DESCRIPTION

TITLE: Composition comprising at least one aromatic peroxide and at least one compound having an ether group

Field of the invention

The present invention deals with a composition comprising at least one aromatic peroxide comprising at least one aromatic ring and at least one peroxo function in its structure, as defined hereinafter, and at least one compound having an ether group. The invention also relates to the use of said composition in order to prepare a polymer, preferably styrenic polymers, or a polymer resin, in particular a polymer ester resin, said polymer ester resin being preferably chosen in the group consisting of unsaturated polyester resin, acrylic resin, methacrylic resin and vinyl ester resin.

The invention also pertains to the use of at least one compound having an ether group for improving the color stability of a composition comprising at least one aromatic peroxide having at least one aromatic ring and at least one peroxo function in its structure as defined hereinafter.

Background of the invention Aromatic peroxides are currently often used as radical initiators in various polymerization reactions, such as for the synthesis of styrenic resins, vinyl ester resins or polyacrylates, for example poly(meth)acrylate having pendant aromatic rings, or as curing agents for the preparation of thermoset polyesters, namely unsaturated polyesters resins which can be implemented for the manufacture of artificial marble products, gel coats, marine watercraft, polymer concrete and more.

Aromatic peroxides are well known in commerce and can be selected among the aromatic peresters family, namely perbenzoates, such as tertio-butyl peroxybenzoate (denoted TBPB) sold for example under the name Luperox® P, aryl peralkylates and aromatic diperesters, the aryl-alkyl peroxides family, such as dicumyl peroxide, the aryl hydroperoxides family such as cumene hydroperoxide, and the aromatic diacyl peroxides family such as di(2,4-dichloro benzoyl)peroxide.

However, one of the main disadvantages of the aforementioned aromatic peroxides is that they are usually subject to a colour transformation after a certain period of time at room temperature or at recommended storage temperature conditions (i.e. between 8 and 30°C) under standard storage conditions. In particular, it has been pointed out that the colour of said aromatic peroxides steadily increases or even soars sometimes over a relatively short period of time, for example the colour of tertio-butyl peroxybenzoate can flare up over a period of time of 21 days, during storage. It bespeaks that the aforementioned aromatic peroxides can experience a colour stability issue during storage, even in the dark.

As a result, this colour stability issue can reduce the time of storage of aromatic peroxides forcing sometimes the manufacturers of the targeted polymer resins to use them earlier than expected before they develop a significant and irreversible colour variation. Indeed, there is a likely risk that said coloured impurities of the aromatic peroxides tint the polymers or polymer resins during their preparations which can turn out to be a relevant issue depending on their designed applications.

Especially, the production of polymers or polymer resins that are unintentionally coloured due to the coloration provided by the aromatic peroxides can easily be misinterpreted by some users as meaning that said polymers or polymer resins are of poor quality. As an example, one can assume that said produced polymers or polymer resins had been subject to photooxidation or photodegradation which altered their natural aspect and properties.

More broadly, the lack of colour stability of said aromatic peroxides during storage may affect the aspect of the targeted polymeric compounds and alter the overall appearance of the final product. It can also lead to a misinterpretation of the quality of said polymeric compounds and the products obtained therefrom.

Moreover, this coloration can render more difficult the manufacture of polymeric compounds which are supposed to have specific light color characteristics imposed by their industrial applications, for instance LDPE blister applications.

Besides, in some cases, this coloration can render more tedious the subsequent addition of dyes designed to impart a specific colour to the final aspect of the polymeric compounds. Indeed, the produced polymeric compounds can exhibit sometimes a colour due to the aromatic peroxides which does not match with the dyes required to be added.

Hence, on a commercial standpoint, the risks of transferring the colour of the aforementioned aromatic peroxides can represent a hurdle to the economic value of the manufactured polymers and polymer resins.

The development of colour in a composition comprising aromatic peroxides might also interfere with the eventual presence of coloured dyes that had been added on purpose into said composition, for example as a visual aid to help the operator during its process.

Accordingly, it remains a real need to provide compositions comprising aromatic peroxides which are able to be colour stable over time under recommended storage conditions in order to mitigate the risks of colour transfer to the targeted polymeric compounds previously detailed.

In particular, one of the goals of the present invention is to minimize the colour development of aromatic peroxides during storage, especially at room temperature, in order to be able to use them efficiently to manufacture said polymeric compounds without negatively impacting their aspect. More specifically, another goal of the present invention is to curb the increase of colour of aromatic peroxides during their storage period.

Description of the invention

The present invention namely results from the unexpected findings, by the inventors, that the use of at least one compound having an ether group is able to improve the colour stability over time of at least one aromatic peroxide as defined hereinafter (i.e. to curb the evolution of colour of said aromatic peroxides) and also to decrease the colouration due to said aromatic peroxides.

Therefore, the present invention relates to a composition comprising: a) at least one aromatic peroxide comprising at least one aromatic ring and at least one peroxo -O-O- function in its structure; preferably the aromatic ring is connected to said peroxo function by a covalent bond, a carbonyl group or an alkyl group comprising from 1 to 20 carbon atoms; b) at least one compound having an ether group.

The composition of the present invention displays a better colour stability over time under standard storage conditions than a composition comprising only the aforementioned aromatic peroxide(s), especially at room temperature, and especially in the dark.

