Peroxide formulations with anti-scorching properties

Abstract

The invention relates to an organic peroxide formulation comprising: – at least one organic peroxide having a half-life temperature of one hour ranging from 90°C to 130°C, and – at least one drying oil, the weight ratio of the drying oil to the organic peroxide being less than or equal to 0.60. The invention also relates to a composition comprising at least one polymer and such an organic peroxide formulation, methods of preparing the same, and a method for manufacturing an article using such a composition. No figure.

Description

Title of the invention: Peroxide formulations with anti-scorching properties Technical field

[0001] The present invention relates to organic peroxide formulations comprising a drying oil and to polymeric compositions comprising such organic peroxide formulations, which are particularly useful for the manufacture of photovoltaic modules. The present invention also relates to articles obtainable by curing said polymer compositions. Technical background

[0002] Solar modules (also called photovoltaic modules) are attracting increasing interest, due to the renewable, non-polluting nature of the resulting energy. A solar module comprises a photovoltaic cell made up of optoelectronic components that generate an electrical voltage when exposed to light.

[0003] Traditionally, in solar modules, photovoltaic cells are placed between a top (or front) protective layer (also called a front sheet), typically a plastic glass plate, and a rear protective panel (commonly called a back sheet), often composed of plastic, or glass. Conventionally, photovoltaic cells are encapsulated by a polymeric material (called an encapsulant), applied as a film on either the front side or both sides of the photovoltaic cells, in order to assemble and bond the photovoltaic cells and the protective layers (such as the top protective layer usually composed of glass), to provide electrical insulation and to protect photovoltaic cells from external environmental elements, including moisture and UV radiation.

[0004] As encapsulants, materials based on ethylene polymers are generally used. In particular, ethylene-vinyl acetate (EVA) copolymers are widely used, since they are capable of producing transparent materials capable of easily adhering to the substrates of a photovoltaic module, while having a high electrical resistivity. Other polymers useful for the production of encapsulant materials include polyolefin elastomers (POE).

[0005] To acquire the thermomechanical properties required for this application, particularly in terms of adhesion properties, resistance to brittleness, and resistance to degradation in relation to weathering, the polymers of the encapsulant must be crosslinked.

[0006] Photovoltaic modules are generally produced by a lamination process. Several module technologies exist. In conventional modules, the encapsulating layer is positioned between the photovoltaic cells and the front protective glass layer, and the back protective panel is composed of other types of protective filters. In so-called "double glass technology", a layer of EVA or POE forms the upper encapsulating layer (between the front protective glass layer and the cells), and a white film (often also composed of EVA or POE) is positioned between the back of the cells and the back protective glass panel. The laminated layers forming the module are then pressed and the encapsulating layers are crosslinked (or cured) by heating, simultaneously or subsequently to the pressing step. The encapsulating layers are generally produced by an extrusion step.

[0007] If premature decomposition of the organic peroxides occurs during the extrusion step, the polymer compositions used to form the encapsulating layers are likely to undergo premature crosslinking over time in the barrel or head of the extruder in which they are processed, before the formation of the laminated structure. This phenomenon, which is called "scorching", results in irregularities (inhomogeneity, surface roughness) in the polymer sheet thus formed and intended to encapsulate the photovoltaic cells. The presence of these irregularities alters the appearance and properties of the photovoltaic module. In addition, in some cases, pressure may build up in the extruder, which requires stopping the extrusion process and results in slowing down productivity.

[0008] Certain peroxide formulations with anti-scorching properties have thus been developed.

[0009] For example, document WO 2019 / 115975 reports the use of a combination of two different monoperoxydicarbonates for crosslinking a polyolefin elastomer.

[0010] WO 2016 / 149898 and WO 2018 / 046700 describe curable compositions comprising an ethylene polymer, a monoperoxydicarbonate and a t-alkyl hydroperoxide in specific amounts.

[0011] In addition to protection against scorching, it is also desirable to achieve a high crosslinking density. Indeed, if the crosslinking density is too low, the resulting material is likely to probably suffer, among other things, from insufficient tear and break resistance, and to flow over time due to the high temperatures that can be reached by the upper faces of the photovoltaic modules. However, the anti-scorching compositions disclosed in the prior art do not always allow excellent crosslinking densities to be achieved. It is also preferable that once the laminated structure is formed and heated above the decomposition temperature of peroxides, crosslinking is achieved quickly to improve productivity.

[0012] There is thus a need for an organic peroxide formulation making it possible to reduce scorching and providing good crosslinking density and rapid crosslinking. Summary of the invention

[0013] The first object of the invention is to provide an organic peroxide formulation comprising:

[0014] - at least one organic peroxide having a half-life temperature of a hour ranging from 90°C to 130°C, preferably having a half-life of one hour ranging from 110°C to 125°C, and

[0015] - at least one drying oil,

[0016] the weight ratio of the drying oil to the organic peroxide being less than or equal to 0.60,

[0017] In some embodiments, the at least one drying oil has an iodine value ranging from 125 to 215 g / 100 g, preferably from 140 to 205 g / 100 g, more preferably from 150 to 180 g / 100 g.

[0018] In some embodiments, the at least one drying oil has a saponification number ranging from 175 to 200 mg KOH / g, preferably from 180 to 195 mg KOH / g.

[0019] In some embodiments, the at least one drying oil is selected from the group consisting of tung oil, hemp oil, linseed oil, poppy oil, walnut oil, sunflower oil, cottonseed oil, corn oil, soybean oil, fish oils such as sardine oil and cod liver oil, herring oil, safflower oil, flax seed oil, perilla oil, oiticica oil, and combinations thereof, preferably the at least one drying oil being a tung oil.

[0020] In some embodiments, the at least one organic peroxide is selected from the group consisting of diperoxyketals, peroxyketals, monoperoxycarbonates, cyclic ketone peroxides, diacyl peroxides, organosulfonyl peroxides, peroxyesters, peroxydicarbonates and combinations thereof, preferably selected from the group consisting of diperoxyketals, peroxyketals, monoperoxycarbonates, peroxyesters and combinations thereof, more preferably selected from the group consisting of OO-t-butyl-O-(2-ethylhexyl)-monoperoxycarbonate, OO-t-butyl-O-2-isopropyl-monoperoxycarbonate, OO-t-amyl-O-(2-ethylhexyl)-monoperoxycarbonate, OO- t-amyl-O-2-isopropyl-monoperoxycarbonate, 00-t-hexyl-O-(2-ethylhexyl)-monoperoxycarbonate and mixtures thereof, optionally in combination with at least one other peroxide.

[0021] In some embodiments, the organic peroxide formulation comprises a combination of at least:

[0022] 1) a monoperoxycarbonate, preferably chosen from the group consisting of OO- t-butyl-O-(2-ethylhexyl)-monoperoxycarbonate, 00-t-butyl-O-2-isopropyl-monoperoxycarbonate, 00-t-amyl-O-(2-ethylhexyl)-monoperoxycarbonate, 00-t-amyl-O-2-isopropyl-monoperoxycarbonate, 00-t-hexyl-O-(2-ethylhexyl)-monoperoxycarbonate and mixtures thereof and

[0023] 2) a peroxyester, preferably selected from the group consisting of: peroxy- tert-butyl 2-ethylhexanoate and tert-amyl peroxy-2-ethylhexanoate,

[0024] more preferably it is a combination of 00-t-amyl-O-(2-ethylhexyl)-monoperoxycarbonate and tert-butyl peroxy-2-ethylhexanoate.

[0025] In some embodiments, the organic peroxide formulation further comprises at least one silane component, preferably selected from the group consisting of vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane and mixtures thereof, and is more preferably 3-methacryloxypropyltriethoxysilane or / and 3-methacryloxypropyltrimethoxysilane.

[0026] In some embodiments, the weight ratio of drying oil to organic peroxide is less than or equal to 0.45, preferably 0.025 to 0.45, more preferably 0.03 to 0.3, more preferably 0.03 to 0.25, and even more preferably 0.05 to 0.2.

