CA2056022A1 - Stabilized red phosphorus, and processes for the preparation thereof - Google Patents
Stabilized red phosphorus, and processes for the preparation thereofInfo
- Publication number
- CA2056022A1 CA2056022A1 CA002056022A CA2056022A CA2056022A1 CA 2056022 A1 CA2056022 A1 CA 2056022A1 CA 002056022 A CA002056022 A CA 002056022A CA 2056022 A CA2056022 A CA 2056022A CA 2056022 A1 CA2056022 A1 CA 2056022A1
- Authority
- CA
- Canada
- Prior art keywords
- red phosphorus
- weight
- phosphorus
- epoxy resin
- stabilized
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 title claims abstract description 61
- 238000000034 method Methods 0.000 title claims abstract description 19
- 238000002360 preparation method Methods 0.000 title claims abstract description 9
- 239000003822 epoxy resin Substances 0.000 claims abstract description 33
- 229920000647 polyepoxide Polymers 0.000 claims abstract description 33
- 230000003647 oxidation Effects 0.000 claims abstract description 24
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 24
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 19
- 239000011574 phosphorus Substances 0.000 claims abstract description 19
- 239000002245 particle Substances 0.000 claims abstract description 17
- BJQHLKABXJIVAM-UHFFFAOYSA-N bis(2-ethylhexyl) phthalate Chemical compound CCCCC(CC)COC(=O)C1=CC=CC=C1C(=O)OCC(CC)CCCC BJQHLKABXJIVAM-UHFFFAOYSA-N 0.000 claims abstract description 15
- 239000004803 Di-2ethylhexylphthalate Substances 0.000 claims abstract description 10
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 10
- 239000003381 stabilizer Substances 0.000 claims abstract description 9
- 239000011248 coating agent Substances 0.000 claims abstract description 8
- 238000000576 coating method Methods 0.000 claims abstract description 8
- 239000000203 mixture Substances 0.000 claims description 15
- 239000000839 emulsion Substances 0.000 claims description 11
- 238000003756 stirring Methods 0.000 claims description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 8
- 239000007900 aqueous suspension Substances 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 6
- 238000001914 filtration Methods 0.000 claims description 6
- 239000002904 solvent Substances 0.000 claims description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 235000014786 phosphorus Nutrition 0.000 description 13
- IISBACLAFKSPIT-UHFFFAOYSA-N bisphenol A Chemical compound C=1C=C(O)C=CC=1C(C)(C)C1=CC=C(O)C=C1 IISBACLAFKSPIT-UHFFFAOYSA-N 0.000 description 9
- 238000004458 analytical method Methods 0.000 description 8
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 150000002924 oxiranes Chemical class 0.000 description 6
- XYFCBTPGUUZFHI-UHFFFAOYSA-N Phosphine Chemical compound P XYFCBTPGUUZFHI-UHFFFAOYSA-N 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 229920005989 resin Polymers 0.000 description 5
- 239000011347 resin Substances 0.000 description 5
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- PXKLMJQFEQBVLD-UHFFFAOYSA-N bisphenol F Chemical compound C1=CC(O)=CC=C1CC1=CC=C(O)C=C1 PXKLMJQFEQBVLD-UHFFFAOYSA-N 0.000 description 4
- LNEPOXFFQSENCJ-UHFFFAOYSA-N haloperidol Chemical compound C1CC(O)(C=2C=CC(Cl)=CC=2)CCN1CCCC(=O)C1=CC=C(F)C=C1 LNEPOXFFQSENCJ-UHFFFAOYSA-N 0.000 description 4
- 238000003860 storage Methods 0.000 description 4
- OBSZRRSYVTXPNB-UHFFFAOYSA-N tetraphosphorus Chemical compound P12P3P1P32 OBSZRRSYVTXPNB-UHFFFAOYSA-N 0.000 description 4
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- 239000004033 plastic Substances 0.000 description 3
- 229920003023 plastic Polymers 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 125000004203 4-hydroxyphenyl group Chemical group [H]OC1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 2
- BRLQWZUYTZBJKN-UHFFFAOYSA-N Epichlorohydrin Chemical compound ClCC1CO1 BRLQWZUYTZBJKN-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000012298 atmosphere Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 235000008504 concentrate Nutrition 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 150000004715 keto acids Chemical class 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 230000006641 stabilisation Effects 0.000 description 2
- 238000011105 stabilization Methods 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229930185605 Bisphenol Natural products 0.000 description 1
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 1
- 239000005751 Copper oxide Substances 0.000 description 1
- 239000004593 Epoxy Substances 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 229910000431 copper oxide Inorganic materials 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000007323 disproportionation reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000012065 filter cake Substances 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- -1 for example Polymers 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000004850 liquid epoxy resins (LERs) Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- LWJROJCJINYWOX-UHFFFAOYSA-L mercury dichloride Chemical compound Cl[Hg]Cl LWJROJCJINYWOX-UHFFFAOYSA-L 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-N phosphoric acid Substances OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/003—Phosphorus
- C01B25/006—Stabilisation
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Epoxy Resins (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Glanulating (AREA)
Abstract
Stabilized red phosphorus, and processes for the preparation thereof Abstract of the disclosure:
In, a stabilized, pulverulent red phosphorus comprising phosphorus particles having a maximum particle size of 2 mm whose surface is covered with a thin coating of an oxidation stabilizer, the oxidation stabilizer comprises an uncured epoxy resin in a proportion of from 0.2 to less than 5% by weight. The red phosphorus stabilized in this way may additionally be covered by a thin coating of di-2-ethylhexyl phthalate as phlegmatizing agent. In addition, processes for the preparation of the stabilized and possibly additionally phlegmatized red phosphorus are described.
