CA1048552A - Ketone peroxide compositions - Google Patents

Abstract

KETONE PEROXIDE COMPOSITIONS

ABSTRACT OF THE DISCLOSURE
Safe ketone peroxide compositions are provided utilizing a novel solvent system which boils smoothly over a wide range of temperatures. In addition, ketone peroxide compositions are prepared by reacting an excess of the ketone with hydrogen peroxide in a homogeneous system, followed by stripping excess ketone and water from the product.

Description

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The present invention is directed to ketone peroxide compositions, particularly "safe" ketone peroxide compositions,and to the preparation of ketone peroxide compositions.

Ketone peroxides are extensively used for the initiation of polymerization of ethylenically unsaturated compounds. Peroxides, however, have a tendency to be 10 inflammable and explosive, with some exhibiting these proper-ties to a greater extent than others. These properties carry withthem obvious hazards to the users of the materials as well as to the manufacturers.
Many suggestions have been made to reduce the inflammability of ketone peroxides, as discussed in more detail bebw, usually involving the incorporation of large ;
quantities of water in the composition, the use of various additives and the use of particular solvents.
The apparent need to provide compositions of this 20 ~ort has led to the widespread adoption of particular procedures for preparing such ketones. A commonly used procedure involves reaction of an aliphatic ketone, typically methyl ethyl ketone, in a solvent system under acid conditions with an aqueous solution of hydrogen peroxide, resulting in a two phase system. An excess of hydrogen peroxide over the stoichiometry to form the ketone peroxide is used in order to react as much of the ketone as possible.
The aqueous phase is separated from the organic phase and usually is discarded. The discarded aqueous phase

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104~S2 contains unreacted hydrogen peroxide and possibly some unreacted ketone, and hence the discard of the aqueous phase results in an uneconomic use of these materials.
The organic phase contains a substantial pro-portion of water, typically about 10 to 15%, and the presence of such large amounts of water has disadvantages associated mainly with the end use of the peroxide material, since the water generally is incompatible with the organic components to be polymerized. The presence of water leads ~o bubbling in polymeric thin film formation.
- In addition, the use of aqueous acids results in residual acidity in the organic phase which promotes continued reaction of the peroxide to higher oligomers. The trimer and higher oligomersare known to impart explosive properties to the composition. Therefore, the acidity has been neutralized, but the presence of commonly-employed neutralizing agents provides surface problems for the products of polymerization initiated by the peroxides containing such agents.
The prior art procedures for the production of aliphatic ketone peroxides therefore suffer from several drawbacks, which are sought to be overcome by the process which constitutes one aspect of the present inve~ntion.
In one aspect of the present invention, there is provided a novel process for forming aliphatic ketone peroxides, resulting in a product having superior stability, improved utility and decreased hazard.
As previously indicated there have been a number of prior art suggestions to provide "safe" ketone compositions, such as is described in U.S. Patent No.3,330,~71 wherein it is indicated that a class of "SaEety Solvents" for the ketone .
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peroxide may be used to provide compositions which exhibit resistance to ignition and once ignited burn mildly. A wide variety of solvents are mentioned including various glycols.
However, it has been found that, while the compositions pro-vided in the manner disclosed in this patent do indeed exhibit some resistance to ignition and once ignited burn mildly, after burning for a period of time, which may vary widely depending on the solvent used and the quantity present, the composition suddenly flares up and burns vigorously. The tendency of these prior art compositions to flare up suddenly is extremely hazardous to a user or manufacturer seeking to extinguish the ignited composition, since while the ignited composition may be burning mildly and the operator can approach the flame with suitable extinguishing equipment, before extinguishing the flame, a sudden flare up may occur, causing injury to the operator.
In the second aspect of the present invention, there is provided a safe acyclic ketone composition which exhibits con-- siderable resistance to ignition and when ignited burns in a controlled manner until all the peroxide composition has been consumed. Thus, the present invention avoids the flare up problem attendant the prior art compositions of U.S.Patent No.

3,330,871.
In accordance with one aspect of the present invention, there is provided a process for the production of an acyclic ketone peroxide which comprises reacting at a temperature below about 35C (a) an acyclic ketone of the formula R-CO-R' where R and R' each are straight or branched chain alkyl groups in which the total number of carbon atoms is from 3 to 6 and (b) hydrogen peroxide in at least one non-benzenoid inert solvent, said solvent being a solvent for water, the aliphatic ketone and the ketone peroxide, the reaction being carried out in the . . , .