In more detail, the composition according to the present invention exhibits a significant lower APHA colour value than the same composition comprising only the aforementioned aromatic peroxide(s) over a period of time of at least 5 days, in particular of at least 15 days, especially of at least 20 days, preferably of at least 30 days, more preferably of at least 50 days and even more particularly over at least 90 days, under standard storage conditions, especially at room temperature , and especially in the dark.

According to the present invention, the expression “room temperature” stands for a range of temperatures from 0°C to 50°C, preferably from 10°C to 40°C, more preferably from 15°C to 30°C, even more preferably from 20°C to 30°C.

According to the present invention, the expression “in the dark” means that the composition is protected from light, and in particular is protected from ultraviolet (UV) radiations.

According to the present invention, the APHA colour is a colour standard named after the American Public Health Association and defined by the standard ASTM D1209, and more precisely ASTMD1209-05(2011). The APHA colour is a colour scale, sometimes also called “yellow index”, which makes it possible to evaluate the quality of specimens that are pale to yellowish in colour. The APHA colour is measured using a colorimeter with a standard range of from 0 to 1000 APHA. The colour of the composition according to the present invention can be assessed with a spectral colorimeter such as the one sold under the name LICO 620 by Hach company.

In other words, the addition of at least one compound having an ether group is able to decrease or to stabilize the APHA colour value of the aforementioned aromatic peroxide(s).

The colour stability of the composition of the present invention helps to minimize the risks that there is an unwanted colour occurring from the aromatic peroxides, due to their time of storage, to the targeted polymeric compounds.

As a consequence, the composition of the present invention can efficiently be used for the preparation of polymer, in particular polystyrene, or polymer resins, preferably a polymer ester resin, without altering their aspect, i.e. without unintentionally tinting them.

More precisely, the use of at least one compound having an ether group is able to significantly curb the evolution of colour of aromatic peroxides with time, especially at room temperature.

It also means that the addition of at least one compound having an ether group is able to extend the time of said aromatic peroxides usages in applications, especially at room temperature.

As a consequence, the use of at least one compound having an ether group is able to restore the economic value of the aromatic peroxides since they can be stored under standard conditions for extended period of times without experiencing a significant and inacceptable colour development.

The present invention also relates to a method for the preparation of the aforementioned composition comprising mixing at least one aromatic peroxide, as previously defined, and at least one compound having an ether group.

As mentioned previously, the composition exhibits an enhanced colour stability.

The invention also deals with the use of a composition as previously defined in order to prepare a polymer, preferably styrenic polymers, or a polymer resin, in particular a polymer ester resin, said polymer ester resin being preferably chosen in the group consisting of unsaturated polyester resin, acrylic resin, methacrylic resin and vinyl ester resin, more preferably chosen in the group consisting of unsaturated polyester resin and vinyl ester resin.

In details, the composition of the present invention can be used efficiently for the polymerization reaction of styrenic polymers, vinyl ester resins or poly(meth)acrylates, or as a curing agent for the preparation of thermoset polyesters, namely unsaturated polyesters resins. Another aspect of the present invention is the use of at least one compound having an ether group to improve the colour stability of at least one aromatic peroxide, in particular at room temperature.

Preferably, one of the aspects of the present invention is to use at least one compound having an ether group in order to curb the evolution of colour of aromatic peroxides.

Other subjects and characteristics, aspects and advantages of the invention will emerge even more clearly on reading the description and the example that follows.

In the text herein below, and unless otherwise indicated, the limits of a range of values are included in that range, in particular in the expressions “between” and “ranging from ... to

Moreover, the expression “at least one” used in the present description is equivalent to the expression “one or more”.

The term “polymerization” encompasses both homo- and co-polymerization of one or more of the involved unsaturated monomers.

As intended herein, the term “comprising” has the meaning of “including” or “containing”, which means that when an object “comprises” one or several elements, other elements than those mentioned may also be included in the object. In contrast, when an object is said to “consist of’ one or several elements, the object is limited to the listed elements and cannot include other elements than those mentioned.

Brief description of the drawings

Figure 1 represents the measurements of APHA values versus time for compositions B to F illustrated in Table 1 at a temperature of 40°C in the dark.

Figure 2 represents the measurements of APHA values versus time for compositions G to J at a temperature of 40°C in the dark.

Composition

As previously detailed, the composition according to the present invention comprises: a) at least one aromatic peroxide comprising at least one aromatic ring and at least one peroxo -O-O- function in its structure; preferably the aromatic ring is connected to said peroxo function by a covalent bond, a carbonyl group or an alkyl group comprising from 1 to 20 carbon atoms; b) at least one compound having an ether group, preferably of the following formula (V) or (VI):

RI-(0-C ₂ H ₄ )„-0-R2 (V)

Or

RI-(0-CH ₂ -CH(CH ))„-0-R2

(VI)

Wherein :

• n represents an integer ranging from 1 to 8,

• Ri and R ₂ represent, independently of each other:

- a hydrogen atom, or

- a linear or branched alkyl Ci-Cs alkyl radical, substituted or not, or

- Ri and R ₂ forming together an ether crown, said ether crown preferably having from 4 to 8 ethylene oxyde groups, more preferably having from 4 to

5 ethylene oxyde groups, and even more preferably having 5 ethylene oxyde groups; preferably, when Ri is an hydrogen atom, R ₂ is a linear or branched alkyl Ci-Cx alkyl radical, substituted or not and when, R ₂ is an hydrogen atom, Ri is a linear or branched alkyl Ci-Cx alkyl radical, substituted or not.