In, a stabilized, pulverulent red phosphorus comprising phosphorus particles having a maximum particle size of 2 mm whose surface is covered with a thin coating of an oxidation stabilizer, the oxidation stabilizer comprises an uncured epoxy resin in a proportion of from 0.2 to less than 5% by weight. The red phosphorus stabilized in this way may additionally be covered by a thin coating of di-2-ethylhexyl phthalate as phlegmatizing agent. In addition, processes for the preparation of the stabilized and possibly additionally phlegmatized red phosphorus are described.
Description
The invention relates to stabilized, pulverulent red phosphorus comprising phosphorus particles having a maximum particle size of ~ mm whosa surface is covered by a thin coating of an oxidi~:ing stabilizer, and to a process for the preparation of the product according to the invention.
As is known, red phosphorus is obtained by thermal con-version of yellow phosphorus into the more stable red modification. The crude red phosphorus containing about 0.5 - 1.5~ by weight of yellow phosphorus forms a compact material when the reaction is complete. It is ground under an inert-gas atmosphere and freed from yellow phosphorus in aqueous suspension by boiling with dilute sodium hydroxide solution. Recently, the conversion has been carried out in rotating reactors, the red phosphorus being produced as a powder. The aqueous suspension of red phosphorus discharged from ~he reactor is heated in stirred vessels using steam and freed from the residual amount of about 0.1% by weight of yellow phosphorus by addition of sodium hydroxide solution in portions.
Red phosphorus is required in pyrotechnology and in the production of striking surfaces for matches and is used as a flameproofing agent for plastics, such as, for example, polyamides or polyurethanes.
As is known, a chemical reaction takes place at the surface of red phosphorus in a moist atmosphere, forming .
. ~ ~ , . . .
various acids of phosphorus in the oxidation states from + 1 to ~ 5 and hydrogen phosphide due to oxidation and of disproportionation.
The object was thus to improve the inadequate oxidation stability of red phosphorus by stabilization.
The term "stabilization" here is taXen to mean a measure which provides red phosphorus with improved protection against atmospheric influences and thus contributes to reduced formation of oxo acids of phosphorus and hydrogen phosphide, for example on storage or further processing.
&erman Patent 29 45 118 (=US Patent 4,315,897) discloses that the oxidation stability of red phosphorus can be improved by a combination of aluminum hydroxide and cured PpOxy resin, whereas the cured epoxy resin alone is relatively ineffective (cf. German Pa~ent 29 45 118, Examples 9 and 10).
Eerman Patent 26 25 674 describes a flameproofing agent for plas~ics which comprises from 50 to 95% of red phosphorus and from 5 to 50% of a cured or uncured epoæy resin. The epoxy resins employed function here as car-riers for the preparation of flameproofing agent concen-trates based on red phosphorus. This can also be seen from the high epoxy resin concentrations in the various examples. Examples 1, 3 and 5 give a composition of 40%
by weight of epoxy resin (cured) and 60% by weight of red phosphorus, and Example 2 gives a composition of 38% by weight of epoxy resin (cured), 57% by weight of red phosphorus and 5% by weight of copper oxide. In Example 8, the granules obtained compri.~e 40% by weight of epoxy resin and 60% by weight of red phosphorus. Examples 4, 6, 7 and 9 to 11 of German Patenl 26 25 674 merely relate to the testing of the concentrates prepared in accordance with the other examples.
