Abstract:
Crystalline aluminum phosphorus compounds are provided which are useful as flame retardants and strength additives for organic polymeric materials. Typical compounds are formed from the reaction of aluminum hydroxide and a monobasic, dibasic or tribasic sodium phosphate.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is a continuation of U.S. patent application Ser. No. 7/143,178, Filed Jan. 13, 1988 re Crystalline Aluminum Phosphorus Compounds to Chanakya Misra, now abandoned. 
    
    
     DESCRIPTION 
     1. Technical Field 
     The invention relates to inorganic crystalline alkali metal and ammonium aluminum phosphorus compounds which are readily prepared and which are useful in providing fire retardation and strength for organic polymeric materials. 
     2. Background of Invention 
     A number of aluminum phosphates are known. For example, U.S. Pat. No. 2,909,451 discloses the reaction of a water-soluble aluminum salt and at least a stoichiometric amount of a water-soluble orthophosphate in an aqueous medium to produce a precipitate. 
     Similarly, U.S. Pat. No. 3,348,910 describes the preparation of magnesium ammonium phosphate by reacting a magnesium compound such as magnesium hydroxide with an excess of monoammonium dihydrogen phosphate. 
     Complex phosphates are illustrated by U.S. Pat. No. 2,550,490 of the formula: 
     
         MM&#39;.sub.3 H.sub.14 (PO.sub.4).sub.8.4H.sub.2 O 
    
     where M is an alkali metal including the ammonium radical, and M&#39; is aluminum or iron. The compounds are useful as baking acids. 
     DISCLOSURE OF INVENTION 
     It has now been discovered that novel crystalline phosphorus compounds can be easily prepared that are useful in imparting flame retardation and strength to host materials such as organic polymers. More particularly, the phosphorus compounds have the general formula: 
     
         x(R.sub.2 O).Al.sub.2 O.sub.3.y(P.sub.2 O.sub.5).z(H.sub.2 O) 
    
     wherein R is an alkali metal, x is an integer from 1 to 4, y is an integer from 1 to 2, and z is a number, to include fractions, from 2 to 3.5. 
     The preferred compounds comprise sodium or potassium as the alkali metal, but sodium is the most preferred. Accordingly, the invention will be discussed with emphasis on the sodium aluminum phosphorus compounds, with the understanding that the other compounds can be employed as well. 
    
    
     DESCRIPTION OF DRAWINGS 
     FIG. 1 is a photo microprint (#000) of the compound of Example 1, and the scale indicated by the rectangle is 2 u (2 micrometers). 
     FIG. 2 is a photo microprint (#010) of the compound of Example 2, and the scale indicated by the rectangle is 3.3 u. 
     FIG. 3 is a photo microprint (#007) of the compound of Example 3, and the scale indicated by the rectangle is 20 u. 
    
    
     MODES FOR CARRYING OUT INVENTION 
     The novel compounds can be prepared by reacting a phosphate of the formula: 
     
         (R).sub.a (H).sub.b PO.sub.4 
    
     wherein R is as previously defined and a is an integer of from 1 to 3, and b=3-a with aluminum hydroxide Al(OH) 3  or water-soluble aluminum salt in an amount to provide between about 1 and about 2.5 moles of aluminum per mole of phosphorus. 
     Water-soluble aluminum salts which can be employed include aluminum nitrate, aluminum chloride, aluminum sulfate, and sodium aluminate but others may also be suitable. 
     The reaction is conducted in a solvent, preferably water, and a reaction temperature of at least about 150° C., preferably between about 150° C. and about 250° C. has been successfully employed at a pressure of the vapor pressure of the mixture at the reaction temperature with agitation of the reaction mixture. 
     The following examples will serve to illustrate the invention. All parts and percentages in said examples and elsewhere in the specification and claims are by weight unless otherwise indicated. 
     EXAMPLES 
     The reactants, quantities, reaction conditions, properties, chemical composition and approximate chemical formula are shown in the following Table I. The reaction was conducted in a one liter stainless steel pressure vessel with vigorous agitation. 
     
