Mixtures of aluminum phosphite with sparingly soluble aluminum salts and foreign ions, process for the production thereof and the use thereof

Abstract

The invention relates to mixtures of aluminum phosphite with sparingly soluble aluminum salts and nitrogen-free extraneous ions, comprising 80 to 99.898% by weight of aluminum phosphite of the formula (I)
Al.sub.2(HPO.sub.3).sub.3xH.sub.2O(I)
in which x is 0 to 4, 0.1 to 10% by weight of sparingly soluble aluminum salts and 0.002 to 10% by weight of nitrogen-free extraneous ions; to a process for preparation thereof and use thereof.

Claims

1. A mixture of aluminum phosphite with sparingly soluble aluminum salts and nitrogen-free extraneous ions, comprising 94 to 99.4% by weight of aluminum phosphite of the formula (I)
Al.sub.2(HPO.sub.3).sub.3xH.sub.2O(I) wherein x is 0 to 0.1, 0.3 to 3% by weight of sparingly soluble aluminum salts, wherein the sparingly soluble aluminum salts are aluminum hydroxide, aluminum hydroxychloride, polyaluminum hydroxyl compounds, aluminum carbonates, hydrotalcites (Mg.sub.6Al.sub.2(OH).sub.16CO.sub.3xnH.sub.2O), dihydroxyaluminum sodium carbonate (NaAl(OH)2CO3), aluminum oxides, aluminum oxide hydrate, mixed aluminum oxide hydroxides, basic aluminum sulfate, basic aluminum alunite or mixtures thereof, and 0.3 to 3% by weight of nitrogen-free extraneous ions, wherein the extraneous ions are chlorides, bromides, hydroxides, peroxides, peroxide hydrates, sulfites, sulfates, sulfate hydrates, acidic sulfates, hydrogensulfates, peroxosulfates, peroxodisulfates, carbonates, percarbonates, stannates, borates, perborates, perborate hydrates, formates, acetates, propionates, lactates, ascorbates, cations of the elements Li, Na, K, Mg, Ca, Ba, Pb, Sn, Cu, Zn, La, Ce, Ti, Zr, V, Cr, Mn, Fe, Co and/or Ni.

2. A flame retardant, a flame retardant for clearcoats and intumescent coatings, a flame retardant for wood and other cellulosic products, a reactive or nonreactive flame retardant for polymers, a flame-retardant polymer molding composition, a flame-retardant for rendering polyester and pure and blended cellulose fabrics flame-retardant by impregnation, or a synergist in flame retardant mixtures comprising a mixture of aluminum phosphite with sparingly soluble aluminum salts and nitrogen-free extraneous ions, comprising 94 to 99.4% by weight of aluminum phosphite of the formula (I)
Al.sub.2(HPO.sub.3).sub.3xH.sub.2O(I) wherein x is 0 to 0.1, 0.3 to 3% by weight of sparingly soluble aluminum salts, wherein the sparingly soluble aluminum salts are aluminum hydroxide, aluminum hydroxychloride, polyaluminum hydroxyl compounds, aluminum carbonates, hydrotalcites (Mg.sub.6Al.sub.2(OH).sub.16CO.sub.3xnH.sub.2O), dihydroxyaluminum sodium carbonate (NaAl(OH).sub.2CO.sub.3), aluminum oxides, aluminum oxide hydrate, mixed aluminum oxide hydroxides, basic aluminum sulfate, basic aluminum alunite or mixtures thereof, and 0.3 to 3% by weight of nitrogen-free extraneous ions, wherein the extraneous ions are chlorides, bromides, hydroxides, peroxides, peroxide hydrates, sulfites, sulfates, sulfate hydrates, acidic sulfates, hydrogensulfates, peroxosulfates, peroxodisulfates, carbonates, percarbonates, stannates, borates, perborates, perborate hydrates, formates, acetates, propionates, lactates, ascorbates, cations of the elements Li, Na, K, Mg, Ca, Ba, Pb, Sn, Cu, Zn, La, Ce, Ti, Zr, V, Cr, Mn, Fe, Co and/or Ni.

Description

EXAMPLE 1

(1) 674 g of aluminum hydroxide, 1511 g of 70% by weight phosphorous acid, 361 g of 25% by weight sulfuric acid and 11 067 g of demineralized water are initially charged in a 16 l high-pressure stirred vessel from Pfaudler, heated to 150 C. and stirred for 3 h. The resulting suspension is discharged and filtered at 80 C. by means of a heatable Seitz pressure filter and washed with demineralized water, redispersed and washed once again, then dried at 220 C. In a very high yield, an inventive mixture of aluminum phosphite with sparingly soluble aluminum salts and nitrogen-free extraneous ions is obtained with very high thermal stability (PH.sub.3 formation from 360 C.).