Surprisingly, it has now been found that the oxidation stability of red phosphorus can be improved by applying small amounts of an uncured epoxy resin. This is surpris-ing and unforeseeable because cured epoxy resins applied by microencapsulation are relatively ineffective (cf.
German Patent 29 45 118, Examples 9 and 10).
The reduction in the formation of hydrogen phosphide on use of about 4Q% by weight of epoxy resin in accordance with German Patent 26 25 674 which is obserYed on incor-poration into plastics does not mean that this was also to be expected in the case of the low epoxy resin concentrations of less than 5% by weight used according to the invention. In fact, it was to be expected that only slight i~provements in the oxidation stability, or none at all, would occur, as in Examples 9 and 10 of German Patent 29 45 118.
The effect of the invention can be increased further if the phlegmatizing agent di-2-ethylhexyl phthalate is ~ .
t ~ ~ W Y~ J . .~
additionally applied by the process of DE-A 34 36 161.
In ~his connection the term ~phlegmatizing~ is ~aken to mean a measure which reduces the tendency of red phospho-rus to form dust, and reduces the risk of dust explosions and increases the processing safety.
Epoxy resins have been known for some time lcf. Rompp Chemie Lexikon [Rompp's Lexicon of Chemistry], 9th Edition, p. 1196; h. and M. Fieser, Organische Chemie tOrganic Ch~mistry], Verlag Chemie (1965), p. 1754 ff.).
In the context of the invention, suitable epoxy resins are, in particular, products of the reaction of 2,2-bis(4-hydroxyphenyl~propane (bisphenol A) and epichloro-hydrin (bisphenol A resins) ~nd of bis~4-hydroxyphenyl) methane (bisphenol F) and epichlorohydrin (bisphenol ~
resins), so long as they can be emulsified with water or can be employed dissolved in water-miscible solvents.
Bisphenol A can for its part be prepared by condensation of phenol with acetone, while bisphenol F is prepared by condensation of phenol and formaldehyde (cf. Runststoff Hand~uch [Plastics Handbook3, Vol. 10, Thermosets, Carl Hanser Verlag, Munich, Vienna, 2nd ~dition, 1988, p.1004, with data on epoxy-based resins in Table 13.2 on p. 1005).
Indeed, the invention relates ~o stabilized, pulverulent red phosphorus comprising phosphorus particles having a maximum particle size of 2 mm whose surface is covered 5 -- ' ) ~" 1 ) ~,,1 with a thin coating of an oxidation stabilizer, wherein the oxidation stabilizer is an uncured epoxy resin in a proportion oE from 0.2 to less than 5% by weiyht.
Furthermore, the stabilized, pulverulent red phosphorus of the invention may optionally and preEerably have the features that a] it is additionally covered by a thin coating of di-2-ethylhexyl phthalate as phlegmatizing agent in a proportion of from 0.05 to 2% by weight, preferably from 0.3 to 1.5% by weight;
b) the proportion of the oxidation stabilizer is from 0.5 to 3~ by weight.
Furthermore the invention relates to a process for the preparation oE stabilized, pulverulent red phosphorus, which comprises stirring an aqueous emulsion of epoxy resin or a solution of epoxy resin in a water-miscible solvent into an aqueous suspension of red phosphorus so that the proportions in the mixture are from more than 95 to 99.8 parts by weight of red phosphorus and from less than 5 to 0.2 parts by weight of epoxy resin; adjusting the pH to .Erom 4 to 9, stirring the mixture at a temperature oE from 40 to 80C Eor from 0.5 to 3 hours, and finally isolating the phosphorus particles by filtration and drying at elevated temperature.
, , .~ : ~, :' '. ' Finally, the invention also relates to a process for the preparation of stabilized and phlegmatized, pulverulent red phosphorus, which comprises stirring an aqueous emulsion of epoxy resin or a solution of epoxy resin in a water-miscible solvent into an aqueous suspension of red phosphorus, adjusting the pll to from 4 to 9, stirring the mixture at a temperature of from 40 to 80C for from 0.5 to 3 hours, adding an ac~eous emulsion of di-2-ethylhexyl phthalate and stirring the mixture at a temperature of from 20 to 90C for from 0.5 to 3 hours so that the proportions in the mixture are from more than 93 to 99.75 parts by weight of red phosphoxus, from less than 5 to 0.2 parts by weight of epoxy resin and from 2 to 0.05 parts by weight of di-2-ethylhexyl phthalate; and finally isolating the phosphorus particles by filtration and drying at elevated temperature.