                                           TABLE I__________________________________________________________________________                     Properties of CompoundsSynthesis Conditions      Prod           Decomp   g    g       g  Time                 Temp                     wt  Crystal                              Density                                    Temp °C.Ex.   Al(OH).sub.3   Na-Phosphate           H.sub.2 O              h  °C.                     g   Shape                              g/cm.sup.3                                    TGA__________________________________________________________________________1  30   60 g NaH.sub.2 PO.sub.4           400              4  200 61  Rod  2.60  150-5002  30   60 g Na.sub.2 HPO.sub.4           400              4  200 80  Rod  2.60  270-5503  30   60 g Na.sub.3 PO.sub.4           400              4  200 40  Rod  2.50  450-580__________________________________________________________________________Chemical Compositionof Compound   wt %  wt %      wt %          wt %                IdentificationEx.   Al.sub.2 O.sub.3  Na.sub.2 O      P.sub.2 O.sub.5          H.sub.2 O              Approximate Chemical Formula                              SEM  XRD Pattern__________________________________________________________________________1  32.0  16.7      40.0          11.3              Na.sub.2 O.Al.sub. 2 O.sub.3.P.sub. 2 O.sub.5.2H.sub.              2 O             FIG. 1                                    Table II2  24.4  28.4      32.7          14.5              2Na.sub.2 O.Al.sub. 2 O.sub.3.P.sub.              2 O.sub.5.3.5H.sub. 2 O                              FIG. 2                                    Table III3  15.2  38.0      40.0           6.8              4Na.sub.2 O.Al.sub. 2 O.sub.3 .2P.sub.2 O.sub.5              .2.5H.sub.2 O   FIG. 3                                    Table IV__________________________________________________________________________ 
    
     As can be seen from the Table I all three crystalline sodium aluminum phosphates form acicular (or rod-shaped) crystals. They release water endothermically when heated in the temperature range of 150° C. to 580° C. Because of their acicular shape, endothermic decomposition and phosphate content, these compounds can be used as strength-improving and flame retardant additives in rubbers, polymers, plastics, papers and other organic materials. 
     Typically from 10 to about 60% of the phosphate will be sufficient for its use as a flame retardant and as a strength improving material. 
     The following Tables II to IV depict the X-ray diffraction patterns for the three examples. 
     While the invention has been illustrated by several embodiments, obvious variations may occur to one of ordinary skill and thus the invention is intended to be limited only by the appended claims. 
     
                                           TABLE II__________________________________________________________________________X-ray Diffraction Pattern of the Compound Obtained in Example 1   2THETA FROM: 7   2THETA TO: 87      MAX CTS/SEC: 3860   STEP PEAK: .03     ICO12: 378838   STEP-BKGRND: .09   SENSITIVITY: 2   SECOND/STEP: 1     SHOULDER CT: 102-THETA D-SPACE       NET-C/S             I/I-MAX                  2-THETA                        D-SPACE                              NET-C/S                                    I/I-MAX__________________________________________________________________________7.34  12.0481       1076  29.9 42.70 2.1176                              416   11.612.13 7.2977       1123  31.2 43.51 2.0797                              365   10.114.80 5.9855       739   20.5 44.11 2.0532                              123   3.415.16 5.8441       155   4.3  44.96 2.0163                               87   2.415.85 5.5903       1218  33.9 45.35 1.9995                              448   12.518.28 4.8532       1432  39.8 46.96 1.9349                              420   11.718.63 4.7622       103   2.9  47.64 1.9087                              219   6.119.12 4.6419       443   12.3 48.18 1.8885                              995   27.620.37 4.3598       1246  34.6 48.75 1.8678                              436   12.120.96 4.2391       1503  41.8 49.42 1.8443                              328   9.121.37 4.1578       529   14.7 50.08 1.8214                              190   5.321.85 4.0676       158   4.4  50.17 1.8184                              156   4.322.15 4.0134       236   6.6  50.26 1.8153                              117   3.222.30 3.9865       201   5.6  50.51 1.8068                              164   4.522.48 3.9550       158   4.4  52.22 1.7517                              448   12.522.64 3.9283       154   4.3  52.45 1.7445                              213   5.922.75 3.9087       125   3.5  52.60 1.7399                              259   7.222.97 3.8715       120   3.3  54.49 1.6839                              203   5.623.83 3.7339       2283  63.5 54.79 1.6754                              430   12.024.19 3.6791       263   7.3  55.21 1.6637                              169   4.725.45 3.4998       1231  34.2 58.84 1.5694                              190   5.326.80 3.3265       1588  44.1 59.31 1.5582                              357   9.928.15 3.1699       3135  87.1 60.42 1.5320                              254   7.128.66 3.1147       1079  30.0 60.61 1.5277                              220   6.129.52 3.0255       1792  49.8 61.99 1.4970                              394   10.930.08 2.9711       3598  100.0                  62.59 1.4840                               94   2.630.46 2.9346       175   4.9  63.35 1.4681                              124   3.430.82 2.9011       209   5.8  63.50 1.4651                              105   2.931.60 2.8310       213   5.9  63.82 1.4584                              127   3.532.71 2.7377       150   4.2  65.78 1.4196                               95   2.633.24 2.6953       1345  37.4 66.52 1.4057                              123   3.434.00 2.6370       1057  29.4 67.24 1.3923                              300   8.334.41 2.6060       322   8.9  67.36 1.3901                              307   8.535.38 2.5370       695   19.3 67.81 1.3820                              432   12.036.28 2.4759       447   12.4 71.68 1.3166                              106   3.036.55 2.4584       312   8.7  71.85 1.3140                              131   3.636.94 2.4334       334   9.3  75.47 1.2597                              141   3.937.67 2.3877       503   14.0 75.55 1.2585                              142   4.038.29 2.3507       431   12.0 75.66 1.2569                              137   3.838.74 2.3243       135   3.7  75.77 1.2554                              121   3.439.52 2.2802       137   3.8  75.86 1.2542                               96   2.740.15 2.2459       240   6.7  78.22 1.2220                              110   3.140.63 2.2205        99   2.7  78.46 1.2190                               90   2.541.63 2.1695       187   5.2  78.58 1.2173                               83   2.341.95 2.1536       193   5.4  83.04 1.1630                              111   3.142.04 2.1492       177   4.9  83.20 1.1611                              133   3.7__________________________________________________________________________ 
    
