CA1120050A - Phosphorus compounds - Google Patents

Abstract

- 1 -ABSTRACT Compositions comprising organic phosphorus com-pounds having a peroxygen group which is either a hydro-peroxyalkyl (H-OO-C-) group or a peroxyether (-C-OO-C-) group. There is at least one such group per 500 phos-phorus atoms in the composition. These peroxygen com-pounds may be made by passing oxygen through a liquid comprising a phosphorus compound which has an aliphatic carbon, having an abstractable hydrogen, directly at-tached to a carbon of an aryl ring; for example, an iso-propylphenyl phosphate. The peroxygen compounds may be added to compositions comprising peroxide-reactive or-ganic polymers to increase flame resistance.

Description

f,~

PHOSPHORUS COMPOUNDS
Organic phosphorus compounds, such as phosphates, are well known for use as flame retarding agents in organic plastics, either as the sole such agents or in combination with other ingredients such as halogen com-pounds. In such uses the phosphorus compound often also acts as a plasti-cizer.
One aspect of this invention relates to a peroxygen composition which comprises a phosphate ester with at least one ester coupling to a sub-stituted aromatic ring, said aromatic ring having at least one substituent comprising an aliphatic carbon directly attached to the ring and with an ether peroxide group attached to said aliphatic carbon.
Another aspect is a process for preparing a peroxygen composi-tion by contacting oxygen gas, an acid acceptor and a compound comprised of a phosphate ester with at least one ester coupling to a substituted aromatic ring, said aromatic ring having at least one substituent compris-ing an aliphatic carbon with at least one abstractable hydrogen directly attached thereto, and continuing sald process until said composition contains at least 1 peroxygen group per 100 phosphorus atoms.
In the said peroxygen comFosition the peroxy group -00- is directly bonded on the one hand to an aliphatic carbon directly attached to an aromatic ring and on the other hand to (a) a hydrogen atom or (b~
aliphatic carbon. In (a) the campound is a hydroperoxide (HOOC-); in (b) it is a peroxyether (-C-00-¢-). Ei-ther or both t~pes of groups may be present. Preferably the peroxy group (-00-) is on a tertiary carbon atom (e.g. in a peroxyisopropylphenyl group of the formula fH3 -oo-c~) The pnosphorus-containing peroxy compounds of this invention have a flame retarding effect on plastics into which they are incorporated, owing in large part to their phosphorus content. They also have addition-al effects. For instance, they may increase the flame resistance (as com-pared to identical phosphorus compounds without the peroxy groups); see, for example, the data tabulated in Example 1 below. They may improve the flame resistance of plastics while reducing the often-undesirable decrease in glass -transition temperature (Tg) that often results from incorporation of flame retardants; see, for example, ".. . .. ..
i ... . . .. ..
:
.. ,: . :~

:
, , " ''

- 2 -the data tabulated in Example 5, below. Their use may increase the compatibility of the organic plastic with the organic phosphorus compound; see, for instance, the improvement in blooming characteristics noted in Example 7 below. They may act synergistically with flame re-tarding halogen compounds; see, for instance, the data in Example 8, below.
The phosphorus-containing peroxy compounds of this invention may also be used in place of other peroxy com-pounds such as those conventionally employed in the artas curing (cross-linking; vulcanizing~ agents, polymeri-zation catalysts or initiators for other free radical re-actions such as grafting or synergism with halogen-con-taining flame retardants. In conventional processes of this type, the peroxy compound (such as dicumyl peroxide) forms low molecular weight decomposition products which are volatile, subject to migration and easily extracted.
The resultant odor is objectionable and has been a major drawback in their use. In contrast decomposition of the peroxy compounds of this invention yields phosphorus-containing residues which are generally of relatively high molecular weight, less extractable, less volatile and less odorous. Furthermore, these phosphorus-con-taining residues are less likely to be flammable than the residues (such as hydrocarbons) from conventional per-oxides. As noted above, their use may incorporate a phosphorus-containing residue directly into the chemical structure of the polymer.
In one preferred aspect of the invention, the phos-phorus-containing peroxy compounds are formed, and used, in admixture with unperoxidized flame-retarding phos-phorus compounds. Conveniently, a mixture of peroxidized and unperoxidized phosphorus compounds is formed by par-tially peroxidizing the phosphorus compound. Such a mix-ture may also contain molecules of varying peroxide con-tents, that is, a mixture of molecules, some having one peroxy group per molecule and others having two or even ,,s: ~ ~
, .:, ; .. . ,. -. ,, , : . , .:

, - -:

three or more peroxy groups per molecule. Also there may be both hydroperoxy and peroxy ether groups in the mix-ture. One may carry out the peroxidation process to ob-tain a relatively high conversion to peroxy compounds (and concomitant formation of molecules having a plural-ity of peroxy groups) and then blend the resulting per-oxy rich mixture with more of the phosphorus-containing starting material or with another phosphorus-containing flame retardant compound. One may carry out the peroxi-10 dation process on a mixture of phosphorus compounds, one (or more) of which is resistant to peroxidation and one (or more) of which is more readily peroxidized. The per-oxidation process may also be carried out in the presence of other compounds such as solvents or diluents (see Ex.
15 9 _ below) or polymerizable monomeric or polymeric ma-terials such as styrene, which may contain dispersed or dissolved polymeric materials such as unsaturated poly-ester resin (a relatively low polymer which copolymerizes with the styrene) or higher polymers such as diolefin 20 polymers (for example, rubbery polybutadiene-1,3, buta-diene copolymers, and the like). In the peroxy-con-taining mixture, there is preferably at least one peroxy-alkylaryl group per 500 phosphorus atoms, more preferably at least one such group per 100 P atoms (for example, 25 about 3, 5, 10, 20, 100, 200 or even 300 such groups per 100 P atoms) and the carbon:phosphorus atomic ratio i5 preferably less than about 100:1, a C:P ratio well below 50:1 (such as about 30:1 or less) being more preferred in order to provide a desirable level of phosphorus con-30 tent for flame retardancy.
The following Examples are given to illustrate this invention further. In this application all proportions are by weight and all temperatures are ~C unless other-wise indicated.