Preferably, the composition of the invention is a curing composition or a composition for initiating a radical polymerization. In other words, the composition of the invention is preferentially devoid of any monomer and/or polymer to be cured and/or polymerized.

Preferably, the weight ratio between the compound having an ether group as defined above and the aromatic peroxide as defined above is ranging from 0.001 to 1, preferably from 0.01 to 0.5, preferably from 0.03 to 0.4, even more preferably from 0.05 a 0.1.

Aromatic peroxide

The aromatic ring of the aromatic peroxide can be substituted by a linear or branched Ci-Cio alkyl radical, especially C1-C4 alkyl radical, and/or one or more halogen atoms, preferably a linear or branched C1-C10 alkyl radical., especially C1-C4 alkyl radical.

Preferably, the aromatic peroxide comprises at least one benzene ring.

The benzene ring is preferably connected to the peroxo function by a covalent bond, a carbonyl group (-C(=0)-) or an alkyl group comprising from 1 to 20 carbon atoms, preferably from 1 to 10 carbon atoms, more preferably from 1 to 2 carbon atoms, even more preferably 1 carbon atom.

Preferably, the aromatic peroxide comprises at least one benzene ring and at least one peroxo -O-O- function in its structure; the benzene ring being connected to said peroxo function by no more than two carbon atoms, even more preferably no more than one carbon atom.

According to the present invention, the expression “the benzene ring being connected to said peroxo function by no more than two carbon atoms” means that the benzene ring is connected to -O-O- function of the aromatic peroxide by a covalent bond, a carbonyl group or alkyl group which does not comprise more than two carbon atoms (an alkyl group of two carbon atoms being included).

According to the present invention, the expression “the benzene ring being connected to said peroxo function by no more than one carbon atoms” means that the benzene ring is connected to -O-O- function of the aromatic peroxide by a covalent bond, a carbonyl group or alkyl group which does not comprise more than one carbon atom (one carbon atom being included).

Preferably, the aromatic peroxide comprises at least one benzene ring and at least one peroxo -O-O- function in its structure; the benzene ring being connected to said peroxo function by a covalent bond, a carbonyl group or an alkyl group comprising from 1 to 2 carbon atoms, even more preferably 1 carbon atom; the benzene ring being optionally substituted by a linear or branched Ci-Cio alkyl radical, especially C ₁ -C ₄ alkyl radical, and/or one or more halogen atoms.

Preferably, the aromatic peroxide as defined above is liquid at room temperature.

The aromatic peroxide can be chosen among the group consisting of aromatic peresters, aryl-alkyl peroxides, aryl hydroperoxides, aromatic diacyl peroxides and mixtures thereof.

Preferably, the aromatic peroxide can be chosen among the group consisting of aromatic peresters.

Preferably, the aromatic peroxide comprises at least one benzene ring and at least one peroxo -O-O- function in its structure; the benzene ring being connected to said peroxo function by a covalent bond, a carbonyl group or an alkyl group comprising from 1 to 2 carbon atoms, even more preferably 1 carbon atom; the benzene ring being optionally substituted by a linear or branched C ₁ -C ₄ alkyl radical and/or one or more halogen atoms; and the aromatic being chosen among the group consisting of aromatic peresters, aryl-alkyl peroxides, aryl hydroperoxides, aromatic diacyl peroxides and mixtures thereof; especially aromatic peresters.

The aromatic peroxide selected from aromatic peresters is preferably chosen among the group consisting of perbenzoates, aryl peralkylates, aromatic diperesters and mixtures thereof.

Advantageously, the aromatic peroxide is selected among the group consisting of perbenzoates.

Preferably, the aromatic peroxide has the following formula (I):

R1-O-O-R2 (I) in which

• Ri represents:

- a -C(=0)R’i group, wherein R’ _I denotes an aryl group having from 3 to 30 carbon atoms optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical and/or one or more halogen atoms, or

- a linear or branched C ₁ -C ₂₀ alkyl radical terminated with an aryl group having from 3 to 30 carbon atoms optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical and/or one or more halogen atoms, or

- a -CR’l group, wherein R’l denotes an aryl group having from 6 to 32 carbon atoms optionnaly substituted by a linear or branched Cl -CIO alkyl radical and/or one or more halogen atoms,

• R2 represents:

- a linear or branched C ₁ -C ₂₀ alkyl radical,

- an aryl group having from 3 to 30 carbon atoms optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical and/or one or more halogen atoms,

- a -R ₃ OOR ₄ group, wherein R ₃ represents a linear or branched C ₈ -C ₂₀ alkyl radical, preferably Cx-Cio alkyl radical, and R ₄ represents a -C(=0)R ⁵ ₄ group in which R’ ₄ denotes an aryl group having from 3 to 30 carbon atoms optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical and/or one or more halogen atoms,

- a linear or branched C ₁ -C ₂₀ alkyl radical terminated with an aryl group having from 3 to 30 carbon atoms optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical and/or one or more halogen atoms,

- a -C(=0)R ⁵ ₂ group, wherein R’ ₂ denotes an aryl group having from 3 to 30 carbon atoms optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical and/or one or more halogen atoms, or

- a hydrogen atom.