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presence of a cation exchange resin in ~he hydrogen form, the quantity of acyclic ketone being at least 1.1 times the molar stoichiometric amount to produce the acyclic ketone peroxide, the quantity of the solvent being sufficient to maintain a homogeneous reaction medium throughout the reaction and to obtain from the reaction a homogeneous system of the solvent, acyclic ketone peroxide, unreacted acyclic ketone and water;
separating the cation exchange resin from the hom~geneous system and stripping water and unreacted acyclic ketone from the homogeneous system by boiling the homogeneous system at a temperature below the decomposition temperature of the ketone peroxide.
In complete contrast to prior art systems, an excess of the ketone is used in the process of the invention to ensure as complete reaction of the hydrogen peroxide as possible, the excess being preferably about 1.1 to 1.6 times the stoichiometric requirement. A homogeneous liquid medium is maintained throughout the reaction since it is unnecessary in the present invention to separate and discard excesshydrcgen , per~xide, or to ensure complete reaction of the ketone, in contrast to the prior art procedures discussed above.
The use of the cation exchange resin results in substan-tially no residual acid and hence the necessity to add neutralizers is avoided. In addition, the cation exchange resin assists in the removal of metal ions from the composi-tion which otherwise may lead to decomposition of the peroxide product.
The stripping of the homogeneous solution of solvent, ketone peroxide, unreac~ed ketone and water resulting from the initial reaction at a temperature below the decomposition tem-perature of the ketone peroxide removes water and unreacted ketone from the solution as a mixture and leaves a solution ~ - 5 ~34~
~f ketone pero~ide in non-benzenoid solvent having a low content of, preferably substantially free from, water and unreacted ketone. The excess ketone distilled from the solution also may assist in the removal of any unreacted hydrogen peroxide from the vapour produced by the ".,.,.. ,. ~ - - - . , . . , : .. : . : . :

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distillation.
The cation exchange resin may be separated from the liquid phase, either before or after the stripping operation, typically by simple filtration. The presence of the cation exchange resin during the stripping operation has no adverse effect on the product and may assist in driving the reaction to completion.
The maximum water content of the product depends on the ketone peroxide concentration, and for very low ketone peroxide concentrations, the water content may exceed 35%.
However, due to the deleterious effect of water in the product, as mentioned above, it is preferred to provide a water content less than about 5%, preferably from 0 to about 4%. The water content of the products may be determined readily by gas chromatographic techniques. This technique also may be used to determine the free ketone content of the product, which preferably, is as low as possible. The free ketone concentra-tion of the product should be below a value which will sub-stantially lower the flash point of the product, usually below about 0.5% and, preferably, from 0 to about 0.4%.
The product containing the preferred water content conforms to the so-called "Freezing Test". In the Freezing Test, the product is cooled to -50C and then thawed. To pass this test, the product must remain mobile on lowering the temperature to -50C and homogeneous on thawing.
When a conventional aliphatic ketone peroxide composition containing substantial quantities of water is cooled and subsequently thawed, freezing occurs on lowering the temperature, and a phase separation occurs on thawing which is extremely difficult to reverse and, additionally, . ~ . ., : ~ -.
, 104~SS;2 following such phase separation, the composition becomes more susceptible to explosio~.
Further, it has been observed that upon subjecting commercially-available peroxide compositions of low water content to the Freezing Test, the products solidified between 0C and -5C.
The product of the process of this invention has been found to have improved stability properties as compared to conventionally-produced ketone peroxide compositions, thereby providing a product which may be stored over long periods without substantial loss of activity and danger of instability if stored through cold weather.
The presence of the unreacted ketone in the product solution allows the water to be stripped off since the two form azeotropic mixtures. Therefore, the excess of ketone utilized in the process of the present invention serves a dual role, namely, to ensure the reaction of substantially all the hydrogen peroxide and to assist in the removal of the water from the product.
The stripped mixture of water and aliphatic ketone may be readily processed to recover the aliphatic ketone, which may be recycled for reuse. The process of the invent-ion therefore is economic in its use of both the aliphatic ketone and the hydrogen peroxide, and in addition, is less polluting since aqueous peroxide solutions are not sewered.
The stripping operation, which is an essential step in the process of this invention, has multifold advantages including:
1) The quantity o~ water present in the final pro-duct may be substantially decreased to a very low level, the 1041~5S2 stability of the composition thereby being improved without an increase in flammability;
2) The quantity of volatile solvents is reduced, resulting in a higher flash point product, a low concentration of explosive vapours and a reduction in bubbling caused by the volatile solvents in polyester films and 3) The product does not separate into phases on cooling and thawing.
The solvent used in the process of the invention to maintain homogeneity in the aqueous phase throughout the reac-tion may be a single solvent or a mixture of solvents, more particularly the mixture of solvents used to provide the safe ketone peroxide composition of the second aspect of the inven- ~-tion.
Among the solvents which may be used are alkylene glycols, ethylene glycol monoalkyl ethers, diethylene glycol monoalkyl ethers, alkanols having 3 to 12 carbon atoms, cyclo-alkanols having 3 to 6 carbon atoms in the ring, and cyclic ether substituted alcohols.
Examples of such solvents are ethylene glycol, propy-lene glycol, dipropylene glycol, hexylene glycol, 1,4-butylene glycol, 2,3-butylene glycol, ethylene glycol monoethyl ether, butylllcELLosoLvE'~ (Trademark), diethylene glycol monoethyl ether and butyl carbitol.
In accordance with the second aspect of the invention, there is provided an acyclic ketone peroxide composition having an active oxygen content of about O.I to about 13% and a flash point of at least about 200F and comprising a homogeneous solu-tion of 10 to 95% of (a) an acyclic ketone peroxide derived from an acyclic ketone of the formula R-CO-R' where R and R' each are straight or branched chain alkyl groups and in which the total number of carbon atoms is from 3 to 6, in 90 to 5~ of ~ - 8 : ~. '' ', ., : , .
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(b) a solvent system consisting of a mixture of solvents. The solvent system and the individual solvents thereof essentially conform to several characteristics:

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~i) a mixture of solvents which boils smoothly over a wide range of temperatures, preferably at least 40C and which commences to boil at a temperature of at least 175C, the individual solvents having differing boiling points, preferably between about 200 and 300C;
(ii) a mixture of solvents which has a flash point of at least 200F, preferably at least 220F;
(iii) a mixture of solvents which has an auto-ignition temperature of at least 225C, preferably about 300 to 1000C; ~;. .
(iv) a mixture of solvents which is a solvent for the ketone peroxide, water and free ketone, and additionally is compatible with the polymer system to be formed; ~
(v) a mixture of solvents having low volatility; .:. :
~vi) a mixture of solvents inert to the ketone and hydrogen peroxide reactants and product peroxide;
(vii) a mixture of solvents which has a low toxicity; I;
(viii) a mixture of solvents which does not lea~e a ~.
solid residue after burning, which otherwise would result ~.
in afterglow;
(ix) the individual solvents must be non-benzenoid; -~
(x) the individual solvents must contain from 2 to 8 acyclic carbon atoms;
(xi) the individual solvents should be inert and incapable of degradation under conditions of formation of the product to materials which may decompose the product peroxide; -~
(xii) the individual solvents must be non-halogenated, and (xiii) the individual solvents should be incapable of forming amine oxides.
~utoignition temperatures for various solvents and the determination thereof are described in an article entitled 104~5S2 "Autoignition Temperatures of Organic Chemicals" by Carlos J. Hilads et al, Chemical Engineering, Sept.4, 1972, pp 75 to 80. Autoignition is the lowest temperature at which a material begins to self-heat at a high enough rate to result in combustion.
By utilizing a mixture of solvents of differing boiling points and which boils smoothly over a wide temperature range, the heat of decomposition of the peroxide is used as heat of vaporization of the solvents and hence f~are up due to decomposition of the aliphatic ketone peroxide is not possible.
The ketone peroxide composition provided in accordance with the second aspect of this invention, has been found to have excellent end use properties. For example, in spray coat applications where polyester gels of only a few thousandths of an inch thick, typically 10 to 15 thou, are provided, the product of the invention does not give rise to blisters or pin holes, in contrast to many commercially-available ketone peroxide formulations.
Additionally, it has been found that where tapered sections or sections of irregular thickness are cured from curable polyester materials in which the ketone peroxide composition of this invention is used as the polymerization initiator, this curing takes place uniformly throughout the thickness of the film. This result is of importance in particular in the fabrication of boats where the use of uneven thickness of polyester film is common.
As a result of this unexpected uniformity of curing, there is less laminate stress and lack of excessive localised heat build up. The stresses and heat build up can cause 1~4~S5;;~ .
damage to the expensive molds used in the boat lndustry and hence shou~d be avoided. In addition, bubbling caused by solvents is not observed in the polyester films.
A further result achieved in film formation initiated with the compositions of the invention is that when the cured article, such as a boat, is removed from the mold, the film is completely cured. In many conventional systems, the film is not completely cured upon removal from the mold.
Compositions in accordance with the present invention have improved solubility in diallyl phthalate, as compared to conventional commercially-availa~le fire retardent ketone peroxide compositions. This property is important since diallyl phthalate is widely used as a cross-linking diluent in spray applications of ketone peroxides.