[0027] In some embodiments, the organic peroxide formulation further comprises at least one coagent, preferably selected from the group consisting of triallyl cyanurate, triallyl isocyanurate, N,N'-m-phenylene dimaleimide, triallyl trimellitate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, trivinylcyclohexane and mixtures thereof.

[0028] The invention further relates to a composition comprising at least one polymer and an organic peroxide formulation as described above.

[0029] In some embodiments, the at least one polymer is an ethylene polymer, particularly a poly(ethylene vinyl acetate) and / or a polyolefin elastomer.

[0030] In some embodiments, the amount of the at least one drying oil in the composition is from 0.005 to 10 parts by weight, preferably from 0.01 to 5 parts by weight, more preferably from 0.02 to 1 parts by weight, per 100 parts by weight of the at least one polymer.

[0031] The invention also relates to a process for the preparation of an organic peroxide formulation as described above, comprising mixing the at least one organic peroxide and the at least one drying oil.

[0032] The invention also relates to a method for manufacturing an article comprising a step of hardening the composition as described above.

[0033] The invention also relates to an article, in particular a film, obtainable by the method as described above.

[0034] The invention also relates to the use of an organic peroxide formulation as described above for curing a polymer, said polymer preferably being selected from the group consisting of poly(ethylene-vinyl acetate), polyolefin elastomers and corresponding combinations.

[0035] The present invention makes it possible to satisfy the above-mentioned need. In particular, the invention provides organic peroxide formulations making it possible to increase the scorching time and thus minimize the risk of premature crosslinking, and to improve the crosslinking density and the crosslinking speed.

[0036] This is achieved by the presence in the peroxide formulation of a drying oil which is present in a specific weight ratio relative to the organic peroxide. Detailed description

[0037] The invention will now be described in more detail without limitation in the following description.

[0038] Unless otherwise stated, the percentages in this text are percentages by weight.

[0039] In this text, the quantities indicated for a given species may apply to this species according to all its definitions (as mentioned in this text), including the narrower definitions. Organic peroxide formulation

[0040] The organic peroxide formulation of the invention comprises at least one organic peroxide having a one-hour half-life temperature (HLT) ranging from 90°C to 130°C.

[0041] The organic peroxide may be any organic peroxide having a one-hour HLT as mentioned above.

[0042] Preferably, the organic peroxide has a half-life temperature of a hour ranging from 95°C to 125°C, more preferably has a half-life of one hour ranging from 110°C to 125°C, even more preferably from 115 to 125°C.

[0043] The term "one-hour half-life temperature" represents the temperature at which half of the organic peroxide has decomposed in a given time of one hour. Conventionally, the "one-hour half-life temperature" is measured in n-decane or n-dodecane.

[0044] For example, the organic peroxide may be selected from the group consisting of diperoxyketals, peroxyketals, monoperoxycarbonates, cyclic ketone peroxides, diacyl peroxides, organosulfonyl peroxides, peroxyesters, peroxydicarbonates, and combinations thereof. More particularly, the organic peroxide may be selected from the group consisting of diperoxyketals, peroxyketals, monoperoxycarbonates, peroxyesters, and combinations thereof.

[0045] For the purposes of the invention, “diperoxyketals” include peroxides which contain two peroxide groups (OO) on at least one carbon.

[0046] Examples of diperoxyketals suitable for the invention are l,l-di(t-butylperoxy)-3,3,5-trimethylcyclohexane; l,l-di(t-butylperoxy)cyclohexane; n-butyl 4,4-di(t-amylperoxy)valerate; ethyl 3,3-di(t-butylperoxy)butyrate; 2,2-di(t-amylperoxy)propane; 3,6,6,9,9-pentamethyl-3-ethoxycarbonylmethyl-1,2,4,5-tetraoxacyclononane; n-butyl 4,4-bis(t-butylperoxy)valerate; ethyl 3,3-di(t-amylperoxy)butyrate; and mixtures thereof.

[0047] The term “peroxyketal” means a compound of the general formula (R3)(R4)C(-ORi)(-OOR2), in which:

[0048] - Ri represents a linear or branched alkyl group, preferably C1-C12, preferably preferably C1-C4, and more preferably C1, or represents a cycloalkyl group with R2,

[0049] - R2 represents a linear or branched alkyl group, preferably CrCi2, preferably preferably C4-C12, and more preferably C5, or represents a cycloalkyl group with Rb

[0050] - R3 represents a hydrogen atom or a linear or branched alkyl group, preferably preferably C4-C12, more preferably C4-C12, or represents a cycloalkyl group with R4,

[0051] - R4 represents a hydrogen atom or a linear or branched alkyl group, preferably preferably C1-C12, more preferably C4-C12, or represents a cycloalkyl group with R3.

[0052] Preferably, R3 forms a cycloalkyl group with R4.

[0053] Preferably, when R3 is a hydrogen atom, R4 is an alkyl group linear or branched, preferably CrCi2, more preferably C4-Ci2.

[0054] The peroxyketal according to the invention preferably has the general formula (I) below:

[0055] R O..^Û-O' / \ 1 ï

[0056] in which formula (I):

[0057] - Ri represents a linear or branched C1-C4 alkyl group, preferably C1

[0058] - R2 represents a branched C4-C12 alkyl group, preferably C5,

[0059] - n denotes zero or an integer from 1 to 3,

[0060] - R3 represents a linear or branched C1-C3 alkyl group,

[0061] Ri preferably represents a linear alkyl group, more particularly CrC 2, more preferably Cp

[0062] R2 preferably represents a branched C4-C5 alkyl group, more preferably C5.

[0063] Preferably n denotes zero.

[0064] R3 preferably represents a linear or branched alkyl group, CrC2, more preferably Cp

[0065] Preferably, in formula (I), RI represents a linear or branched alkyl group, C1-C2, R2 represents a branched alkyl group, C4-C5, and n denotes zero.

[0066] Even more preferably, in formula (I), R 1 represents a C 1 -C 1 alkyl group, R 2 represents a C 5 -C 5 branched alkyl group, and n denotes zero.

[0067] The organic peroxide or peroxides is or are selected from the group consisting of 1-methoxy-1-tert-amylperoxycyclohexane (TAPMC), 1-methoxy-lt-butylperoxycyclohexane (TBPMC), 1-methoxy-lt-amylperoxy-3,3,5-trimethylcyclohexane, 1-methoxy-lt-butylperoxy-3,3,5-trimethylcyclohexane, 1-ethoxy-1-t-amylperoxycyclohexane, 1-ethoxy-1-t-butylperoxycyclohexane, 1-ethoxy-lt-butyl-3,3,5-peroxycyclohexane and mixtures thereof.

[0068] Even more preferably, the organic peroxide according to the invention is the 1 -methoxy-1 -tert-amylperoxycyclohexane (TAPMC).

[0069] As peroxyesters useful for the present invention, mention may be made of 2,5-dimethyl-2,5-di(benzoylperoxy)hexane; t-butyl perbenzoate; t-butyl peroxyacetate; t-butyl peroxy-2-ethylhexanoate; t-amyl perbenzoate; t-amyl peroxyacetate; t-butyl peroxyisobutyrate; t-butyl peroxy-2-ethylhexanoate 3-hydroxy-l,l-dimethyl-t-butyl; OO-t-amyl-O-hydrogen-monoperoxysuccinate; OO-t-butyl-O-hydrogen-monoperoxysuccinate; di-t-butyl diperoxyphthalate; t-butyl peroxy(3,3,5-trimethylhexanoate); l,4-bis(t-butylperoxycarbo)cyclohexane; t-butyl peroxy-3,5,5-trimethylhexanoate; t-butyl peroxy-(cis-3-carboxy)propionate; allyl 3-methyl-3-t-butylperoxybutyrate; and mixtures thereof.

