Mixed alkali-aluminum phosphites, method for producing same, and the use thereof

Abstract

The invention relates to mixed alkali-aluminum phosphites of the formula (I)
Al.sub.2.00M.sub.z(HPO.sub.3).sub.y(OH).sub.vx(H.sub.2O).sub.w(I)
in which
M represents alkali metal ions,
z is 0.01 to 1.5,
y is 2.63 to 3.5,
v is 0 to 2,
w is 0 to 4;
to a process for preparation thereof and to the use thereof.

Claims

1. A mixed alkali-aluminum phosphite of the formula (I)
Al.sub.2.00M.sub.z(HPO.sub.3).sub.y(OH).sub.vx(H.sub.2O).sub.w(I) wherein M is alkali metal ions, z is 0.01 to 1.5, y is 2.63 to 3.5, v is 0 to 2, and w is 0 to 4, wherein the mixed alkali-aluminum phosphate phosphite includes a particle size of 0.1 to 1000 pm, a solubility in water of 0.01 to 10 g/l, a bulk density of 80 to 800 g/l, and a thermal stability with respect to PH.sub.3 formation of 325 to 450 C.

2. A synergist, a synergist in flame retardant mixtures and in flame retardants, a flame retardant for clearcoats and intumescent coatings, a flame retardant for wood and other cellulosic products, a reactive and nonreactive flame retardant for polymers, a flame-retardant polymer molding composition, a flame-retardant polymer molding or a polyester and pure and blended cellulose fabric flame- retardant produced by impregnation comprising a mixed alkali-aluminum phosphite of the formula (I)
Al.sub.2.00M.sub.z(HPO.sub.3).sub.y(OH).sub.vx(H.sub.2O).sub.w(I) wherein M is alkali metal ions, Z is 0.01 to 1.5, y is 2.63 to 3.5, v is 0 to 2, and w is 0 to 4, wherein the mixed alkali-aluminum phosphate phosphite includes a particle size of 0.1 to 1000 m, a solubility in water of 0.01 to 10 g/l, a bulk density of 80 to 800 g/l, and a thermal stability with respect to PH.sub.3 formation of 325 to 450 C.

3. A mixed alkali-aluminum phosphite of the formula (I)
Al.sub.2.00M.sub.z(HPO.sub.3).sub.y(OH).sub.vx(H.sub.2O).sub.w(I) wherein M is alkali metal ions, z is 0.01 to 1.5, y is 2.63 to 3.5, v is 0 to 2, and w is 0 to 4, wherein the mixed alkali-aluminum phosphite includes a particle size of 0.1 to 1000 m, a solubility in water of 0.01 to 10 g/l, a bulk density of 80 to 800 g/l, a thermal stability with respect to PH.sub.3 formation of 325 to 450 C., and wherein the mixed alkali-aluminum phosphite has an SO.sub.4 content of between 0.5 and 1.0% by weight.

4. A mixed alkali-aluminum phosphite as claimed in claim 3, wherein M is Na or K, z is 0.1 to 1.2, y is 2.75 to 3.1, v is 0.05 to 0.5, and w is 0 to 1.

5. A mixed alkali-aluminum phosphite as claimed in claim 3, wherein M is Na, z is 0.15 to 0.4, y is 2.80 to 3, v is 0.1 to 0.4, and w is 0.01 to 0.1.

6. A mixed alkali-aluminum phosphite as claimed in claim 3, selected from the group consisting of: Al.sub.2.00Na.sub.0.3(HPO.sub.03).sub.2.99(OH).sub.0.32x(H.sub.2O).sub.0-4; Al.sub.2.00Na.sub.0.14(HPO.sub.03).sub.3.06(OH).sub.0.02x(H.sub.2O).sub.0-4; Al.sub.2.00Na.sub.0.19(HPO.sub.03).sub.2.85(OH).sub.0.49x(H.sub.2O).sub.0-4; Al.sub.2.00Na.sub.0.18(HPO.sub.03).sub.2.97(OH).sub.0.24x(H.sub.2O).sub.0-4; Al.sub.2.00Na.sub.0.02(HPO.sub.03).sub.2.83(OH).sub.0.36x(H.sub.2O).sub.0-4; Al.sub.2.00Na.sub.0.13(HPO.sub.03).sub.2.73(OH).sub.0.66x(H.sub.2O).sub.0-4; Al.sub.2.00Na.sub.0.12(HPO.sub.03).sub.2.74(OH).sub.0.63x(H.sub.2O).sub.0-4; and Al.sub.2.00Na.sub.1.15(HPO.sub.03).sub.2.63(OH).sub.1.88x(H.sub.2O).sub.0-4.