130 parts of a blend of styrene and ethylenically unsaturated polyester resins which are soluble in styrene : ~ . . .
. :

.iL'Z~ DSC~ -and copolymerizable therewith i5 mixed with the following additives in the indicated amounts and then heat-cured in sealed glass tubes of 6 mm diameter (at the temperatures indicated below) overnight (16 hours) after which the 5 cured material is removed from its tube and its oxygen index is determined; in some cases, as indicated, the cured material, after removal from its tube, is given a post-cure in air at 100 C overnight. Oxygen index is a measure of flame resistance (ASTM D2863).
The styrene-polyester resin solution is made by mixing 50 parts styrene, 50 parts "Dion 6421" (a poly-ester of [a slight excess of3 propylene glycol and a 1:1 [molar] mi~ture of maleic and isophthalic acid manufac-tured by Diamond Shamrock Corporation and 30 parts "Dow 15 FR-1540n -(a blend of 30% styrene and 70% of a polyester derived from ~aleic anhydride and dibromoneopentyl gly-- col manufactured by Dow Chemical Company).
- The results are as follows:
Oxygen 20 Additive and curing conditions Index (a) 3 parts benzoyl peroxide; cured at 70 C. 23 (b) 3 parts benzoyl peroxide plus 20 parts 4-isopropylphenyl diphenyl phosphate;
cured at 70 C. 25.7 25 (c) 20 parts of product made by treating 4-isopropylphenyl diphenyl phosphate with oxygen to form peroxyalkyl compound (as in Example 3 below~; cured at 70 C. 28~0 . (d) 3 parts benzoyl peroxide plus 20 parts of phosphate ester of partially isopro-pylated phenol, made in the general manner described in Example 4a below; cured at 70 C and then post-cured in air at 100~C. 28.8 . (e) 20 parts of product made by treating the phosphate named in d above with oxygen to form peroxyalkyl compound (as in Ex-ample 2a below); cured at 70 C and post-* Trade Mark . , :. .: ~ - :,:, ,. : ~ . . ,, :
-, ' ' ~
: :

z~o ~ 5 --Oxygen Additive and curi_~ conditions Index cured in air at 100 C. 29.9 (f) 10 parts of oxygen-treated material of Example 2a below ~i) cured at 70 C 29.6 (ii) cured at 110-C 33.5 tg) 3 parts benzoyl peroxide plus 30 parts tris (3-ethylphenyl) phosphate 27.4 (h) 30 parts of product made by treating tris (3-ethylphenyl) phosphate with oxygen to form peroxyalkyl compound (as in Example 2b below) 31.3 These results indicate that the addition of the triaryl phosphates improves the flame resistance and that treat-15 ing the phosphate ester to form peroxyalkylaryl phos-phates prior to mixing with the polymerizable mixture gives an additional significant improvement.
In each of Examples la, 1b, 1d and 1g there is also present an amount of tricresyl phosphate equal to the 20 amount of benzoyl peroxide, since the latter is, in each case, added in the form of 50:50 mixture ~ith tricresyl phosphate, sold as "Luperco ATC paste~ by Lveidol Divi-sion of Pennwalt Corporation.

(a) The additive used in Example 1e and f is pre-pared by passing oxygen through 20g of the phosphate ester having dispersed therein 0.2g of sodium formate and 10 mg of manganese naphthenate at about 125-C. The oxygenis bubbled through the material for about 8 1/2 30 hours giving a product which, according to hydropero~ide titration (described below~ contains about 28 hydroper-oxyalkyl groups per 100 phosphorus atoms.
(b) The product used in Example 1h is made in a similar manner, in the presence of 1% sodium formate and 35 0.05% manganese naphthenate the oxygen being bubbled through for about 23 hours; the hydroperoxide titration ,* Trade i~ark '?, ~iJ j j ,, , . - . . `
. .

.,, ~

:

indicates that there are about 20 hydroperoxyalkyl groups per 100 phosphorus atoms.
In view of these analyses for hydroperoxyalkyl con-tent, it is quite probable, statistically, that the pro-S ducts of Example 2a and _ contain triaryl phosphate mole-cules having two (or three) hydroperoxyalkyl groups per molecule together with triaryl phosphate molecules having only one hydroperoxyalkyl group and unchanged triaryl phosphate molecules.

The additive used in Example lc is prepared by pas-sing oxygen through lOg of 4-isopropylphenyl diphenyl phosphate having dispersed therein O.lg of sodium formate and 10 mg manganese naphthenate at 125C. The oxygen is bubbled through the material for about 57 hours giving a product which, according to hydroperoxide titration des-cribed below, contains about 60 hydroperoxyalkyl groups per 100 phosphorus atoms.
EX~PLE 4 (a) Phenol is alkylated with propylene, in the man-ner described in U.S. patent 3,576,923, dated April 27, 1971, to produce a mixture having about 0.33 isopropyl groups per phenol (about 15 parts of propylene reacted, per 100 parts of phenol) and in which the ratio of o-isopropyl groups to m- and p-isopropyl groups is in the neighborhood of about 2:1~ This mixture is then iso-merized, in the manner described in U.S. patent 3,859,395 to change the o:m,p ratio (from its initial value of about 2:1) to about 1:2. The resulting isomerized alkyl-ate is then esterified with POC13 (in the general manner described in U.S. Patent 3,576,923) to produce a triaryl-phosphate which is purified by distillation at subatmo-spheric pressure. The presence of 0.33 isopropyl groups per phenol (in the alkylate) indicates that in the tri-aryl phospate there are about 100 isopropyl groups per 100 phosphorus atoms.

, :~

.
, ' ' ~ ' "'' '' ~ ' :
.~ .

z~s~

(b) To the triarylphosphate of 4a there are added 0.5~ sodium formate and 0.05% manganese naphthenate, and oxygen at substantially atmospheric pressure is then bubbled (from a capillary tube) through the phosphate 5 maintained at about 125 C for about 16 hours. As in the other Examples herein, the mixture is treated, by fil-tering or decanting after settling, to remove solids.
Hydroperoxide titration indicates about 20-30 hydroperoxy groups per 100 phosphorus atoms, which indicates that a 10 significant number (for example, 70-80%) of the isopropyl groups of the triaryl phosphate are unreacted and that the product contains unoxidized original triarylphosphate molecules as well as triaryl phosphate molecules having one peroxyalkylaryl group; it is believed, on the basis 15 of statistical probability, that there are also present triaryl phosphate molecules having two such peroxyalkyl-aryl groups and some triaryl phosphate molecules having three such groups. The product is a pale yellow oily liquid having a viscosity of about 42 centistokes at 20 38 C~ Differential scanning calorimetry of its thermal decomposition shows a peak at about 230 C (indicating that its peroxide content is largely hydroperoxide) with a shoulder in the neighborhood of about 200 C (indi-cating the presence of peroxy ether groups, which have a 25 lower decomposition temperature than the hydroperoxide groups).
~XA~PLE 5 This example relates to treatment of high impact polystyrene whose high impact properties are provided by 30 modification of the polystyrene with a rubber. The polymer used in this Example is ~DOW Styron 470 impact - polystyrene" t a polystyrene polybutadiene copolymer manufactured by Dow Chemical Company. The treatment is effected on a steam heated, differential speed two-roll 35 ~ompounding mill (135~C front rollr 120-C back roll~O
First the high impact polystyrene is placed on the mill, forming a sheet on the hotter roll. Then there is added * Trade Mark . . ~ . .