     
                                           TABLE III__________________________________________________________________________X-ray Diffraction Pattern of the Compound Obtained in Example 2   2THETA FROM: 7   2THETA TO: 87      MAX CTS/SEC: 7025   STEP PEAK: .03     ICO12: 357207   STEP-BKGRND: .09   SENSITIVITY: 2   SECOND/STEP: 1     SHOULDER CT: 102-THETA D-SPACE       NET-C/S             I/I-MAX                  2-THETA                        D-SPACE                              NET-C/S                                    I/I-MAX__________________________________________________________________________11.53 7.6721       1623  23.9 46.69 1.9454                              567   8.312.05 7.3440       1295  19.0 47.51 1.9136                              1570  23.113.03 6.7943       226   3.3  49.14 1.8539                              163   2.415.20 5.8296       189   2.8  49.24 1.8505                              146   2.116.72 5.3022       782   11.5 49.71 1.8341                              648   9.517.05 5.2000        92   1.4  50.40 1.8107                              359   5.317.20 5.1568        91   1.3  50.69 1.8008                              129   1.917.35 5.1111        87   1.3  50.85 1.7956                              124   1.818.47 4.8041       6076  89.3 51.38 1.7784                              133   2.020.26 4.3828       1235  18.2 51.57 1.7721                              160   2.420.50 4.3323       513   7.5  51.85 1.7633                              320   4.721.52 4.1285       139   2.0  52.54 1.7417                              797   11.723.22 3.8299       130   1.9  54.40 1.6865                              272   4.024.07 3.6974       144   2.1  55.43 1.6576                               34   1.224.78 3.5922       4284  62.9 55.66 1.6513                              104   1.525.57 3.4836       315   4.6  57.25 1.6092                              190   2.826.26 3.3942       570   8.4  57.34 1.6068                              191   2.826.92 3.3119       508   7.5  57.52 1.6022                              113   1.728.10 3.1749       762   11.2 58.14 1.5867                              145   2.128.33 3.1502       579   8.5  58.30 1.5826                               97   1.428.78 3.1021       258   3.8  58.60 1.5753                              167   2.531.78 2.8157       107   1.6  58.78 1.5709                              136   2.032.08 2.7904       175   2.6  59.05 1.5643                              180   2.632.62 2.7451       585   8.6  59.23 1.5600                              132   1.933.85 2.6481       6720  98.7 59.68 1.5493                              300   4.434.21 2.6210       1085  15.9 60.04 1.5409                              156   2.334.81 2.5772       2982  43.8 60.74 1.5247                              1305  19.235.53 2.5265       3397  49.9 62.17 1.4932                              1362  20.036.76 2.4450       1150  16.9 64.03 1.4542                              556   8.236.94 2.4333       955   14.0 64.68 1.4412                              119   1.737.60 2.3921       696   10.2 64.79 1.4388                               96   1.438.07 2.3639       106   1.6  66.17 1.4122                              138   2.039.65 2.2730       630   9.3  68.85 1.3636                              128   1.940.05 2.2510       199   2.9  70.76 1.3314                               83   1.240.61 2.2216       469   6.9  70.86 1.3297                               99   1.440.99 2.2018       124   1.8  71.29 1.3228                              247   3.641.15 2.1937       103   1.5  71.43 1.3205                              237   3.541.73 2.1644       237   3.5  72.38 1.3056                              112   1.642.92 2.1073       368   5.4  73.58 1.2873                              230   3.443.19 2.0944       281   4.1  75.31 1.2619                              201   3.043.51 2.0799       338   5.0  75.43 1.2602                              169   2.544.05 2.0557       550   8.1  75.52 1.2589                              169   2.544.65 2.0294       327   4.8  79.61 1.2042                              140   2.144.89 2.0191       113   1.7  79.69 1.2032                              155   2.345.46 1.9952       281   4.1  80.16 1.1973                              297   4.445.78 1.9820       155   2.3__________________________________________________________________________ 
    
