Mixtures of dialkylphosphinic acids and alkylphosphinic acids, a process for preparation thereof and use thereof

Abstract

The invention relates to mixtures of at least one dialkylphosphinic acid of the formula (I) ##STR00001##
in which R.sup.1, R.sup.2 are the same or different and are each independently C.sub.1-C.sub.18-alkyl, C.sub.2-C.sub.18-alkenyl, C.sub.6-C.sub.18-aryl, C.sub.7-C.sub.18-alkylaryl,
with at least one alkylphosphonic acid of the formula (II) ##STR00002##
in which R.sup.3 is C.sub.1-C.sub.18-alkyl, C.sub.2-C.sub.18-alkenyl, C.sub.6-C.sub.18-aryl or C.sub.7-C.sub.18-alkylaryl;
to a process for preparation thereof and to the use thereof.

Claims

1. A mixture of at least one dialkylphosphinic acid of the formula (I) ##STR00005## with at least one alkylphosphonic acid of the formula (II) ##STR00006## wherein R.sup.1, R.sup.2 and R.sup.3 are the same or different and are ethyl, n-propyl, n-butyl, isobutyl, tert-butyl, or mixtures thereof, and at least one synergist, wherein the at least one synergist is melamine cyanurate, melamine polyphosphate, aluminum hydroxide, boehmite, magnesium hydroxide, or zinc borate, and wherein the mixture includes 95 to 99.9% by weight of dialkylphosphinic acid of the formula (I) and 5 to 0.1% by weight of alkylphosphonic acid of the formula (II).

2. The mixture as claimed in claim 1, comprising 98 to 99.9% by weight of dialkylphosphinic acid of the formula (I) and 2 to 0.1% by weight of alkylphosphonic acid of the formula (II).

3. The mixture as claimed in claim 1, wherein the at least one dialkylphosphinic acid is diethylphosphinic acid and the at least one alkylphosphonic acid is ethylphosphonic acid and the mixture comprises 98 to 99.9% by weight of diethylphosphinic acid and 0.1 to 2% by weight of ethylphosphonic acid.

4. A binder, a crosslinker or accelerator in the curing of epoxy resins, polyurethanes and unsaturated polyester resins, a polymer stabilizer, a crop protection composition, a sequestrant, a mineral oil additive, an anticorrosive, a washing composition, a cleaning composition or an electric composition comprising a mixture of at least one dialkylphosphinic acid of the formula (I) ##STR00007## with at least one alkylphosphonic acid of the formula (II) ##STR00008## wherein R.sup.1, R.sup.2 and R.sup.3 are the same or different and are ethyl, n-propyl, n-butyl, isobutyl, tert-butyl, or mixtures thereof, and at least one synergist, wherein the at least one synergist is melamine cyanurate, melamine polyphosphate, aluminum hydroxide, boehmite, magnesium hydroxide or zinc borate, and wherein the mixture includes 95 to 99.9% by weight of dialkylphosphinic acid of the formula (I) and 5 to 0.1% by weight of alkylphosphonic acid of the formula (II).

Description

EXAMPLE 1

(1) First of all, according to example 2 of EP-B-1544205, the sodium salt of diethylphosphinic acid is prepared by dissolving 1500 g of sodium hypophosphite monohydrate in 7.5 kg of water and, after heating the reaction mixture to 100 C., introducing ethylene into the reactor until saturation. Under ethylene pressure, a solution of 17 g of sodium peroxodisulfate in 300 g of water was then metered in.

(2) This gives an aqueous reaction solution of the sodium salt of diethylphosphinic acid, which is converted by treatment with nitric acid, concentration, filtration and distillation (1 mbar, 184 C.) to a mixture of diethylphosphinic acid (99.9% by weight) and ethylphosphonic acid (0.1% by weight). (Yield: 92%).

EXAMPLE 2

(3) First of all, as in example 1, an aqueous reaction solution of the sodium salt of diethylphosphinic acid is prepared. This is subsequently converted by treatment with nitric acid, concentration, filtration and distillation (1 mbar, 180-190 C.) to a mixture of diethylphosphinic acid (98% by weight) and ethylphosphonic acid (2% by weight) (yield: 92%).

EXAMPLE 3

(4) First of all, as in example 1, an aqueous reaction solution of the sodium salt of diethylphosphinic acid is prepared, except using only 95% of the required amount of ethylene. This solution is subsequently converted by treatment with nitric acid, concentration, filtration and distillation (1 mbar, 180-190 C.) to a mixture of diethylphosphinic acid (90% by weight) and ethylphosphonic acid (10% by weight) (yield: 89%).

EXAMPLE 4

(5) First of all, as in example 1, an aqueous reaction solution of the sodium salt of diethylphosphinic acid is prepared, except using only 80% of the required amount of ethylene. This solution is subsequently converted by treatment with nitric acid, concentration, filtration and distillation (1 mbar, 175-195 C.) to a mixture of diethylphosphinic acid (60% by weight) and ethylphosphonic acid (40% by weight) (yield: 93%).

EXAMPLE 5

(6) First of all, as in example 1, an aqueous reaction solution of the sodium salt of diethylphosphinic acid is prepared, except using only 75% of the required amount of ethylene. This solution is subsequently converted by treatment with nitric acid, concentration, filtration and distillation (1 mbar, 175-195 C.) to a mixture of diethylphosphinic acid (50% by weight) and ethylphosphonic acid (50% by weight) (yield: 92%).

(7) Method for Producing Polymer Moldings:

(8) a) Preparation of phosphorus-modified epoxy resin

(9) A 2 l five-neck flask apparatus is initially charged with 1000 g of the epoxy resin (e.g. Beckopox EP 140). It is heated to 110 C. for one hour and volatile components are removed under reduced pressure.