to the sheet, over a period of 10 minutes while milling continues, 10 parts of additive (as listed below) per 100 parts of polymer; the mixing is continued for another 10 minutes. During the entire period the hot material is exposed to the atmosphere. The material is then compres-sion molded (between heated platens) into sheets 75 mils thick; the sheets are cut into strips for testing burning time and burning behavior according to nUL-94" test method. The following results are obtained:

Condition of hot material on mill at end of 20 minute mix- Tg Burning Additive _ _ing period ( C)* Time (secs)**
(a) None Fluid (plastic) 83 and (b) Unoxidized triaryl More fluid than phosphate of Exam- a but re~ovable 65-ple 4a fro~ mill 67 80 (c) Same as b plus 1 E~rt c~mene hydro-peroxide per 100 Less fluid parts of polymer than b 70 90 (d) Same 25 b plus 3 parts of cumene hydroperoxide per Slightly more fluid 100 parts of poly- than c 62 123 mer ~`
(e) Peroxidized phos- More fiuid tnan '~
phate of Ex~i~le a but less 75-4b fluid than b 77 81 * Tg is determined on a "DuPont 9Q0 Differential Thermal Analyzer"
manufactured by E. I. duPont de ~'e~ours ~ Ccmpany.
** Burning time is in seconds (the sl~m o~ ~he b~rniny times of 5 strips in the UL-94 test).

:

_ 9 In the burning te~t all samples drip and ignite the cot-ton used in the test, but the behavior of e is a little better in this respect.
Diferential scanning calorimetry (DSC) of the ma-terials after milling indicates that very little or noperoxide remains; after molding~ DSC shows no evidence of the presence of peroxide. All samples mold well and the molded sheets are tough as shown by the fact that they can be folded back on themselves without breaking.
In the worXing of the polymer on the heated mixing surfaces (that is, tbe mill rolls) in this Example (and others below) heat is generated internally by the mixing forces so that any particular tiny zone within the ma-terial being mixed the temper~ure may rise, locally, to above the roll temperature; also, the hot mixing process occurs in the open air for an appreciable time, which may promote decomposition of a significant proportion of the peroxide without reaction of tha~ portion of the perox-ide (or radicals generated therefrom) with the polymer.
20 This is also indicated by ~he fact that the product con-tains little if any residual peroxide. It will be understood that the mixing may be conducted under con-ditions in which these effects of the atmosphere and of mixing time are reducedl as in an inert (for example, nitrogen~ atmosphere or in a closed high speed mixing apparatus such as a screw e~truder (in which the resi~
dence time may be about 1 to 2 minutes, for example) or a high torque sigma blade mixing apparatus, so that the mixed product may retain a significant proportion of the peroxide enabling the latter to act during, or after~
the shaping of the polymer to its final formO
EX~MPLE 6 This Example relates to treatment of moldable poly-ethylene. Using the two-roll compounding mill described in Example 5~ but with both rolls at 132'C, low density high pressure polyethylene (density 0.924g/cm3, Union Car-bide Corporation ~DNB-0195 ~atural 7n~ is sheeted on the . .
,: : - . ,:
~, , . ~ , : ~.". ,1.. .

: , . . .
~ .

5~
, .

mill, with the gap adjusted to permit a small bead in the nip of the rolls. Then 6 parts of additive (as listed below) per 100 parts polyethylene are added slowing drop-wise over a 20 minute period while milling continues.
5 The materials are then compression molded at 160 C into sheets 0.75 mm thick, which are tested for horizontal burning rate. The following results are obtained:

Horizontal Condition of surning hot material Rate Burning Additive on mill (cm/min) Behavior (a) None Plastic (fluid) 1008 Severe -- ~ dripping (b) Unoxidized Becomes increasingly 15 triaryl fluid and at end is phosphate too sticky to remove from mill hot. Re- ~
moved by chilling Severe rolls 8.8 dripping (c) Peroxida- Appears to "gel"
20 tion pro- locally where drops duct of of additive contact phosphate the polymer but then of b becomes uniform as milling continues.
Easier to work on mill, and easier to Moderate strip off, than a 7.6 dripping ~5 In b the phosphate is a triarylphosphate of a highly iso-propylated phenol, like that used in Example 1~ below;
the peroxidation product used in c contains about 14 hy-droperoxyalkyl groups per 100 P atoms (as measured by

3 hydroperoxide titration). Burning rate is measured ac- ¦
cording to ASTM D-635-72 flame test~ , I

, : , ., ~ ~, . . .
' ,,; ~ .: ~ -, . . . . .

~2~

In a repetition of the milling and molding steps of Example 6 it is found that when the peroxidized phosphate is added the polyethylene begins to ball up on the mill (poor fluxing); good fluxing is obtained by then raising the roll temperature hy about 5 C It is also found that the molded product made with the peroxidized phosphate retains the additive to a mar~edly greater degree than the product made with the unoxidized phosphate; the lat-]. ter product has a quite oily surface owing to markedphosphate migration to the surface (~blooming~). This indicates that aryl phospha~e-containing radicals (such as a diphe~ylphosphatophenylalkyl rad~cal) may be grafted to the polyethylene (which has pendent methyl groups) thus forming a modified polymer which has greater com-patibility with the unreac~ed aryl phosphate. The raising of the temperature needed for fluxing may indi-cate that a limited degree of cross linking of the poly-ethylene chains has occurred.

Ordinary general-purpose polystyrene (Union Carbide Corporation ~GP" polystyrene) is mixed with additiv2s on a mill as in Example 5, using a front roll temperature of 135-C and a back roll temperature of 120-C, and then compres~ion molded into ~heets. The following tabulation gives the proportions of additives and th~ resultsO
Proportions Additive a b c d e 3 Poly~tyrene 100 100 100 100 100 Peroxidi zed 9.-isopropylphenyl diphenyl phosphate 10 Di Cup R (96%
dicumyl peroxide manufactured by ~ercules Incorporated) 10 2 , .,, . , :

:; ~

5(~

Proportions Additive a b c d e Hexabromo-cyclo-5 dodecane 10 10 10 10 Tg(-C) 80,80 75,76 84,85 93,94 86,87 Oxygen Index 23~9 19.8 20.818.0 21.0 The peroxidized phosphate used in this Example con-tains (by hydroperoxide titration) about 20 hydroperoxy-alkyl groups and (by peroxyether titratlons) about 2.3 peroxyether groups per 100 phosphorus atoms~

