HK1080864B

HK1080864B - Process for preparing of dialkylphosphinic salts

Info

Publication number: HK1080864B
Application number: HK06100921.8A
Authority: HK
Inventors: H.鲍尔; W.克劳斯; M．西肯; N．威夫林
Original assignee: 科莱恩产品（德国）有限公司
Priority date: 2003-12-19
Filing date: 2006-01-20
Publication date: 2011-05-06

Description

Process for preparing dialkylphosphinic salts

The present invention relates to a process for preparing dialkylphosphinic salts and to the use of the dialkylphosphinic salts prepared by this process.

Salts of organic phosphoric acids are known as flame retardants. They can be made by various processes.

EP-A-0699708, for example, describes flame-resistant polyester molding compositions in which the flame resistance is imparted to the polyester by adding calcium or aluminum salts of phosphinic or diphosphinic acids. The above salts are obtained by reacting the corresponding dialkylphosphinic acids with calcium hydroxide or with aluminum hydroxide.

DE 2447727 describes flame-retardant polyamide molding compositions comprising phosphinic acid or salts of diphosphinic acids.

However, the above-described processes have the disadvantage that firstly a complicated preparation of suitable organophosphorus compounds is required. This is particularly the case for dialkylphosphinic acids, the aluminum salts of which produce the best results in flame retardant applications, and a number of synthetic routes have been described for this purpose.

For example, DE 2100779A 1 describes a process for preparing alkyl dialkylphosphinate by addition of olefins having from 2 to 22 carbon atoms to alkylphosphonites which are only difficult to obtain.

WO 99/28327 describes a process for obtaining phosphinates in two steps starting from alkali metal salts of hypophosphorous acid.

The disadvantage of this process is the use of organic solvents, preferably acetic acid. These substances have to be recovered in complex processes and left as impurities in the final product, leading to undesired side effects when intended to be incorporated into plastics. In addition, the use of organic solvents in the first process stage leads to undesirable telomeric by-products due to the high solubility of the olefin reactants.

It is therefore an object of the present invention to provide a process for preparing salts of dialkylphosphinic acids which makes it possible to prepare dialkylphosphinic salts of certain metals in high purity in a particularly simple and cost-effective manner. This means that the use of organic solvents is to be avoided.

This object is achieved by a method of the kind described at the outset, comprising

a) Reacting hypophosphorous acid and/or its salts with olefins in the presence of a free radical initiator in a solvent system to give dialkylphosphinic acids and/or their alkali metal salts, and

b) reacting the dialkylphosphinic acids and/or alkali metal dialkylphosphinic salts obtained in a) with metal compounds of Mg, Ca, Al, Zn, Ti, Sn, Zr and/or Fe to give dialkylphosphinic salts of these metals, wherein the solvent system comprises solvent system additives and water, and wherein the solvent system comprises from 50 to 100% by weight of water and from 0 to 50% by weight of solvent system additives, preferably from 80 to 100% by weight of water and from 0 to 20% by weight of solvent system additives, and wherein the solvent additives are mineral acids, acid salts, carboxylic acids, bases, and/or electrolytes, and the mineral acids are elemental hydrogen acids, oxo acids, peroxy acids, and/or peroxy diacids of the seventh, sixth, fifth, fourth or third main group elements.

Preferably, the solvent system comprises 95 to 100% by weight water and 0 to 5% by weight solvent system additive.

Preferably, the acid salt is sodium bisulfate, sodium bisulfite, and/or potassium bisulfite.

Preferably, the carboxylic acid is formic acid, acetic acid, propionic acid, butyric acid and/or a longer chain carboxylic acid, and/or dimers, oligomers, and/or polymers thereof.

Preferably, the salt of hypophosphorous acid is an alkali metal salt, especially the sodium salt.

Preferably, the dialkylphosphinic salts of process stage a) are alkali metal salts, especially sodium salts.

Preferably, the hypophosphorous acid is made in situ from a salt of hypophosphorous acid and at least one inorganic acid, wherein the ratio (on an equivalent basis) of additive acid to hypophosphite salt is from 0: 1 to 2: 1.

Preferably, the reaction is carried out in step a) in the presence of a free radical initiator.

Preferably, the free-radical initiator used comprises a peroxide-forming compound and/or a peroxy compound, such as hydrogen peroxide, potassium persulfate, sodium persulfate, ammonium persulfate and/or an azo compound, such as 2, 2 ' -azobis (2-amidinopropane) dihydrochloride and/or 2, 2 ' -azobis (N, N ' -dimethyleneisobutyramidine) dihydrochloride.

Preferably, the free-radical initiator is used in an amount of 0.001 to 10 mol%, based on the phosphorus-containing compound.

Preferably, the free-radical initiator is metered in at a rate of from 0.01 to 10 mol% of initiator per hour, based on the phosphorus-containing compound.

Preferably, the olefins used include ethylene, propylene, n-butene and/or isobutene, or any desired mixtures of these.

Preferably, the ratio of olefin to hypophosphite and/or hypophosphorous acid (on a molar basis) is from 0: 1 to 3: 1, preferably from 0.5: 1 to 2.5: 1.

Preferably, the reaction in step a) is carried out at a pressure of from 1 to 100 bar, preferably from 2 to 50 bar, of the olefin used.

Preferably, the atmosphere in step a) during the reaction consists of from 50 to 99.9% by weight, preferably from 70 to 95% by weight, of the constituents of the solvent system and of the olefin.

Preferably, the atmosphere contains gaseous components that do not participate in the reaction.

Preferably, the gaseous component comprises oxygen, nitrogen, carbon dioxide, noble gases, hydrogen, and/or alkanes.

Preferably, the reaction in process stage a) is carried out at a temperature of from 0 to 250 ℃, preferably from 20 to 200 ℃ and particularly preferably from 50 to 150 ℃.

Preferably, the reaction in process step a) is carried out in an absorption column, a spray column, a bubble column, a stirred tank, and/or a kneader.

Preferably, the mixer units used comprise anchor stirrers, blade stirrers, MIC stirrers, propeller stirrers, impeller stirrers, turbine stirrers, cross stirrers, dispersion discs, cavitation (gasification) stirrers, rotor-stator mixers, static mixers, Venturi (Venturi) nozzles and/or pneumatic pumps (mamutpumpen).

Preferably, the reaction solution in process stage a) is subjected to a mixing intensity corresponding to a rotational reynolds number of from 1 to 1000000, preferably from 100 to 100000.

Preferably, in process stage a), the energy introduced is from 0.083 to 10kW/m³Preferably 0.33-1.65kW/m³In the case of (2) an intensive mixing process of the olefin, the radical initiator, the solvent system and hypophosphorous acid and/or its salts is carried out.

Preferably, the dialkylphosphinic acids and/or salts thereof are reacted with the metals and/or metal compounds in process stage b) in a molar ratio dialkylphosphinic acid/salt to metal of from 6: 1 to 1: 0.66 for tetravalent metal ions or metals having a stable tetravalent oxidation state.

Preferably, the dialkylphosphinic acids and/or salts thereof are reacted with the metals and/or metal compounds in process stage b) in a molar ratio of dialkylphosphinic acid/salt to metal of from 4.5: 1 to 1: 0.66 for trivalent metal ions or metals having a stable trivalent oxidation state.

Preferably, the dialkylphosphinic acids and/or salts thereof are reacted with the metals and/or metal compounds in process stage b) in a dialkylphosphinic acid/dialkylphosphinic salt to metal ratio of from 3: 1 to 1: 0.66 for divalent metal ions or metals having a stable divalent oxidation state.

Preferably, the dialkylphosphinic acids and/or salts thereof are reacted with the metals and/or metal compounds in process stage b) in a dialkylphosphinic acid/dialkylphosphinic salt to metal ratio of from 1.5: 1 to 1: 0.66 for monovalent metal ions or metals having a stable monovalent oxidation state.

Preferably, the metal compound of Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe used in process stage b) is a metal, a metal oxide, a metal hydroxide, a metal oxide hydroxide, a metal borate, a metal carbonate, a metal hydroxycarbonate hydrate, a mixed metal hydroxycarbonate hydrate, a metal phosphate, a metal sulfate hydrate, a metal hydroxysulfate hydrate, a mixed metal hydroxysulfate hydrate, an oxysulfate, a metal acetate, a metal nitrate, a metal fluoride hydrate, a metal chloride hydrate, a metal oxychloride, a metal bromide, a metal iodide hydrate, a metal derivative of a carboxylic acid, and/or a metal alcoholate.