The final drying of the filtered-off phosphorus particles may preferably be carried out at a temperature of from 80 to 120C in a stream of nitrogen.
Preferred water-miscible solvents are acetone, methanol and ethanol.
The working examples and tables below serve to further illustrate the invention. The percentages are % by weight.
~' ~, ...
Determination of the oxidation stability The oxidation stability was determined by a humid/warm storage test. To this end, 5.0 g of red phosphorus (particle size: 100% < 150 ~m) were weighed out into a crystallization dish having a diameter of 50 mm, and the dish was stored in a closed glass vessel at 80C and 100%
relative atmospheric humidity. The hydrogen phosphide fo~med was either expelled from the glass vessel by a stream of air (10 1/h), reacted in a gas washing bottle with 2.5% strength mercury (II) chloride solution and the amount of hydrochloric acid produced determined titri-metrically, or analyzed using a Drager "hydrogen phos-phide 50~a" tube.
In order to determine the content of the various oxo acids of phosphorus, the phosphorus sample was trans-ferred into a 250 ml beaker, 200 ml of 1% strength hydrochloric acid were added, and the mixture was boiled for 10 minutes and subsec~uently filtered. The acid-soluble phosphorus was then determined in the filtrate by the photometric molybdato-vanadato-phosphoric acid method.
In order to cletermine the initial value for acid-soluble phosphorus, t:he red phosphorus was subjected to the same analytical procedure -without prior humid/warm storage.
This value is then subtracted from the content of acid-soluble phosphorus determined after humid/warm storage.
: . ,, . ~ .
;. . .:. : .
., - .
~'J-In Examples 1-3 and 5-7 below, the epoxy resin employed was an unmodified liquid epoxy resin of the bisphenol A
type having a density of 1.16 g/cm3, an epoxide eguivalent weight of from 180 to 192 and a dynamic viscosity of about 14 Pa . s (at 23C), which is marketed under the name DBeckopox EP 140 from Hoechst AG, Frankfurt (Main) and is described in greater detail in the Technical Data Sheet from Hoechst A&, Synthetic Resin Sales, November 1981 edition.
Example l 500 ml of an aqueous phosphorus suspension containing 250 g of red phosphorus (particle size: 100% < 150 ~m) were diluted with 500 ml of water in a glass stirred reactor and warmed to 60C. An aqueous emulsion of 2.5 g of an unmodified epoxy resin (~Beckopox ~P 140 from Hoechst AG, Frankfurt/N.) was then added. The pH was adjusted to 5 by addition of 5~ streng~h sulfuric acid;
the suspension was subsequently s-tirred at 60C for 1 hour.
After filtration, the filter cake was washed with water and dried at 100C in a stream of nitrogen. Analysis gave an epoxy resin content of 0.9%. The values for the oxidation stability are shown in Table 1.
. , 9 _ Example 2 The procedure was analogous to Example 1, but 5.0 g of ~Beckopox EP 140 were employed. Analysis gave an epoxide content of 2.0%. The values for the oxidation stability are shown in Table 1.
Example~ 3 The procedure was analogous to Example 1, but 7.5 g of ~Beckopox EP 140 were employed. Analysis gave an epoxide content of 2.9~. The values for the oxidation stability are shown in Table 1.
Example 4 (comparison) The procedure was analogous to Example 1, but no epoxy resin emulsion was added. The values for the oxidation stability are shown in Table 1.
Example 5 The procedure was analogous to Example 1, but 5 g of a 25% strength aqueous emulsion of di-2-ethylhexyl phtha-late (DOP) were added after the epoxy resin emulsion had been added and after the mixture had been stirred for 1 hour; the filtration was carried out after the mixture had been stirred at 60C for 30 minutes.
.
Analysis gave an epoxide content of 1.0% and a DOP
content of 0.5%. The values for the oxidation stability are shown in Table 2.
Example 6 The procedure was analogous to Example 5, but 5.0 g of ~Beckopox EP 140 were employed. Analysis gave an epoxide content of 2.0% and a DOP content of 0.5%. The values for the oxidation stability are shown in Table 2.
Example 7 The procedure was analogous to Example 5, but 7.5 g of ~Beckopox EP 140 were employed. Analysis gave an epoxide content of 3.0% and a DOP content of 0.5%. The values for the oxidation stability are shown in Table 2.