(a) ;J~ -7 grams of 4-isopropylph~nyl diphenyl phos-15 phate is mixed with 1.0 gram of sodium 2-ethylhexanoate.
A stream of oxygen, from a capillary tube, is bubbled through the mi~ture, maintained at 12S C for 118 hours.
Iodometric kitration of the product indicates 28% conver sion to 4 (~-hydroperoxy-a-methylethylphenyl) diphenyl phosphate-The crude reaction mixture is purified by column chromatography (silica gel; successive elution with ben-zene, chloroform and acetone) and the resulting purified hydroperoxy compound is tested as follows: NMR (CDCl3) indicates 1.55 (s, 6H, CH3~, 7.13 (s, 14~, aromatic) and 5.93 (s, lH, 00~). The infrared spectrum is nearly iden-tical to that of the unoxidized starting material except that it contains the typical O~ band (3300 cm 1) for hy-droperoxides (cumene hydroperoxide has an OH absorption at 3380 cm 1) The elemental analysis, calculated for C21H2106P: C, 63.00; H, 5~29; found: C, 63.32; H, 5.45 The purified compound al~o tests positive for peroxide activity (starch iodide and acetic acid-isopropyl al-cohol-sodium iodide). When tested by polarography it be-haves similarly to cumene hydroperoxide ~-0.B5 volts vs.
SLE for the subject hydroperoxide and -1.1 volts vs. SLE
for cumene hydroperoxide~.

05~

(b) A mixture of 14.2 4-isopropylphenyl diphenyl phosphate, 40 ml xylene and O.lg sodium 2-ethylhexanoate is treated as in 9a with oxygen for 119 hours. At this stage the hydroperoxide titration indicates 42% conver-sion to hydroperoxide.
(c) A mixture of 50 grams of 4-isopropylphenyl di-phenyl phosphate and 0.5g sodium formate is treated with oxygen as in 9a. At various stages hydroperoxide titra-tions indicate the following conversions to hydro-peroxide: 28% in 58 hours; 55% in 70 hours, 71% in 72 hours.
(d) A mixture of 10 grams of 4-isopropylphenyl di-phenyl phosphate, O.lg sodium formate and 5 mg manganese naphthenate is treated with oxygen as in lla for 30 `
hours. Hydroperoxide titration at this stage indicates 60% conversion to the hydroperoxide. The DSC thermogram of a solution of 1% of the product in diallyl phthalate shows two peaks, one at about 230C indicating the pres-ence (as in Example 9a) of hydroperoxide and the other at about 200C indicating the presence of peroxyether.
In polarographic tests the material showed activity at -0.85 volts vs. SLE (as in Example 9a) as well as ac-tivity at -1.75 volts (representing the activity of the peroxyether); it should be noted that dicumyl peroxide, which is a peroxyether, similarly shows polarographic activity at a lower voltage than cumyl hydroperoxide, which is the corresponding hydroperoxide (-2.05 volts for dicumyl peroxide, -1.1 volts for cumene hydroper-oxide) and that dicumyl peroxide similarly has its peak exotherm in diallyl phthalate at a lower temperature (182C) than cumyl hydroperoxide (205C)~
(e) Example 9d is repea~ed except that the dur-ation of the oxygen treatment is shorter; titration indicates a 28% conversion to hydroperoxide. The DSC
thermogram of a solution of 1% of the product in di-allyl phthalate is shown in Fig. 1. It will be seen that it has two peaks as discussed in 9_.

.. ,. ' , ,. i . :' . :; :
.: ~ : .. :
. .

(f) A triarylphosphate is prepared from a 70:30 mixture of 3-isopropylphenol and 4-isopropylphenol and is mixed with sodium formate and manganese naphthenate and then treated with oxygen as in 9a. After 30 hours the conversion to hydroperoxide (as indicated by hydro-peroxide titration) is 52%. Since only 30% of the origi-nal isopropyl groups are 4-isopropyl this degree of con-version shows that the 3 isopropyl groups are also con-verted to hydroperoxide.

_ Phenol is alkylated with different amounts of pro-pylene, in the general manner described in U~S. patent 3,576,923 to produce mixtures (of phenol and isopropy-lated phenols) having differing isopropyl contents, the isopropyl groups being largely in ortho position. The same, or similar, mixtures are then isomerized in the manner described in U.S. patent 3,859,395, dated January 7, 1975, to increase their content of m- and p-isopropyl groups. Each phenolisopropylated phenol mixture is then 20 esterified with POC13 (in the general manner described in U.S. patent 3,576,923~ to produce a triarylphosphate and each of these triaryl phosphates is then treated with oxygen in the general manner described in Example 4b for 25 various periods. In each case hydroperoxide titration shows formation of hydroperoxides with the conversions being higher for the phosphates made from the isomerized alkylates. Some typical results are tabulated belowO

.- , ~ : . .

:
, . . .

-~z~s~

Peroxide Approximate oontent Approximate Isopropyl oonr Approx~te (hydrcper- Viso~ity tent (number of Vis ~ it~ oxide group6 after peroxi~
isopropyl group6 before Feroxi- per 100 dation (cenr per 100 phosphor- dation (centi phosphorus tistokes 5 ous atoms) stokes at 38'C) a~) at 38-C) (a) 110 6 (b) 110 i~rized 20 28 42 _ (c) 160 30 (d) 160 isomerized 30 37 67 .
(e) 230 50 12 (f) 280 i~rized 50 65 550 -(g) 270 65 22 160 (h) 310 i~rized 65 40 Particularly in the case of the pho~phat~s made from the more highly alkylated products, there is a signifi-cant proportion of molecules of phosphates having two or more isopropylphenyl groups (for example, in the neigh-borhood of 80% by weight of such molecules in a phosphate made from an alkylated phenol having about 310 isopropyl groups per 100 phosphorus atoms and about 70~ in a phos-phate having about 280 isopropyl groups per 100 phos-phorus atoms). The treatment with oxygen is believed ~
convert signif icant proportion of these molecules into molecules of triaryl phosphate having at lea~t two per-oxygen groups (for example, hydroperoxyi~opropyl groups) per molecule.

.
Tris (4-isopropylphenyl) phosphate is treated with oxygen at about 125'C and the following conversions tin-dicated by hydroperoxide tltration~ are obtained after the following periods of treatment:

'' : ' '`' :: , , .~ , - Conversion thydroperoxyalk Period groups per 100 (hrs.) phosphorus atoms) of the tris (4-isopropylphenyl) ~hosPhate _ (a) contains 1%
sodium octoate 32 17 ~b) contains 1/2%
sodium octoate 31 1/2 43 (c) dissolved in a triaryl phosphate of a t-butylated phenQ~ .(0.33 t-butyl groups per phenol~ and con-tains sodium for-mate and manganese naphthenate * 20 1~5 * 10 g of the t-butyl phenyl phosphate, 5 g of the tris (4-isopropylphenyl~ phosphate, 25 mg sodium formate, 8 drops manganese naphthenate.
In view of the oxidation resis~ance of the t~
butylphenyl groups it is believed that little, if any, peroxidation of the solvent used in c occurs; this sol-vent is high boiling and is retained in the product.
The high proportion of hydroperoxide indicates that the product c must have a relatively high content of tri aryl phosphate molecules having two or three hydroper-oxyalkyl groups per molecule. It is probable that such molecules are also present in a and b.