Preferably, the metal compound is aluminum chloride, aluminum hydroxide, aluminum nitrate, aluminum sulfate, titanyl sulfate, zinc nitrate, zinc oxide, zinc hydroxide and/or zinc sulfate.

Preferably, the reaction in process stage b) is carried out at a temperature of from 20 to 250 ℃, preferably at a temperature of from 80 to 120 ℃.

Preferably, the reaction in process stage b) is carried out at a pressure of from 1Pa to 200MPa, preferably from 0.01MPa to 10 MPa.

Preferably, the reaction of the dialkylphosphinic acids and/or alkali metal salts thereof with metal compounds of Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe in process stage b) gives dialkylphosphinic salts of these metals in a time of 1 to 10^-7To 1 x 10²h。

Preferably, in process stage b), the solids content of the dialkylphosphinic salts of these metals in the reaction of dialkylphosphinic acids and/or alkali metal salts thereof with metal compounds of Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe to give dialkylphosphinic salts of these metals is from 0.1 to 70% by weight, preferably from 5 to 40% by weight.

Preferably, the reaction in process stage b) is carried out in stirred tanks, mixers and/or kneaders.

Preferably, the energy introduced for the reaction in process stage b) is from 0.083 to 1.65kW/m³Particularly preferably 0.33 to 1.65kW/m³。

Preferably, in process stage a1), the dialkylphosphinic acids and/or alkali metal salts thereof from process stage a) are converted into the corresponding other classes of compounds to give homogeneous products before process stage b).

Preferably, the alkali metal dialkylphosphinic salts obtained in process stage a) are converted into dialkylphosphinic acids in process stage a1) and, in process stage b), are reacted with metal compounds of Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe to give dialkylphosphinic salts of these metals.

Preferably, the dialkylphosphinic acid obtained in process stage a) is converted into the alkali metal dialkylphosphinic salt in process stage a1) and, in process stage b), it is reacted with metal compounds of Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe to give the dialkylphosphinic salts of these metals.

Preferably, the dialkylphosphinic salts of the metals Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe from process stage b) are separated from the reaction mixture by filtration and/or centrifugation.

Preferably, in process stage b), the dialkylphosphinic salts are separated using a pressure filter funnel, a vacuum filter funnel, a filter funnel with stirrer, a pressure candle filter, a shaft leaf filter, a round leaf filter, a centrifugal disc filter, a chamber/frame filter press, an automatic chamber filter press, a vacuum multi-chamber drum filter, a vacuum multi-chamber disc filter, an evacuated chamber filter, a rotary pressure filter, a vacuum belt filter.

Preferably, the filtration pressure is 0.5Pa to 6 MPa.

Preferably, the filtration temperature is 0 to 400 ℃.

Preferably, the specific filter efficiency is 10 to 200kg x h^-1*m^-2。

Preferably, the residual moisture content of the filter cake is 5 to 60%.

Preferably, the dialkylphosphinic salts are separated in process stage b) using a solid-disk centrifuge, such as a top-drain centrifuge, a plow centrifuge, a chamber centrifuge, a spiral-conveyor centrifuge, a disk centrifuge, a tube centrifuge, a screen centrifuge, such as a ceiling-mounted centrifuge and a basket centrifuge, a screen-screw centrifuge, a screen-plow centrifuge or a pulse centrifuge.

Preferably, the centrifugal force ratio is 300 to 15000.

Preferably, the suspension passing efficiency is2 to 400m³*h^-1。

Preferably, the solids passage efficiency is from 5 to 80t h^-1。

Preferably, the residual moisture content of the filter cake is 5 to 60%.

Preferably, after process stage b), the dialkylphosphinic salts of the metals Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe which are separated off from the reaction mixture by filtration and/or centrifugation are dried.

Preferably, the dialkylphosphinic salts of the metals Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe have a residual moisture content of from 0.01 to 10% by weight, preferably from 0.1 to 1% by weight.

Preferably, the dialkylphosphinic salts of the metals Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe have an average particle size of from 0.1 to 2000. mu.m, preferably from 10 to 500. mu.m.

Preferably, the dialkylphosphinic salts of the metals Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe have a bulk density of from 80 to 800g/l, preferably from 200 to 700 g/l.

The invention also provides a process for preparing dialkylphosphinic salts, which comprises

the dialkylphosphinic acid derivatives obtained under a) are interconverted in a 1).

a) Hypophosphorous acid and/or its salts are reacted with olefins in the presence of a free radical initiator in a solvent system to give dialkylphosphinic acids and/or their alkali metal salts.

The invention also provides solutions of dialkylphosphinic acids and/or alkali metal salts thereof, comprising from 10 to 100% by weight of dialkylphosphinic acid and/or alkali metal salt thereof and from 10 to 100% by weight of solvent system, where the sum is 100% by weight.

The invention also provides for the use of the dialkylphosphinic salts prepared by the process according to the invention for preparing flame retardants for thermoplastic polymers, such as polyesters, polystyrenes or polyamides, and for thermosets.

The invention also provides a flame-retardant polymer molding composition comprising such inventive dialkylphosphinic salts of the metals Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe.

Preferably, the flame-retardant polymer molding composition comprises from 1 to 50% by weight of dialkylphosphinic salts of the metals Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe prepared according to the invention, from 1 to 99% by weight of polymer or mixtures thereof, from 0 to 60% by weight of additives, from 0 to 60% by weight of fillers.

It is particularly preferred that the flame-retardant polymer molding composition comprises from 5 to 30% by weight of the dialkylphosphinic salts of the metals Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe prepared according to the invention, from 5 to 90% by weight of the polymer or mixtures thereof, from 5 to 40% by weight of additives, from 5 to 40% by weight of fillers.

The invention also provides polymer moldings, polymer films, polymer filaments, and polymer fibers, which contain the inventive dialkylphosphinic salts of the metals Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe.

Preferably, the polymer molding, polymer film, polymer filament or polymer fiber comprises from 1 to 50% by weight of dialkylphosphinic salts of the metals Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe prepared according to the invention, from 1 to 99% by weight of polymer or mixtures thereof, from 0 to 60% by weight of additives, from 0 to 60% by weight of fillers.

It is particularly preferred that the polymer molding, polymer film, polymer filament or polymer fiber comprises from 5 to 30% by weight of a dialkylphosphinic salt of the metals Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe prepared according to the invention, from 5 to 90% by weight of a polymer or a mixture thereof, from 5 to 40% by weight of additives and from 5 to 40% by weight of fillers.

Finally, the invention also provides dialkylphosphinic salts of the metals Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe having

Residual moisture content of 0.01 to 10% by weight, preferably 0.05 to 1% by weight

Average particle size 0.1 to 1000. mu.m, preferably 10 to 100. mu.m

Bulk density 80 to 800g/l, preferably 200 to 700 g/l.

Preferably, the dialkylphosphinic salts of the metals Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe are prepared by

A process for preparing these dialkylphosphinic salts, wherein

a) Hypophosphorous acid and/or its salts are reacted with olefins in the presence of a free radical initiator in a solvent system to give dialkylphosphinic acids and/or their alkali metal salts, and

b) reacting the dialkylphosphinic acids and/or alkali metal dialkylphosphinic salts obtained in a) with metal compounds of Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe to give the dialkylphosphinic salts of these metals.

It is also preferred that the dialkylphosphinic acids and/or alkali metal salts thereof are obtained by reacting phosphinic acids and/or salts thereof with olefins in the presence of a free-radical initiator in a solvent system.

It is also preferred that the dialkylphosphinic acids and/or alkali metal salts thereof are obtained by reacting phosphinic acid and/or salts thereof with olefins in the presence of a free-radical initiator in a solvent system and subsequently converting the obtained dialkylphosphinic acid derivatives into the corresponding other classes of compounds to give homogeneous products.

It is further preferred that the dialkylphosphinic salts are obtained by the following steps

a) Reacting hypophosphorous acid and/or alkali metal salts thereof with olefins in the presence of a free radical initiator in a solvent system to give dialkylphosphinic acids and/or alkali metal salts thereof, and subsequently

a1) Converting the dialkylphosphinic acid derivatives obtained in a) into the corresponding other classes of compounds to give homogeneous products and subsequently

b) Reacting the dialkylphosphinic acid derivatives obtained in a1) with compounds of Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe metals to give dialkylphosphinic salts of these metals.