Example 3 The procedure was analogous to Example 5, but no epoxy resin emulsion was employed. Analysis gave a DOP content of 0.5~. The values for the oxidation stability are shown in Table 2.
.
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~ a~ o a~ I ~ ~
'~ ~ ~ 0~ ~ ~
O N ~ ~
r~ ~0~0 ~
O ~ ~ 3 O
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o bo à
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H )--I H
As is known, red phosphorus is obtained by thermal con-version of yellow phosphorus into the more stable red modification. The crude red phosphorus containing about 0.5 - 1.5~ by weight of yellow phosphorus forms a compact material when the reaction is complete. It is ground under an inert-gas atmosphere and freed from yellow phosphorus in aqueous suspension by boiling with dilute sodium hydroxide solution. Recently, the conversion has been carried out in rotating reactors, the red phosphorus being produced as a powder. The aqueous suspension of red phosphorus discharged from ~he reactor is heated in stirred vessels using steam and freed from the residual amount of about 0.1% by weight of yellow phosphorus by addition of sodium hydroxide solution in portions.
Red phosphorus is required in pyrotechnology and in the production of striking surfaces for matches and is used as a flameproofing agent for plastics, such as, for example, polyamides or polyurethanes.
As is known, a chemical reaction takes place at the surface of red phosphorus in a moist atmosphere, forming .
. ~ ~ , . . .
various acids of phosphorus in the oxidation states from + 1 to ~ 5 and hydrogen phosphide due to oxidation and of disproportionation.
The object was thus to improve the inadequate oxidation stability of red phosphorus by stabilization.
The term "stabilization" here is taXen to mean a measure which provides red phosphorus with improved protection against atmospheric influences and thus contributes to reduced formation of oxo acids of phosphorus and hydrogen phosphide, for example on storage or further processing.
&erman Patent 29 45 118 (=US Patent 4,315,897) discloses that the oxidation stability of red phosphorus can be improved by a combination of aluminum hydroxide and cured PpOxy resin, whereas the cured epoxy resin alone is relatively ineffective (cf. German Pa~ent 29 45 118, Examples 9 and 10).
Eerman Patent 26 25 674 describes a flameproofing agent for plas~ics which comprises from 50 to 95% of red phosphorus and from 5 to 50% of a cured or uncured epoæy resin. The epoxy resins employed function here as car-riers for the preparation of flameproofing agent concen-trates based on red phosphorus. This can also be seen from the high epoxy resin concentrations in the various examples. Examples 1, 3 and 5 give a composition of 40%
by weight of epoxy resin (cured) and 60% by weight of red phosphorus, and Example 2 gives a composition of 38% by weight of epoxy resin (cured), 57% by weight of red phosphorus and 5% by weight of copper oxide. In Example 8, the granules obtained compri.~e 40% by weight of epoxy resin and 60% by weight of red phosphorus. Examples 4, 6, 7 and 9 to 11 of German Patenl 26 25 674 merely relate to the testing of the concentrates prepared in accordance with the other examples.
Surprisingly, it has now been found that the oxidation stability of red phosphorus can be improved by applying small amounts of an uncured epoxy resin. This is surpris-ing and unforeseeable because cured epoxy resins applied by microencapsulation are relatively ineffective (cf.
German Patent 29 45 118, Examples 9 and 10).
The reduction in the formation of hydrogen phosphide on use of about 4Q% by weight of epoxy resin in accordance with German Patent 26 25 674 which is obserYed on incor-poration into plastics does not mean that this was also to be expected in the case of the low epoxy resin concentrations of less than 5% by weight used according to the invention. In fact, it was to be expected that only slight i~provements in the oxidation stability, or none at all, would occur, as in Examples 9 and 10 of German Patent 29 45 118.
The effect of the invention can be increased further if the phlegmatizing agent di-2-ethylhexyl phthalate is ~ .
t ~ ~ W Y~ J . .~
additionally applied by the process of DE-A 34 36 161.
In ~his connection the term ~phlegmatizing~ is ~aken to mean a measure which reduces the tendency of red phospho-rus to form dust, and reduces the risk of dust explosions and increases the processing safety.
Epoxy resins have been known for some time lcf. Rompp Chemie Lexikon [Rompp's Lexicon of Chemistry], 9th Edition, p. 1196; h. and M. Fieser, Organische Chemie tOrganic Ch~mistry], Verlag Chemie (1965), p. 1754 ff.).