10g of phosphate triester are sparged with oxygen at about 125-C in the presence of sod~um formate and manganese naphthenat2; the following results are ob-tained:

- .,,, .

; . , , . . ~- ,.
:: : ;. ~ . .

:: ~
': . ~: :
': , : ' ' ~

~L~LZ~

Period Conversion Alkylaryl phosphate (hrs.) (as in Example 11) a. Tris cresyl phosphate n which the "cresyl"
is largely (85~i) m-and p-cresols, the balance being essen--tially ethyl phenols and xylenols 12 8 b. 2-ethylhexyl di (4-isopropylphenyl) phos-phate 4 41 c. 2-chloroethyl di (4-isopropylphenyl) phos-phate 9 18 d. tris (4-sec-butylphenyl) phosphate 26 12 15 e. n-butyl di (4-isopro-pylphenyl) phosphate 20 31 The proportions of sodium formate and manganese naph-thenate, respectively employed in these runs are (a) 0.1g and 10 mg, (b) 0.1 g and 5 mg, (c) 0.05 g and 5 mg, (d) 0.05g and 5 mg, (e) 0.1g and 5 mg. The DSC
thermogram of a solution of l~i of the product of 12 e is shown in Figure 2; it will be seen that it has a hy-droperoxide peak at about 220C and a shou]der at a lower temperature, indicating the presence of peroxyether.

(a) Oxygen is buk,bled through a mixture of 110 grams of 4-isopropylphenyl diphenyl phosphate, 0.6g of sodium formate and 50 mg of manganese naphthenate for 5 3/4 hours; hydroperoxide titration indicates that there are about 37 hydroperoxyalkyl groups per 100 P
atoms. After several months of storage at room temper-ature analysis by titration indicates that the hydro-peroxyalkyl content ls substantially unchanged and that there are about 10 peroxyether groups per 100 P atoms.
(b) Example 13 a is repeated, using, as the phos-phate, an isopropylated phenyl phosphate like that used .. O ` `
1~, .

.- . ~ :, : . ... ,. , :
1 , . : , .

z~

in Example 10g. After 4 3/4 hours of treatment the product is found (hydroperoxide titration) to contain about 17 hydroperoxyalkyl groups per 100 P atoms. After several months storage at room temperature analysis by titration indicates that there are about 12 hydroperoxy-alkyl groups per 100 P atoms and substantially no per-oxyether groups~
(c) Example 13a is repeated, using, as the phos-phate, an isomerized isopropylated phenyl phosphate like that used in Example lOb. After 11 hours of treatment the product is found ~hydroperoxide titration) to contain about 26 hydroperoxyalkyl groups per 100 P atoms. After several months' storage at room temperature analysis by titration indicates that there are about 25 hydroperoxy-alkyl groups and about 3.4 peroxyether groups per 100 Patoms.
(d) Example 13a is repeated, using, as the phos-phate, an isopropylated phenyl phosphate like that used in Example 1Oa (the amount of sodium formate is lg in 20 this case). After 14 hours of treatment the product is found (hydroperoxide titrationl to contain about 5-hy-droperoxyalkyl groups per 100 P atoms. After several months' storage at room temperature analysis by titration indicates that there are about 4.7 hydroperoxyalkyl and5 0.7 peroxyether groups per 130 P atoms.

(a) A mixture of 20 grams of 4-isopropylphenyl di-phenyl phosphate, 100 mg sodium formate and 10 mg mang-anese naphthenate is sparged with fine bubbles of oxygen 30 fed through fritted glass. During the course of the re-action samples of the product are analyzed for hydroper-oxyalkyl and peroxy ether groups; by titration as de-scribed below. The following results are obtained.

i ~ :
.
: :. : :
~,~
' ~ :

~ 5(~

Hydroperoxyalkyl Peroxyether groups Time groups per per 100 P
(hrs.) 100 P atoms atoms 2 2~.4 0 3 22.5 4.7

4 1~.1 4.8 (b) ~ mixture of 110 grams of triaryl phosphate of isomerized isopropylated phenol tlike that used in Ex-ample 1Ob), 0.69 of sodium formate and 50 mg of manga-nese naphthenate is sparged with oxygen. After 2 hours treatment little, if any, hydropero~yalkyl formation is noted (prQsumably due to antioxidant impurities in the sample) and an additional 50 mg of manganese naphthe-nate is added. Analysis, as in 1 4A~ gives the following results:
Time after addition of 2nd portion 20 f man~anese Hydroperoxyalkyl Peroxyether groups naphthenate groups per per 100 P
(hrs.) _ _ 100 P atoms atoms 1 1/2 3.7 2.5 2 1/2 10.2 1.8 253 1/2 14.9 4.0 4 1/2 13.4 4.8 (c) A mixture of 110 grams of ~riaryl phosphate ofhighly isopropylated phenyl (like that used in Example 10~)~ 0.6g sodium formate and 5G mg of manganese naph-thenate is sparged with oxygen~ Analysis as in 14a gives the following results.

-., ~ , . ..

, , :,: . - .
: . , , ~ . ...

~,9.Z~

Hydroperoxyalkyl Peroxyether groups Time groups per per 100 P
(hrs.) 100 P atoms _ atoms 1 7.9 0.8 3 14.8 5.2 4 17.6 2.3 12.7 10.7 (d) A mixture of 110 grams of triaryl phosphate of highly isopropylated phenol (like that used in Example 10g), 50 mg of sodium formate and 5 mg cobalt phthalo-cyanine is sparged with oxygen. After 1 1/2 hours, little, if any, hydroperoxyalkyl formation is noted and an additional 500 mg of sodium formate and 50 mg of cobalt phthalocyanine are added. Analysis as in 14_ gives the following results:
Time after addition of 2nd portion of cobalt Hydroperoxyalkyl Peroxyether groups compound groups per per 100 P
(hrs.) 100 P atoms atoms 1/2 7.2 1.5 3 13.0 12.1 4 1/2 12.5 16.1 EXA~PLE 15 Oxygen is bubbled through a mixture of 10g of an isopropylated phosphate like that used in Example 10g, ~ -0.2g of monosodium bis (4-isopropylphenyl) phosphate and

5 mg of manyanese naphthenate for 5 1/2 hours; hydroper-oxide titration indicates that the product has 14 hydro-peroxyalkyl group:, per 100 P atoms.

,. . ~ . . . .