The sole figure of the drawing shows a schematic flow sheet of one embodiment of this invention.

' The acyclic ketone which is formed into a peroxide by the process of the present invention and into the peroxide derivativesof which may be present in the composition of the present invention are acyclic ketones of the formula R-C0-R', where R and R' each are straight or branched chain alkyl groups in which the total number of carbon atoms in R and R' : -, -. .
is from 3 to 6.
Suitable ketones include diethyl ketone, methyl ethyl ketone (M~K), methyl propyl ketone and methyl isobutyl ketone.

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The ketone most commonly employed to form ketone peroxides is methyl ethyl ketone and this particular material is preferred in both aspects of the present invention. The invention will be described hereinafter with particular re~erence to this ketone.
Referring to the drawing, hydrogen peroxide, typically-as an aqueous solution thereof containing 50% H2O2, is fed by line 10 to a react.or 12 containing methyl ethyl ketone fed by line 14 and solvent fed by line 16. A cation exchange resin in hydrogen ion form, fed by line 18 generally in the form of beads and insoluble.in the reactants or the solvent, also is present in the reactor 12. The hydrogen peroxide generallyis added dropwise to the solution to react with the methyl ethyl ketone and the reaction may be continued after compl-etion of addition of the hydrogen peroxide. .

The quantity of methyl ethyl ketone fed by line 14 .
is at least 1.1 times the stoichiometric quantity required to react with the hydrogen peroxide fed by line 10. Typically the amount is at least 1.5 times the weight of the hydrogen peroxide solution fed by line 10.
The solvent fed by li.ne 16 preferably is one con-forming to the requirements of the solvent system usedin the second aspect of the invention. Each of the solvents may contain from 2 to 6 acyclic carbon atoms.
Typical mixtures which may be used to provide the solvent system, especially with methyl ethyl ketone peroxide, include various mixtures of C2 to C6 glycols and C3 to C6 trialkyl phosphates, for example, mixtures of numbers of the following materials:

1~48SS2 Boilinq PointC. Flash PointF
Ethylene Glycol 197.2 240.8 Diethylene Glycol 245.0 290 Dipropylene Glycol 233 330 Hexylene Glycol 198 230 Triethyl phosphate 216 240 Crude ethylene glycol, usually containing quantities of diethylene glycol and triethylene glycol, may be used in the solvent system fed by line 16. Glycol deriv~tives, such as ethylene glycol acetate, may be used in the solvent system.
The relative proportions of the solvents, their - number, and the difference between their individual boiling points in the solvent system may vary widely and are a matter of choice, provided that the overall composition and the individual components conform to the above-described parameters.
Where other solvents are fed by line 16, such solvents should be non-benzenoid, non-toxic, compatible with and inert to the peroxide product, peroxide reactant, water and the hydrogen peroxide and generally oxygenated.
. The quantity of solvent fed by line 16 should be at least sufficient to maintain a homogeneous reaction mixture throughout the addition of hydrogen peroxide. .
The reaction is carried out at as low a temperature as possible cornpatible with speed of reaction. Higher temperatures favour decomposition of the product, whereas low temperatures below 10C result in long reaction times.
The process is carried out at a temperature below about 35C, preferably between about 20 to 30C, with reaction times from about 1 to 2 hours.