It is furthermore preferred that the dialkylphosphinic salts are obtained by the following steps: the alkali metal dialkylphosphinic salts obtained in process stage a) are converted into dialkylphosphinic acids and the dialkylphosphinic acids are subsequently reacted with metal compounds of Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe to give the dialkylphosphinic salts of these metals.

It is furthermore preferred that the dialkylphosphinic salts are obtained by the following steps: the dialkylphosphinic acids obtained in process stage a) are converted into alkali metal dialkylphosphinic salts and the alkali metal dialkylphosphinic salts are subsequently reacted with metal compounds of Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe to give the dialkylphosphinic salts of these metals.

It has been unexpectedly found that in the solvent system of the present invention, olefins can be reacted at unexpectedly good reaction rates and the formation of telomeric products, i.e., multiple olefin additions, is greatly suppressed.

Preferred solvent system additives are inorganic acids such as the elemental hydrogen acids, oxo acids, peroxy acids and/or peroxy diacids of the seventh, sixth, fifth, fourth or third main group elements of the periodic table.

Particularly preferred inorganic acids are hydrofluoric acid, hydrochloric acid, perchloric acid, sulfurous acid, sulfuric acid, peroxomonosulfuric acid (Caro's acid), peroxodisulfuric acid, nitrous acid, nitric acid, phosphorous acid, phosphoric acid, pyrophosphoric acid, polyphosphoric acid, peroxomonophosphoric acid, peroxodiphosphoric acid, carbonic acid, silicic acid, boric acid, peroxoboric acid.

The preferred solvent system additive is a base.

A preferred solvent system additive is an electrolyte.

Hypophosphorous acid is preferably used in the form of an aqueous solution and/or an anhydrous product.

Preferred cations of salts of hypophosphorous acid are Li, Na, K, NH₄TI, Be, Mg, Ca, Sr, Ba, Zn, Cd, Pb, Mn, Ni, Co, Fe, Cu, Al, Cr, Ce, uranyl, Sc, Zr, Hf, Th, Ta and Ti.

The free hypophosphorous acid is preferably formed in situ from the alkali metal hypophosphite salt and the acid. According to the invention, the ratio of acid to hypophosphite (on an acid equivalent basis) is from 0: 1 to 2: 1.

The equivalent weight is expressed herein as a fraction calculated by dividing the number of moles of acid by the number of acidic protons.

The olefin preferably carries a functional group.

Preferred functional groups are sulfonic acids, aldehydes, carboxylic acids, carbonyl groups, hydroxyl groups, sulfinyl groups, amino groups, monoalkylamino groups, dialkylamino groups, amino groups, amido groups and nitro groups.

The olefin used particularly preferably comprises ethylene.

Suitable free-radical initiators are in principle any free-radical-generating system. The olefin addition reaction can be initiated by anionic or free radical initiators, or photochemically.

Particularly preferred free radical initiators are peroxy compounds, such as peroxomonosulfuric acid, potassium peroxomonosulfate (potassium peroxomonosulfate), caroate (tm), oxone (tm), peroxodisulfuric acid, potassium peroxodisulfate (potassium peroxodisulfate), sodium peroxodisulfate (sodium peroxodisulfate), ammonium persulfate (ammonium peroxodisulfate).

Particularly preferred are compounds which form peroxides in solvent systems, such as sodium peroxide, sodium peroxide diperoxy hydrate, sodium peroxide dihydrate, sodium peroxide octahydrate, lithium peroxide monoperoxy hydrate trihydrate, calcium peroxide, strontium peroxide, barium peroxide, magnesium peroxide, zinc peroxide, potassium superoxide, potassium peroxide diperoxy hydrate, sodium perborate tetrahydrate, sodium perborate trihydrate, sodium perborate monohydrate, anhydrous sodium perborate, potassium perborate peroxyhydrate, magnesium perborate, calcium perborate, barium perborate, strontium perborate, potassium perborate, peroxymonophosphate, peroxydiphosphate, potassium perdiphosphate, ammonium perdiphosphate, potassium ammonium perdiphosphate (double salt), sodium carbonate peroxyhydrate, urea hydrate, ammonium oxalate peroxide, barium peroxide peroxyhydrate, calcium hydrogen peroxide, calcium peroxide peroxyhydrate, ammonium diperoxyphosphate triphosphate hydrate, potassium fluoride peroxyhydrate, potassium fluoride triperoxyhydrate, potassium fluoride diperoxyhydrate, sodium pyrophosphate diperoxyhydrate octahydrate, potassium acetate peroxyhydrate, sodium phosphate peroxyhydrate, sodium silicate peroxyhydrate.

Particularly preferred are hydrogen peroxide, performic acid, peracetic acid, benzoyl peroxide, di-tert-butyl peroxide, dicumyl peroxide, 2, 4-dichlorobenzoyl peroxide, decanoyl peroxide, lauroyl peroxide, cumene hydroperoxide, pinene hydroperoxide, p-menthane hydroperoxide, tert-butyl hydroperoxide, acetyl acetone peroxide, methyl ethyl ketone peroxide, succinic acid peroxide, dicetyl peroxydicarbonate, tert-butyl peracetate, tert-butyl permaleate, tert-butyl perbenzoate, acetyl cyclohexyl sulfonyl peroxide.

Preferably, the free-radical initiator used comprises a water-soluble azo compound.

Also preferred are azo initiators, such as 2-tert-butylazo-2-cyanopropane, dimethyl azobisisobutyrate, azobisisobutyronitrile, 2-tert-butylazo-1-cyanocyclohexane, 1-tert-amylazo-1-cyanocyclohexane. Preference is furthermore given to alkyl perketals, such as 2, 2-di (tert-butylperoxy) butane, ethyl 3, 3-di (tert-butylperoxy) butyrate, 1, 1-di (tert-butylperoxy) cyclohexane.

Particularly preferred are azo initiators, such as VAZO 52, VAZO 64(AIBN), VAZO67, VAZO 88, VAZO 44, VAZO 56, VAZO 68 (from Dupont-Biesteritz), V-702, 2 '-azobis (4-methoxy-2, 4-dimethylpentanenitrile), V-652, 2' -azobis (2, 4-dimethylpentanenitrile), V-601 dimethyl 2, 2 '-azobis (2-methylpropionate), V-592, 2' -azobis (2-methylbutyronitrile), V-40, VF-0961, 1 '-azobis (cyclohexane-1-carbonitrile), V-301- [ (cyano-1-methylethyl) azo ] formamide, VAm-1102, 2' -azobis (N-butyl-2-methylpropionamide), VAm-1112, 2 '-azobis (N-cyclohexyl-2-methylpropionamide) VA-0412, 2' -azobis [2- (5-methyl-2-imidazolin-2-yl) propane ] dihydrochloride, VA-0442, 2 '-azobis [2- (2-imidazolin-2-yl) propane ] dihydrochloride, VA-046B 2, 2' -azobis [2- (2-imidazolin-2-yl) propane disulfate dihydrate, V-502, 2 '-azobis (2-amidinopropane) hydrochloride, VA-0572, 2' -azobis [ N- (2-carboxyethyl) -2-methylpropionamide ] tetrahydrate, VA-0582, 2 ' -azobis [2- (3, 4, 5, 6-tetrahydropyrimidin-2-yl) propane ] dihydrochloride, VA-0602, 2 ' -azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl ] propane } dihydrochloride, VA-0612, 2 ' -azobis [2- (2-imidazolin-2-yl) propane ], VA-0802, 2 ' -azobis { 2-methyl-N- [1, 1-bis (hydroxymethyl) -2-hydroxyethyl ] propionamide, VA-0852, 2 ' -azobis { 2-methyl-N- [2- (1-hydroxybutyl) ] propionamide }, VA-0862, 2' -azobis [ 2-methyl-N- (2-hydroxyethyl) propionamide ] (from Wako Chemicals).

Among the aluminium compounds preferred are metallic aluminium and aluminium salts with anions of the seventh main group, such as aluminium fluoride, aluminium fluoride trihydrate, aluminium chloride (anhydrous, crystalline; anhydrous, sublimed), aluminium chloride hexahydrate, aluminium hydroxychloride, ALCHLORAC (from Hardman Australia), alkaline aluminum chloride solution, sulfate-treated polyaluminum chloride solution (PACS) (from LurgiLife science), OBRAFLOC 18(from Oker Chemie GmbH), Alkaflock，EkocidGrade 60, SachtoklarClass, EkoflocGrade, Ekozet grade (from Sachtleben), LocronAnd ParimalGrade (from Clariant), anhydrous aluminum bromide, aluminum iodide hexahydrate.