[0070] Monoperoxycarbonates suitable for the invention are 00-t-butyl-O-2-isopropyl-monoperoxycarbonate; 00-t-amyl-O-2-isopropyl-monoperoxycarbonate, 00-t-hexyl-O-isopropyl-monoperoxycarbonate, 00-t-butyl-O-(2-ethylhexyl)-monoperoxycarbonate; 00-t-amyl-O-(2-ethylhexyl)-monoperoxycarbonate, 00-t-hexyl-O-(2-ethylhexyl)-monoperoxycarbonate, 1,1,1-tris [2-(t-butylperoxy-carbonylox y)ethoxymethyl]propane; 1,1,1 -tris[2-(t-amylperoxy-carbonyloxy)ethoxymethyl]propane; 1,1,1-tris[2-(cumylperoxy-cabonyloxy)ethoxymethyl]propane; 00-t-amyl-On-propylmonoperoxycarbonate; 00-t-octyl-O-isopropyl-monoperoxycarbonate; 00- t-octyl-O-(2-ethylhexyl)-monoperoxycarbonate; and mixtures thereof.

[0071] Diacyl peroxides suitable for the invention include di(4-methylbenzoyl) peroxide; di(3-methylbenzoyl) peroxide; di(2-methylbenzoyl) peroxide; didecanoyl peroxide; dilauroyl peroxide; 2,4-dibromobenzoyl peroxide; succinic acid peroxide; dibenzoyl peroxide; di(2,4-dichlorobenzoyl) peroxide; and mixtures thereof.

[0072] Imidoperoxides may also be used, such as those of the type described in PCT application publication WO 97 / 03961.

[0073] Preferably, the organic peroxide comprises or consists of at least one monoperoxydicarbonate. More preferably, the peroxide comprises or consists of at least one OO-t-alkyl-O-alkyl monoperoxycarbonate.

[0074] Advantageously, the organic peroxide is chosen from the group consisting of 00-t-amyl-O-2-isopropyl-monoperoxycarbonate (TAIC), OO-t-amyl-On-propyl monoperoxycarbonate (TAPC), OO-t-butyl-O-2-isopropyl-monoperoxycarbonate (TBIC), t-octyl-isopropyl-monoperoxycarbonate (TOIC), 00-t-hexyl-O-isopropyl-monoperoxycarbonate (THIC), 00-t-amyl-O-(2-ethylhexyl)-monoperoxycarbonate (TAEC), 00-t-butyl-O-(2-ethylhexyl)-monoperoxycarbonate (TBEC), 00-t-octyl-O-(2-ethylhexyl)-monoperoxycarbonate (TOEC), 00-t-hexyl-O-(2-ethylhexyl)-monoperoxycarbonate (THEC) and mixtures thereof. More preferably, the organic peroxide is selected from the group consisting of OO-t-butyl-O-(2-ethylhexyl)-monoperoxycarbonate (TBEC), 00-t-butyl-O-2-isopropyl-monoperoxycarbonate (TBIC), 00-t-amyl-O-(2-ethylhexyl)-monoperoxycarbonate (TAEC), 00-t-amyl-O-2-isopropyl-monoperoxycarbonate (TAIC), 00-t-hexyl-O-(2-ethylhexyl)-monoperoxycarbonate (THEC) and mixtures thereof. These monoperoxydicarbonates may optionally be used in combination with at least one other peroxide, such as those mentioned above (e.g. t-butyl peroxy-2-ethylhexanoate).

[0075] Even more preferred organic peroxides are TBEC, TAEC, THEC, or a mixture thereof, optionally in combination with at least one other peroxide, such as those mentioned above (e.g. t-butyl peroxy-2-ethylhexanoate). Most preferred organic peroxides are TBEC, TAEC, or a mixture thereof, optionally in combination with at least one other peroxide, such as those mentioned above (e.g. t-butyl peroxy-2-ethylhexanoate).

[0076] Advantageously, the formulation of the organic oxide of the invention comprises a combination of at least

[0077] 1) a monoperoxycarbonate, preferably chosen from the group consisting of 00- t-butyl-O-(2-ethylhexyl)-monoperoxycarbonate, 00-t-butyl-O-2-isopropyl-monoperoxycarbonate, 00-t-amyl-O-(2-ethylhexyl)-monoperoxycarbonate, 00-t-amyl-O-2-isopropyl-monoperoxycarbonate, 00-t-hexyl-O-(2-ethylhexyl)-monoperoxycarbonate and mixtures thereof and

[0078] 2) a peroxyester, preferably selected from the group consisting of: peroxy- tert-butyl 2-ethylhexanoate and tert-amyl peroxy-2-ethylhexanoate,

[0079] more preferably it is a combination of at least 00- t-amyl-O-(2-ethylhexyl)-monoperoxycarbonate and tert-butyl peroxy-2-ethylhexanoate.

[0080] Preferably, when a combination of at least one monoperoxydicarbonate and one peroxyester is used, it comprises from 70 to 97% by weight of monoperoxydicarbonate and from 3 to 30% by weight of peroxyester, relative to the total weight of the combination.

[0081] The organic peroxide may preferably be present in the formulation in an amount ranging from 40 to 99% by weight, based on the total weight of the organic peroxide formulation. Preferably, the organic peroxide is present in the formulation in an amount ranging from 50 to 98% by weight, preferably from 60 to 97% by weight, based on the total weight of the organic peroxide formulation.

[0082] The formulation of the organic peroxide of the invention also comprises at least a drying oil. The term "drying oil" means an oil having an iodine value greater than 110 g / 100 g, as measured according to GB / T5532-2008. Any drying oil known to those skilled in the art may be employed in the organic peroxide formulation of the present invention. Drying oils may include oils derived from plant, animal and fish sources, for example, glycerol triesters of fatty acids which are characterized by relatively high levels of polyunsaturated fatty acids, including eleostearic acid and alpha-linolenic acid. Advantageously, the at least one drying oil is selected from the group consisting of tung oil, hemp oil, biofen or trans-beta-farnesene (e.g., that prepared by Amyris), linseed oil, poppy seed oil, walnut oil, sunflower oil, cottonseed oil, corn oil, soybean oil, fish oils such as sardine oil and cod liver oil, herring oil, safflower oil, linseed oil, perilla oil, oiticica oil, and combinations thereof, preferably from the group consisting of tung oil, hemp seed oil, linseed oil, poppy seed oil, walnut oil, sunflower oil, cottonseed oil, corn oil, soybean oil, fish oils such as sardine oil and cod liver oil, herring oil, safflower oil, linseed oil, perilla oil, oil of oïticica, and corresponding combinations.

[0083] More preferably, the drying oil comprises, consists essentially of, or consists of tung oil, linseed oil, fish oils, in particular cod liver oil, walnut oil, oiticica oil, poppy oil. Most preferably, the drying oil comprises, consists essentially of, or consists of tung oil, linseed oil, and in particular tung oil.

[0084] The above-mentioned oil may be modified or not. It may be virgin oil or refined oil.

[0085] The drying oil used in the formulation of the invention preferably has an iodine value ranging from 125 to 215 g / 100 g, preferably from 140 to 205 g / 100 g, more preferably from 150 to 180 g / 100 g. The iodine value can be measured according to GB / T5532-2008.

[0086] The drying oil may have a saponification index ranging from 175 to 210 mg KOH / g, preferably from 182 to 195 mg KOH / g.

[0087] The peroxide formulation advantageously contains the drying oil in an amount ranging from 1 to 35% by weight, based on the total weight of the organic peroxide formulation. More preferably, the organic peroxide formulation of the invention comprises the drying oil in an amount ranging from 2 to 25% by weight, more preferably from 3 to 20% by weight, more preferably from 5 to 15% by weight, based on the total weight of the organic peroxide formulation.

[0088] The weight ratio of drying oil to organic peroxide in the organic peroxide formulation is less than or equal to 0.60, preferably less than 0.45. More preferably, the weight ratio of drying oil to organic peroxide is 0.025 to 0.45, preferably 0.03 to 0.3, more preferably 0.03 to 0.025, even more preferably 0.05 to 0.2, even more preferably 0.1 to 0.2.

[0089] When two or more organic peroxides are present in the organic peroxide formulation, the weight ratio of drying oil to organic peroxide is based on the total weight of the organic peroxides.