: , , : ' ,: ~ , " " .; . :' , ~ : ' . :

`': ' ' 9.~L2V~S~

A product made by oxygen-sparging an isomerized triaryl phosphate like that used in Example 10_ in the presence of sodium formate and manganese naphthenate and having (by hydroperoxide titration) about 19 hydroper-oxyalkyl groups per 100 P atoms is tested for stability by storing it at a temperature of about 25C for about 20 weeks in contact with a mass of (a) nickel wire, (b) stainless steel wire, (c) carbon steel wire. In each case the hydroperoxyalkyl content remains substan-tially unchanged.
Conventional techniques may be used for making the phosphorus compounds used as starting materials. In one procedure (to make the phosphates of Examples8 and 9) diphenylphosphochloridate is reacted with 4-isopropyl-phenyl (or 3-isopropylphenol or mixture of 4-isopropyl-and 3-isopropylphenol in Example 9_), as follows. To a stirred solution of 1 gram mole of isopropylphenol and 1.15 gram moles of triethylamine and 700 ml of methylene chloride in a nitrogen atmosphere, there is added drop~
wise a solution of 1 gram mole of diphenylphosphoro-chloridate and 500 ml of methylen~ chloride. The tem-perature is maintained at 0-10C during the addition which is complete in 1 1/2 to 2 hours. The solution is then allowed to warm to room temperature and heated to -~reflux overnight. The cooled reaction mixture is slur~
ried with 1 liter of distilled water and washed with 750 ml each of water, 5% aqueous sulfuric acid, 10% aqueous sodium carbonate and 10% aqueous sodium bicarbonate. The solution is dried over magnesium sulfate, filtered and concentrated (rotary evaporator). The crude product is flash distilled under vacuum with moderate care to remove the lower boiling fractions (phenols and chloridate) and then distilled~ under vacuum through a heated packed col-umn for further purification.
The phosphates of Examples 12_ and e may be produced by reacting one mole of the alcohol with a mole of POCl3 : . . , ~ . . ~ : , - . . .
.:

.

and then reacting the product with the sodium salt of 4-isopropyl phenol. The phosphate of Example 12c may be produced by reacting ethylene oxide with di (4-isopropylphenyl) phosphochloridate.
The phenol alkylphenol mixtures produced by partial alkylation of phenol (as in Examples 4, 10, ll and 13) are complex mixtures, containing di-alkylated as well as monoalkylated phenol molecules; see for instance Example 21 of U.S. Patent 3,576,923 and the analyses in Example l of U.S. Patent 3,859,395. Typical compositions of alkyl-ates of the types used in Example 10 a,c,e, and g are:
Weight percent of component in a _ e Phenol 6039 22 14 2-isopropylphenol 2733 35 30 3- and 4-isopropylphenol 1114 16 19 2,6-diisopropylphenol .2 4 7 5 2,4-diisopropylphenol 1.67 12 16 2,5 and 3,5-diisopropylphenol 2 5 14 2,4,6-triisopropylphenol 1 3 2 2,3,5-triisopropylphenol tr tr tr On reaction of the alkylphenol-phenol mixture (as such or after isomerization) with POCl3 there is formed a still more complex mixture containing triphenyl phosphate mole-cules, isopropylphenyldiphenyl phosphate molecules with -isopropyl groups in various positions, di(isopropyl-phenyl) phenylphosphate molecules with isopropyl groups in various positions and tris (isopropylphenyl) phosphate molecules with isopropyl groups in various positions, as well as molecules containing one, two or even three di-isopropylphenyl groups.
In the above Examples, dispersed Na salts (formate, octoate) settle out from the reaction mixture after agi-tation ceases and may be filtered off; Mn or Co compounds (when present) remain dissolved in the reaction mixture.

':
' 5~[3 In the hydroperoxide titration mentioned above the sample is boiled with NaI in a weakly acidified alcohol solution to liberate iodine. The iodine is then titrated with sodium thiosulfate as a measure of total hydroper-oxide content. Specifically, a 100 microliter (0.1 ml) aliquot of the sample is removed by a syringe and placed in a 125 ml Erlenmeyer flask. To this is added 10 ml of anhydrous isopropyl alcohol, 1 ml of acetic acid, and 10 ml of isopropyl alcohol saturated with sodium iodide.
This mixture is refluxed for 10 minutes (at atmospheric pressure). If the aliquot being tested contains very little or no peroxide the solution remains colorless or turns a very pale yellow. With increasing peroxide COIl-centration the color of the refluxed titration mixture is yellow, then orange, then brownish orange and sometimes reddish brown. After the mixture has been heated to re-flux for 10 minutes, it is cooled to room temperature and 5-10 ml of water added. The solution is then titrated in conventional manner with 0.01 M sodlum thiosulfate. The end point is arrived at when the solution turns from pale yellow to colorless. This is easily determined to within 1-2 drops. Each milliliter of O.OlM sodium thiosulfate used in the titration represents 0.005 gram mole of hy droperoxide groups. It is believed that this method does not indicate that total peroxide content or take into account the content of peroxyether groups.
In the peroxyether titration mentioned above the sample is refluxed in an inert atmosphere with acetic acid containing sodium iodide and a definite amount of water. Specifically of an aliquot of the sample is taken -up in deoxygenated xylene (about 1.5 grams of sample per 50 ml xylene) and the resulting solution is added to de-oxygenated acetic acid, after which 6g NaI in 3 ml deoxy-genated water are added and the mixture is refluxed under nitrogen for 30 minutes and then cooled under nitrogen, mixed with 100 ml of deoxygenated water, swirled to mix and titrated immediately with 0.1 N sodium thiosulfate .: . .
., ., ~
, . , . ~ .
~ . .
. .. , , i ~ ~ ~

.2~ 5~

solution. A blank titration is also made to correct for interfering materials in the reagents. Further details as to the procedure are set forth in Hercules Inc. Di-Cup bulletin PRC-205B relating to iodometric assay methods for dicumyl peroxide; in the titrations yielding the per-~oxy ether analyses described above, ground glass equip-ment equivalent to the flask arrangements described in that bulletin is used; also, the same 93~ reaction factor is applied.
In the oxygenation process the time needed to attain a given content of hydroperoxide groups is influenced considerably by the degree of dispersion of the oxygen.
A small tall body of liquid may undergo rapid reaction with oxygen supplied from a capillary tube, with the gas lS bubbles serving also to agltate the mixture. With a larger body, or a shallower one, mechanical stirring may be used to promote intimate contact. The use of fine bubbles of oxygen (such as can be supplied from a porous fritted-glass outlet) leads to faster results. Increase in the pressure under which the reaction is conducted (for example, to 2 atmospheres gauge as compared to the atmospheric pressure at which the above Examples are con-ducted) also leads to faster results, presumably because --more oxygen is dissolved in the reaction mixture. The oxygen fed to the reaction may be substantially pure oxygen or it may be in admixture with other materials which may be substantially inert in the reaction; for ex-ample, air may be employed. The oxygen may be dry or may contain moisture; the inclusion of some moisture in the system (for example, by partly saturating the oxygen with moisture) has been found to increase the rate of reaction (perhaps by promoting formation of a hydrated salt of the pro-oxidant or increasing its tendency to dissolve) but too high a moisture content appears to inhibit the in-crease in the desired peroxide content during reaction.
In a preferred embodiment of the process an acidacceptor such as a weak base is present (for example, in . .