Preferred are aluminum salts with anions of the sixth main group, such as aluminum sulfide, aluminum selenide.

Preferred are aluminum salts having anions of the fifth main group, such as aluminum phosphide, aluminum hypophosphite, aluminum antimonide, aluminum nitride, and aluminum salts having anions of the fourth main group, such as aluminum carbide, aluminum hexafluorosilicate; and aluminum salts having anions of the first main group, such as aluminum hydride, calcium aluminum hydride, aluminum borohydride, or aluminum salts of oxyacids of the seventh main group, such as aluminum chlorate.

Preferred are the aluminium salts of oxo acids of the sixth main group, e.g. aluminium sulphate, hydrated aluminium sulphate, hexahydrate aluminium sulphate, hexadecaneHydrated aluminum sulfate, aluminum sulfate octadecahydrate, aluminum sulfate solution (from Eka Chemicals), liquid aluminum sulfate (from Oker Chemie GmbH), sodium aluminum sulfate dodecahydrate, potassium aluminum sulfate dodecahydrate, ammonium aluminum sulfate dodecahydrate, magnesium aluminum hydrate (Al₅Mg₁₀(OH)₃₁(SO₄)₂xnH₂O)。

Also preferred are aluminum salts of oxyacids of the fifth main group, such as aluminum nitrate nonahydrate, aluminum metaphosphate, aluminum phosphate, low density aluminum phosphate hydrate, aluminum monophosphate solution; and aluminum salts of oxyacids of the fourth main group, such as aluminum silicate, aluminum magnesium silicate, hydrated aluminum magnesium silicate (almasilate), aluminum carbonate, hydrotalcite (Mg)₆Al₂(OH)₁₆CO₃*nH₂O), sodium dihydroxyaluminum carbonate, NaAl (OH)₂CO₃And aluminum salts of oxyacids of the third main group, such as aluminum borate, or aluminum salts of pseudohalides, such as aluminum thiocyanate.

Preferred are aluminium oxide (purum, technical grade, alkaline, neutral, acidic), hydrated aluminium oxide, aluminium hydroxide or mixed aluminium oxide hydroxides, and/or polyaluminium hydroxide compounds, which preferably have an aluminium content of 9 to 40% by weight.

Preferred aluminium salts are those having organic anions, such as aluminium salts of mono-, di-, oligo-, or polycarboxylic acids, such as aluminium diacetate, basic aluminium acetate, aluminium hypoacetate, aluminium acetyltartrate, aluminium formate, aluminium lactate, aluminium oxalate, aluminium tartrate, aluminium oleate, aluminium palmitate, aluminium monostearate, aluminium stearate, aluminium trifluoromethanesulphonate, aluminium benzoate, aluminium salicylate, hexaurea aluminium triiodide, aluminium 8-hydroxyquinoline.

Among the zinc compounds, preference is given to elemental metallic zinc, as well as zinc salts with inorganic anions, such as zinc halides (zinc fluoride, zinc fluoride tetrahydrate, zinc chloride (zinc oil), bromide, zinc iodide).

Preferred are zinc salts of oxo acids of the third main group (zinc borates, such as FibrakeZB, Fibrake 415, Fibrake 500), and zinc salts of oxo acids of the fourth main group, such as (basic) zinc carbonate, zinc hydroxide carbonate, anhydrous zinc carbonate, hydrated basic zinc carbonate, (basic) zinc silicate, zinc hexafluorosilicate hexahydrate, zinc stannate hydroxide, zinc magnesium aluminum carbonate hydroxide), and zinc salts of oxo acids of the fifth main group (zinc nitrate, zinc nitrate hexahydrate, zinc nitrite, zinc phosphate, zinc pyrophosphate); and zinc salts of oxo acids of the sixth main group (zinc sulfate, zinc sulfate monohydrate, zinc sulfate heptahydrate), and zinc salts of oxo acids of the seventh main group (hypohalites, halites, such as zinc iodate, and perhalogenates, such as zinc perchlorate).

Preferred are the zinc salts of pseudohalides (zinc thiocyanate, zinc cyanide).

Preferred are zinc oxide, zinc peroxide (e.g., zinc peroxide), zinc hydroxide, or mixed zinc oxide hydroxides (standard zinc oxides, such as from Grillo, activated zinc oxides, such as from Rheinchemie, wurtzite).

Preference is given to zinc salts of oxo acids of transition metals (zinc chromate (VI) hydroxide (zinc yellow), zinc chromite, zinc molybdate, e.g.^TMKemgard 911B, zinc permanganate, zinc molybdate-magnesium silicate, such as Kemgard 911C).

Preferred zinc salts are those having organic anions, among which are zinc salts of mono-, di-, oligo-, and polycarboxylic acids, salts of formic acid (zinc formate), salts of acetic acid (zinc acetate, zinc acetate dihydrate, Galzin), salts of trifluoroacetic acid (zinc trifluoroacetate hydrate), zinc propionate, zinc butyrate, zinc valerate, zinc octanoate, zinc oleate, zinc stearate, salts of oxalic acid (zinc oxalate), salts of tartaric acid (zinc tartrate), salts of citric acid (zinc tricitrate dihydrate), salts of benzoic acid (benzoate), zinc salicylate, salts of lactic acid (zinc lactate, zinc lactate trihydrate), acrylic acid, maleic acid, succinic acid, salts of amino acids (glycine), salts having acidic hydroxy functions (zinc phenol, etc.), zinc p-phenolsulfonate hydrate, zinc acetylacetonate hydrate, zinc tannate, zinc dimethyldithiocarbamate, zinc trifluoromethanesulfonate.

Preferred are zinc phosphide, zinc selenide, zinc telluride.

Among the titanium compounds, there are metallic titanium, and titanium salts having an inorganic anion, such as chloride, nitrate, or sulfate ion, or an organic anion, such as formate or acetate ion. Particularly preferred is titanium dichloride, titanium sesquisulfate, titanium (IV) bromide, titanium (IV) fluoride, titanium (III) chloride, titanium (IV) chloride tetrahydrofuran complex, titanium (IV) oxychloride) -hydrochloric acid solution, titanyl (IV) sulfate-sulfuric acid solution, or titanium oxide. The preferred titanium alcoholate is titanium (IV) n- (IV) propanolateTilcom NPT，Vertec NPT), titanium (IV) n-butoxide, titanium (IV) triisopropoxide chloride, titanium (IV) ethoxide, titanium (IV) 2-ethylhexanoate (IV) ((II)TilcomEHT，Vertetec EHT)。

Among tin compounds, metallic tin is preferred, as well as tin salts (stannous chloride, stannous chloride dihydrate, stannic chloride), and stannic oxide, and tin tert-butoxide is a preferred tin alcoholate.

Among the zirconium compounds, preference is given to metallic zirconium and zirconium salts, such as zirconium (IV) chloride, zirconium sulfate tetrahydrate, zirconyl acetate, zirconium oxychloride, zirconyl chloride octahydrate. Further preferred compounds are zirconium oxide, and zirconium (IV) tert-butoxide as preferred zirconium alcoholate.

The product mixture obtained according to process stage a) is preferably reacted without further purification with a metal compound in process stage b).

Preference is given to reacting in process stage b) in the solvent system provided by stage a).

The solvent system provided is preferably changed during the reaction used in process stage b). Preferred methods of modifying the solvent system are the addition of acidic components, solubilizers, foam inhibitors, and the like.

In a further embodiment of the process, the product mixture obtained in process stage a) is worked up.

In a further embodiment of the process, the product mixture obtained in process stage a) is worked up and the dialkylphosphinic acids and/or alkali metal salts thereof obtained according to process stage a) are subsequently reacted with metal compounds in process stage b).

The product mixture is preferably worked up by separating the dialkylphosphinic acids and/or alkali metal salts thereof.

The separation step is preferably carried out by removing the solvent system, e.g. by concentration by evaporation.

The separation step is preferably carried out by removing the solvent system and dissolving the auxiliary components therein, such as by a solid/liquid separation process.

The product mixture is preferably treated by removing insoluble by-products, such as by solid/liquid separation methods.

The subject of the invention is also, inter alia, a process in which sodium hypophosphite is reacted with ethylene in the presence of sodium peroxodisulfate in water to give the sodium salt of diethylphosphinic acid as the main product, and this product is subsequently converted into diethylphosphinic acid using sulfuric acid and reacted with aluminum hydroxide to give the aluminum salt of diethylphosphinic acid.