[0090] When two or more drying oils are present in the organic peroxide formulation, the weight ratio of drying oil to organic peroxide is based on the total weight of the drying oils.

[0091] The organic peroxide formulation may also comprise a silane component. The silane component has a scorch protection effect and makes it possible to further increase the scorch time. The silane component may further act as a coupling agent, the silane component making it possible to improve the adhesion properties of the polymer composition in which the peroxide formulation is used.

[0092] In some embodiments, the silane component may be a silane component with amino functionality, a silane component with sulfur functionality, a silane component with epoxy functionality, a silane component with (meth)acryl functionality, a silane component with chloro functionality, and / or a silane component with vinylyl functionality.

[0093] The silane component may be selected from the group consisting of 3-aminopropyltriethoxysilane; 3-aminopropyltrimethoxysilane; aminopropylmethyl-dimethoxysilane; N-2-(aminoethyl)-3-aminopropyltrimethoxysilane; N-2-(aminoethyl)-3-aminopropyltriethoxysilane; N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane; diethylenetriaminopropyltri-methoxysilane; diethylenetriaminopropyltriethoxysilane; diethylenetriaminopropyl-methyldimethoxysilane; diethylenetriaminopropylmethyldiethoxysilane; 3-cyclohexylaminopropyltrimethoxysilane; hexanediaminomethyldiethoxysilane; ani-linomethyltrimethoxy silane; anilinomethyltriethoxy silane; diethylaminomethyltriethoxysilane; (diethylaminoethyl)methyldiethoxysilane; N-methylaminopropyltrimethoxysilane; bis(triethoxysilylpropyl)tetrasulfide; bis(triethoxysilylpropyl)disulfide; bis (3-ethoxydimethylsilylpropyl) oligosulfur, 3-mercaptopropyltrimethoxysilane; 3-mercaptopropyltriethoxysilane; 3-mercaptopropylmethyldimethoxysilane; 3-thiocyanatopropyltriethoxysilane; 3-glycidoxypropyltrimethoxysilane; 3-glycidoxypropyltriethoxysilane; 3-glycidoxypropylmethyldiethoxysilane; 3-glycidoxypropylmethyldimethoxysilane; 3-methacryloxypropyltrimethoxysilane; 3-methacryloxypropyltriethoxysilane; 3-methacryloxypropylmethyldimethoxysilane; 3-chloropropyltrimethoxysilane; 3-chloropropyltriethoxysilane; chloromethyltriethoxysilane; chloromethyltrimethoxysilane; dichloromethyltriethoxysilane; vinyltrimethoxysilane; vinyltriethoxysilane; vinyltris(2-methoxyethoxy)silane; and mixtures thereof.

[0094] Preferably, the silane component is selected from the group consisting of vinyl-triethoxysilane, vinyltris(2-methoxyethoxy)silane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane and mixtures thereof. More preferably, the silane component comprises, or consists of, 3-methacryloxypropyltriethoxysilane or / and 3-methacryloxypropyltrimethoxysilane, even more preferably the silane component is 3-methacryloxypropyltrimethoxysilane.

[0095] The amount of silane component in the organic peroxide formulation is advantageously 5 to 50% by weight, more preferably 10 to 50% by weight, more preferably 20 to 40% by weight, based on the total weight of the organic peroxide formulation.

[0096] The weight ratio of the silane component to the organic peroxide is preferably 0.1 to 1, more preferably 0.3 to 0.7.

[0097] When two or more organic peroxides are present in the organic peroxide formulation, the weight ratio of the silane component to the organic peroxides is based on the total weight of the organic peroxides.

[0098] When two or more silane components are present in the organic peroxide formulation, the weight ratio of silane components to organic peroxide is based on the total weight of the silane components.

[0099] The organic peroxide formulation may consist essentially of, or consist of, the at least one organic peroxide and the at least one drying oil.

[0100] Alternatively, the organic peroxide formulation may consist essentially of, or consist of, the at least one organic peroxide, the at least one drying oil, and the at least one silane component.

[0101] Alternatively, the organic peroxide formulation may further comprise a coagent (which is not an organic peroxide). Advantageously, said coagent carries at least one carbamate, maleimide, acrylate, methacrylate, or allyl functional group. Allyl carboxylates may be used, which may be selected from the group consisting of those of the allyl, diallyl, and triallyl type.

[0102] The coagent may be selected from the group consisting of divinylbenzene, diisopropenylbenzene, alpha-methylstyrene, alpha-methylstyrene dimer, ethylene glycol dimethacrylate, phenylene dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol 200 dimethacrylate, polyethylene glycol 400 dimethacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,12-dodecanediol dimethacrylate, 1,3-glycerol dimethacrylate, diurethane dimethacrylate, trimethylolpropane trimethacrylate, bisphenol A epoxy diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polyethylene glycol 600 diacrylate, diethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate,tetraethylene glycol diacrylate, neopentyl glycol ethoxylate diacrylate, butanediol diacrylate, hexanediol diacrylate, an aliphatic urethane diacrylate, trimethylolpropane triacrylate, trimethylolpropane ethoxylate triacrylate, trimethylolpropane pro-poxylate triacrylate, glycerol propoxylate triacrylate, an aliphatic diurethane triacrylate, dipentaerythritol pentaacrylate, triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), triallyl trimellitate, N,N'-m-phenylene dimaleimide, butadiene, chloroprene, isoprene, a trivinylcyclohexane and mixtures thereof.

[0103] More preferably, the coagent is selected from the group consisting of triallyl cyanurate, triallyl isocyanurate, N,N'-m-phenylene dimaleimide, triallyl trimellitate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, trivinylcyclohexane and mixtures thereof, even more preferably selected from the group consisting of triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTMA) and mixtures thereof, and most preferably is triallyl isocyanurate (TAIC).

[0104] The main objective of using a coagent is to increase the level of crosslinking of the cured polymer using the formulation of the invention. The coagent also makes it possible to reduce residual gas emissions during the decomposition of peroxides, and ultimately to reduce the number of bubbles in the encapsulating film.

[0105] The weight ratio of the coagent to the organic peroxide is preferably from 0.1 to 10, more preferably from 0.3 to 3, even more preferably from 0.4 to 1.

[0106] When two or more organic peroxides are present in the organic peroxide formulation, the weight ratio of coagent to organic peroxide is based on the total weight of the organic peroxides.

[0107] When two coagents are present in the organic peroxide formulation, the weight ratio of coagents to organic peroxide is based on the total weight of coagents.

[0108] In some embodiments, the organic peroxide formulation may consist essentially of, or consist of, the at least one organic peroxide, the at least one drying oil, the at least one silane component, and the at least one coagent.

[0109] In other embodiments, the organic peroxide formulation may comprise one or more other additives, preferably selected from the group consisting of UV stabilizers, UV absorbers, coupling agents, fillers, plasticizers, flame retardants, antioxidants, dyes and pigments, free radical scavengers and mixtures thereof. UV stabilizers may be selected from hindered amine light stabilizers (HALS). UV absorbers may be selected, for example, from benzophenones, triazines and benzotriazoles. UV stabilizers and UV absorbers may be present in the organic formulation in a weight ratio relative to the organic peroxide ranging from 0.0005 to 0.01. As examples of coupling agents (other than the silane components described above), mention may be made of monoalkyl titanates.Inorganic fillers such as silicon dioxide, alumina, talc, calcium carbonate may be added to increase the mechanical strength of the polymeric material once crosslinked using the present peroxide formulation, although nanoscale clays are preferred for the transparency they provide. Examples of plasticizers are paraffinic or aromatic mineral oils, phthalates, azelates, adipates and the like. Antioxidants may be phenolic, phosphate or sulfur antioxidants. Alternatively or additionally, quinolines such as 1,2-dihydro-2,2,4-trimethylquinoline may be used as the antioxidant. Organic or inorganic pigments may also be added for coloring the polymer composition in which the formulation is intended to be used.Particular mention may be made of titanium dioxide, which makes it possible to produce a white color, which may be particularly useful when the formulation is used in a polymer composition employed for the manufacture of a film for use at the back side of photovoltaic modules. Examples of free radical scavengers suitable for the present invention are those selected from the group consisting of nitroxides (particularly 4-hydroxy-TEMPO) and quinones. In the present context, the term "quinone" includes both quinones and hydroquinones. Non-limiting examples of quinones that may be used in formulations of the present invention include mono-tert-butylhydroquinone (MTBHQ), hydroquinone, monomethyl ether. hydroquinone (HQMME) also called 4-methoxyphenol, mono-t-amyl-hydroquinone, bis(2-hydroxyethyl)ether hydroquinone, 4-ethoxyphenol, 4-phenoxyphenol, 4-(benzyloxy)phenol, 2,5-bis(morpholinomethyl)hydroquinone and benzoquinone.