Preferably, the aromatic peroxide has the following formula (I):

R1-O-O-R2

(I) in which: · Ri represents:

- a -C(=0)R’i group, wherein R’ _I denotes a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical and/or one or more halogen atoms, preferably chlorine atoms, or - a linear or branched C ₁ -C ₂₀ alkyl radical terminated with a benzene ring which is optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical and/or one or more halogen atoms, preferably chlorine atoms;

• R ₂ represents:

- a linear or branched C ₁ -C ₂₀ alkyl radical,

- a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical and/or one or more halogen atoms, preferably chlorine atoms,

- a -R ₃ OOR ₄ group, wherein R ₃ represents a linear or branched C ₈ -C ₂₀ alkyl radical, preferably Cx-Cio alkyl radical, and R ₄ represents a -C(=0)R ₄ group in which R’ ₄ denotes a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical and/or one or more halogen atoms,

- a linear or branched C ₁ -C ₂₀ alkyl radical terminated with a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical and/or one or more halogen atoms,

- a -C(=0)R 2 group, wherein R’2 denotes a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical and/or one or more halogen atoms, preferably chlorine atoms,

- a hydrogen atom.

Preferably, Ri represents:

- a -C(=0)R’i group, wherein R’i denotes a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical, preferably C ₁ -C ₄ alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms, or

- a linear or branched C ₁ -C ₁₀ alkyl radical, preferably a branched C ₁ -C ₁₀ alkyl radical, which is terminated with a benzene ring which is optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical, preferably C ₁ -C ₄ alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms.

Preferably, R ₂ represents:

- a linear or branched C ₁ -C ₁₀ alkyl radical, especially C ₁ -C ₅ alkyl radical, more preferably a branched C ₁ -C ₅ alkyl radical,

- a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical, especially a linear or branched C ₁ -C ₄ alkyl radical and/or one or more halogen atoms, preferably chlorine atoms,

- a -R ₃ OOR ₄ group, wherein R ₃ represents a linear or branched C ₈ -C ₂₀ alkyl radical, preferably Cs-Cio alkyl radical, and R4 represents a -C(=0)R 4 group in which R’ ₄ denotes a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical, especially C ₁ -C ₄ alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms, - a linear or branched Ci-Cio alkyl radical, preferably a branched Ci-Cio alkyl radical, which is terminated with a benzene ring optionnaly substituted by a linear or branched Ci-Cio alkyl radical, especially C ₁ -C ₄ alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms,

- a -C(=0)R’ ₂ group, wherein R/ ₂ denotes a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical, preferably C ₁ -C ₄ alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms,

- a hydrogen atom.

Preferably, in formula (I):

• Ri represents:

- a -C(=0)R’i group, wherein R’i is a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical, preferably C ₁ -C ₄ alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms, or

- a linear or branched C ₁ -C ₁₀ alkyl radical, preferably a branched C ₁ -C ₁₀ alkyl radical, which is terminated with a benzene ring which is optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical, preferably C ₁ -C ₄ alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms,

• R ₂ represents:

- a linear or branched C ₁ -C ₁₀ alkyl radical, especially C ₁ -C ₅ alkyl radical, more preferably a branched C ₁ -C ₅ alkyl radical,

- a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical, especially a linear or branched C ₁ -C ₄ alkyl radical and/or one or more halogen atoms, preferably chlorine atoms,

- a -R ₃ OOR ₄ group, wherein R ₃ represents a linear or branched C ₈ -C ₂₀ alkyl radical, preferably Cx-Cio alkyl radical, and R ₄ represents a -C(=0)R’ ₄ group in which R’ ₄ denotes a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical, especially C ₁ -C ₄ alkyl radical, and/or one or more halogen atoms,

- a linear or branched C ₁ -C ₁₀ alkyl radical, preferably a branched C ₁ -C ₁₀ alkyl radical, which is terminated with a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical, especially C ₁ -C ₄ alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms,

- a -C(=0)R’ ₂ group, wherein R’ ₂ denotes a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical, preferably C ₁ -C ₄ alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms,

- a hydrogen atom.

Preferably, the aromatic peroxide has the following formula (I): R1-O-O-R2

(I) in which:

• Ri represents:

- a -C(=0)R’i group, wherein R’ _I denotes a benzene ring optionnaly substituted by a linear or branched C1-C10 alkyl radical, preferably C1-C4 alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms,

• R2 represents:

- a linear or branched C ₁ -C ₁₀ alkyl radical, especially C ₁ -C ₅ alkyl radical, more preferably a branched C ₁ -C ₅ alkyl radical,

- a benzene ring optionnaly substituted by a linear or branched C1-C10 alkyl radical, especially a linear or branched C1-C4 alkyl radical, even more preferably a branched C1-C4 alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms,

- a -R ₃ OOR ₄ group, wherein R ₃ represents a linear or branched C ₈ -C ₂₀ alkyl radical, preferably Cx-Cio alkyl radical, and R ₄ represents a -C(=0)R ₄ group in which R’ ₄ denotes a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical, especially C ₁ -C ₄ alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms,

- a -C(=0)R 2 group, wherein R’2 denotes a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical, preferably C ₁ -C ₄ alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms.

