The present invention relates to a composition comprising at least one dialkyl peroxide, in liquid form at ambient temperature, comprising at least one so lvant selected from mineral oils having a viscosity greater than 1 5 MPa. s measured at a temperature of 10 ° C and a shear rate of 1000s "1 , preferably selected from paraffin oils.
The invention also relates to the use of the composition as defined above, to alter the rheo logy in the molten state, in particular to reduce the viscosity in the molten state of the polypropylene.

The invention also relates to the use of one or more mineral oils having a viscosity greater than 15 mPa.s, measured at a temperature of 10 ° C at a shear rate of 1000 s "1 , to reduce the intensity of explosion of a composition comprising at least one dialkyl peroxide in a strictly content greater than 70% by weight, to 72% in particular greater by weight based on the total weight of the composition.

The controlled preparation of grades polyo léfine, that is to say the production of different types of polymers having mo lar masses, viscosities in the molten state, density or mass distributions specific mo lar adapted to different types of application may be accomplished by employing conventional methods, for example during an extrusion process or by inj ection molding.

Control logy rheo to melt po lyo léfines, and in particular of their viscosity, can be especially achieved, during the extrusion step or molding inj ection in the presence of compounds capable of generate free radicals. Depending on the type of prepared po lyo léfine, exemp by the polyethylene or polypropylene, changing their rheo logy in the melt can lead to an increase or decrease in their mo lecular mass.

Specifically, the use of compounds capable of generating free radicals such as organic peroxides, especially dialkyl peroxides, leads to a controlled degradation of the viscosity of the polypropylene.

Indeed, polypropylene is a polyo léfine usually obtained by polymerization of propylene monomers in the presence of catalysts in the reaction of Ziegler Natta followed by controlled degradation step in the presence of dialkyl peroxides added in liquid form lide or so, during a step of extrusion or inj ection molding at temperatures above 1 80 ° C. Under these operating conditions, the dialkyl peroxides and generate free radicals that will have the function of cutting channels polypropylene inducing beta-scission reactions known. Following such reactions, polypropylenes having masses mo léculaires lowest will be obtained.

Specifically, the controlled degradation of polypropylene makes it possible to lead to products having a mo lecular weight lower, a higher melt flow index (Melt Flow Index in the English language) as well as a viscosity at the lowest melt. Such degradation is a visbreaking process (visbreaking process called in English).

Polypropylenes thus obtained have a controlled rheology and are particularly attractive commercially because they can be used in many application areas. In addition, their method of obtaining easy to implement and allows the generation of polypropylenes having various mechanical properties.

However, organic peroxides, regularly used during the controlled degradation step polypropylenes are species typically very unstable when they are heated. Indeed, in case of an uncontrolled rise in temperature, some organic peroxides may undergo exothermic self-accelerating decomposition and s may ignite and / or explode so vio slow. Such behavior s' therefore is incompatible with the particular rules for the transport and storage of hazardous materials in the production units of polyo léfine, in particular polypropylene.

So it s' is particularly advantageous to formulate as liquid organic peroxides include dialkyl peroxides, in so lvants (also called desensitation), that is to say to the diluted state, to reduce their danger potential and to be able to transport and store them safely. The presence of phlegmatisant or solvent also allows to greatly reduce vio lence of decomposition.

Moreover, the interest of the phlegmatisée form may also reside in the gain storage in terms of the amount of organic peroxide by changing storage class according to national regulations. This allows to maintain in production workshops a larger amount of organic peroxide as the peroxide is so diluted in lvant.

For example, the peroxide 2.5 -diméthyle-2,5 -di (tert-butylperoxy) -hexane in the pure state is classified UN3 103 or Type C while diluted to 50% by weight in mineral oil the product is classified UN3 109 or F type as recommended for the transportation of hazardous materials a, 19 th edition 20 15, in the section on organic peroxides. In llandaise ho regulatory storage of organic peroxides, PGS 8 version 1 201 1, the maximum size of the metering equipment is of 5000 liters for a peroxide type F or 100 liters for a C-type peroxide. The dilution therefore allows to transport and store a larger amount of organic peroxide into larger containers.

By way of clarification, the recommendations A stated above, taking into account the concentration at which the organic peroxide generates including (i) a propagation of a detonation, (ii) a deflagration more or less rapidly under the effect of a initiation or combustion as well as (iii) the intensity of the decomposition reaction of the peroxide during heating under confinement tests can be vio slow, moderate, low or zero.