[0110] The organic peroxide formulation may consist essentially of, or consist of, the at least one organic peroxide, the at least one drying oil, the at least one silane component, the at least one coagent and optionally one or more additives selected from the group consisting of UV stabilizers, UV absorbers, coupling agents, fillers, plasticizers, flame retardants, antioxidants, dyes and pigments, free radical scavengers and mixtures thereof.

[0111] The organic peroxide formulation may comprise free radical scavengers selected from the group consisting of nitroxides, quinones and mixtures thereof.

[0112] The organic peroxide formulation may comprise free radical scavengers in a weight ratio of free radical scavengers to organic peroxide of 0 to 0.5, more preferably 0 to 0.15, even more preferably 0 to 0.05, even more preferably 0 to 0.002.

[0113] The organic peroxide formulation may comprise a total amount of nitroxide and quinone free radical scavengers in a weight ratio relative to the organic peroxide ranging from 0 to 0.5, more preferably ranging from 0 to 0.15, more preferably ranging from 0 to 0.05, even more preferably ranging from 0 to 0.002.

[0114] When two or more organic peroxides are present in the organic peroxide formulation, the weight ratio of free radical scavengers to organic peroxide is based on the total weight of organic peroxide.

[0115] In certain advantageous embodiments, the organic peroxide formulation does not comprise (i.e., is free of) 4-hydroxy-TEMPO and / or MTBHQ, and more particularly, does not comprise nitroxide and / or quinone free radical scavengers.

[0116] The organic peroxide formulation may be free of any free radical scavenger. Polymer composition

[0117] The present invention also relates to a composition comprising at least one polymer and an organic peroxide formulation as described above (this composition is also called “polymer composition” in the present text).

[0118] Thus, the present invention relates in particular to a composition comprising:

[0119] - at least one polymer,

[0120] - at least one organic peroxide having a half-life temperature of a hour ranging from 90°C to 130°C,

[0121] - at least one drying oil, and

[0122] - optionally at least one silane-type component,

[0123] the weight ratio of the drying oil to the organic peroxide being less than or equal to 0.60.

[0124] The components of the organic peroxide formulation (organic peroxides, drying oils, optional silane components, optional coagents, other optional additives, optional free radical scavengers), and their weight ratios, may be as described in the section above.

[0125] The polymer of the polymer composition of the invention is preferably an ethylene polymer. The ethylene polymer may be an ethylene homopolymer or preferably an ethylene copolymer. Examples of ethylene copolymers are those prepared from ethylene monomers and at least one other monomer selected from hydrocarbons having at least one unsaturation such as methylene, propylene, butene, pentene, hexene, heptene, octene, butadiene, isoprene and styrene; acryl monomers such as acrylic acid, methacrylic acid, an alkyl methacrylate and an alkyl acrylate; the alkyl group may be selected from methyl, ethyl, propyl and butyl, for example; and vinyl monomers such as vinyl acetate and vinyl butyrate. Typically, these copolymers comprise at least 30% by weight of ethylene and at most 70% by weight of the other monomer(s).

[0126] Thus, the polymer may advantageously be a copolymer of ethylene and at least one vinyl monomer, and is preferably a copolymer of the poly(ethylene-vinyl acetate) (EVA) type.

[0127] The EVA copolymer may comprise from 15 to 60% by weight, preferably from 25 to 45% by weight, of units derived from vinyl acetate (VA) monomers. Examples of such EVA copolymers are available under the trade name "Evatane® 18-150" and "Evatane® 40-55" from ARKEMA.

[0128] Other ethylene polymers that can be used in the invention have been disclosed, e.g., in EP 2242647. They comprise a functionalized polyolefin, such as a homopolymer of ethylene or a copolymer of ethylene with an alkyl (meth)acrylate or vinyl acetate, which can be functionalized either by grafting or by copolymerization with maleic anhydride or glycidyl methacrylate. This functionalized polyolefin can optionally be blended with an ethylene / carboxylic acid vinyl ester copolymer such as EVA.

[0129] Alternatively, or in addition, the polymer may advantageously be a polyolefin elastomer (comprising units derived from ethylene or not).

[0130] A "polyolefin" as used herein means a polymer derived from an olefin, for example ethylene, propylene, butene, hexene, etc.

[0131] By the terms "derived from [a monomer]", it is meant that the polymer comprises in its main chain and / or in its adjacent chains (or pendant chains) units resulting from the polymerization or copolymerization of at least said monomer.

[0132] The terms "polyolefin elastomer" as used herein mean an elastomeric polymer derived from an olefin (e.g. ethylene, propylene, butene, hexene, etc.).

[0133] The term "elastomer" in the sense of the present invention means a polymer which is capable of undergoing uniaxial deformation, preferably of at least 20%, at room temperature (for example 20°C) over a time of fifteen minutes, and of returning to its initial shape, preferably with a residual deformation of less than 5% compared to its initial shape, when this stress is no longer exerted.

[0134] The polyolefin elastomer according to the present invention is advantageously derived from ethylene. In other words, the polyolefin elastomers preferably comprise at least one unit derived from ethylene.

[0135] The polyolefin elastomer according to the present invention further preferably comprises probably patterns derived from at least one alpha-olefin.

[0136] The polyolefin elastomer preferably comprises a content of at least 15% by weight of units derived from an alpha-olefin, preferably at least 20% by weight, and more preferably at least 25% by weight, based on the total weight of the polymer. The polyolefin elastomer preferably comprises a content of alpha-olefin units of less than 50% by weight, preferably less than 45% by weight, and more preferably still less than 35% by weight, based on the total weight of the polymer. The polyolefin elastomer may therefore comprise a content of alpha-olefin units ranging from 15% to 50% by weight, preferably from 15% to 45% by weight, more preferably from 15% to 35% by weight, even more preferably from 20% to 35% by weight, based on the total weight of the polymer. The content of alpha-olefin units in the polymer can be measured by carbon-13 nuclear magnetic resonance (NMR) spectroscopy according to the protocol described by Randall (J. Macromol. Sci. : Rev. Macromol. Chem. Phys., C29 (2 and 3),201-317, 1989). .

[0137] The alpha-olefin is preferably a C3-C20 alpha-olefin. It can be linear, branched or cyclic. Preferably, the alpha-olefin is a linear or branched C3-C20 alpha-olefin.

[0138] The polyolefin elastomer is advantageously a copolymer of ethylene and at least one alpha-olefin, in particular a linear or branched C3-C20 alpha-olefin, the exclusion of any other comonomer.

[0139] The C3-C20 alpha-olefin is preferably selected from the group consisting of propene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene and 1-octadecene.

[0140] Preferably, the polyolefin elastomer comprises, or consists of, units derived from ethylene and units derived from an alpha-olefin selected from the group consisting of 1-butene, 1-hexene and 1-octene.

[0141] The alpha-olefin may also contain a cyclic structure, for example, a cyclohexane or cyclopentane type structure, leading to an alpha-olefin such as 3-cyclohexyl-l-propene (allylcyclohexane) or vinylcyclohexane.

[0142] Certain cyclic olefins, such as norbornene and corresponding olefins, are considered alpha-olefins for the purposes of the present invention and may be used in place of the alpha-olefins described above.