Preferably, the aromatic peroxide has the following formula (I):

R1-O-O-R2

(I) in which:

• Ri represents:

- a -C(=0)R’i group, wherein R’ _I denotes a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical, preferably C ₁ -C ₄ alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms,

• R ₂ represents:

- a linear or branched C ₁ -C ₁₀ alkyl radical, especially C ₁ -C ₅ alkyl radical, more preferably a branched C ₁ -C ₅ alkyl radical.

Preferably, the aromatic peroxide is selected from the group consisting of t- butyl-peroxybenzoate, such as the one sold under the name Luperox® P, cumyl peroxyneoheptanoate, such as the one sold under the name Luperox® 288, cumyl peroxyneodecanoate, such as the one sold under the name Luperox® 188, 2,5-dimethyl- 2,5-(dibenzoylperoxy)hexane, such as Luperox® 118, tert-butyl cumyl peroxide, such as the one sold under the name Luperox® 801, dicumyl peroxide, such as the one sold under the name Luperox® DCP, cumene hydroperoxide, such as the one sold under the name Luperox® CU80, di(2,4-dichloro benzoyl)peroxide, such as the one under the name Luperox® DCBP, 1,3 l,4-Bis(tert-butylperoxyisopropyl)benzene, such as the one under the name Luperox® F, tert-amyl peroxybenzoate, such as Luperox® TAP and mixtures thereof.

Preferably, the aromatic peroxide is selected from the group consisting of t- butyl-peroxybenzoate, cumyl peroxyneoheptanoate, cumyl peroxyneodecanoate, 2,5- dimethyl-2,5-(dibenzoylperoxy)hexane, tert-amyl peroxybenzoate, and mixtures thereof.

Advantageously, the aromatic peroxide is t-butyl-peroxybenzoate.

Preferably, the aromatic peroxide is present in the composition at a concentration ranging from 30 to 99.9%, preferably ranging from 70 to 99.9%, more preferably ranging from 90 to 99.9% by weight relative to the total weight of the composition.

In particular, the aromatic peroxide is t-butyl-peroxybenzoate and is present at a concentration ranging from 30 to 99.9%, preferably ranging from 70 to 99.9%, more preferably ranging from 90 to 99.9% by weight relative to the total weight of the composition.

In a specific embodiment, the composition of the present invention does not comprise other aromatic peroxides than the one as defined above.

Compound having an ether group

The composition of the invention further comprises a compound having an ether group, preferably is a compound having the following formula (V) or (VI):

RI-(0-C ₂ H ₄ )„-0-R2

(V)

Or

RI-(0-CH ₂ -CH(CH ))„-0-R2

(VI)

Wherein :

• n represents an integer ranging from 1 to 8,

• Ri and R ₂ represent, independently of each other: - a hydrogen atom, or

- a linear or branched alkyl Ci-Cx alkyl radical, substituted or not, or

- Ri and R2 forming together an ether crown, said ether crown preferably having from 4 to 8 ethylene oxyde groups, more preferably having from 4 to 5 ethylene oxyde groups, and even more preferably having 5 ethylene oxyde groups; preferably, when Ri is an hydrogen atom, R2 is a linear or branched alkyl Ci-Cx alkyl radical, substituted or not and when, R2 is an hydrogen atom, Ri is a linear or branched alkyl Ci-Cx alkyl radical, substituted or not.

Preferably, Ri represents a hydrogen group or a methyl group, more preferably an hydrogen group.

Preferably, R2 represents a linear or branched alkyl Ci-Cx alkyl radical, substituted or not, more preferably represents a linear Ci-Cs alkyl radical, more preferably a C2 alkyl radical.

Preferably, n represents an integer ranging from 1 to 3, more preferably is equal to 2.

Preferably, Ri represents a hydrogen group or a methyl group, more preferably an hydrogen group and R2 represents a linear or branched alkyl Ci-Cx alkyl radical, substituted or not, more preferably represents a linear Ci-Cx alkyl radical, more preferably a C2 alkyl radical.

Preferably, Ri represents a hydrogen group or a methyl group, more preferably an hydrogen group, R2 represents a linear or branched alkyl Ci-Cx alkyl radical, substituted or not, more preferably represents a linear Ci-Cx alkyl radical, more preferably a C2 alkyl radical and n represents an integer ranging from 1 to 3, more preferably is equal to 2.

Preferably, the compound having an ether group has the formula (V) as defined above. Preferably, the compound having an ether group is chosen in the group consisting of a di(ethylene glycol) ethyl ether (EDGE), di(ethylene glycol) ethyl methyl ether (DEGMEE), 1,4,7,10,13-pentaoxycyclopentadecane, di(propylene glycol) ethyl ether, di (propylene glycol) ethyl methyl ether and mixture thereof, more preferably is chosen in the group consisting of a di(ethylene glycol) ethyl ether, di(ethylene glycol) ethyl methyl ether and mixture thereof, and even more preferably is di(ethylene glycol) ethyl ether.

Preferably, the compound having an ether group is present at a concentration ranging from 0,1% to 30%, preferably from 0,1% to 20%, and more preferably from 0,1% to 10% by weight relative to the total weight of the composition. Preferably, the weight ratio between the compound having an ether group as defined above and the aromatic peroxide as defined above is ranging from 0.001 to 1, preferably from 0.01 to 0.5, preferably from 0.03 to 0.4, even more preferably from 0.05 a 0.1.

Ketone Peroxide

The composition of the invention can further comprises at least one ketone peroxide.