These three criteria are the main and essential criteria for assigning the product a rating from Type A to H. They may be supplemented by other criteria for the slowest vio products (types B and C) or less vio slow (types E and F).

One type of F classification means that the product when tested in the laboratory using the methods of the UN Manual of Tests and Criteria recommendations for the transportation of hazardous materials, 6 th revised edition of 2015:

1) does not detonates in the cavitated state

2) nor deflagrates

3) has a low or no effect on heating under confinement, and

4) has little or no explosive power.

It is possible to package this product meets a type of F classification in IBCs or tanks in quantities ranging up to several tons. Additional testing for sizing the emergency vent to confirm that the product can be transported in the form of IBC or tank for amounts ranging up to several tons. An essential criterion to be considered for a type of classification according to F A regulation corresponds to the intensity of decomposition of the organic peroxide to reaction at heating under confinement tests. In particular, the intensity of the decomposition reaction in these tests of an organic peroxide to a type of product F is low or zero. These tests are described in the Manual of Tests and Criteria recommendations for the transportation of hazardous materials, 6 th revised edition in 2015.

In the prior art, it has already been envisaged to use different types of additives in order to delay the decomposition of organic peroxides, including dialkyl peroxides.

By way of illustration, US 5,155,192 describes the use of hydroperoxides, preferably a tertiary hydroperoxide, as so lvant to improve the ability of compositions peroxydicarbonates to be transported and stored.

Similarly, patent application WO 2002/092561 relates to the use of nitroxyl radicals, especially of compounds N-

heterocyclic with the nitrogen atom bearing the nitroxyl radical, for thermally stabilizing organic peroxides such as dialkyl peroxides, in order to increase their storage stability.

EP 123 1206 discloses on the other hand the use of unsaturated dicarboxylic acids to improve stability during manufacture, transport and storage of compositions based on dialkyl peroxydicarbonates.

Furthermore, it is also known to formulate dialkyl peroxides, including peroxide 2.5 -diméthyle-2,5 -di (tert-butylperoxy) -hexane, to a maximum content of 70% by weight based on the weight total composition, in isododecane in order to obtain a product having a type of classification F a according to the recommendations described above.

However, it was found that it wasn 't possible to further increase the concentration of dialkyl peroxide in a composition comprising isododecane, ie beyond 70% by weight, otherwise degrade the rankings type F established according to UN regulations. Indeed, the effect of heating under confinement of such a composition according to the A test is not "low" or "no" but "average" and can cause explosion hazards. That is, beyond a content of 70%) by weight of dialkyl peroxide, it is not possible to condition the same amount of composition under the same conditions (the package size must be decreased).

In addition, in some applications, the presence of a significant amount of solvent, in particular from isododecane, may have, in use of a composition based on an organic peroxide, a number

of drawbacks such as exudation of lvant so, especially when the organic peroxide is used in extrusion at high temperature or potential exudation ( "fogging") when using polypropylene wherein the organic peroxide is added.

Another disadvantage of this type of composition also lies in the presence of traces of N lvant in polypropylenes finally obtained by visbreaking. The result of logistic efforts and additional costs in terms of implementation to separate polypropylene traces of solvent.

Thus one of the obj ective of the present invention is especially to propose compositions based on dialkyl peroxide having a concentration greater than 70% by weight while maintaining the type classification F A according to regulations.

In other words, there is a real need to offer more concentrated compositions dialkyl peroxide without degrading type of classification F according to UN regulations so that they are transportable and storable at least under the same conditions security than conventional compositions comprising 70 wt% of dialkyl peroxide in isododecane.

In view of the above, the invention in particular obj ective to provide liquid compositions based on dialkyl peroxide which does not have the drawbacks mentioned above.

The present invention thus has particular obj and a liquid composition comprising at mo ins a dialkyl peroxide, in liquid form at room temperature, in a content greater than 72%> by weight and less strictly to 80% by weight based on the weight total

composition, and at least a mineral oil having a viscosity greater than 15 mPa. s measured at a temperature of 10 ° C at a shear rate of 1000 s 1 .

The composition according to the present invention has a low or no effect on heating under confinement.

The terms "" weak "reaction" and "reaction" null "" corresponds to a result likely to be obtained with heating under confinement test, as defined in Section 25 of the Manual of Tests and Criteria recommendations A for transportation of hazardous materials ( "Transport of dangerous goods", chapter "A Manual of Tests of Criteria", revised 2015).