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1~485S2 Following completion of the reaction of the hydrogen - peroxide with the methyl ethyl ketone there is obtained a homogeneous solution of solvent, product ketone peroxide, water and unreacted methyl ethyl ketone in admixture with - resin. The admixture is passed by line 20 to a filter 22 wherein the solid resin is filtered from the homogeneous solution. Alternatively, the resin may be separated after the next processing step.
- The recovered resin is passed by line 24 to a regenerator 26 prior to recycle of regenerated cation exchan~e resin to the reactor 12 by line 18.
The filtered solution then is passed by line 28 to a stripper 30 wherein the solution is heated under reduced pressure to remove an azeotrope o~ methyl ethyl ketone and water. While three separate units, namely reactor 12,~filter 22 and stripper 30 are described, this is for ease of illustration of the process of the invention, and the three operations may be carried out in a single vessel.
The stripper 30 generally is maintained under a vacuum in order to lower the stripping temperature and hence reduce the danger of decomposition of the ketone peroxide.
The temperature of operation of the stripper 30 generally is less than about 40c with the applied vacuum being as high as possible. The excess methyl ethyl ketone and water are removed from the homogeneous system in the stripper 30 by line 32. The stripping usually is continued until no further material can be stripped from the product, and usually is complete in less than 4 hours, usually about 1 hour.
The resulting solution of methyl ethyl ketone :

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peroxide in solvent in line 34 is substantially free from unreacted methyl ethyl ketone and free water, and passes the Freezing Test mentioned above.
The concentration of the ketone peroxide in the product in line 34 may be in excess of the industry standard of 11% active oxygen, in which case the product may be diluted with further amounts of solvent, either during the stripping operation or thereafter, to provide the required active oxygen value. "~
The active oxygen content of the final composition may vary widely, typically from 0.1 to 13% A0, with varying quantities of solvent being employed, typically from 5 to 90% of the composition.
The material in line 32 may be passed to a separator 36 wherein the methyl ethyl ketone is separated and forwarded by line 38 to mix with further methyl ethyl ketone fed by line 40 to provide the methyl ethyl ketone feed in line 14.
By utilizing an excess of methyl ethyl ketone there is reallzed an economic utilization of hydrogen peroxide, and since the excess is recovered for recycling, hence, there is also economic utilization of ketone.

The invention is illustrated further by the following Examples:
EXAMPLE I
A mixture of solvents consisting of 7.38 lbs of triethyl phosphate, 2.62 lbs of ethylene glycol, 2.62 lbs of diethylene glycol and 2.62 lbs of dipropylene glycol was charged to a reaction vessel and 66.5 lbs of methyl ethyl .

ketone was a~ded. 1.36 lbs. of "DOWEX" (Trademark) 50W - X8 cation exchange resin in hydrogen ion form was added to the solution in the reaction vessel.
The mixture of solvents charged to the reaction vessel was found to commence boiling at 179.5C and to boil smoothly to dryness over an increasing temperature range to 224.0C.
41.6 lbs. of 50~ aqueous solution of hydrogen peroxide was added slowly with stirring over a 45-minute period, with the temperature being controlled by cooling below about 88F.
The resulting mixture was allowed to react, with stirring and agitation by nitrogen gas bubbled through, for a further 75 minutes.
The liquid in the reaction vessel remained homogeneous throughout the reaction and then was cooled to ambient tempera-ture prior to filtration of the cation exchange resin therefrom.
Under a vacuum of approximately 27 inches mercury, the filtrate was stripped of water and unreacted methyl ethyl ketone over a period of about 31/2 hours at a rising temperature between 70 and 116F.
41.2 lbs. of stripped material was recovered and 70 lbs. of methyl ethyl ketone peroxide solution was obtained.
The product was very difficult to ignite, and when ignited burned with a controlled flame until all the liquid was con-sumed.
In addition, the product was subjected to the Freeze Test and the liquid remained mobile on cooling to -50C and did not exhibit phase separation on cooling and thawing.
The product has an active oxygen content of about 11.5% and samples after storage for 183 days under laboratory condi~ions in which the temperature ranged from 50 to 95F, mainly 65 to 75F exhibited an active oxygen content of 1q~4~S5~2 11.2%, thereby indicating the stability of the product.
In sLmilar storage tests when exposed to outdoor weather conditions in which the temperature ranged from -5F
to 80F (shade temperature), the active oxygen content of the product after 148 days was 7.4%, while comparative samples of "APOSET" ~Trademark) 720 and FR 222 had exploded by that time.
EXAMPLE II
A two-gram sample of the product of Example 1 was placed in a small aluminum dish 12.5 mm high by 44 mm diameter.
Similar two-gram samples of commercially-available peroxide co~positions known as DNF (Wallace & Tiernan and formulated in accordance with U.S. Patent 3,330,871) and Aposet 720 (M
and T) were placed in similar dishes.
A 3/4 inch flame from a small pilot burner was adjusted to impinge the liquid surface at about a 60 degree angle. The flame was removed on ignition of the sample. The times to ignition were recorded for a number of samples and the average times are reproduced in the Table I:
TABLE I
Example 1 71 secs.
DNF 68 secs.
Aposet 720 25 secs. ~-' Total burning times varied within samples of each product and a true comparison in this regard was not possible.
The product of Example 1 burned mildly until all the peroxide had been consumed. On the other hand the DNF burned mildly for a short time before burning very vigorously.
A sample product formed from methyl ethyl ketone and hydrogen peroxide in ethylene glycol burned very readily.