As intended herein a “ketone peroxide” refers to an organic compound comprising at least one peroxide functional group (-OOH).

Preferably, the ketone peroxide as defined above is liquid at room temperature.

Preferably, the ketone peroxide according to the invention is of the following formula (II):

(II) R CR ₄ (OOH) ₂

Wherein R ₃ and R ₄

- Independently of each other represents a linear or branched C1-C20 alkyl radical, or

. form together a cyclic group, substituted or not, preferably a C4-C6 cyclic group.

According to a particular embodiment, the ketone peroxide can be in the form of a dimer (having the formula (III) R ₃ R ₄ C(OOH)OOC(OOH)R ₃ R ₄ , R ₃ and R ₄ being as defined above) or a turner (having the formula (IV) R ₃ R ₄ C(OOH)OOCR ₃ R ₄ OOC(OOH)R ₃ R ₄ , R ₃ and R ₄ being as defined above), preferably a dimer.

The ketone peroxide is preferably chosen among the group consisting of methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, 2,4-pentanedione peroxide and mixtures thereof, even more preferably the ketone peroxide is chosen among the group consisting of methyl ethyl ketone peroxide, such as the one sold under the name Luperox® K1 and and methyl isobutyl ketone peroxide, such as the one sold under the name Luperox® K2.

Preferably, the ketone peroxide is present in the composition at a concentration ranging from 0.1 to 30%, especially ranging from 1 to 29%, preferably ranging from 2 to 25%, more preferably 4 to 20%, even more preferably 5 to 10% by weight, relative to the total weight of the composition.

In particular, the ketone peroxide is methyl ethyl ketone peroxide and is present in the composition at a concentration ranging from 0.1 to 30%, especially ranging from 1 to 29%, preferably ranging from 2 to 25%, more preferably 4 to 20%, even more preferably 5 to 10% by weight, relative to the total weight of the composition. Preferably, the weight ratio between the ketone peroxide and the aromatic peroxide is ranging from 0.001 to 1, preferably from 0.01 to 0.5, even more preferably from 0.05 a 0.1.

In a specific embodiment, the composition of the present invention does not comprise other ketone peroxides than the one as defined above.

Hydrogen peroxide (Ή ₂ O ₂₎

Preferably, the composition according to the invention further comprises hydrogen peroxide (H2O2).

Hydrogen peroxide may be present in the composition according to the invention at a concentration ranging from 0.0005 to 3%, preferably ranging from 0.001 to 2%, even more preferably 0.01 to 1.5% by weight, even more preferably 0.1 to 1.5% by weight relative to the total weight of the composition.

Preferably, the composition according to the present invention comprises: a) at least one aromatic peroxide having the following formula (I):

R1-O-O-R2

(I) in which:

• Ri represents:

- a -C(=0)R’i group, wherein R’i denotes a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical, preferably C ₁ -C ₄ alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms, · R2 represents:

- a linear or branched C ₁ -C ₁₀ alkyl radical, especially C ₁ -C ₅ alkyl radical, more preferably a branched C ₁ -C ₅ alkyl radical,

- a benzene ring optionnaly substituted by a linear or branched C1-C10 alkyl radical, especially a linear or branched C1-C4 alkyl radical, even more preferably a branched C1-C4 alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms,

- a -R ₃ OOR ₄ group, wherein R ₃ represents a linear or branched C ₈ -C ₂₀ alkyl radical, preferably Cx-Cio alkyl radical, and R ₄ represents a -C(=0)R’ ₄ group in which R’ ₄ denotes a benzene ring optionnaly substituted by a linear or branched C1-C10 alkyl radical, especially C1-C4 alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms,

- a -C(=0)R’ ₂ group, wherein R’ ₂ denotes a benzene ring optionnaly substituted by a linear or branched C ₁ -C ₁₀ alkyl radical, preferably C ₁ -C ₄ alkyl radical, and/or one or more halogen atoms, preferably chlorine atoms; the aromatic peroxide being present in said composition at a concentration ranging from 30 to 99.9% by weight relative to the total weight of the composition; b) at least on compound having an ether group, preferably having a formula (V) or (VI), more preferably having a formula (V) as defined above; c) at least hydrogen peroxide which may be present in the composition at a concentration ranging from 0.0005 to 3% by weight relative to the total weight of the composition.

Solvent

The composition may further comprise at least one solvent. The solvent according to the invention can be of any type known to one of skill in the art suitable for solvating organic peroxides, especially aromatic peroxides.

In particular, the presence of a solvent can help to promote the homogeneity of the composition of the present invention.

Preferably, the solvent according to the invention is an organic solvent selected from the group consisting of a ketone solvent, an aryl solvent, an ether solvent, an alcohol solvent, a mineral oil and a hydrocarbon solvent.

More preferably, the solvent is selected form the group consisting of dimethyl phthalate, dimethyl terephthalate, methyl isobutyl ketone, cyclohexanone, ethyl acetate, isododecane, glycol ether, ethylene glycol, isopropanol or a combination thereof.

In the meaning of the present invention, it is understood that the glycol ether is different than a compound having an ether group according to the invention.