Preferably, the composition according to the present invention does not detonates in the cavitated state nor deflagrates, has a low or no effect on heating under confinement, and has little or no explosive power.

The set of tests to meet the above criteria are defined in Sections 20 to 28 of the Manual of tests and criteria recommendations for the transportation of hazardous materials identified above.

Still preferably, the composition according to the present invention satisfies the classification tests for organic peroxide type F, and more preferably has a type of classification F such that follows guidelines A. The compo sition according to the present invention can therefore be transported and stored safely in the production of polypropylene units.

One type of F classification means that the product when tested in the laboratory using methods A Manual of Tests and Criteria recommendations for the transportation of hazardous materials, 6 th

revised 2015 edition does not detonates in the cavitated state nor deflagrates at a low or no effect when heated under confinement, and has little or no explosive power.

The composition according to the invention has the advantage of being able to increase the weight concentration of dialkyl peroxide with respect to a composition containing 70 wt% of dialkyl peroxide in isododecane without degrading the ranking established in parallel according to the A regulation for transportation and storage.

Thus, the composition according to the present invention allows to increase the concentration of dialkyl peroxide while ensuring a level of vio decomposition lence, during heating under confinement in tests, less than or equal to that observed with a composition containing 70% by weight dialkyl peroxide in iso dodecane. In other words, the vio lence decomposition of dialkyl peroxide is lower or the same between the composition according to the invention and a composition containing 70%> by weight of dialkyl peroxide in isododecane. In addition, for the same concentration of dialkyl peroxide, there are obtained effects reduced during heating under confinement in the decomposition of the composition according to the invention relative to a composition containing dialkyl peroxide in isododecane.

Furthermore, the composition according to the invention reduces the amount of n lvant employed resulting in reduced logistics effort to recover polypropylenes obtained in method of modifying their logy rheo in the molten state, in particular when methods of visbreaking.

In addition, the composition according to the invention makes it possible to limit exudation of the so lvant during extrusion.

The invention also relates to a composition of the present invention packaged in a container, preferably a freight container having a vo lume of at least 450 liters.

In other words, the invention also relates to a container, preferably a freight container having a vo lume of at least 450 liters comprising a composition as defined above.

Preferably, said container has a vo lume from 450 liter

2000 liters, preferably between 1000 and 1500 liters.

Preferably, said container is provided with a vent to release gases.

Preferably, said container is made of plastic or metal, even more preferably plastic.

The invention also obj and use of the composition as defined above for modifying the logy rheo to melt the polypropylene, preferably to change its viscosity in the molten state and / or flow rate at melt.

Similarly, the present invention also relates to the use of one or more mineral oil having a viscosity greater than 15 mPa. s measured at a temperature of 10 ° C at a shear rate of 1000 s "1 , to reduce the intensity of the explosion of a composition comprising at least one dialkyl peroxide in a strictly content greater than 70% by weight , relative to the total weight of the composition.

Other features and advantages of the invention will become apparent from reading the description and examples that follow.

In what follows, and unless otherwise indicated, the limits of a range of values ​​are included in that range.

The term "at least one" is equivalent to the term "one or more".

As indicated above, the composition according to the invention comprises at least one dialkyl peroxide, in liquid form at room temperature, in an amount greater than 72 wt% and strictly less than 80% by weight, preferably ranging from 73 to 79% by weight, preferably from 74 to 78%) by weight, and more preferably from 75 to 77% by weight, based on the total weight of the composition.

Within the meaning of the present invention, the term dialkyl peroxide in liquid form at room temperature, a peroxide in liquid form at a temperature between 10 ° C and 30 ° C, preferably between 15 ° C and 25 ° C.

dialkyl peroxide is present in the following conventional crude forms:

ROOR or R-OO-R '-OO-R

R or R segments' may consist of aliphatic components but also optionally in the branches having aromatic or cyclic functions.

Preferably, the compounds belonging to the family of the dialkyl peroxides are selected from 2,5 -diméthyle-2,5 -di (tert-butylperoxy) -hexyne-3 (Luperox ® 130), the di-tertbutyl peroxide (Luperox ® dI), ditertiary-amyl peroxide (Luperox ® DTA), 2,5-dimethyl-2,5 (di (tert-butylperoxy) hexane (Luperox ® 101) and mixtures thereof.