'~

" , " .

h6~05~
- 25 ~
about 0.1 to 5% concentration, preferably about 0.5 or 1%) during the treatment with oxygen. It is believed that this serves to neutralize acidity present, or formed, in the reaction mixture. Particularly good re-sults have been obtained with a dispersed sodium saltof a relatively strong carboxylic acid, such as sodium formate which is usually substantially insoluble in the organic phosphorus compound being treated; sodium formate is known to form aqueous solutions of pH about 7 and to have a buffering action. Other salts, such as sodium octoate (for example, 2-ethylhexoate), sodium oleate and sodium aryl phosphate (as in Example 15) have also been found to be effective. It is possible that sodium aryl phosphates or sodium salts of the weakly acidic hydro-peroxides, or both, are formed in the reaction mixturewhen other sodium salts (for example, sodium formate) are used as the antacides; in an analysis of a filtered prod-uct having about 13 hydroperoxyalkyl groups per 100 P
atoms, made from a highly isopropylated triaryl phosphate like that used in Example 10g, it is found that the acid number is about 1.6 mg KOH per gram and the sodium con-tent is in the neighborhood of 500 ppm.
The peroxidation reaction may be speeded up by in-cluding a small amount of a pro-oxidant, such as suitable transition metal pro-oxidant compound, preferably soluble in the phosphorus compound. Good results are obtained with such compounds as manganese naphthenate (for ex-ample, a salt which, as in the above Examples, contains ;
about 6% Mn), manganese phthalocyanine, and cobalt phthalocyanine in an effective metal concentration ofsay, in the range of about 0.0005 to 0.05% such as about 0.003 or 0.006%). It is found that the pro-oxidant re-duces the induction period without causing rapid de-composition of the resulting peroxide. As shown in the Examples above, the pro-oxidant may be permitted to re-main in the peroxidized mixture in use and no special separation steps are needed. At times the phosphate .

, - ' ,; - ' ' , ', , ...

,z~30~

being treated may contain antioxldant compounds (antioxi-dant effects may be possibly due, for instance, to sig-nificant concentrations of lower-boiling impurities such as unesterified or partially esterified reactan-ts used to make the phosphate triester) in which case it may be desirable to add a further quantity of pro-oxidant in order to start a more rapid peroxidation reaction (as can be seen in Example 14 _ and d).
The peroxidation reaction may be erfected at room temperature but it is preferable, particularly in the initial stages of the reaction, to use elevated temper-atures, such as within the range of about 100 to 150C, more preferably about 120 to 130C. The reaction may be effected at a series of temperatures, such as an initial higher temperature (for example, above about 120C, for example, 125 or 130C or higher) to minimize the induc-tion period and then a lower temperature (for example, below about 120C such as 115, 110 or 100C or lower~.
The preferred peroxides are those made from com-pounds having benzylic hydrogen (that is, compounds having an aliphatic carbon having an abstractable hydro-gen and directly attached to a carbon of an aryl ring), the peroxide thus being formed by a process involving abstraction of that hydrogen and its replacement with an -00- group. While (as shown in Examples 12a and 2_ above) that carbon atom may carry two or one additional hydrogen atoms, best results are obtained when the ring-attached carbon atom is a secondary carbon attached to two other carbon atoms, as when it is part of an isopropyl or secbutyl radical. It is believed that t-butyl radicals, such as are present in Example llc above, are resistant to peroxide formation so that the t-butyl- --ated triaryl phosphate of that Example serves as a sub-stantially inert solvent in the reaction as well as a flame resistant component (for example, plasticizer) in the organic plastic to which the mixture is added. It is believed that molecules of ortho-isopropylated phenyl .,~ ,, , :
'~ 'n.:
., , .. . . :.: .

phosphates, such as 2-isopropylphenyl diphenyl phosphate (pre-sent, for instance, in relatively large proportions in the phosphate used in Examples 10 and 13_) serve a similar function;
it appears that there may be steric hindrance, owing to proxi-mity to the phosphorus-oxy portion of the molecule, that makes the o-isopropyl substituent resistant to peroxidation. It is preferred that the peroxidizable alkyl substituent be relative-ly small, for example, containing less than nine carbon atoms (more preferably less than six carbons), but it is within the broader scope of the invention to employ longer substituents such as those having twelve or eighteen carbon atoms. The sub- ..
stituent is preferably saturated hydrocarbon but it may carry substituents such as Cl, F, ester (for example, CH3COO-), amide (for example, NH2CO-) or aryl (for example, phenyl). The aro-matic ring is preferably a benæene ring and it may have sub-stituents such as Cl, F, other alkyl (for example, t~butyl), chloroalkyl, fluoroalkyl, aryl (for example, phenyl~, aralkyl (for example, benzyl); it may be a condensed ring (for example, a naphthalene ring).
As illustrated in the above Examples, the phosphorus compounds to be peroxid.ized are phosphates, such as triaryl phosphates (which are preferred), monoalkyl diaryl phosphates ~including, of course, compounds having substituents on the alkyl group as in Example 12_~ or dialkyl monoaryl phosphates.
They may also be another ester (for example, a mixed ester such as mixed 4-isopropylphenyl phenyl ester or mixed ~-isopro-pylphenyl methyl ester) of phosphoric acid. Other substituents may be present as discussed above.
The compounds may be esters of polyhydric alcohols or polyhydric phenols, such as the mixed ester of phosphoric acid with propanediol-1,3 and 4-isopropylphenol (for example, having the formula O C
/\~
\0/ ~ I

wherein R represents the carbon chain portion of polyhydric (alcohol). It will be understood that such compounds may have a plurality of phosphorus atoms, for example, the mixed phos-phate ester of pentaerythritol and isopropylphenol having the type formula 1 Il/o-C /C-O\II f Cl~O` F~ o c/C\ C-O~`P-O~ I :

or the mixed phosphate ester of bis-phenol A and isopropyl~
phenol having the type formula 1 1l IC f==\ O~ Cl f ~ -O-P-O ~ C ~ ~ cc C R