[0143] Preferably, the at least one organic peroxide is present in the polymer composition in an amount ranging from 0.05 to 20 parts by weight per 100 parts by weight of polymer (preferably ethylene polymer). More preferably, the organic peroxide is present in the polymer composition in an amount ranging from 0.1 to 3 parts by weight, even more preferably from 0.3 to 1.5 parts by weight, per 100 parts by weight of polymer.

[0144] The at least one drying oil may advantageously be present in the polymer composition in an amount ranging from 0.005 to 10 parts by weight per 100 parts by weight of polymer (preferably, ethylene polymer), preferably from 0.01 to 5 parts by weight, even more preferably from 0.02 to 1 part by weight, per 100 parts by weight of polymer.

[0145] When present, the at least one silane component may preferably be present in the polymer composition in an amount ranging from 0.01 to 20 parts by weight per 100 parts by weight of polymer (preferably ethylene polymer), preferably from 0.05 to 5 parts by weight, even more preferably from 0.1 to 1 part by weight, per 100 parts by weight of polymer.

[0146] When present, the at least one coagent may be included in the polymer composition in an amount ranging from 0.005 to 10 parts by weight, preferably from 0.01 to 5 parts by weight, more preferably from 0.05 to 2 parts by weight, even more preferably from 0.1 to 1 part by weight, per 100 parts by weight of polymer (preferably ethylene polymer).

[0147] Other additives, preferably selected from UV stabilizers, UV absorbers, coupling agents, fillers, plasticizers, flame retardants, antioxidants, dyes and pigments, free radical scavengers and mixtures thereof, may be present in the polymer composition.

[0148] The polymer composition of the invention may consist essentially of, or consist of, the at least one polymer (preferably an ethylene polymer), the at least one organic peroxide, the at least one drying oil, optionally the at least one silane component, optionally the at least one coagent, and optionally the additives (preferably selected from the group consisting of UV stabilizers, UV absorbers, coupling agents, fillers, plasticizers, flame retardants, antioxidants, dyes and pigments, free radical scavengers and mixtures thereof).

[0149] In some embodiments, the polymer composition is free of 4-hydroxy-TEMPO and / or MTBHQ, and more particularly, is free of nitroxide and / or quinone free radical scavengers. The polymer composition may be free of free radical scavengers. Preparation processes

[0150] The invention also relates to a process for the preparation of an organic peroxide formulation as described above, comprising mixing the at least one organic peroxide and the at least one drying oil and optionally other components of the formulation (such as the at least one silane component, the at least one coagent and / or the other additives).

[0151] The mixing step may be carried out in one or more steps (some of the components may thus be premixed before being mixed with the other components of the formulation). The mixing step may be carried out using any kind of apparatus suitable for mixing formulations containing mainly a liquid.

[0152] The mixing step is preferably carried out at a temperature below the decomposition temperature of the organic peroxide. It can be carried out at a temperature of -10°C to 50°C, preferably of 10°C to 40°C.

[0153] The invention also relates to a process for the preparation of a polymer composition as described above. Said process comprises a step of mixing the at least one polymer and the organic peroxide formulation as described above. The polymer may be mixed with a previously prepared organic peroxide formulation, or may be mixed, in one or more steps, with all or each of the components of the organic peroxide formulation, and / or any premix of components of the organic peroxide formulation.

[0154] The mixing step may be carried out in any conventional device, such as a continuous mixer, a batch mixer, a compound extruder, or directly in the barrel of a film extrusion line. The temperature of the mixing step is preferably lower than the decomposition temperature of the peroxide. In particular, the mixing step may preferably be carried out at a temperature in the range of -10 to 120°C, preferably 10 to 120°C.

[0155] Preferably, the method also comprises an impregnation step after the mixing step. In such an impregnation step, the polymer, preferably in the form of pellets, is allowed to stand after being mixed with the organic peroxide formulation, preferably for at least 1 h, so that the organic peroxide impregnates the polymer pellets.

[0156] In the above methods, the components and their amounts may be as described in the preceding sections. Applications

[0157] Another object of the invention is the use of an organic peroxide formulation as described above for curing a polymer, preferably an ethylene polymer, more preferably a polymer selected from the group consisting of poly(ethylene vinyl acetate), polyolefin elastomers and combinations thereof. Preferably, a polymer composition as described above is formed.

[0158] The polymer may be as described above.

[0159] The invention also relates to a method for manufacturing an article comprising the steps of:

[0160] - optionally providing a polymer composition as described above; and

[0161] - hardening of said composition.

[0162] The curing step is advantageously carried out at a temperature ranging from 120 to 250°C, preferably from 130 to 180°C, more preferably from 130 to 165°C. It can last from 4 to 50 minutes, preferably from 6 to 35 minutes.

[0163] Advantageously, the hardening step is carried out in the absence of oxygen.

[0164] The expression "in the absence of oxygen" means that the curable composition is at least not intentionally in contact with oxygen during the curing step. In other words, the curable composition is substantially not in the presence of oxygen during the curing step, and preferably the curable composition is not in the presence of oxygen during the curing step.

[0165] Advantageously, the hardening step takes place during a lamination step.

[0166] Preferably, the method also comprises a step of shaping the polymer composition. This step can be carried out before and / or simultaneously with the curing step. Advantageously, the step of shaping the polymer composition is chosen from a molding step, an extrusion step, and a step of injection molding the polymer composition. Preferably, it is an extrusion step.

[0167] Preferably, the step of shaping the polymer composition is carried out before the step of curing the polymer composition. Thus, preferably, no crosslinking or substantially no crosslinking takes place during the shaping step. When the shaping step is carried out before the curing step, said shaping step may be carried out at a temperature ranging from 80 to 150°C, more preferably from 95 to 120°C. Alternatively, the shaping step and the curing step may be carried out in a single step.

[0168] In some embodiments, the produced article is a film (or sheet). In such embodiments, the method comprises a step of shaping the polymer composition so as to form a film. Said step can be carried out using a T-die extruder or, alternatively, using a twin-screw extruder coupled to a twin-roll mill.

[0169] The film may for example have a thickness ranging from 50 to 2,000 μm, preferably from 100 to 1,000 μm.

[0170] The article manufactured by the method described above may advantageously be selected from the group consisting of encapsulant materials, particularly encapsulants for solar cells, wires and cable insulations, tubes and pipes (including those for automobile radiators, potable water, and floor heating, for example), roll coverings, rotational moldings, cellular articles, and shoe soles.

[0171] Most preferably, the article is an encapsulant material and more particularly an encapsulant for solar cells.

[0172] The invention also relates to an article obtainable, or obtainable, by the method as described above. The polymer may be as described above.

[0173] Another subject of the invention is a photovoltaic module comprising an article as described above, preferably a film as described above. The photovoltaic module comprises one or more solar cells, and the article according to the invention (preferably the film) is advantageously an encapsulant for solar cell(s). Preferably, the film directly covers the solar cell(s), for example is in contact with the solar cell(s). A film according to the invention may cover both sides of the solar cell(s) or only one side of the solar cell(s), either the side facing the front of the photovoltaic module or the side facing the rear of the photovoltaic module.

[0174] The photovoltaic module preferably further comprises a front sheet, which can directly cover a film according to the invention, and / or (preferably and) a back sheet, which can directly cover a film according to the invention.

[0175] The front sheet may most preferably be a transparent sheet. It may be, for example, a glass sheet or a poly(methyl methacrylate) sheet. (PMMA).

[0176] The backsheet may be, for example, a glass sheet (preferably a thin glass sheet) or a PMMA sheet. Alternatively, the backsheet may be a multilayer structure (multilayer film), preferably comprising, or consisting of, an electrically insulating polymer film, such as a polyethylene terephthalate (PET) or a polyamide (PA), one or more fluoropolymer-based films, such as a polyvinyl fluoride (PVF) or a polyvinylidene fluoride (PVDF), and optionally a metal film, for example aluminum (the layers preferably being in this order). The backsheet is advantageously a PVDF / PET multilayer film. Alternatively, the multilayer structure of the backsheet may comprise, or consist of, a glass sheet and a film obtainable by curing a polymer composition according to the invention as described above.