7. A synergist, a synergist in flame retardant mixtures and in flame retardants, a flame retardant for clearcoats and intumescent coatings, a flame retardant for wood and other cellulosic products, a reactive and nonreactive flame retardant for polymers, a flame-retardant polymer molding composition, a flame-retardant polymer molding or a polyester and pure and blended cellulose fabric flame-retardant produced by impregnation comprising a mixed alkali-aluminum phosphite of the formula (I)
Al.sub.2.00M.sub.z(HPO.sub.3).sub.y(OH).sub.vx(H.sub.2O).sub.w(I) wherein M is alkali metal ions, z is 0.01 to 1.5, y is 2.63 to 3.5, v is 0 to 2, and w is 0 to 4, wherein the mixed alkali-aluminum phosphite includes a particle size of 0.1 to 1000 m, a solubility in water of 0.01 to 10 g/l, a bulk density of 80 to 800 g/l, a thermal stability with respect to PH.sub.3 formation of 325 to 450 C., and wherein the mixed alkali-aluminum phosphite has an SO.sub.4 content of between 0.5 and 1.0% by weight.

Description

EXAMPLE 1

(1) 1080 g of water are heated to 100 C. and stirred in a 4 liter five-neck flask. Then 2 mol of aluminum sulfate solution (Al content 4.4% by weight) to which 349 g of 25% sulfuric acid have been added and 3 mol of sodium phosphite solution (39%) are pumped in simultaneously within 2 hours. The mixture is stirred at 100 C. for a further 20 h. The solids are filtered off, washed with hot demineralized water and dried. After further drying at 220 C. under nitrogen, the product still contains 0.3% residual moisture (muffle furnace at 300 C., 1 h). The product is x-ray-amorphous. The .sup.31P NMR indicates a 100% phosphite content. In a high yield, an inventive mixed alkali-aluminum phosphite is obtained with very high thermal stability (PH.sub.3 formation from 360 C.).

EXAMPLE 2

(2) Analogously to example 1, water is initially charged; aluminum sulfate solution and sodium phosphite solution to which 25% sodium hydroxide solution has been added are metered in at 100 C. while stirring over the course of 2 h, and the mixture is stirred for a further 16 h. The pH of the suspension is 4 and the nominal solids concentration is 5.6% by weight. In a high yield, an inventive mixed alkali-aluminum phosphite is obtained with very high thermal stability (PH.sub.3 formation from 360 C.).

EXAMPLE 3

(3) Analogously to example 1, 2 mol of aluminum sulfate solution and 3 mol of solid sodium phosphite are stirred at 100 C. for 6 h. The solids concentration is 22.8% by weight. In a high yield, an inventive mixed alkali-aluminum phosphite is obtained with very high thermal stability (PH.sub.3 formation from 360 C.).

EXAMPLE 4

(4) 3251 g of water are initially charged in a 16 l high-pressure stirred vessel, heated and stirred. Over the course of 3 h, 6 mol (3694 g) of aluminum sulfate solution and 9 mol (3055 g) of sodium phosphite solution are metered in simultaneously. The suspension is discharged and filtered at 80 C., washed with hot water, redispersed and washed once again. The filtercake is dried in a Reaktotherm drier at 220 C. In a very high yield, an inventive mixed alkali-aluminum phosphite is obtained with very high thermal stability (PH.sub.3 formation from 380 C.).

EXAMPLE 5

(5) Analogously to example 1, water is initially charged at 80 C. aluminum sulfate solution and sodium phosphite solution are metered in simultaneously within 2 h, and the mixture is stirred for a further 22 h. In a high yield, an inventive mixed alkali-aluminum phosphite is obtained with very high thermal stability (PH.sub.3 formation from 360 C.).

EXAMPLE 6

(6) Analogously to example 4, water is initially charged at 120 C. and aluminum sulfate solution and sodium phosphite solution are metered in within 1 h. In 89% yield, an inventive mixed alkali-aluminum phosphite is obtained with very high thermal stability (PH.sub.3 formation from 360 C.).

EXAMPLE 7

(7) Analogously to example 4, water is initially charged at 155 C. and aluminum sulfate solution and sodium phosphite solution are metered in within 0.5 h. The yield is 85% and the thermal stability (PH.sub.3 formation from 360 C.) of the product is very high.

EXAMPLE 8

(8) Analogously to example 1, water is initially charged at 100 C. and aluminum sulfate solution and sodium phosphite solution are metered in in excess within 2 h and the mixture is stirred for a further 22 h. In a good yield, an inventive mixed alkali-aluminum phosphite is obtained with very high thermal stability (PH.sub.3 formation from 360 C.).