~, ~

:
, - , ' , in which R may be aliphat.ic (including cycloaliphatic) such as methyl, butyl or octyl or aromatic (such as phenyl or isopropylphenyl).
It is also withi.n the broader scope of the inven-tion to use, as the phosphorus compound having the per-oxidizable alkylaryl group, a phosphaæene, such as an alkylaryloxyphosphazene, for example, a reaction product of sodium isopropylphenoxide and hexachlorocyclotriphos-phazene.
It will be understood, of course, that the composi-tion should be substantially free of amounts of active peroxide-destabilizing groups which would destroy the peroxide g~ups by reaction there~ith or by catalytic action. For instance, the presence of unneutralized or 15 unbuffered active acidic ~-OH groups (or ~P-Cl groups in the pre-sence of moisture which would form such strongly acidic 20 groups) could prevent formation of the desired peroxide h content or act to destroy already formed peroxide; also the presence of certain reducing agents (for example, phosphites) or amines, or certain concentrations of metal contaminants could act to destabilize the peroxides. The 25 preferred compositions are sufficiently free of su~h de-stabilizing materials that on storage (for example, for at least l day at 27-C and, as indicated in Examples 13 and 16, preferably for well over a week, such as a month or more at room temperature) they 105e less than 1/3 of : 30 their peroxide content; more preferably there is sub-stantially no loss on such storage.
We believe that when isopropylphenyl phosphates of the type used as plasticizers or hydraulic fluids are exposed to oxidizing conditions, in such use, traces of hydroperoxy-alkylphenyl phosphatPs may be formed ini-tially and that these break down quickly under such oxi-dizing conditions, possibly owing to the presence of :

o~5~

sufficient quantities of unbuffered acidic species (for example, hydrolysis products having ~\ 101 /P-OH groups). The following Example describes an oxidation in the absence of a buffering agent in the presence of a pro-oxidant.

Oxygen is bubbled through a mixture of 42 g of a triarylphosphate of a highly isopropylated phenol (like that used in Example 10g above) and 28 mg of manganese naphthenate at 120-125C for 20 hours. The reaction mixture turns a dark reddish-brown; hydroperoxide titra-tion of this mixture indicates that no peroxide is pre-sent (the titration is carried out under such conditions that a positive result would be obtained if 2 hydroper-oxide groups per 1000 phosphorus atoms were present).
As mentioned above, organic peroxides have been used '! as cross-linking agents, polymerization catalysts, graft-ing agents and halogen synergists with a wide variety of polymers. The uses of peroxides are discussed, for in-stance, in the article of Peroxy Compounds in the Ency-clopedia of Polymer Science and Technology, Vol. 9, pages ; 827-838 (published by Interscience Publishers, Inc., New York, N.Y. 10001, United States of America) and the per-oxy compounds of this invention may be empioyed in those uses, with the various types of polymers named in that article. The peroxy compounds of this invention may be employed as the peroxides in the compositions described in U.S. patents 3,637,578, dated January 25, 1972, 3,936,414, dated February 3, 1976, and 3,684,616, dated August 15, 1972. Among the halogen compounds with which ~ 35 the peroxide compounds of this invention may be used as - synergists are those named in U.S. patents 3,338,864, dated August 29, 1967, and 3,420,786, dated January 7, 1969.

~) :

:.
' As mentioned earlier, organophosphorus compounds have been conventionally employed as -flame retarding additives, for example, plasticizers, in organic polymers such as polyvinyl chloride, phenol-Eormaldehyde resins, nylons, acrylic resins, polystyrene, aminoplasts such as melamineformaldehyde resins, polyolefins (for example, polyethylene, polypropylene), poly-urethane foams, other elastomers such as neoprene, cellulose esters (for example, cellulose acetate or acetate butyrate) and engineering plastics (for example, polyphenylene oxide). The peroxy compounds and mixtures of this invention may be used in the same way. They may be similarly included in other poly-mers such as polycarbonates (for example, polycarbonates of bis- phenol A) or ABS polymers (acrylonitrilebutadiene-styrene -copolymers, including block and graft copolymers).
The proportions of the peroxy-containing phosphorus compounds will depend, of course, on the intended use and will generally be more than 0.1% and less than 50% oE the weight of the polymer.
The conditions used for obtaining the thermograms of Figs. 1 and 2 are as follows: The instrument used is a Dupont 900 Differential Thermal Analyzer set at: T; 50C/inch, ~Tr 0.5C/inch, and Rate 20C/minute. Sample sizes are 5-10 mg.

,p : ':

Claims (18)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A peroxygen composition which comprises a phosphate ester with at least one ester coupling to a substituted aro-matic ring, said aromatic ring having at least one substituent comprising an aliphatic carbon directly attached to the ring and with an ether peroxide group attached to said aliphatic carbon.

2. A composition of claim 1 wherein the aromatic group is a benzene ring.

3. A composition of claim 1 wherein the phosphate ester also contains at least one additional ester coupling to a phenyl group.

4. A composition of claim 1 wherein the phosphate ester contains at least one additional ester coupling to an aliphatic group.

5. A composition of claims 2, 3 or 4 wherein the ali-phatic carbon is directly attached to no more than two other aliphatic carbons.

6. A composition of claim 1 wherein the phosphate ester is a peroxygenated trisisopropylphenyl phosphate.

7. A composition of claim 1 wherein the phosphate ester is a peroxygenated diphenyl isopropylphenyl phosphate.

8. A composition of claim 1 wherein the phosphate ester is a peroxygenated trisethylphenyl phosphate.

9. A composition of claim 1 wherein the phosphate ester is a peroxygenated triscresyl phosphate.

10. A composition of claim 1 wherein the phosphate ester is a peroxygenated ethylhexyl bisisopropylphenyl phos-phate.

11. A composition of claim 1 wherein the phosphate ester is a peroxygenated bischloroethyl isopropylphenyl phosphate.

12. A process for preparing a peroxygen composition by contacting oxygen gas, an acid acceptor and a compound comprised of a phosphate ester with at least one ester coup-ling to a substituted aromatic ring, said aromatic ring hav-ing at least one substituent comprising an aliphatic carbon with at least one abstractable hydrogen directly attached thereto, and continuing said process until said composition contains at least 1 peroxygen group per 100 phosphorus atoms.

13. A process of claim 12 wherein said acid acceptor is a weak base.

14. A process of claim 12 wherein said oxygen treat-ment takes place in the presence of a transition metal prooxidant.

15. A process of claim 12 wherein said oxygen treat-ment is effected at a temperature of 25°-125°C.

16. A mixture of a peroxygen composition of claim 1 with a peroxide-crosslinkable olefin polymer.

17. A mixture of a peroxygen composition of claim 1 with a moldable polystyrene.

18. A mixture of a peroxygen composition of claim l with a moldable polymer comprising styrene and an unsatu-rated polyester copolymerizable therewith.