In the context of the invention, suitable epoxy resins are, in particular, products of the reaction of 2,2-bis(4-hydroxyphenyl~propane (bisphenol A) and epichloro-hydrin (bisphenol A resins) ~nd of bis~4-hydroxyphenyl) methane (bisphenol F) and epichlorohydrin (bisphenol ~
resins), so long as they can be emulsified with water or can be employed dissolved in water-miscible solvents.
Bisphenol A can for its part be prepared by condensation of phenol with acetone, while bisphenol F is prepared by condensation of phenol and formaldehyde (cf. Runststoff Hand~uch [Plastics Handbook3, Vol. 10, Thermosets, Carl Hanser Verlag, Munich, Vienna, 2nd ~dition, 1988, p.1004, with data on epoxy-based resins in Table 13.2 on p. 1005).
Indeed, the invention relates ~o stabilized, pulverulent red phosphorus comprising phosphorus particles having a maximum particle size of 2 mm whose surface is covered 5 -- ' ) ~" 1 ) ~,,1 with a thin coating of an oxidation stabilizer, wherein the oxidation stabilizer is an uncured epoxy resin in a proportion oE from 0.2 to less than 5% by weiyht.
Furthermore, the stabilized, pulverulent red phosphorus of the invention may optionally and preEerably have the features that a] it is additionally covered by a thin coating of di-2-ethylhexyl phthalate as phlegmatizing agent in a proportion of from 0.05 to 2% by weight, preferably from 0.3 to 1.5% by weight;
b) the proportion of the oxidation stabilizer is from 0.5 to 3~ by weight.
Furthermore the invention relates to a process for the preparation oE stabilized, pulverulent red phosphorus, which comprises stirring an aqueous emulsion of epoxy resin or a solution of epoxy resin in a water-miscible solvent into an aqueous suspension of red phosphorus so that the proportions in the mixture are from more than 95 to 99.8 parts by weight of red phosphorus and from less than 5 to 0.2 parts by weight of epoxy resin; adjusting the pH to .Erom 4 to 9, stirring the mixture at a temperature oE from 40 to 80C Eor from 0.5 to 3 hours, and finally isolating the phosphorus particles by filtration and drying at elevated temperature.
, , .~ : ~, :' '. ' Finally, the invention also relates to a process for the preparation of stabilized and phlegmatized, pulverulent red phosphorus, which comprises stirring an aqueous emulsion of epoxy resin or a solution of epoxy resin in a water-miscible solvent into an aqueous suspension of red phosphorus, adjusting the pll to from 4 to 9, stirring the mixture at a temperature of from 40 to 80C for from 0.5 to 3 hours, adding an ac~eous emulsion of di-2-ethylhexyl phthalate and stirring the mixture at a temperature of from 20 to 90C for from 0.5 to 3 hours so that the proportions in the mixture are from more than 93 to 99.75 parts by weight of red phosphoxus, from less than 5 to 0.2 parts by weight of epoxy resin and from 2 to 0.05 parts by weight of di-2-ethylhexyl phthalate; and finally isolating the phosphorus particles by filtration and drying at elevated temperature.
The final drying of the filtered-off phosphorus particles may preferably be carried out at a temperature of from 80 to 120C in a stream of nitrogen.
Preferred water-miscible solvents are acetone, methanol and ethanol.
The working examples and tables below serve to further illustrate the invention. The percentages are % by weight.
~' ~, ...
Determination of the oxidation stability The oxidation stability was determined by a humid/warm storage test. To this end, 5.0 g of red phosphorus (particle size: 100% < 150 ~m) were weighed out into a crystallization dish having a diameter of 50 mm, and the dish was stored in a closed glass vessel at 80C and 100%
relative atmospheric humidity. The hydrogen phosphide fo~med was either expelled from the glass vessel by a stream of air (10 1/h), reacted in a gas washing bottle with 2.5% strength mercury (II) chloride solution and the amount of hydrochloric acid produced determined titri-metrically, or analyzed using a Drager "hydrogen phos-phide 50~a" tube.
In order to determine the content of the various oxo acids of phosphorus, the phosphorus sample was trans-ferred into a 250 ml beaker, 200 ml of 1% strength hydrochloric acid were added, and the mixture was boiled for 10 minutes and subsec~uently filtered. The acid-soluble phosphorus was then determined in the filtrate by the photometric molybdato-vanadato-phosphoric acid method.
In order to cletermine the initial value for acid-soluble phosphorus, t:he red phosphorus was subjected to the same analytical procedure -without prior humid/warm storage.