EXAMPLE 2

(2) As in example 1, aluminum hydroxide, 70% by weight phosphorous acid, 25% by weight sulfuric acid and 11 067 g of demineralized water are initially charged, heated to 150 C. and stirred for 23 h, then 688 g of 25% by weight sodium hydroxide solution are added and the mixture is stirred for 1 h. As in example 1, the suspension is discharged, filtered, washed and dried. In a very high yield, an inventive mixture of aluminum phosphite with sparingly soluble aluminum salts and nitrogen-free extraneous ions is obtained with very high thermal stability (PH.sub.3 formation from 380 C.).

EXAMPLE 3

(3) As in example 1, aluminum hydroxide, 70% by weight phosphorous acid and demineralized water are initially charged, heated to 120 C. and stirred for 6 h. During the reaction time, the pH of the solution is kept at pH=1 by metered addition of 1237 g of 25% by weight sulfuric acid. Shortly before the end of the reaction, 1054 g of 25% by weight sodium hydroxide solution are added. As in example 1, the suspension is discharged, filtered, washed and dried. In a very high yield, an inventive mixture of aluminum phosphite with sparingly soluble aluminum salts and nitrogen-free extraneous ions is obtained with very high thermal stability (PH.sub.3 formation from 380 C.).

EXAMPLE 4

(4) As in example 1, aluminum hydroxide, 70% by weight phosphorous acid and demineralized water are initially charged, heated to 100 C. and stirred for 24 h. During the reaction time, the pH of the solution is kept at pH=1.5 by metered addition of 361 g of 25% by weight sulfuric acid. As in example 1, the suspension is discharged, filtered, washed and dried. In a very high yield, an inventive mixture of aluminum phosphite with sparingly soluble aluminum salts and nitrogen-free extraneous ions is obtained with very high thermal stability (PH.sub.3 formation from 380 C.).

EXAMPLE 5(COMPARATIVE)

(5) A noninventive, commercially available aluminum phosphite shows a lower thermal stability in comparison (PH.sub.3 formation from 320 C.).

(6) Flame-Retardant Polymer Molding Compositions and Polymer Moldings

(7) 50% by weight of nylon 6,6 polymer, 30% by weight of glass fibers, 3.6% by weight of inventive mixture of aluminum phosphite with sparingly soluble aluminum salts and nitrogen-free extraneous ions according to example 3 and 16.4% by weight of Exolit OP1230 aluminum diethylphosphinate (from Clariant) are used in accordance with the general methods specified to produce flame-retardant polymer molding compositions and flame-retardant polymer moldings in the form of UL-94 test specimens. The UL-94 test gives V-0 classification.

(8) 50% by weight of polybutylene terephthalate polymer, 30% by weight of glass fibers, 3.6% by weight of inventive mixture of aluminum phosphite with sparingly soluble aluminum salts and nitrogen-free extraneous ions according to example 3 and 16.4% by weight of Exolit OP1240 aluminum diethylphosphinate (from Clariant) are used in accordance with the general methods specified to produce 30 flame-retardant polymer molding compositions and flame-retardant polymer moldings in the form of UL-94 test specimens. The UL-94 test gives V-0 classification.

(9) TABLE-US-00001 TABLE 1 Starting weights and reaction conditions Starting weights Conditions Phosphorous Aluminum Sulfuric Sodium hydroxide Reaction Water acid hydroxide acid 25% solution 25% Temperature time Example [g] [g] [g] [g] [g] [ C.] [h] 1 11067 1511 674 361 150 3 2 11067 1511 674 361 688 150 24 3 11067 1511 674 1237 1054 120 6 4 11067 1511 674 361 100 24 5 aluminum phosphite (comp.) Aluminum hydroxide: Hydral 710, from Caldic

(10) TABLE-US-00002 TABLE 2 Analysis results, compositions of the inventive products, test results Addn. of the aluminum phosphite mixtures Analyses aluminum aluminum aluminum phosphorus sodium sulfate phosphite hydroxide sodium sulfate Example [%] [%] [%] [%] [%] [%] [%] [%] 1 18.3 30.6 0.007 0.993 96.7 1.4 0.007 0.093 2 18.7 30.3 0.340 0.087 95.8 3.0 0.340 0.087 3 17.2 29.5 5.000 0.190 93.2 0.1 5.000 0.190 4 18.4 29.2 0.003 3.000 92.3 4.0 0.003 3.000 5 96.0 4.0 (comp.)