According to the invention, the dialkylphosphinic salts obtained in process stage a) are converted into dialkylphosphinic acids and then reacted with metal compounds of Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe to give dialkylphosphinic salts of these metals.

According to the invention, the dialkylphosphinic acids obtained in process stage a) are converted into dialkylphosphinic salts and then reacted with metal compounds of Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe to give dialkylphosphinic salts of these metals.

According to the invention, the dialkylphosphinic salts are separated off from the reaction mixture of stage b) by the solid/liquid separation process according to the invention. The solid/liquid separation process of the present invention is settling, hydrocyclone, filtration, and/or centrifugation.

The inventive dialkylphosphinic salts of Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe are dried.

The drying combination device of the invention is a cavity dryer, a channel dryer, a belt dryer (air speed 2 to 3m/s), a disc dryer (temperature 20 to 400 ℃), a drum dryer (hot gas temperature 100 to 250 ℃), a blade dryer (temperature 50 to 300 ℃), an air flow dryer (air speed 10 to 60m/s, exhaust gas temperature 50 to 300 ℃), a fluidized bed dryer (air speed 0.2 to 0.5m/s, exhaust gas temperature 50 to 300 ℃), a roll dryer, a tube dryer (temperature 20 to 200 ℃), a blade dryer, a vacuum drying cabinet (temperature 20 to 300 ℃, pressure 0.001 to 0.016MPa), a vacuum roll dryer (temperature 20 to 300 ℃, pressure 0.004 to 0.014MPa), a vacuum blade dryer (temperature 20 to 300 ℃, pressure 0.003 to 0.02MPa), a vacuum conical dryer (temperature 20 to 300 ℃, pressure 0.003 to 0.02 MPa).

The inventive dried dialkylphosphinic salts have a residual moisture content of from 0.01 to 10% by weight, preferably from 0.1 to 1% by weight.

The particle size of the inventive dialkylphosphinic salts is preferably from 0.1 to 1000. mu.m, particularly preferably from 10 to 100. mu.m.

The preferred bulk density of the inventive dialkylphosphinic salts is from 80 to 800g/l, particularly preferably from 200 to 700 g/l.

The invention also provides the use of the metal dialkylphosphinate salts prepared by the process of the invention for preparing flame retardants.

In particular, the invention provides the use of the inventive dialkylphosphinic salts of Mg, Ca, Al, Zn, Ti, Sn, Zr or Fe for producing flame retardants for thermoplastic polymers, such as polyesters, polystyrenes or polyamides, and for thermosetting polymers.

Suitable polyesters are derived from dicarboxylic acids and diols, and/or from hydroxycarboxylic acids or the corresponding lactones, such as polyethylene terephthalate, polybutylene terephthalate (Celanex2500, Celanex 2002, Celanese; Ultradur, BASF), poly-1, 4-dimethylolcyclohexane terephthalate, polyhydroxybenzoates, and block polyether esters derived from polyethers having hydroxyl end groups; and polyesters modified with polycarbonates or MBS.

Suitable polystyrenes are polystyrene, poly- (p-methylstyrene), and/or poly (. alpha. -methylstyrene).

Suitable polystyrenes are preferably copolymers of styrene or alpha-methylstyrene with dienes or with acrylic acid derivatives, such as styrene-butadiene, styrene-acrylonitrile, styrene-alkyl methacrylate, styrene-butadiene-alkyl acrylate, and styrene-butadiene-alkyl methacrylate, styrene-maleic anhydride, styrene-acrylonitrile-methyl acrylate; high impact system mixtures consisting of a styrene copolymer and another polymer, such as a polyacrylate, a diene polymer, or an ethylene-propylene-diene terpolymer; or block copolymers of styrene, such as styrene-butadiene-styrene, styrene-isoprene-styrene, styrene-ethylene/butylene styrene, or styrene-ethylene/propylene-styrene.

Suitable polystyrenes are preferably styrene or alpha-methylstyrene, e.g. styrene on polybutadiene, styrene on polybutadiene-styrene copolymer, or styrene on polybutadiene-acrylonitrile copolymer, styrene and acrylonitrile (and/or methacrylonitrile) on polybutadiene; styrene, acrylonitrile and methyl methacrylate on polybutadiene; styrene and maleic anhydride on polybutadiene; styrene, acrylonitrile and maleic anhydride or maleimide on polybutadiene; styrene and maleimide on polybutadiene, styrene and alkyl acrylates and/or alkyl methacrylates on polybutadiene, styrene and acrylonitrile on ethylene-propylene-diene terpolymers, styrene and acrylonitrile on polyalkyl acrylates or on polyalkyl methacrylates, graft copolymers of styrene and acrylonitrile on acrylate-butadiene copolymers, and mixtures of these, such as those known as ABS polymers, MBS polymers, ASA polymers, or AES polymers.

Suitable polyamides and copolyamides are derived from diamines and dicarboxylic acids, and/or from aminocarboxylic acids, or the corresponding lactams, for example polyamide-4, polyamide-6 (Akulon K122, DSM; Zytel7301, DuPont; Durethan B29, Bayer), polyamide-6, 6(Zytel 101, DuPont; Durethan A30, Durethan AKV, Durethan AM, Bayer; Ultramid A3, BASF), -6, 10, -6, 9, -6, 12, -4, 6, -12, 12, polyamide-11, and polyamide-12 (GrilamidL 20, Ems Chemie), aromatic polyamides based on m-xylene, diamines and adipic acid; polyamides prepared from hexamethylenediamine and isophthalic and/or terephthalic acid and, if appropriate, elastomers as modifier, such as poly-2, 4, 4-trimethylhexamethyleneterephthalamide or poly-m-phenyleneisophthalamide. Other suitable polymers are the abovementioned polyamides with polyolefins, with olefin copolymers, with ionomers, or with chemically bonded or grafted elastomers; or block copolymers with polyethers, such as with polyethylene glycol, polypropylene glycol, or polytetramethylene glycol. EPDM-or ABS-modified polyamides or copolyamides are also suitable, as well as polyamides condensed during processing ("RIM polyamide systems").

The inventive dialkylphosphinic salts are preferably used in compounding materials for further use in the production of polymer moldings. The preferred process for producing polymer moldings is injection molding.

The following examples illustrate the invention in further detail.

Example 1: aluminium diethylphosphinate

1500g (14mol) of sodium hypophosphite monohydrate and 35g of concentrated sulfuric acid are dissolved in 7.5kg of water and used as initial charge in a 16l jacketed pressure reactor composed of enamelled steel. Once the reaction mixture had been heated to 100 ℃, ethylene was added through a pressure reducing valve set to 6 bar until saturation in the reactor was reached. A solution of 80g (5 mol%) of hydrogen peroxide (33% by weight) in 300g of water is metered in uniformly over 6h with continuous stirring under an ethylene pressure of 6 bar and at a temperature of 100 to 110 ℃. After continuing the reaction for 1h, depressurizing the reactor, and cooling to about 90 ℃, 746g (4.67mol aluminum) of aluminum acetate in 2254g of water were added over 60 min. The resulting solid was then filtered off, washed with 21 hot water, and dried under vacuum at 130 ℃. Yield: 1721g (93.5% of theory).

³¹P NMR：

Diethyl phosphinic acid Al: 97 mol%

Butyl ethyl phosphinic acid Al: 2.5 mol%

Ethyl phosphonic acid Al: 0.5 mol%

Example 2: aluminium diethylphosphinate

1500g (14mol) of sodium hypophosphite monohydrate were dissolved in 7.5kg of water and used as initial charge in a 16l jacketed pressure reactor consisting of enamelled steel. Once the reaction mixture had been heated to 100 ℃, ethylene was added through a pressure reducing valve set to 6 bar until saturation in the reactor was reached. A solution of 17g (0.5 mol%) of sodium peroxodisulfate in 300g of water is metered in uniformly over 6h with constant stirring under an ethylene pressure of 6 bar and at a temperature of 100 to 110 ℃. After continuing the reaction for 1h, depressurizing the reactor, and cooling to about 90 ℃, 3000g (4.67mol aluminum) of 46% strength Al was added₂(SO₄)₃·14H₂The O aqueous solution was added over 60 min. The resulting solid was subsequently filtered off, washed with 2l of hot water and dried under vacuum at 130 ℃. Yield: 1730g (95% of theory).