EXAMPLE 9

Comparative

(9) Analogously to example 1, water is initially charged at 100 C. and aluminum sulfate solution in excess and sodium phosphite solution are metered in within 2 h. The yield and thermal stability (PH.sub.3 formation from 340 C.) are reduced; the composition is not in accordance with the invention.

EXAMPLE 10

Comparative

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

(11) TABLE-US-00001 TABLE 1 Reaction conditions and amounts used Aluminum Phosphite H.sub.2SO.sub.4 NaOH Temper- Solids Ex- Water source source 25% 25% Time ature concentration ample [g] [mol] [mol] [g] [g] [h] [ C.] pH [%] 1 1080 2 3 349 22 100 1 10.0 2 1080 0.5 0.75 5 18 100 4 5.6 3 0 2 3 6 100 2.8 22.8 4 3251 6 9 3 155 3.1 11.0 5 1080 2 3 24 80 2.6 11.0 6 3251 6 9 1 120 2.8 11.0 7 3251 6 9 0.5 155 2.4 11.0 8 1080 2 3.3 24 100 11.8 9 1080 2 2.7 24 100 10.2 (comp.) 10 (comp.)

(12) TABLE-US-00002 TABLE 2 Yields PH.sub.3 Residual formation moisture P Al Na SO.sub.4 temper- content content content content content Ex- Yield ature [% by [% by [% by [% by [% by ample [%] [ C.] wt.] wt.] wt.] wt.] wt.] 1 95 360 0.3 30.7 17.9 2.3 0.5 2 94 360 0.35 32.4 17.0 1.2 0.23 3 96 360 1.8 27.5 16.8 4.2 5.9 4 98 380 0.27 30.7 18.0 1.5 0.29 5 93 360 1.13 29.7 18.3 0.7 1.2 6 89 360 0.49 29.0 18.5 1.9 1.9 7 87 360 0.70 30.4 19.3 1.1 0.3 8 93 360 3.61 24.8 16.4 8.5 1.0 9 75 340 4.90 24.3 18.3 0.1 13.4 (comp.) 10 320 0.00 31.62 18.36 0.0 0.0 (comp.)

(13) TABLE-US-00003 TABLE 3 Composition of the end products Ratio of Mixed alkali-aluminum A B Ex- P/Al phosphite empirical [% by [% by ample [mol/mol] formula wt.] wt.] 1 1.50 Al.sub.2.00Na.sub.0.3(HPO.sub.3).sub.2.99(OH).sub.0.32 99.0 0.7 2 1.53 Al.sub.2.00Na.sub.0.14(HPO.sub.3).sub.3.06(OH).sub.0.02 99.3 0.3 3 1.42 Al.sub.2.00Na.sub.0.19(HPO.sub.3).sub.2.85(OH).sub.0.49 89.4 8.9 4 1.49 Al.sub.2.0Na.sub.0.18(HPO.sub.3).sub.2.97(OH).sub.0.24 99.3 0.4 5 1.41 Al.sub.2.00Na.sub.0.02(HPO.sub.3).sub.2.83(OH).sub.0.36 97.1 1.8 6 1.37 Al.sub.2.00Na.sub.0.13(HPO.sub.3).sub.2.73(OH).sub.0.66 96.7 2.8 7 1.37 Al.sub.2.00Na.sub.0.12(HPO.sub.3).sub.2.74(OH).sub.0.63 98.9 0.4 8 1.32 Al.sub.2.00Na.sub.1.15(HPO.sub.3).sub.2.63(OH).sub.1.88 94.9 1.5 9 1.16 (comp.) 10 1.50 Al.sub.2(HPO.sub.3).sub.3 (comp.) A: mixed alkali-aluminum phosphite and alkali metal salt: AAP content B: mixed alkali-aluminum phosphite and alkali metal salt: alkali metal salt content (sodium sulfate here)

(14) The very small difference (in the addition of A and B) from 100% by weight corresponds to the very small residual moisture or water of crystallization content and is included in the empirical formula (I) with a very small index w.

(15) Production of Flame-retardant Polymer Molding Compositions and Polymer Moldings

(16) 50% by weight of nylon 6,6 polymer, 30% by weight of glass fibers, 3.6% by weight of mixed alkali-aluminum phosphite according to example 4 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.

(17) 50% by weight of polybutylene terephthalate polymer, 30% by weight of glass fibers, 3.6% by weight of mixed alkali-aluminum phosphite according to example 4 and 16.4% by weight of Exolit OP1240 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.