More preferably, the dialkyl peroxide is the 2,5 -dimethyl-2,5 (di (tert-butylperoxy) hexane, sold under the trade name Luperox ® 101.

Advantageously, the dialkyl peroxides is or are present (s) in a content of about 77% by weight relative to the total weight of the composition according to the invention.

Still preferably, the compound 2,5-dimethyl-2,5 (di (tert-butylperoxy) hexane is at a content of about 77% by weight relative to the total weight of the composition according to the invention.

Alternatively, the one or more dialkyl peroxides is or are present (s) in a content of about 75%> by weight based on the total weight of the composition according to the invention.

According to this variant, the compound 2,5-dimethyl-2,5 (di (tert-butylperoxy) hexane is preferably at a content of about 75%> by weight based on the total weight of the composition according to the invention.

As indicated above, the composition according to the invention further comprises at least a mineral oil having a viscosity greater than 1 5 MPa. s measured at a temperature of 10 ° C at a shear rate of 1000 s 1 .

The viscosity is measured at a temperature of 10 ° C at a shear rate of 1000 s "1 with a Haake VT550 equipped with a viscotesteur of NV rotor.

Within the meaning of the present invention, mineral oil is a mixture of cyclic or unsaturated alkanes, branched or unbranched (eg oils

isoparaffin, naphthenic oils), aromatic derivatives substituted or unsubstituted (eg aromatic oils), poly alphao léfines (more commonly known as PAO) (eg synthetic oils). Mineral oil is liquid at atmospheric pressure and room temperature, that is to say at a temperature between 10 ° C and 30 ° C, preferably between 1 5 ° C and 25 ° C, and is insoluble in water.

Preferably, the mineral oil has a viscosity of from 15 to 1000 mPa. s, preferably from 100 to 1000 mPa. s, preferably from 100 to 500 mPa. s, and more preferentially ranging from 250 to 400 mPa. s measured at a temperature of 10 ° C at a shear rate of 1000 s 1 .

Preferably, the mineral oil is selected from paraffin oils. According to one embodiment, the composition according to the invention comprises the compound 2,5-dimethyl-2,5 (di (tert-butylperoxy) hexane in a content of about 75% by weight relative to the total weight of said composition and at least one mineral oil having a viscosity ranging from 15 to 1000 mPa.s, measured at a temperature of 10 ° C at a shear rate of 1000 s "1 , preferably a mineral oil selected from liquid paraffin. Pursuant in this embodiment, the mineral oil preferably has a viscosity preferably ranging from 100 to 1000 mPa. s, preferably from 100 to 500 mPa. s, and even more preferably from 250 to 400 mPas.

The composition according to the invention may also comprise one or more functional additives to provide the po lymère which is added the peroxide properties / special features.

Thus, with regard to the additive, it may be selected from antioxidants; UV protection agents; the implementation of agents, having the function of improving the final appearance during its implementation, such as fatty amides, stearic acid and its salts, ethylene bis-stearamide or fluoropolymers; anti-fog agents; anti-blocking agents such as silica or talc; fillers such as calcium carbonate and nanofillers such as clays; coupling agents such as silanes; crosslinking agents such as peroxides; antistatic agents; nucleating agents; pigments; co lorants; plasticizers; the plasticizers and flame retardant additives such as aluminum or magnesium hydroxides.

The composition according to the invention may optionally also contain additives including pH adjusting agents such as phosphate and citrate buffers, chelating agents, biocides, for example fungicides, antiozonants, antioxidants, antidegradants, blowing agents and mold release agents.

These additives may be added in amounts usually used and known to those skilled in the art. These additives are generally used in contents of between 10 ppm and 10,000 ppm by weight based on the weight of final polymer. P lastifiants, flow and flame retardant additives can reach much higher amounts to 10 000 ppm.

The invention also relates to the use of the composition as defined above for modifying the rheo logy in the molten state of the polypropylene.

According to one embodiment, the composition is used to reduce the viscosity in the molten state and / or increase the melt index of the polypropylene.

Preferably, the composition according to the invention is used to reduce the viscosity in the molten state of the polypropylene.

Similarly, the composition according to the invention is used to increase the melt index to melt the polypropylene.

The melt flow rate in the molten state of the polypropylene is measured according to methods commonly used to characterize the thermoplastic materials for obtaining information on the extrudability and the shaping possibilities of material such as those described in ASTM D 1238 or NF T 5 1 -016.