Preferably, the composition according to the present invention displays a APHA colour value lower or equal to 200, preferably 150, more preferably 100 over a period of time of at least 5 days, in particular of at least 15 days, especially of at least 20 days, preferably of at least 30 days, more preferably of at least 50 days and even more particularly over at least 90 days, especially at room temperature, preferably in the dark. Preparation of the composition

The present invention also deals with a method for the preparation of the aforementioned composition comprising mixing at least one aromatic peroxide, as previously defined, and at least at least one compound having an ether group as previously defined, optionally at least a ketone peroxide as defined above, optionally at least hydrogen peroxide as defined above, and optionally at least one solvent as defined above.

Preferably, the at least aromatic peroxide, as previously defined, and the one compound having an ether group as previously defined can be blended and stirred by any methods known by the one skilled in the art. The obtained composition displays the advantage of being colour stable over time.

Use of the composition

Another object of the present invention concerns the use of the aforementioned composition in order to prepare a polymer, preferably styrenic polymers, or a polymer resin, in particular a polymer ester resin, said polymer ester resin being preferably chosen in the group consisting of unsaturated polyester resin, acrylic resin, methacrylic resin and vinyl ester resin, more preferably chosen in the group consisting of unsaturated polyester resin and vinyl ester resin.

Preferably, styrenic polymers are selected among the group consisting of polystyrene, high-impact polystyrene (HIPS), acrylonitrile-butadiene-styrene (ABS) copolymers, acrylonitrile- styrene acrylate (ASA) copolymers, styrene acrylonitrile (SAN) copolymers, SAN modified by elastomers, methacrylate-butadiene-styrene (MBS) copolymers, styrene-butadiene copolymers, styrene-butadiene- styrene block (SBS) copolymers and their partially or fully hydrogenated derivatives, styrene-isoprene copolymers, styrene-isoprene-styrene (SIS) block copolymers and their partially or fully hydrogenated derivatives, and styrene-(meth)acrylate copolymers such as styrene- methyl methacrylate copolymers (S/MMA).

Preferably, styrenic polymers are selected among the group consisting of polystyrene, acrylonitrile-butadiene-styrene (ABS) copolymers and styrene acrylonitrile (SAN) copolymers.

As intended herein, the expression “polymer resin” refers to a polymer in association or not with a reactive monomer.

As intended herein, the expression “polymer ester resin” refers to a polymer comprising repetitive ester units in association or not with a reactive monomer.

Preferably, the polymer resin is selected from the group consisting of a polymer ester resin, in particular unsaturated polyester resin, acrylic resin, methacrylic resin and a vinyl ester resin. More preferably, the polymer ester resin is chosen in the group consisting of unsaturated polyester resin and vinyl ester resin, and even more preferably, the polymer resin is an unsaturated polyester resin.

Methods for the synthesis of a polymer resin are well known to one of skill in the art. Preferably, the polymer is dissolved in a reactive monomer composition, i.e. a composition which comprises the reactive monomer. Preferably, said reactive monomer according to the invention may react with the polymer according to the invention by a copolymerisation reaction.

Preferably, the reactive monomer is selected from the group consisting of a vinylic compound, an acrylic compound and an allylic compound. By way of example of a vinylic compound which can be used according to the invention, it is possible to cite a styrene compound, such as styrene, methylstyrene, p- chlorostyrene, t-butyl styrene, divinylbenzene or bromostyrene, vinylnaphthalene, divinylnaphtalene, vinylacetate, vinylpropionate, vinylpivalate, vinylether and divinylether.

By way of example of an acrylic compound which can be used according to the invention, it is possible to cite methylacrylate, ethyl acrylate, propyl acrylate, isopropylacrylate, butyl acrylate, isobutylacrylate, phenyl acrylate, and benzyl acrylate.

By way of example of an allyl compound which can be used according to the invention, it is possible to cite allylphthalate, diallylphthalate, diallylisophthalate, triallylcyanurate and diallylterephthalate.

Preferably, the polymer of the unsaturated polyester resin according to the invention is obtainable by condensation of one or more acid monomers and/or one or more acid anhydride monomers with one or more polyol monomers provided that at least one of the component comprises an ethylenic unsaturation. More preferably, the unsaturated polyester resin according to the invention is obtained by condensation of one more polycarboxylic acid monomers and/or one or more polycarboxylic acid anhydride monomers and one or more glycol monomers, provided that at least one of the component comprises an ethylenic unsaturation.

Preferably, the polymer of the vinyl ester resin according to the invention is obtainable by condensation of one or more poly-epoxide resin with one or more monocarboxylic acid monomer having an ethylenic unsaturation.

The acid monomer according to the invention can be of any type known to one of skill in the art. However, the acid monomer according to the invention is preferably selected from the group consisting of phthalic acid, maleic acid, oxalic acid, malonic acid, isophthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, succinic acid, sebacic acid, azelaic acid, adipic acid and fumaric acid.

The monocarboxylic acid monomer according to the invention can be of any type known to one of skill in the art. Preferably, the monocarboxylic acid monomer according to the invention is selected from the group consisting of acrylic acid such as methacrylic acid, ethylacrylic acid, propylacrylic acid, isopropylacrylic acid, butylacrylic acid, isobutylacrylic acid, phenylacrylic acid, benzylacrylic acid, halogenated acrylic acid, and cinnamic acid.