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Example III
72.0 l~s. of methyl ethyl ketone, 16.50 lbs. of hexylene glycol and 1.3 lbs. of "AMBERLITE" ~Trademark) IR 120 cation exchange resin in hydrogen ion form were charged to a glass reactor fitted with a reflux condenser, an external jacket for heating or cooling and an agitator.
45.04 lbs. of a 50% aqueous solution of hydrogen peroxide was added slowly with stirring while the mixture was maintained by cooling at a temperature of above 70 to 88F. When addition of hydrogen peroxide was complete, the reaction was allowed to proceed for a further 75 minutes.
The liquid in the reaction vessel remained homogeneous throughout the reaction and then was cooled to ambient tempera-ture prior to filtration of the cation exchange resin therefrom.
The mixture thereafter was subjected to vacuum dis-tillation at a temperature ranging from 88F initially to 116F at the end while the pressure changed from 100 mm mercury to 54 mm mercury from the beginning to the end, which was after 255 minutes of reaction. The product 78 lbs. of peroxide con-tained 11.5% active oxygen.
Modifications are possible within the scope of the i~vention.

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Claims (31)

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

1. A process for the production of an acyclic ketone peroxide which comprises reacting at a temperature below about 35°C (a) an acyclic ketone of the formula R-CO-R' where R and R' each are straight or branched chain alkyl groups in which the total number of carbon atoms is from 3 to 6 and (b) hydrogen peroxide in at least one non-benzenoid inert solvent, said solvent being a solvent for water, the aliphatic ketone and the ketone peroxide, the reaction being carried out in the presence of a cation exchange resin in the hydrogen form, the quantity of acyclic ketone being at least 1.1 times the molar stoichiometric amount to produce the acyclic ketone peroxide, the quantity of said solvent being sufficient to maintain a homogeneous reaction medium throughout the reaction and to obtain from said reaction a homogeneous system of said solvent, acyclic ketone peroxide, unreacted acyclic ketone and water;
separating the cation exchange resin from said homogeneous system; and stripping water and unreacted acyclic ketone from said homogeneous system by boiling said homogeneous system at a temperature below the decomposition temperature of the ketone peroxide.

2. The process of claim 1 wherein said stripping step is continued until the resulting solution of acyclic ketone peroxide in said solvent has an unreacted ketone content less than about 0.5% and a water content less than about 5%.

3. The process of claim 2 wherein said stripping is carried out until the product contains from 0 to about 0.4 of unreacted ketone and from 0 to about 4% of water.

4. The process of claim 1 wherein said acyclic ketone is methyl ethyl ketone.

5. The process of claim 1 wherein said quantity of acyclic ketone is about 1.1 to about 1.6 times the molar stoichiometric amount necessary to produce the acyclic ketone peroxide.

6. The process of claim 5 wherein said quantity of acyclic ketone is about 1.5 times the molar stoichiometric amount necessary to produce the acyclic ketone peroxide.

7. The process of claim 1 wherein said reaction takes place at a temperature of about 20 to 30°C for about 1 to 2 hours.

8. The process of claim 1 wherein said stripping is carried out at a temperature below about 40°C under a vacuum.

9. The process of claim 1 including altering the solvent proportion of said resulting solution to provide an active oxygen content of about 11%.