[0177] The solar cells are preferably cells composed of crystalline silicon or organic photovoltaic substances.

[0178] The present invention also relates to a method for manufacturing a photovoltaic module, said method comprising the following steps:

[0179] - stratification of an assembly successively comprising at least:

[0180] ❖ a front sheet (such as a glass sheet or a PMMA sheet),

[0181] ❖ a layer of a polymer composition according to the invention,

[0182] ❖ at least one solar cell (preferably composed of crystalline silicon or organic photovoltaic substances),

[0183] ❖ another layer of a polymer composition according to the invention, and

[0184] ❖ a back sheet (such as a PVDF / PET multilayer film or a sheet of glass or PMMA sheet)

[0185] - pressing the laminated assembly.

[0186] The laminate assembly may be pressed by conventional techniques while heating and / or under vacuum, for example at a temperature ranging from 130 to 250°C, preferably from 130 to 180°C, more preferably from 140 to 165°C under vacuum, for a time which may be in the range of 4 to 40 minutes, for example from 6 to 35 minutes. The polymer compositions of the invention may be crosslinked (or cured) during this pressing step or afterward. Preferably, the step of pressing the laminate assembly and the step of curing the polymer compositions are simultaneous. Examples

[0187] The following examples illustrate the invention without limiting it. Example 1

[0188] A first base composition was prepared by mixing a POE-type polymer (14 MI, ENGAGE® from DOW Chemical Company), 0.75 phr of 00-t-butyl-O-2-ethylhexyl-monoperoxycarbonate (TBEC) (Luperox® TBEC from Arkema), 0.3 phr of 3-methacryloxypropyltrimethoxysilane (KH-570 from Sigma-Aldrich) and 0.5 phr of triallyl isocyanurate (TAIC) (from Ourchem) in a 125 mL bottle. The mixture was then heated for 7.5 hours at 40 °C in an oven. During the heating step, the mixture required stirring every 2 to 3 hours.

[0189] Phr means "parts per percent rubber", and thus, in the present example, means "parts by weight per 100 parts of POE-type polymer".

[0190] A second base composition was prepared in the same manner as the first base composition except that 0.75 phr of OO-tert-amyl 0-(2-ethylhexyl) monoperoxycarbonate (T AEC) (Luperox® T AEC, available from Arkema) was used instead of 0.75 phr of TBEC.

[0191] To these base compositions, a certain amount of tung oil (from Anhui Refined Oil and Fat CO., Ltd), odorless mineral spirits (synthetic iso-paraffin hydrocarbon, from Idemitsu kosan Co. Ltd.) or refined tung oil (from Anhui Refined Oil and Fat CO., Ltd) was added, as shown in the table below. The tung oil used in the examples has a saponification value of 193 (determined according to GB / T5534-1995) and an iodine value of 167 g / 100 g (determined according to GB / T5532-2008).

[0192] [Tables 1] Composition No. Tung Oil (phr) Refined Tung Oil (phr) Mineral Spirits (phr) Oil / Organic Peroxide Weight Ratio Peroxide = TBEC 1 - - - 2 - - 0.1125 0.15 3 0.0375 - - 0.05 4 0.075 - - 0.1 5 0.1125 - - 0.15 6 - 0.0375 - 0.05 7 - 0.075 - 0.1 Peroxide = TAEC 8 - - - 9 0.1125 - - 0.15

[0193] Compositions Nos. 3, 4, 5, 6, 7 and 9 are compositions according to the invention; compositions Nos. 1, 2 and 8 are comparative compositions. Compositions Nos. 1 and 7 comprise TBEC as organic peroxide; compositions 8 and 9 comprise T AEC as organic peroxide.

[0194] Samples of about 2 to 3 g of the compositions thus produced were deposited in a plate on a Rubber Process Analyzer (RPA), of the model type EKT-2003RPA-N of EKTRON TEK.CO., LTD, which is capable of measuring the curing properties of the samples and includes software for analyzing the results. Each of the samples was placed in a temperature-controlled cavity between two plates, the lower of which oscillates to apply cyclic stress or strain to the sample while the upper die is connected to a torque sensor to measure the torque response of the sample to deformation. Under these conditions, the surfaces of the sample are protected from the presence of air (and thus oxygen) by the metal surfaces of the plates. The stiffness is recorded continuously as a function of time. The stiffness of the sample increases with crosslinking.

[0195] The RPA is capable of providing, inter alia, calculated values ​​of ML (minimum torque), MH (maximum torque), tSi (time to reach an increase of 1 dN.m in torque from the most minimal) and tc90 (time to reach 90% of the state of MH-ML curing) as defined by international standards (such as ASTM D5289). Ts[ represents the curing time. From these data, the relative degree of MH-ML curing (or crosslink density) can be determined.

[0196] The RPA was operated at a temperature of 145°C with an oscillation amplitude (degree of deformation) of 0.5°, an oscillation frequency of 1.667 and a stress index of 7 applied to the sample for 30 min, except for examples 10 and 11 where the test was carried out for 45 minutes.

[0197] The results are described in the table below.

[0198] [Tables2] Composition No. TS1 (s) Mh-Ml (dN.m / s) TC90 (s) Peroxide = TBEC (30 min RPA test) 1 411 2.59 1136 2 418 2.53 1163 3 433 2.56 1153 4 446 2.56 1181 5 471 2.55 1218 6 419 2.50 1150 7 436 2.51 1161 Peroxide = TAEC (45 min RPA test) 8 240 2.34 772 9 268 2.50 824

[0199] The compositions of the invention, which comprise tung oil, result in a longer scorch time compared to compositions not comprising oil or comprising mineral spirits. Thus, tung oil is effective as a scorch protection agent. In addition, the crosslink density obtained with the compositions of the invention is not altered and the tc90 remains within an acceptable range. This conclusion is true regardless of the peroxide used. Furthermore, it can be seen that refined tung oil also acts as an effective scorch protection agent. Example 2

[0200] A first base composition was prepared by mixing an EVA type polymer (V2825 from JiangSu Sailboat Petrochemical), 0.6 phr of TBEC (Luperox TBEC® from Arkema), 0.3 phr of 3-methacryloxypropyltrimethoxysilane (KH-570 from Sigma-Aldrich) and 0.5 phr of TAIC (from Ourchem) in a 125mL bottle. The mixture was was then heated for 6.5 h at 40 °C in an oven. During the heating step, the mixture required stirring every 2 to 3 hours.

[0201] In this example, phr means “parts by weight per 100 parts of EVA-type polymer”.

[0202] Another base composition was prepared in the same manner except that 0.6 phr of OO-tert-amyl O-(2-ethylhexyl) monoperoxycarbonate (TAEC) (Luperox® TAEC, available from Arkema) was used instead of 0.6 phr of TBEC.

[0203] Yet another base composition was prepared in the same manner as the first base composition, except that 1.2 phr of TAEC (Luperox® TAEC) was used instead of 0.6 phr of TBEC.

[0204] Yet another base composition was prepared in the same manner as the first base composition, except that 1.2 phr of a mixture of 90% by weight TAEC (Luperox® TAEC) and 10% by weight t-butyl peroxy-2-ethylhexanoate (TBPO) (Luperox® 26 from Arkema) was used instead of 0.6 phr of TBEC.

[0205] Yet another base composition was prepared in the same manner as the first base composition, except that 0.75 phr of TBEC was used instead of 0.6 phr of TBEC.

[0206] To each of these compositions, tung oil or castor oil (ADANI castor oil) was added or not, as indicated in the following table.

[0207] Castor oil has a saponification value of 180 mg KOH / g and an iodine value of 85 g / 100 g determined as described above.