³¹P NMR：

Diethyl phosphinic acid Al: 98.6 mol%

Butyl ethyl phosphinic acid Al: 0.9 mol%

Ethyl phosphonic acid Al: 0.5 mol%

Example 3: aluminium diethylphosphinate

1500g (14mol) of sodium hypophosphite monohydrate were dissolved in 7.5kg of water and used as initial charge in a 16l jacketed pressure reactor consisting of enamelled steel. Once the reaction mixture had been heated to 100 ℃, ethylene was added through a pressure reducing valve set at 20 bar until saturation in the reactor was reached. A solution of 32g (1 mol%) of ammonium peroxodisulfate in 300g of water is metered in uniformly over 6h with continuous stirring at an ethylene pressure of 20 bar and a temperature of from 100 to 110 ℃. After continuing the reaction for 1h, depressurizing the reactor, and cooling to about 90 ℃, 3000g (4.67mol aluminum) of 46% strength Al was added₂(SO₄)₃·14H₂The O aqueous solution was added over 60 min. The resulting solid was subsequently filtered off, washed with 2l of hot water and dried under vacuum at 130 ℃. Yield: 1750g (95.1% of theory).

³¹P NMR：

Diethyl phosphinic acid Al: 93.9 mol%

Butyl ethyl phosphinic acid Al: 5.5 mol%

Ethyl phosphonic acid Al: 0.6 mol%

Example 4: aluminium diethylphosphinate

1500g (14mol) of sodium hypophosphite monohydrate were dissolved in 7.5kg of water and used as initial charge in a 16l jacketed pressure reactor consisting of enamelled steel. Once the reaction mixture had been heated to 100 ℃, ethylene was added through a pressure reducing valve set to 6 bar until saturation in the reactor was reached. A solution of 19g (0.5 mol%) of 2, 2' -azobis (2-amidinopropane) hydrochloride (Wakopure Chemical Industries, Ltd., grade 98.8% V50) in 300g of water was metered in uniformly over 6h with constant stirring under ethylene pressure 6 bar and at a temperature of 100 to 110 ℃. After continuing the reaction for 1h, depressurizing the reactor, and cooling to about 90 ℃, 650g (4.67mol aluminum) aluminum chloride hexahydrate in 2350g water was added over 60 min. The resulting solid was subsequently filtered off, washed with 2l of hot water and dried under vacuum at 130 ℃. Yield: 1740g (94.5% of theory).

³¹P NMR：

Diethyl phosphinic acid Al: 97.7 mol%

Butyl ethyl phosphinic acid Al: 1.6 mol%

Ethyl phosphonic acid Al: 0.7 mol%

Example 5: aluminium diethylphosphinate

1500g (14mol) of sodium hypophosphite monohydrate and 14g of concentrated sulfuric acid are dissolved in 7.5kg of water and used as initial charge in a 16l jacketed pressure reactor composed of enamelled steel. Once the reaction mixture had been heated to 100 ℃, ethylene was added through a pressure reducing valve set to 6 bar until saturation in the reactor was reached. A solution of 22g (1 mol%) of sodium percarbonate in 300g of water is metered in uniformly over 6h with constant stirring under an ethylene pressure of 20 bar and a temperature of 100 to 110 ℃. After continuing the reaction for 1h, depressurizing the reactor, and cooling to about 90 ℃, 3000g (4.67mol aluminum) of 46% strength Al was added₂(SO₄)₃·14H₂The O aqueous solution was added over 60 min. The resulting solid was subsequently filtered off, washed with 2l of hot water and dried under vacuum at 130 ℃. Yield: 1706g (92.7% of theory).

³¹P NMR：

Diethyl phosphinic acid Al: 98.7 mol%

Butyl ethyl phosphinic acid Al: 0.8 mol%

Ethyl phosphonic acid Al: 0.5 mol%

Example 6: aluminium diethylphosphinate

1500g (14mol) of sodium hypophosphite monohydrate were dissolved in 7.5kg of water and used as initial charge in a 16l jacketed pressure reactor consisting of enamelled steel. Once the reaction mixture had been heated to 100 ℃, ethylene was added through a pressure reducing valve set to 6 bar until saturation in the reactor was reached. A solution of 22g (1 mol%) of sodium percarbonate and 16g of tetraacetylethylenediamine in 300g of water is metered in uniformly over 6h with constant stirring under an ethylene pressure of 20 bar and a temperature of 100 to 110 ℃. After continuing the reaction for 1h, depressurizing the reactor, and cooling to about 90 ℃, 3000g (4.67mol aluminum) of 46% strength Al was added₂(SO₄)₃·14H₂The O aqueous solution was added over 60 min. The resulting solid was subsequently filtered off, washed with 2l of hot water and dried under vacuum at 130 ℃. Yield: 1720g (93.4% of theory).

³¹P NMR：

Diethyl phosphinic acid Al: 97.6 mol%

Butyl ethyl phosphinic acid Al: 1.8 mol%

Ethyl phosphonic acid Al: 0.6 mol%

Example 7: aluminium diethylphosphinate

1500g (14mol) of sodium hypophosphite monohydrate were dissolved in 7.5kg of water and used as initial charge in a 16l jacketed pressure reactor consisting of enamelled steel. Once the reaction mixture had been heated to 100 ℃, ethylene was added through a pressure reducing valve set to 6 bar until saturation in the reactor was reached. A solution of 49g (1 mol%) of dibenzoyl peroxide (70% by weight solution in water) in 300g of water was metered in uniformly over 6h with continuous stirring under ethylene pressure 6 bar and at a temperature of from 100 to 110 ℃. After continuing the reaction for 1h, depressurizing the reactor, and cooling to about 90 ℃, 1725g (4.67mol aluminum) of aluminum nitrate nonahydrate dissolved in 1275g water was added over 60 min. The resulting solid was subsequently filtered off, washed with 2l of hot water and dried under vacuum at 130 ℃. Yield: 1697g (92.2% of theory).

³¹P NMR：

Diethyl phosphinic acid Al: 96.5 mol%

Butyl ethyl phosphinic acid Al: 2.7 mol%

Ethyl phosphonic acid Al: 0.8 mol%

Example 8: aluminium diethylphosphinate

1.5kg (14mol) of sodium hypophosphite monohydrate were dissolved in 7.5kg of water and used as initial charge in a 16l jacketed pressure reactor consisting of enamelled steel. Once the reaction mixture had been heated to 100 ℃, ethylene was added through a pressure reducing valve set to 6 bar until saturation in the reactor was reached. A solution of 33g (1 mol%) of sodium peroxodisulfate in 300g of water is metered in uniformly over 6h with continuous stirring under ethylene pressure 6 bar and at a temperature of from 100 to 110 ℃. After continuing the reaction for 1h, depressurizing the reactor and cooling to about 90 ℃, 700g of concentrated sulfuric acid were added over 30 minutes. 364g (4.67mol) of aluminum hydroxide were then added and the mixture was heated in a sealed reactor at 150 ℃ for 8 h. After cooling to ambient temperature, the resulting solid was filtered off, washed with 2l of hot water and dried under vacuum at 130 ℃. Yield: 1675g (92% of theory).

³¹P NMR：

Diethyl phosphinic acid Al: 98.7 mol%

Butyl ethyl phosphinic acid Al: 0.8 mol%

Ethyl phosphonic acid Al: 0.5 mol%

Example 9: (comparative) aluminum diethylphosphinate

2.2kg (20.7mol) of sodium hypophosphite monohydrate were dissolved in 8kg (7.62l) of acetic acid and used as starting charge in a 16l jacketed pressure reactor made from enamelled steel. Once the reaction mixture had been heated to 85 ℃, ethylene was added through a pressure reducing valve set to 5 bar until saturation in the reactor was reached. The reaction was initiated by adding 56g (1 mol%) of 2, 2' -azobis (2-amidinopropane) dihydrochloride in 250ml of water with continuous stirring and the reaction was controlled by the free-radical initiator feed rate such that the reaction temperature in the reactor was 80 ℃ at the jacket temperature and 95 ℃ or less with continuous addition of ethylene at an average pressure of about 5 bar. The total addition time was 3 hours. The mixture was then allowed to continue to react at 85 ℃ for another 3 h. The reactor was depressurized and cooled to room temperature. The total weight of the product was 11.7 kg. This corresponds to an ethylene absorption of 1.2kg (100% of theory).