10. The process of claim 1 including recovering un-reacted acyclic ketone from the material and utilizing said recovered acyclic ketone to react with further hydrogen peroxide.

11. The process of claim 1 wherein said cation exchange resin is separated from said homogeneous system prior to said stripping step.

12. The process of claim 1 wherein said cation exchange resin is separated from said homogeneous system after said stripping step.

13. The process of claim 1 wherein said at least one non-benzenoid inert solvent is provided by a solvent system consisting of a mixture of solvents which boils smoothly over a wide range of temperatures and which commences to boil at a temperature of at least of at least 175°C, having a flash point of at least 200°F and an autoignition temperature of at least 225°C, said mixture having a low volatility, low toxicity and being a solvent for and inert to the ketone peroxide, said mixture of solvents being incapable of leaving a solid residue after burning, the individual solvents of said mixture being non-benzenoid, non-halogenated and incapable of forming amine oxides and containing from 2 to 8 acyclic carbon atoms, and having differing boiling points.

14. The process of claim 13 wherein said solvent system boils smoothly over an at least 40°C temperature range.

15. The process of claim 13 wherein said mixture has a flash point of at least 220°F.

16. The process of claim 13 wherein said mixture has an autoignition temperature of about 300° to 1000°C.

17. The process of claim 13 wherein said individual solvents are selected from C2 to C6 glycols and C3 to C6 trialkyl phosphates.

18. The process of claim 17 wherein said individual solvents are selected from ethylene glycol, diethylene glycol, dipropylene glycol, hexylene glycol and triethyl phosphate.

19. The process of claim 13 wherein said individual solvents have differing boiling points between about 200° and 300°C.

20. The process of claim 1 wherein said at least one non-benzenoid inert solvent is provided by at least one solvent selected from the group consisting of alkylene glycols, ethylene glycol monoalkyl ethers, diethylene glycol monoalkyl ethers, alkanols having from 3 to 12 carbon atoms, cycloalkanols having from 3 to 6 carbon atoms in the ring and cyclic ether substituted alcohols.

21. The process of claim 1 wherein said at least one non-benzenoid solvent is provided by at least one solvent selected from the group consisting of ethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, 1,4-butylene glycol, 2,3-butylene glycol, ethylene glycol mono-ethyl ether, butyl Cellosolve, diethylene glycol monoethyl ether and butyl carbitol.

22. An acyclic ketone peroxide composition having an active oxygen content of about 0.1 to about 13% and a flash point of at least about 200°F and comprising a homogeneous solution of 10 to 95% of (a) an acyclic ketone peroxide derived from an acyclic ketone of the formula R-CO-R' where R and R' each are straight or branched chain alkyl groups in which the total number of carbon atoms is from 3 to 6, in 90 to 5% of (b) a solvent system consisting of a mixture of solvents which boils smoothly over a wide range of tempera-tures and which commences to boil at a temperature of at least 175°C, having a flash point of at least 200°F and an auto-ignition temperature of at least 225°C, said mixture having a low volatility, low toxicity and being a solvent for and inert to the ketone peroxide, said mixture of solvents being incapable of leaving a solid residue after burning, the in-dividual solvents of said mixture being non-benzenoid, non-halogenated and incapable of forming amine oxides and con-taining from 2 to 8 acyclic carbon atoms, and having differing boiling points.

23. The composition of claim 22 having an active oxygen content of about 11%.

24. The composition of claim 22 wherein said acyclic ketone peroxide is methyl ethyl ketone peroxide.

25. The composition of claim 22 wherein said solvent system boils smoothly over an at least 40°C temperature range.

26. The composition of claim 22 wherein said mixture has a flash point of at least 220°F.

27. The composition of claim 22 wherein said mixture has an autoignition temperature of about 300° to 1000°C.

28. The composition of claim 22 wherein said individual solvents are selected from C2 to C6 glycols and C3 to C6 trialkyl phosphates.

29. The composition of claim 28 wherein said individual solvents are selected from ethylene glycol, diethylene glycol, dipropylene glycol, hexylene glycol and triethyl phosphate.

30. The composition of claim 22 containing 0 to about 0.5% of free acyclic ketone and from 0 to about 5% water.

31. The composition of claim 22 wherein said individual solvents have differing boiling points between about 200°
and about 300°C.