The acid anhydride monomer according to the invention can be of any type known to one of skill in the art. Preferably, the acid anhydride monomer according to the invention is selected from the group consisting of phthalic anhydride, maleic anhydride, oxalic anhydride, malonic anhydride, isophthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, succinic anhydride, sebacic anhydride, azelaic anhydride, adipic anhydride and fumaric anhydride. The polyol according to the invention can be of any type known to one of skill in the art. Preferably, the polyol according to the invention is a glycol selected from the group consisting of an aliphatic diol and an aromatic diol. More preferably, the polyol according to the invention is selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, pentylene glycol, hexylene glycol and neopentylene glycol.

The polyepoxide resin according to the invention can be of any type known to one of skill in the art. The poly-epoxide resin according to the invention is preferably selected from the group consisting of glycidyl polyethers of polyhydric alcohols and glycidyl polyethers of polyhydric phenols.

Preferably, the polymer resin, in particular the polymer ester resin, preferably selected in the group consisting of unsaturated polyester resin acrylic resin, methacrylic resin and vinyl ester resin, according to the invention is a thermosetting resin.

The polymer of the invention can comprise a reinforcement material, preferably selected from the group consisting of: glass fibers, carbon fibers, nylon fibers and natural fibers.

In particular, the polymer can be a polyurethane-polyacrylate composition, which is mixed with a reinforcement material, preferably selected from the group consisting of: glass fibers, carbon fibers, nylon fibers and natural fibers. In particular, the invention pertains to the use of the composition as previously defined as a curing agent for the preparation of a polymer resin, preferably a polymer ester resin or as radical initiator for the polymerization of unsaturated monomers, preferably unsaturated based styrene monomers.

According to the present invention, the term “polymerization” also encompasses the feature “copolymerization”.

The polymer resin, in particular the polymer ester resin, preferably chosen in the group consisting of unsaturated polyester resin acrylic resin, methacrylic resin and vinyl ester resin, according to the invention is preferably curable by addition of the composition according to the invention as a curing agent under a temperature allowing the curing reaction.

Use of at least one compound having an ether group

Another aspect of the present invention is directed to the use of at least one compound having an ether group, as previously defined, to improve the colour stability of at least one aromatic peroxide, as previously defined, in particular at a temperature ranging from 15°C to 30°C, especially from 20°C to 30°C, and preferentially in the dark.

In addition, the invention concerns the use of at least one compound having an ether group, as previously defined, to decrease APHA value of at least one aromatic peroxide, as previously defined, in particular at a temperature ranging from 15°C to 30°C, especially from 20°C to 30°C. Polymer resin composition

The present invention also relates to a polymer resin composition comprising:

- at least one composition as defined above,

- at least one polymer resin as previously disclosed, preferably selected from the group consisting of unsaturated polyester resins.

The examples below are given as illustrations of the present invention. Examples

I. Tested compounds

The compouds implemented in the experimental protocol described hereafter are listed below:

• Tert-butyl peroxybenzoate sold under the name Luperox® P,

• 1,4,7,10,13-pentaoxycyclopentadecane, (15 Crown 5, CAS N° 33100-27- 5) from Merck

• diethylene glycol monoethyl ether (EDGE, CAS N° 111-90-0) from Merck

• Topanol from Merck

• Tripenylphosphite (TPP) from Merck

II. Tested compositions

In Table 1, composition A corresponds to the blank product Luperox® P sold by Arkema. Compositions B to F have been prepared at the same time with the ingredients listed hereafter.

The contents are expressed in weight percentage relative to the total weight of the composition. [Table 11

III. Experimental protocol

III. 1. Colour stability The colour stability of each composition disclosed in Table 1, stored in the dark in a closed tube, has been assessed with the spectral colorimeter sold under the name LICO 620, from Hach company at a temperature of 30°C for Composition A (Luperox® P alone) and 40°C for Compositions B to F (in order to accelerate the coloration of the composition). The APHA colour values have been determined for each composition over a period of time of 1600 hours. After less than 300 hours, the APHA value of Composition A was higher than 900.

The results for compositions B to F have been plotted in Figure 1. III 2 Colour reduction

To a composition A already having a APHA colour of 750 was added:

- lwt% of EDGE (Composition G)

- 2wt% of EDGE (Composition H)

- 4wt% of EDGE (Composition I) - 4wt% of DEGMEE (Composition J)

The colour stability of each composition disclosed in Table 1, stored in the dark at 40°C in a closed tube, has been assessed as disclosed above, over a period of time of 1400 hours. The results for compositions G to I have been plotted in Figure 2. IV. Results

4.1. Results - Compositions A and B to F

Figure 1 represents the measurements of APHA values versus time for compositions B to F illustrated in Table 1 at a temperature of 40°C.

The results show that the APHA values measured at a temperature of 40°C for compositions B to D according to the invention are lower than the ones measured for composition A comprising only tert-butyl peroxybenzoate and composition E and F comprising other additives. In Figure 1, the results display that the coloration of compositions E and F dramatically increases over time, whereas the coloration remains stable and very low for compositions B to D.

Hence the results substantiate that the composition according to the present invention has a better colour stability over time than a composition comprising only the aromatic peroxide or other additives.

4.2. Results - Compositions G to J

Figure 2 represents the measurements of APHA values versus time for compositions G to J at a temperature of 40°C in the dark.

The results show that the APHA values measured at a temperature of 40°C for compositions G to J according to the invention can durably decrease to APHA values of less than 150.

Hence, the results substantiate that the addition of a compound having an ether group leads to the decrease of the APHA values of tert-butyl peroxybenzoate.