This value is then subtracted from the content of acid-soluble phosphorus determined after humid/warm storage.
: . ,, . ~ .
;. . .:. : .
., - .
~'J-In Examples 1-3 and 5-7 below, the epoxy resin employed was an unmodified liquid epoxy resin of the bisphenol A
type having a density of 1.16 g/cm3, an epoxide eguivalent weight of from 180 to 192 and a dynamic viscosity of about 14 Pa . s (at 23C), which is marketed under the name DBeckopox EP 140 from Hoechst AG, Frankfurt (Main) and is described in greater detail in the Technical Data Sheet from Hoechst A&, Synthetic Resin Sales, November 1981 edition.
Example l 500 ml of an aqueous phosphorus suspension containing 250 g of red phosphorus (particle size: 100% < 150 ~m) were diluted with 500 ml of water in a glass stirred reactor and warmed to 60C. An aqueous emulsion of 2.5 g of an unmodified epoxy resin (~Beckopox ~P 140 from Hoechst AG, Frankfurt/N.) was then added. The pH was adjusted to 5 by addition of 5~ streng~h sulfuric acid;
the suspension was subsequently s-tirred at 60C for 1 hour.
After filtration, the filter cake was washed with water and dried at 100C in a stream of nitrogen. Analysis gave an epoxy resin content of 0.9%. The values for the oxidation stability are shown in Table 1.
. , 9 _ Example 2 The procedure was analogous to Example 1, but 5.0 g of ~Beckopox EP 140 were employed. Analysis gave an epoxide content of 2.0%. The values for the oxidation stability are shown in Table 1.
Example~ 3 The procedure was analogous to Example 1, but 7.5 g of ~Beckopox EP 140 were employed. Analysis gave an epoxide content of 2.9~. The values for the oxidation stability are shown in Table 1.
Example 4 (comparison) The procedure was analogous to Example 1, but no epoxy resin emulsion was added. The values for the oxidation stability are shown in Table 1.
Example 5 The procedure was analogous to Example 1, but 5 g of a 25% strength aqueous emulsion of di-2-ethylhexyl phtha-late (DOP) were added after the epoxy resin emulsion had been added and after the mixture had been stirred for 1 hour; the filtration was carried out after the mixture had been stirred at 60C for 30 minutes.
.
Analysis gave an epoxide content of 1.0% and a DOP
content of 0.5%. The values for the oxidation stability are shown in Table 2.
Example 6 The procedure was analogous to Example 5, but 5.0 g of ~Beckopox EP 140 were employed. Analysis gave an epoxide content of 2.0% and a DOP content of 0.5%. The values for the oxidation stability are shown in Table 2.
Example 7 The procedure was analogous to Example 5, but 7.5 g of ~Beckopox EP 140 were employed. Analysis gave an epoxide content of 3.0% and a DOP content of 0.5%. The values for the oxidation stability are shown in Table 2.
Example 3 The procedure was analogous to Example 5, but no epoxy resin emulsion was employed. Analysis gave a DOP content of 0.5~. The values for the oxidation stability are shown in Table 2.
.
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Claims (8)
1. Stabilized, pulverulent red phosphorus comprising phosphorus particles having a maximum particle size of 2 mm whose surface is covered by a thin coating of an oxidation stabilizer, wherein the oxidation stabilizer is an uncured epoxy resin in a proportion of from 0.2 to less than 5% by weight.
2. Red phosphorus as claimed in claim 1, which is additionally covered by a thin coating of di-2-ethylhexyl phthalate as phlegmatizing agent in a proportion of from 0.05 to 2% by weight.
3. Red phosphorus as claimed in claim 1, which is additionally covered by a thin coating of di-2-ethylhexyl phthalate as phlegmatizing agent in a proportion of from 0.3 to 1.5% by weight.
4. Red phosphorus as claimed in claim 1, wherein the proportion of oxidation stabilizer is from 0.5 to 3% by weight.
5. A process for the preparation of stabilized red phosphorus as claimed in claim 1, which comprises stirring an aqueous emulsion of epoxy resin or a solution of epoxy resin in a water-miscible solvent into an aqueous suspension of red phosphorus so that the proportions in the mixture are from more than 95 to 99.8 parts by weight of red phosphorus and from less than 5 to 0.2 parts by weight of epoxy resin;
adjusting the pH to from 4 to 9, stirring the mixture at a temperature of from 40 to 80°C for from 0.5 to 3 hours, and finally isolating the phosphorus particles by filtration and drying at elevated temperature.
adjusting the pH to from 4 to 9, stirring the mixture at a temperature of from 40 to 80°C for from 0.5 to 3 hours, and finally isolating the phosphorus particles by filtration and drying at elevated temperature.