[0208] [Tables3] Composition No. Peroxide Tung oil (phr) Castor oil (phr) Oil / peroxide weight ratio 10 TBEC (0.6 phr) - 11 TBEC (0.6 phr) 0.09 0.15 12 TAEC (0.6 phr) - 13 TAEC (0.6 phr) 0.09 0.15 14 TAEC (1.2 phr) - 15 TAEC (1.2 phr) 0.1 0.08 16 90% TAEC + 10% TBPO (1.2 phr) - 17 90% TAEC + 10% TBPO (1.2 phr) 0.1 0.08 18 TBEC (0.75 phr) - 19 TBEC (0.75 phr) 0.1125 0.15 20 TBEC (0.75 phr) 0.1125 0.15

[0209] Compositions Nos. 11, 13, 15, 17 and 19 are compositions according to the invention; compositions Nos. 10, 12, 14, 16, 18 and 20 are comparative compositions.

[0210] The crosslinking properties of compositions Nos. 10 to 13 were determined as described in Example 1, with a curing time of 30 min.

[0211] The crosslinking properties of compositions Nos. 14 to 17 were determined as described in Example 1 but at three different temperatures: at 145 °C, at 130 °C and at 110 °C. The RPA measurement was carried out for 45 min. Temperatures of 145 and 130 °C simulate the conditions of a lamination process (e.g., for the manufacture of a photovoltaic module); a temperature of 110 °C simulates the conditions of an extrusion process (e.g., for the formation of a film before a lamination process).

[0212] The crosslinking properties of compositions Nos. 18 to 20 were determined as described in Example 1, with a curing time of 45 min.

[0213] The results are presented in the table below.

[0214] [Tables4] Composition No. Temperature (°C) TS1 (s) Mh-Ml (dN.m / s) TC9O (S) Curing time = 30 min 10 145 235 3.99 871 11 145 335 4.03 1172 12 145 159 3.74 589 13 145 197 3.72 592 Curing time = 45 min RPA operating time = 145 °C 14 145 100 4.37 412 15 145 109 4.38 430 16 145 99 4.09 383 17 145 108 4.31 447 18 145 237 4.13 896 19 145 292 4.04 1089 20 145 231 3.81 875 RPA operating time = 130 °C 14 130 318 3.95 1099 15 130 373 3.95 1188 16 130 290 3.75 1071 17 130 362 3.93 1158 RPA operating time = 110 °C 14 110 ND 0.83 Not relevant 15 110 ND 0.38 Not relevant 16 110 1726 1.1 Not relevant 17 110 ND 0.42 Not relevant

[0215] ND = not determinable. This indicates that the increase of 1 dN.m was not achieved during the 45 minutes of measurement duration.

[0216] A significant increase in roasting time is observed with the compositions of the invention at operating temperatures of 145°C and 130°C per comparison with tung oil-free compositions, regardless of the peroxide used, while the crosslinking density remains good.

[0217] Furthermore, it can be seen that at the operating temperature of 110°C, very little crosslinking takes place with the compositions of the invention. This is desired because it is preferable that no crosslinking or substantially no crosslinking takes place during the extrusion step for shaping the composition. In contrast, the comparative compositions exhibit a higher crosslink density at 110°C, suggesting that the presence of tung oil makes possible a reduction in crosslinking at the temperature of 110°C.

[0218] When comparing Example 20 with Examples 18 and 19, no scorch protection was observed when using castor oil and the crosslink density was even lower than the counterexample without any oil.

Claims

Claims

1. An organic peroxide formulation comprising: - at least one organic peroxide having a one-hour half-life temperature ranging from 90°C to 130°C, preferably having a one-hour half-life ranging from 110°C to 125°C, and - at least one drying oil, the weight ratio of the drying oil to the organic peroxide being less than or equal to 0.

60.

2. An organic peroxide formulation according to claim 1, wherein the at least one drying oil has an iodine value of from 125 to 215 g / 100 g, preferably from 140 to 205 g / 100 g, more preferably from 150 to 180 g / 100 g.

3. An organic peroxide formulation according to claim 1 or 2, wherein the at least one drying oil has a saponification number ranging from 175 to 210 mg KOH / g, preferably from 182 to 195 mg KOH / g.

4. An organic peroxide formulation according to any one of claims 1 to 3, wherein the at least one drying oil is selected from the group consisting of tung oil, hemp oil, linseed oil, poppy seed oil, walnut oil, sunflower oil, cottonseed oil, corn oil, soybean oil, fish oils such as sardine oil and cod liver oil, herring oil, safflower oil, linseed oil, perilla oil, oiticica oil, and combinations thereof, preferably the at least one drying oil is a tung oil.

5. An organic peroxide formulation according to any one of claims 1 to 4, wherein the at least one organic peroxide is selected from the group consisting of diperoxyketals, peroxyketals, monoperoxycarbonates, cyclic ketone peroxides, diacyl peroxides, organosulfonyl peroxides, peroxyesters, peroxydicarbonates and combinations thereof, preferably selected from the group consisting of diperoxyketals, peroxyketals, monoperoxycarbonates, peroxyesters and combinations thereof, more preferably selected from the group consisting of OO-t-butyl-O-(2-ethylhexyl)-monoperoxycarbonate, OO-t-butyl-O-2-isopropyl-monoperoxycarbonate, OO-t-amyl-O-(2-ethylhexyl)-monoperoxycarbonate, OO- t-amyl-O-2-isopropyl-monoperoxycarbonate, 00-t-hexyl-O-(2-ethylhexyl)-monoperoxycarbonate and mixtures thereof, optionally in combination with at least one other peroxide.

6. An organic peroxide formulation according to any one of claims 1 to 5, further comprising at least one silane component, preferably selected from the group consisting of vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane and mixtures thereof, and more preferably being 3-methacryloxypropyltriethoxysilane or / and 3-methacryloxypropyltrimethoxysilane.

7. An organic peroxide formulation according to any one of claims 1 to 6, wherein the weight ratio of drying oil to organic peroxide is less than or equal to 0.45, preferably being 0.025 to 0.45, more preferably 0.03 to 0.3, more preferably 0.03 to 0.25, and even more preferably 0.05 to 0.

2.

8. An organic peroxide formulation according to any one of claims 1 to 7, further comprising at least one coagent, preferably selected from the group consisting of triallyl cyanurate, triallyl isocyanurate, N,N'-m-phenylene dimaleimide, triallyl trimellitate, trimethylolpropane triacrylate, trimethylolpropane trime-thacrylate, trivinylcyclohexane and mixtures thereof.

9. An organic peroxide formulation according to any one of claims 1 to 8, comprising a combination of at least: 1) a monoperoxycarbonate, preferably selected from the group consisting of OO-t-butyl-O-(2-ethylhexyl)-monoperoxycarbonate, OO-t-butyl-O-2-isopropyl-monoperoxycarbonate, OO-t-amyl-O-(2-ethylhexyl)-monoperoxycarbonate, OO-t-amyl-O-2-isopropyl-monoperoxycarbonate, OO- t-hexyl-O-(2-ethylhexyl)-monoperoxycarbonate and mixtures thereof and 2) a peroxyester, preferably selected from the group consisting of: tert-butyl peroxy-2-ethylhexanoate and tert-amyl peroxy-2-ethylhexanoate, more preferably being a combination of 00-t-amyl-O-(2-ethylhexyl)-monoperoxycarbonate and tert-butyl peroxy-2-ethylhexanoate.

10. A composition comprising at least one polymer and an organic peroxide formulation according to any one of claims 1 to 9.

11. Composition according to claim 10, wherein the at least one polymer is an ethylene polymer, in particular a poly(ethylene-vinyl acetate) and / or a polyolefin elastomer.

12. A composition according to claim 10 or 11, the amount of the at least one drying oil in the composition being from 0.005 to 10 parts by weight, preferably from 0.01 to 5 parts by weight, more preferably from 0.02 to 1 part by weight, per 100 parts by weight of the at least one polymer.

13. A process for preparing an organic peroxide formulation according to any one of claims 1 to 9, comprising mixing the at least one organic peroxide and the at least one drying oil.

14. A method for manufacturing an article comprising a step of curing the composition according to any one of claims 10 to 12.

15. An article, in particular a film, obtainable by the method according to claim 14.

16. Use of an organic peroxide formulation according to any one of claims 1 to 9 for curing a polymer, said polymer preferably being selected from the group consisting of poly(ethylene vinyl acetate), polyolefin elastomers and combinations thereof.