     
                                           TABLE IV__________________________________________________________________________X-ray Diffraction Pattern of the Compound Obtained in Example 3   2THETA FROM: 7   2THETA TO: 87      MAX CTS/SEC: 11738   STEP PEAK: .03     ICO12: 223101   STEP-BKGRND: .09   SENSITIVITY: 2   SECOND/STEP: 1     SHOULDER CT: 102-THETA D-SPACE       NET-C/S             I/I-MAX                  2-THETA                        D-SPACE                              NET-C/S                                    I/I-MAX__________________________________________________________________________11.58 7.6394       3623  31.3 45.85 1.9791                              152   1.312.07 7.3336       777   6.7  46.78 1.9419                              187   1.613.06 6.7810       542   4.7  47.56 1.9117                              7440  64.314.74 6.0094       141   1.2  49.25 1.8502                              396   3.415.16 5.8455       205   1.8  49.68 1.8350                              863   7.515.24 5.8120       179   1.5  50.32 1.8133                              282   2.416.75 5.2927       831   7.2  51.49 1.7748                              135   1.218.50 4.7965       1570  13.6 51.82 1.7644                              322   2.821.57 4.1198       293   2.5  52.67 1.7378                              101   0.921.79 4.0786       139   1.2  54.36 1.6877                              637   5.521.94 4.0518       117   1.0  54.76 1.6763                              139   1.222.42 3.9654       163   1.4  55.57 1.6538                              130   1.122.60 3.9347       115   1.0  56.05 1.6408                              104   0.922.90 3.8834       104   0.9  57.31 1.6076                              794   6.923.27 3.8228       567   4.9  58.13 1.5869                               89   0.824.06 3.6982       419   3.6  59.04 1.5646                              257   2.224.81 3.5887       3346  28.9 59.65 1.5500                              132   1.126.28 3.3908       1269  11.0 59.77 1.5472                              148   1.326.96 3.3076       382   3.3  59.89 1.5444                              109   0.928.14 3.1707       201   1.7  59.99 1.5421                               83   0.729.82 2.9957       108   0.9  60.77 1.5242                              2075  17.931.70 2.8222       183   1.6  62.12 1.4941                              1207  10.432.58 2.7484       1174  10.1 64.09 1.4529                              146   1.333.85 2.6479       11572 100.0                  64.79 1.4389                              147   1.334.25 2.6179       1514  13.1 66.32 1.4093                               85   0.734.87 2.5732       1783  15.4 67.15 1.3940                              164   1.435.21 2.5490       2891  25.0 67.78 1.3825                               87   0.835.59 2.5226       1299  11.2 68.57 1.3686                              164   1.436.73 2.4467       1179  10.2 68.72 1.3659                              109   0.937.52 2.3971       103   0.9  70.24 1.3401                              284   2.538.10 2.3621       171   1.5  70.42 1.3370                              205   1.839.71 2.2697       503   4.3  71.25 1.3236                              503   4.340.66 2.2189       224   1.9  73.63 1.2865                              163   1.441.25 2.1885        87   0.8  73.78 1.2842                               96   0.841.80 2.1609       590   5.1  75.76 1.2555                              230   2.043.21 2.0939       520   4.5  75.94 1.2530                              123   1.143.58 2.0769       388   3.4  79.63 1.2039                              781   6.843.96 2.0597       511   4.4  79.84 1.2013                              463   4.044.65 2.0296       152   1.3  80.21 1.1966                              834   7.244.76 2.0247       144   1.2  80.44 1.1939                              422   3.745.22 2.0053       402   3.5  81.83 1.1771                              189   1.6__________________________________________________________________________