6. A process for the preparation of stabilized and phlegmatized red phosphorus as claimed in claim 2, which comprises stirring an aqueous emulsion of epoxy resin or a solution of epoxy resin in a water-miscible solvent into an aqueous suspension of red phosphorus, adjusting the pH to from 4 to 9, stirr-ing the mixture at a temperature of from 40 to 80°C
for from 0.5 to 3 hours, adding an aqueous emulsion of di-2-ethylhexyl phthalate and stirring the mix-ture at a temperature of from 20 to 90°C for from 0.5 to 3 hours so that the proportions in the mix-ture are from more than 93 to 99.75 parts by weight of red phosphorus, from less than 5 to 0.2 parts by weight of epoxy resin and from 2 to 0.05 parts by weight of di-2-ethylhexyl phthalate; and finally isolating the phosphorus particles by filtration and trying at elevated temperature.
for from 0.5 to 3 hours, adding an aqueous emulsion of di-2-ethylhexyl phthalate and stirring the mix-ture at a temperature of from 20 to 90°C for from 0.5 to 3 hours so that the proportions in the mix-ture are from more than 93 to 99.75 parts by weight of red phosphorus, from less than 5 to 0.2 parts by weight of epoxy resin and from 2 to 0.05 parts by weight of di-2-ethylhexyl phthalate; and finally isolating the phosphorus particles by filtration and trying at elevated temperature.
7. A process as claimed in claim 5, wherein the final drying of the filtered-off phosphorus particles is carried out at a temperature of from 80 to 120°C in a stream of nitrogen.
8. A process as claimed in claim 6, wherein the final drying of the filtered-off phosphorus particles is carried out at a temperature of from 80 to 120°C in a stream of nitrogen.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4039906A DE4039906A1 (en) | 1990-12-14 | 1990-12-14 | Stabilised, powdered red phosphorus@ - coated with uncured epoxy! resin as oxidn. stabiliser |
| DEP4039906.0 | 1990-12-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2056022A1 true CA2056022A1 (en) | 1992-06-15 |
Family
ID=6420289
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002056022A Abandoned CA2056022A1 (en) | 1990-12-14 | 1991-11-22 | Stabilized red phosphorus, and processes for the preparation thereof |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0490109B1 (en) |
| JP (1) | JPH04275910A (en) |
| CA (1) | CA2056022A1 (en) |
| DE (2) | DE4039906A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3909751B2 (en) * | 2000-05-25 | 2007-04-25 | 日本化学工業株式会社 | Red phosphorus flame retardant for epoxy resin, red phosphorus flame retardant composition for epoxy resin, production method thereof, epoxy resin composition for semiconductor sealing material, sealing material and semiconductor device |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4208317A (en) * | 1975-06-10 | 1980-06-17 | Rhone-Poulenc Industries | Flameproofed plastic compositions |
| FR2314221A1 (en) * | 1975-06-10 | 1977-01-07 | Rhone Poulenc Ind | COMPOSITIONS INTENDED FOR THE FLAME PROTECTION OF PLASTICS |
| DE2945118C2 (en) * | 1979-11-08 | 1981-12-03 | Hoechst Ag, 6000 Frankfurt | Stabilized red phosphorus and process for its manufacture |
| DE3436161A1 (en) * | 1984-10-03 | 1986-04-10 | Hoechst Ag, 6230 Frankfurt | PHLEGMATIZED RED PHOSPHOR |
-
1990
- 1990-12-14 DE DE4039906A patent/DE4039906A1/en not_active Withdrawn
-
1991
- 1991-11-14 DE DE91119399T patent/DE59101329D1/en not_active Expired - Fee Related
- 1991-11-14 EP EP91119399A patent/EP0490109B1/en not_active Expired - Lifetime
- 1991-11-22 CA CA002056022A patent/CA2056022A1/en not_active Abandoned
- 1991-12-13 JP JP3330954A patent/JPH04275910A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04275910A (en) | 1992-10-01 |
| EP0490109A3 (en) | 1993-02-03 |
| EP0490109A2 (en) | 1992-06-17 |
| DE59101329D1 (en) | 1994-05-11 |
| EP0490109B1 (en) | 1994-04-06 |
| DE4039906A1 (en) | 1992-06-17 |
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