800g of the resulting mixture, consisting essentially of sodium diethylphosphinate, were dissolved in 2500ml of acetic acid, and 38g (0.48m0l) of aluminum hydroxide were subsequently added. The mixture was then heated at reflux for about 4 hours, cooled, and filtered. The solid obtained is washed first with 1 l of glacial acetic acid, then with 1 l of distilled water and finally with 500ml of acetone and then dried under vacuum at 130 ℃. Yield: 183g (92% of theory).

NMR analysis:

diethyl phosphinic acid Al: 87.2 mol%

Ethyl butyl phosphinic acid Al: 11.9 mol%

Ethyl phosphonic acid Al: 0.9 mol%

Example 10 (comparative): aluminium diethylphosphinate

A16 l jacketed pressure reactor made of enameled steel was charged with a mixture of 2.64kg (20mol) of a 50% strength aqueous solution of hypophosphorous acid and 7kg of acetic acid. Once the reaction mixture had been heated to 100 ℃, ethylene was added through a pressure reducing valve set to 5 bar until saturation in the reactor was reached. A solution of 56g of 2, 2 '-azobis (N, N' -dimethyleneisobutyramidine) dihydrochloride in 500g of acetic acid was stirred continuously over 6h under ethylene pressure of 5 bar and temperatureThe mixture was uniformly fed at 100 ℃ and 105 ℃. After further reaction for 1h, depressurization of the reactor, and cooling to room temperature, the resulting solution was substantially freed from the acetic acid solvent on a rotary evaporator and subsequently treated with 10l of water. 4500g (3.5mol) of 46% strength Al are added within 1 hour₂(SO₄)₃·14H₂And (4) O aqueous solution. The resulting solid was subsequently filtered, washed twice with water (2 l each), and dried under vacuum at 130 ℃. Yield: 2520g (82% of theory).

NMR：

Diethyl phosphinic acid Al: 90.8 mol%

Butyl ethyl phosphinic acid Al: 8.4 mol%

Ethyl phosphonic acid Al: 0.8 mol%

Example 11:

the products prepared in examples 1 and 2 and in comparative examples 3 and 4 were mixed with polybutylene terephthalate (PBT-GV;celanex 2300 GV 1/30; celanese, USA) and fed into a twin screw extruder (Leistritz LSM 30/34) at a temperature of 230 to 260 ℃. The homogenized polymer strand is drawn off, cooled in a water bath and then granulated. To evaluate the polymer degradation, the solution viscosity (SV value) of the polyester pellets obtained was determined and compared with the pure polyester. The following results were obtained:

containing additives	Purity [% ]]	Viscosity number
containing additives	Purity [% ]]	Viscosity number	Product of example 2	98.6	1023
Product of example 8	98.7	1034	Product of example 2	98.6	1023
Product of example 8	98.7	1034	Example 9 (comparative) product	87.2	719
Example 10 (comparative) product	90.8	758	Example 9 (comparative) product	87.2	719
Example 10 (comparative) product	90.8	758	Without additives	-	1072

Based on the main component

The table illustrates the advantages of the products produced according to the invention. The single acetate-free phosphinate of the present invention reduced the solution viscosity only slightly after incorporation into the polymer matrix, indicating that the molecular weight was nearly unchanged. In contrast, the product as prepared in PCT/EP 98/07350 showed significant polymer degradation (greatly reduced viscosity values).

Claims

1. A process for preparing dialkylphosphinic salts, which comprises

b) reacting the dialkylphosphinic acids and/or alkali metal dialkylphosphinic salts obtained in a) with aluminum compounds to give aluminum dialkylphosphinic salts,

wherein the solvent system comprises a solvent system additive and water, and wherein the solvent system comprises from 50 to 100% by weight water and from 0 to 50% by weight of the solvent system additive, and wherein the solvent system additive is acetic acid and/or sulfuric acid.

2. A process as claimed in claim 1, wherein the solvent system comprises 80 to 100% by weight of water and 0 to 20% by weight of solvent system additives.

3. A process as claimed in claim 1 wherein the solvent system comprises 95 to 100% by weight water and 0 to 5% by weight solvent system additive.

4. The method of claim 1, wherein the salt of hypophosphorous acid is an alkali metal salt.

5. The method of claim 4 wherein the salt of hypophosphorous acid is the sodium salt.

6. The process of claim 1 wherein the dialkylphosphinic salt of process stage a) is an alkali metal salt.

7. The process of claim 1 wherein the dialkylphosphinic salt of process stage a) is a sodium salt.

8. The process of claim 1 wherein the hypophosphorous acid is made in situ from a salt of hypophosphorous acid and at least one mineral acid, wherein the equivalent ratio of additive acid to hypophosphite is from 0: 1 to 2: 1.

9. The process of claim 1, wherein the reaction in step a) is carried out in the presence of a free-radical initiator, wherein the free-radical initiator used comprises a compound capable of forming peroxides and/or peroxy compounds, and/or azo compounds.

10. The method of claim 9, wherein the peroxygen compound is hydrogen peroxide, potassium persulfate, sodium persulfate, or ammonium persulfate.

11. The process of claim 9, wherein the azo compound is 2, 2 ' -azobis (2-amidinopropane) dihydrochloride and/or 2, 2 ' -azobis (N, N ' -dimethyleneisobutyramidine) dihydrochloride.

12. The process of claim 1, wherein the free-radical initiator is used in an amount of 0.001 to 10 mol%, based on the phosphorus-containing compound.

13. The process of claim 1 wherein the free radical initiator is metered in at a rate of from 0.01 to 10 mol% of initiator per hour, based on the phosphorus-containing compound.

14. The process as claimed in claim 1, wherein the olefins used comprise ethylene, propylene, n-butene and/or isobutene, or mixtures of these.

15. The process of claim 1, wherein the molar ratio of olefin to hypophosphite and/or hypophosphorous acid is from 0: 1 to 3: 1.

16. The process of claim 15 wherein the molar ratio of olefin to hypophosphite and/or hypophosphorous acid is from 0.5: 1 to 2.5: 1.

17. The process of claim 1, wherein the reaction in step a) is carried out at a pressure of from 1 to 100 bar of the olefin used.

18. The process of claim 1, wherein the reaction in step a) is carried out at a pressure of from 2 to 50 bar of the olefin used.

19. The process of claim 1 wherein the atmosphere in step a) during the reaction consists of from 50 to 99.9% by weight of the solvent system components and the olefin.

20. The process of claim 1 wherein the atmosphere in step a) during the reaction consists of 70 to 95% by weight of the solvent system components and the olefin.

21. The process of claim 1, wherein the reaction in process stage a) is carried out at a temperature of from 0 to 250 ℃.

22. The process of claim 1, wherein the reaction in process stage a) is carried out at a temperature of from 20 to 200 ℃.

23. The process of claim 1, wherein the reaction in process stage a) is carried out at a temperature of from 50 to 150 ℃.

24. The process of claim 1, wherein the reaction in process step a) is carried out in an absorption column, a spray column, a bubble column, a stirred tank and/or a kneader.

25. The process according to claim 1, wherein the mixer units used comprise anchor stirrers, blade stirrers, MIC stirrers, propeller stirrers, impeller stirrers, turbine stirrers, cross stirrers, dispersion discs, cavitation stirrers, rotor-stator mixers, static mixers, venturi nozzles, and/or pneumatic pumps.

26. The process of claim 1, wherein the reaction solution in process stage a) is subjected to a mixing intensity corresponding to a rotational Reynolds number of from 1 to 1000000.

27. The process of claim 1, wherein the reaction solution in process stage a) is subjected to a mixing intensity corresponding to a rotational Reynolds number of from 100 to 100000.

28. The process of claim 1 wherein in the processIn stage a), the energy introduced is from 0.083 to 10kW/m³In the case of (a), the thorough mixing of the olefin, the radical initiator, the solvent system, and the hypophosphorous acid, and/or its salts is carried out.

29. The process of claim 1, wherein in process stage a) the energy introduced is from 0.33 to 1.65kW/m³In the case of (a), the thorough mixing of the olefin, the radical initiator, the solvent system, and the hypophosphorous acid, and/or its salts is carried out.

30. The process of claim 1, wherein the reaction of the dialkylphosphinic acid and/or salt with the aluminum and/or aluminum compound is carried out in process stage b) in a molar ratio of dialkylphosphinic acid or salt to aluminum of from 4.5: 1 to 1: 0.66.