(10) Thereafter, the reaction mixture is inertized with nitrogen and the temperature in the flask is increased to 170 C. 118 g of the mixture of the phosphorus compounds (selected from examples 1 to 5) are added in each case, while stirring under flowing nitrogen, and an exothermic reaction is observed. The resulting resin is yellow in color and free-flowing.

(11) b) Production of epoxy resin specimens

(12) 100 parts of the phosphorus-modified epoxy resin are mixed with one corresponding OH equivalent of phenol novolac (hydroxide equivalents 105 g/mol, melting point 85-95 C.) and heated to 150 C. This liquefies the components. The mixture is stirred gradually until a homogeneous mixture has formed and is allowed to cool to 130 C. Then 0.03 part 2-phenylimidazole is added and the mixture is stirred once again for 5-10 min. Thereafter, the mixture is poured warm into a dish and cured at 140 C. for 2 h and at 200 C. for 2 h.

(13) c) Production of epoxy resin laminate

(14) 100 parts phosphorus-modified epoxy resin as per b) are added to 63 parts acetone and 27 parts Dowanol PM, and the appropriate amount of phenol resin is added. The mixture is left to stir for 30 min. and then 2-phenylimidazole is added. Thereafter, the mixture is filtered through a 400 m sieve in order to remove excess resin particles. Then a woven glass fabric (7628 type, 203 g/m.sup.2) is immersed into the solution until complete wetting of the fabric had taken place. The wetted fabric is pulled out of the mixture and excess resin is removed. Thereafter, the wetted fabric is initially cured in stages in a drying cabinet for a brief period at temperatures up to 165 C. and then fully cured in a heated press. The resin content of the cured laminates is 30-50%.

(15) The thermal expansion of the molding produced, a laminate, is determined to ASTM E831-06.

EXAMPLE 6

(16) According to the general method for producing a polymer molding, 100% of a bisphenol A resin is used to produce a laminate, without fractions of the inventive mixture of diethylphosphinic acid and ethylphosphonic acid.

EXAMPLE 7

(17) According to example 3 of EP-B-1544205, 1500 g of sodium hypophosphite monohydrate are dissolved in 7.5 kg of water and, after heating the reaction mixture to 100 C., ethylene is introduced into the reactor until saturation. Under ethylene pressure, a solution of 32 g of ammonium peroxodisulfate in 300 g of water was then metered in. The resulting product was then neutralized with the equivalent amount of sulfuric acid and converted to diethylphosphinic acid and purified appropriately.

(18) According to the general method for producing a polymer molding, a composition composed of 90% by weight of bisphenol A resin with hardener and catalyst and 10% by weight of the aforementioned diethylphosphinic acid is used to produce a molding.

EXAMPLE 8

(19) According to EP-A-2178891, phosphinic acid, by means of catalyst and ethylene, is used to obtain ethylphosphinic acid, which is purified by means of esterification and distillation. Subsequent oxidation with oxygen affords pure ethylphosphonic acid.

(20) According to the general method for producing a polymer molding, a composition composed of 90% by weight of bisphenol A resin with hardener and catalyst and 10% by weight of the resulting ethylphosphonic acid is then used to produce a molding.

EXAMPLE 9

(21) According to the general method for producing a polymer molding, a composition composed of 90% by weight of bisphenol A resin with hardener and catalyst and 10% by weight of the inventive mixture of diethylphosphinic acid and ethylphosphonic acid according to example 1 is used to produce a molding.

EXAMPLE 10

(22) According to the general method for producing a polymer molding, a composition composed of 90% by weight of bisphenol A resin with hardener and catalyst and 10% by weight of the inventive mixture of diethylphosphinic acid and ethylphosphonic acid according to example 2 is used to produce a molding.

EXAMPLE 11

(23) According to the general method for producing a polymer molding, a composition composed of 90% by weight of bisphenol A resin with hardener and catalyst and 10% by weight of the inventive mixture of diethylphosphinic acid and ethylphosphonic acid according to example 3 is used to produce a molding.

EXAMPLE 12

(24) According to the general method for producing a polymer molding, a composition composed of 90% by weight of bisphenol A resin with hardener and catalyst and 10% by weight of the inventive mixture of diethylphosphinic acid and ethylphosphonic acid according to example 4 is used to produce a molding.

EXAMPLE 13

(25) According to the general method for producing a polymer molding, a composition composed of 90% by weight of bisphenol A resin with hardener and catalyst and 10% by weight of the inventive mixture of diethylphosphinic acid and ethylphosphonic acid according to example 5 is used to produce a molding.

(26) The results are reproduced in the following table:

(27) TABLE-US-00002 Composition Mixture of Coefficient of of polymer dialkylphosphinic thermal expansion system/substance acid/alkylphosphonic 0-100 [ppm/ C.] Example mixture acid Z X Y 6 100:0 69 20 7 7 90:10 100:0 68 20 7 8 90:10 0:100 70 21 7 9 90:10 999:0.1 66 18 5 10 90:10 98:2 63 16 5 11 90:10 90:10 60 16 5 12 90:10 60:40 58 14 4 13 90:10 50:50 58 13 4

(28) Compared to the pure laminate (example 6), there is a decrease in the values for the laminate comprising the inventive mixture of diethylphosphinic acid and ethylphosphonic acid; thermal expansion is thus very low. An increase in the ethylphosphonic acid content brings about a further improvement.

(29) Compared to the prior art (example 6), the inventive mixtures exhibit lower values for the coefficient of thermal expansion, meaning that the inventive products lead to lower expansion of the moldings produced and hence meet the demands on dimensional stability.