Finally, the present invention also relates to a rheology modification process in the molten state of the polypropylene comprising a step of extruding the polypropylene at a temperature between 140 and 300 ° C and more particularly between 170 and 250 ° C, for a few seconds to a few minutes or less in the presence of a composition as defined above.

Preferably, the process according to the invention is a polypropylene visbreaking process.

Also preferably, the visbreaking process polypropylene includes a step of extruding the polypropylene at a temperature between 140 and 300 ° C and more particularly between 170 and 250 ° C for several seconds to several minutes or less in the presence of a composition as as defined above.

Within the meaning of the present invention, the expression "a few seconds to minutes," 3 seconds to 9 minutes, preferably from 1 0 seconds to 5 minutes and more preferably from 30 seconds to 2 minutes.

Advantageously, the composition comprises 77% by weight of the compound 2,5-dimethyl-2,5 (di (tert-butylperoxy) hexane based on the total weight of said composition.

Also advantageously, the composition comprises 75% by weight of the compound 2,5-dimethyl-2,5 (di (tert-butylperoxy) hexane based on the total weight of said composition.

The obtained polypropylene is preferably a propylene homopolymer or a propylene copolymer comprising at least one co-monomer selected from ethylene, 1-butene, 1-hexene and 1-octene.

More preferably, the polypropylene is a propylene homopolymer or copolymer having mainly derivatives of propylene units.

Furthermore, the invention also relates to the use of at least a mineral oil having a viscosity greater than 15 mPa. s measured at a temperature of 10 ° C at a shear rate of 1000 s "1 , to reduce the intensity of the explosion of a composition comprising at least one dialkyl peroxide in a strictly content greater than 70% by weight , in particular greater than 71%, preferably greater than 72%, preferably greater than 73%, preferably greater than 74%, more preferably greater than 75%, by weight relative to the total weight of the composition.

With "intensity means 'explosion' assessment of vio lence from the decomposition of the composition as measured on heating under confinement of the composition, as described above, according to tests performed in the laboratory using methods a section 25 of the manual of tests and criteria recommendations for the transportation of hazardous materials, 6 th revised edition 20 15.

The dialkyl peroxide present in the composition is as defined above and is preferably the compound 2,5-dimethyl-2,5 (di (tert-butylperoxy) hexane.

Preferably, the mineral oil as described above is used to reduce the intensity of explosion of a composition comprising at least one dialkyl peroxide in a strictly content higher than 70 wt% and strictly less than 80% by weight relative to the total weight of the composition.

The following examples serve to illustrate the invention without being limiting in nature.

EXAMPLES

The composition according to the invention (A) and two comparative compositions (B) and (C) were prepared using the following raw material:

A. Raw material used

The dialkyl peroxide used is 2,5-dimethyl-2,5 (di (tert-butylperoxy) hexane to 94.4% pure product marketed under the Luperox 101 trade name ® by Arkema.

B. preparing compositions Protocol

First, 2,5-dimethyl-2,5- (di (tert-butylperoxy) hexane is diluted in white mineral oil having a viscosity of 321 mPa.s at 10 ° C, 1000 sec "1 so to obtain :

a composition comprising 77 wt% of dialkyl peroxide based on the total weight of the composition (composition A of the invention), and

a composition comprising 71 wt% of dialkyl peroxide based on the total weight of the composition (comparative composition B).

On the other hand, 2,5-dimethyl-2,5- (di (tert-butylperoxy) hexane is diluted in isododecane having a viscosity of 1.7 mPa.s at 10 ° C, 1000 sec "1 so as to obtain:

a composition comprising 71 wt% of dialkyl peroxide based on the total weight of the composition (comparative composition C).

The viscosities are measured at a temperature of 10 ° C using a Haake VT550 viscotesteur of a rotor equipped with NV at different shear rates. The viscosity at 1000 sec "1 was interpolated from the results to neighboring shear rate.

C. comparative tests

Comparative tests were carried out following the methods AN s and E2 described in the manual of tests and criteria recommendations for the transportation of hazardous materials to the chapters on organic peroxides ( "Transport of dangerous goods", chapter "A Manual of Tests of Criteria ", revised 2015).