31. The process of claim 1, wherein the aluminum compound used in process stage b) is aluminum, aluminum oxide, aluminum hydroxide, aluminum oxide hydroxide, aluminum borate, aluminum carbonate, aluminum hydroxycarbonate hydrate, mixed aluminum hydroxycarbonate hydrate, aluminum phosphate, aluminum sulfate hydrate, aluminum hydroxysulfate hydrate, mixed aluminum hydroxysulfate hydrate, aluminum hydroxysulfate sulfate hydrate, aluminum oxysulfate, aluminum acetate, aluminum nitrate, aluminum fluoride hydrate, aluminum chloride hydrate, aluminum oxychloride, aluminum bromide, aluminum iodide hydrate, aluminum carboxylic acid derivative, and/or aluminum alcoholate.

32. The method of claim 31, wherein the aluminum compound is aluminum chloride, aluminum hydroxide, aluminum nitrate, and/or aluminum sulfate.

33. The process of claim 1, wherein the reaction in process stage b) is carried out at a temperature of from 20 to 250 ℃.

34. The process of claim 1, wherein the reaction in process stage b) is carried out at a temperature of from 80 to 120 ℃.

35. The process of claim 1, wherein the reaction in process stage b) is carried out at a pressure of from 1Pa to 200 MPa.

36. The process of claim 1, wherein the reaction in process stage b) is carried out at a pressure of from 0.01MPa to 10 MPa.

37. The process of claim 1, wherein in process stage b) the dialkylphosphinic acid and/or alkali metal salt thereof is reacted with an aluminum compound to give the aluminum dialkylphosphinate for a period of 1 x 10^-7To 1 x 10²h。

38. The process of claim 1, wherein in process stage b) the solids content of the aluminum dialkylphosphinate in the reaction of dialkylphosphinic acid and/or alkali metal salts thereof with an aluminum compound to give an aluminum dialkylphosphinate is from 0.1 to 70% by weight.

39. The process of claim 1, wherein in process stage b) the solids content of the aluminum dialkylphosphinate in the reaction of dialkylphosphinic acid and/or alkali metal salts thereof with an aluminum compound to give an aluminum dialkylphosphinate is from 5 to 40% by weight.

40. The process of claim 1, wherein the reaction in process stage b) is carried out in stirred tanks, mixers and/or kneaders.

41. The process of claim 1, wherein the energy introduced during the reaction in process stage b) is from 0.083 to 1.65kW/m³。

42. The method of claim 1, whereinThe energy introduced during the reaction in process stage b) is from 0.33 to 1.65kW/m³。

43. The process of claim 1, wherein the alkali metal dialkylphosphinic salt obtained in process stage a) is converted into dialkylphosphinic acid in process stage a1) and reacted with an aluminum compound in process stage b) to give the aluminum dialkylphosphinic salt.

44. The process of claim 1, wherein the dialkylphosphinic acid obtained in process stage a) is converted into the alkali metal dialkylphosphinic salt in process stage a1) and reacted with an aluminum compound in process stage b) to give the aluminum dialkylphosphinic salt.

45. The process of claim 1, wherein the aluminum dialkylphosphinate from process stage b) is separated from the reaction mixture by filtration and/or centrifugation.

46. The process of claim 1, wherein, in process stage b), the diethylphosphinate is isolated using a pressure filter funnel, a vacuum filter funnel, a filter funnel with stirrer, a pressure candle filter, a shaft leaf filter, a round leaf filter, a centrifugal disc filter, a chamber or frame filter press, an automatic chamber filter press, a vacuum multi-chamber drum filter, a vacuum multi-chamber disc filter, an evacuated chamber filter, a vacuum multi-chamber disc filter, a rotary pressure filter, a vacuum belt filter.

47. The process of claim 1, wherein the filtration pressure is from 0.5Pa to 6 MPa.

48. The process of claim 1, wherein the filtration temperature is from 0 to 400 ℃.

49. The method of claim 1, whereinThe filter efficiency is 10 to 200kg x h^-1*m^-2。

50. The process of claim 1, wherein the residual moisture content of the filter cake is from 5 to 60%.

51. The process of claim 1, wherein the diethyl phosphinate is separated in process stage b) using a solid disk centrifuge, a plow centrifuge, a chamber centrifuge, a spiral conveyor centrifuge, a disk centrifuge, a tube centrifuge, a screen screw centrifuge, a screen-plow centrifuge, or a pulse centrifuge.

52. The method of claim 51, wherein the solid bowl centrifuge is a top drain centrifuge.

53. The method of claim 51, wherein the screen centrifuge is selected from the group consisting of a ceiling-mounted centrifuge and a basket-type centrifuge.

54. The method of claim 1, wherein the centrifugal force ratio is 300 to 15000.

55. The method of claim 1, wherein the suspension passage rate is 2 to 400m³*h^-1。

56. The method of claim 1, wherein the solids passage rate is 5 to 80t h^-1。

57. The process of claim 1, wherein the residual moisture content of the filter cake is 5 to 60%.

58. The process of claim 1, wherein, after process stage b), the aluminium diethylphosphinate separated from the reaction mixture by filtration and/or centrifugation is dried.

59. The method of claim 1 wherein the aluminum dialkylphosphinate has a residual moisture content of from 0.01 to 10 weight percent.

60. The method of claim 1 wherein the aluminum dialkylphosphinate has a residual moisture content of from 0.1 to 1 weight percent.

61. The method of claim 1 wherein the dialkylphosphinic salt of aluminum has an average particle size of 0.1 to 2000 μm.

62. The method of claim 1 wherein the dialkylphosphinic salt of aluminum has an average particle size of from 10 to 500 μm.

63. The method of claim 1 wherein the aluminum dialkylphosphinate has a bulk density of 80 to 800 g/l.

64. The method of claim 1 wherein the aluminum dialkylphosphinate has a bulk density of 200 to 700 g/l.

65. A flame-retardant polymer molding composition comprising from 1 to 50% by weight of a dialkylphosphinic salt prepared by the process as claimed in any of claims 1 to 64, from 1 to 99% by weight of a polymer or a mixture thereof, from 0 to 60% by weight of additives and from 0 to 60% by weight of fillers.

66. A flame-retardant polymer molding composition comprising from 5 to 30% by weight of a dialkylphosphinic salt or mixture of dialkylphosphinic salts prepared by a process as claimed in any of claims 1 to 64, from 5 to 90% by weight of a polymer or mixture of polymers, from 5 to 40% by weight of additives and from 5 to 40% by weight of fillers.

67. A polymer molding, polymer film, polymer filament or polymer fiber comprising the dialkylphosphinic salt prepared by the process as claimed in any of claims 1 to 64.

68. A polymer molding, polymer film, polymer filament, or polymer fiber comprising from 1 to 50% by weight of a dialkylphosphinic salt prepared by the process according to any of claims 1 to 64, from 1 to 99% by weight of a polymer or a mixture thereof, from 0 to 60% by weight of additives, from 0 to 60% by weight of fillers.

69. A polymer molding, polymer film, polymer filament, or polymer fiber comprising 5 to 30% by weight of a dialkylphosphinic salt prepared by the process according to any of claims 1 to 64, 5 to 90% by weight of a polymer or a mixture thereof, 5 to 40% by weight of additives, 5 to 40% by weight of fillers.

70. Aluminum dialkylphosphinic salts obtained by a process for preparing these dialkylphosphinic salts, wherein

71. Dialkylphosphinic acids and/or alkali metal salts thereof, which are obtained by: reacting hypophosphorous acid and/or salts thereof with an olefin in the presence of a free radical initiator in a solvent system to give a dialkylphosphinic acid and/or alkali metal salt thereof, wherein the solvent system comprises a solvent system additive and water, and wherein the solvent system comprises from 50 to 100% by weight of water and from 0 to 50% by weight of a solvent system additive, and wherein the solvent system additive is acetic acid and/or sulfuric acid.

72. A dialkylphosphinic salt obtained by the following steps: converting the alkali metal dialkylphosphinate obtained in process stage a) to a dialkylphosphinic acid and subsequently reacting the dialkylphosphinic acid with an aluminum compound to obtain the aluminum dialkylphosphinate, wherein the solvent system comprises a solvent system additive and water, and wherein the solvent system comprises from 50 to 100% by weight of water and from 0 to 50% by weight of a solvent system additive, and wherein the solvent system additive is acetic acid and/or sulfuric acid.