40.7                                  
Silicone DC-193  0.5                                                      
                    →                                              
                        →                                          
                            →                                      
                                →                                  
                                    →                              
Freon R-11B     13.0                                                      
                    →                                              
                        →                                          
                            →                                      
                                →                                  
                                    →                              
Mondur MR (index = 1.10)                                                  
                50.5                                                      
                    49.8                                                  
                        49.0                                              
                            47.1                                          
                                46.0                                      
                                    45.8                                  
Time (sec), Mixing                                                        
                15  12   15 12  10  12                                    
Cream            26 17  24  17  15  17                                    
Gel             104 52  60  57  39  42                                    
Tack Free       134 59  69  62  44  50                                    
Rise            141 103 94  99  76  112                                   
Initial Surface Friability                                                
                none                                                      
                    →                                              
                        →                                          
                            →                                      
                                →                                  
                                    →                              
Foam Appearance good                                                      
                    →                                              
                        →                                          
                            →                                      
                                →                                  
                                    →                              
Physical Properties                                                       
Density, lbs/ft.sup.3                                                     
                2.05                                                      
                    1.96                                                  
                        1.74                                              
                            2.13                                          
                                2.12                                      
                                    2.25                                  
K-Factor        0.122                                                     
                    0.117                                                 
                        0.127                                             
                            0.115                                         
                                0.112                                     
                                    0.113                                 
Comp. Str. (psi), .sup.--w rise                                           
                48.89                                                     
                    37.35                                                 
                        31.30                                             
                            47.86                                         
                                44.57                                     
                                    44.31                                 
-x rise         16.17                                                     
                    20.23                                                 
                        10.13                                             
                            16.25                                         
                                15.32                                     
                                    13.64                                 
Heat Distortion, °C.                                               
                171 158 168 155 180 171                                   
% Closed Cells  92.3                                                      
                    94.1                                                  
                        89.0                                              
                            93.2                                          
                                93.5                                      
                                    93.7                                  
Friability (% wt loss, 10 min)                                            
                 3.9                                                      
                     1.9                                                  
                         6.1                                              
                             3.5                                          
                                 3.0                                      
                                     3.0                                  
ASTM 1692 Burn, in/min (BHA)                                              
                2.124                                                     
                    2.802                                                 
                        3.210                                             
                            2.970                                         
                                2.700                                     
                                    2.664                                 
Butler chimney Test                                                       
Flame height, in.                                                         
                &gt;11 &gt;11 &gt;11 &gt;11 &gt;11 &gt;11                                   
Sec. to extinguish                                                        
                 20  28  28  36  30  23                                   
% wt. retained  60.0                                                      
                    36.3                                                  
                        39.2                                              
                            26.7                                          
                                46.3                                      
                                    59.7                                  
__________________________________________________________________________
 
    
     Polymethylol melamine modified R-350-X foams gave faster reaction profiles and in certain cases lower K-factors and less friability. 
     Modified R-650-X foams gave faster reaction profiles, lower K-factors, higher heat distortion temperatures, lower friability and a decreased tendency to burn. 
     It will be understood that the foregoing examples are given by way of illustration only and not by way of limitation and that the scope of the present invention is defined solely by the appended claims.