Methods A E l and E2 are intended to determine the sensitivity of the compositions (A), (B) and (C) to the effect of intense heat under defined confinement. These methods are described in Section 25 "test series E" of the UN Manual of Tests and Criteria, 6 th revised edition. A method E l is to heat rapidly in a clo s tube with a calibrated orifice in its upper part a certain quantity of the product to be tested. Depending on the possible deformation of the pipe or tube rupture pattern, the result is classified as "explosion" or

"No explosion" for each test performed. The tests are made by diameter increasing from 1 to 10 mm up to 3 get results "no explosion" for a given diameter. The diameter limit reported in the results is the greatest diameter for which at least one test on three led to an "explosion" result. Depending on the limit diameter and optionally the tube deformation pattern, the effect is classified as "vio slow", "medium", "low" or "zero".

A method E2 is to quickly heat a quantity of the product to be tested in a clo s tube provided in its upper portion with a calibrated orifice and a burst disc burst pressure 6 bar. The degree of susceptibility of a substance on heating under confinement after the test A E2 is expressed by the diameter limit.

It is a question of larger diameter, expressed in mm, of the calibrated orifice for which it has been at least one burst of the rupture disc on three tests.

D. Results

The results are summarized in the following tables: Results according to method A El

^ Measured at 10 ° C, 1000

Results by method E2

Tests conducted for heating under confinement resulted in a current "low" of the decomposition of dialkyl peroxide for the three products tested according to the UN recommendations.

These results, in addition to other tests, led to the classification by the BAM ( "Bundesanstalt fur Materialforschung und -prüfung") of the three products tested as type F for the transport and storage according to the UN classification.

Furthermore, the use of a so lvant having a high viscosity reduces vio lence of the same concentration to decomposition or the same level of vio lence decomposition at heating under confinement test to significantly increase the concentration of active ingredient.

CLAIMS
1. Liquid composition comprising at least one dialkyl peroxide, in liquid form at room temperature, in a greater than 72% content by weight and less strictly to 80%> by weight relative to the total weight of the composition, and at least one mineral oil having a viscosity greater than 15 mPa. s measured at a temperature of 10 ° C at a shear rate of 1000 s "1 .

2. Composition according to claim 1, characterized in that the dialkyl peroxide is selected from 2,5 -diméthyle-2,5 -di (tert-butylperoxy) - hexyne-3, di-tertbutyl peroxide, ditert- amyl peroxide, 2,5 - dimethyl-2,5 (di (tert-butylperoxy) hexane and mixtures thereof.

3. Composition according to claim 1 or 2, characterized in that the dialkyl peroxide is 2,5-dimethyl-2, 5 (di (tert-butylperoxy) hexane.

4. Composition according to any one of the preceding claims, characterized in that the dialkyl peroxide is in an amount ranging from 73 to 79% o by weight, preferably from 74 to 78% by weight, and more preferably from 75 to 77% by weight relative to the total weight of the composition.

5. Composition according to any one of the preceding claims, characterized in that the mineral oil has a viscosity of from 1 5 to 1000 mPa. s, preferably from 100 to 1000 mPa. s, preferably from 100 to 500 mPa.s, even more preferably from 250 to 400 mPa.s, measured at a temperature of 10 ° C at a shear rate of

1000 s 1.

6. Composition according to any one of the preceding claims, characterized in that the mineral oil is chosen from liquid paraffins.

7. Composition according to any one of the preceding claims, characterized in that it has a low or no effect on heating under confinement.

8. Use of the composition as defined according to any one of the preceding claims, for modifying the rheology melt polypropylene.

9. Use according to claim 8 for reducing the viscosity in the molten state of the polypropylene.

10. Use according to claim 8 for increasing the melt index to polypropylene melt.

11. A method of modifying the rheology melt polypropylene comprising a step of extruding or injection molding the polypropylene at a temperature between 140 and 300 ° C and more particularly between 170 and 250 ° C, for a few seconds to a few minutes or less in the presence of a composition as defined according to any one of claims 1 to 7.

12. The method of claim 11 visbreaking polypropylene.

13. The method of claim 1 1 or 12 wherein the polypropylene is a propylene homopolymer or a propylene copolymer comprising at least one co-monomer selected from ethylene, 1-butene, 1-hexene and 1- octene.

14. Use of at least a mineral oil having a viscosity greater than 1 5 MPa. s measured at a temperature of 10 ° C at a shear rate of 1000 s- 1, to reduce the intensity of the explosion of a composition comprising at least one dialkyl peroxide in a strictly content greater than 70% by weight , particularly greater than 72% by weight relative to the total weight of the composition.

15. Composition according to any one of claims 1-7, packaged in a container having a vo lume of at least 450 liters.