Article suitable for food contact and method for producing same

Abstract

The invention relates to an article suitable for food contact, notably a food packaging, which comprises a first substrate and a second substrate which are joined by an adhesive, said first substrate comprising a support coated with a silicone coating suitable for food contact, said adhesive being inserted between the two substrates and being in contact with the silicone coating of said first substrate, characterized in that said adhesive is a structural silicone adhesive, suitable for food contact, obtained by crosslinking a polyaddition-crosslinkable silicone composition.

Description

[0001] DESCRIPTION

[0002] TITLE: Article suitable for food contact and its manufacturing process

[0003] Technical field

[0004] The present invention relates to the field of food packaging, and more specifically to food packaging based on a silicone substrate.

[0005] State of the prior art

[0006] Faced with evolving regulations aimed at limiting the use of single-use plastics, the industry is seeking alternatives to food packaging, which typically consists of paper coated with a polyolefin coating. In this context, there is a need to offer coated paper solutions with water barrier properties and capable of withstanding significant temperature variations, particularly in the field of packaging suitable for food contact.

[0007] To meet this need, it is possible to use silicone papers typically used in baking and commonly called baking paper or greaseproof paper. These papers are made of a paper base (cellulose) with particular porosity and roughness properties and having a weight of approximately 40 g / m 2as well as a thin layer of silicone coated on one or both sides of this paper and having a thickness between 0.1 μm and 1 μm. These silicone papers are suitable for food contact. They are non-stick and water-repellent: food does not stick to its packaging even after a storage period of one year or more at temperatures as low as -30°C, or even as low as -70°C. They can withstand, without disintegrating, the constraints of rapid cooking techniques for frozen foods (temperatures of around 300°C in microwave ovens, steam cooking). They are therefore interesting candidates for the manufacture of food packaging.

[0008] The manufacture of food packaging involves one or more assembly steps to create the sides and bottom of a bag, for example. These assembly steps can be carried out in the case of papers coated with a polyolefin coating, either by reusing an adhesive or by a fusion welding step of the surface plastic layer.

[0009] In this context, a difficulty in reusing silicone paper for the manufacture of food packaging lies in the gluing step on the silicone face(s).

[0010] This problem has been described, for example, in Japanese patent application JP H05-319461. This document describes the manufacture of a bag for packaging food made from silicone paper and a silicone adhesive that allows the formation of a watertight seal. Said silicone adhesive is a PSA (“pressure sensitive adhesive”) made from resin and silicone gum.

[0011] Tests have shown that the choice of a PSA as a silicone adhesive does not allow satisfactory bonding and is not suitable for food packaging. Similarly, document KR20150057550 discloses a food packaging comprising a silicone adhesive. However, this silicone adhesive is a composition crosslinkable by polycondensation releasing acetic acid. This type of composition is illustrated as a comparative example in the context of the present invention and has the disadvantage of an unpleasant acetic acid odor for the consumer and during the bonding step. Furthermore, the presence of acetic acid can present health and safety issues for operators.

[0012] Summary of the invention

[0013] In this context, the subject of the present invention is an article suitable for food contact, in particular food packaging, which preferably meets the following needs: it is desired to have an article not comprising a petro-sourced polymer coating, capable of withstanding significant thermal amplitudes, having water barrier properties, waterproof, in particular at the assembly zones, and the manufacture of which is possible at high speed, preferably with standard industrial tools in the field of packaging.

[0014] To meet these needs, the article suitable for food contact according to the present invention comprises a first substrate and a second substrate joined by an adhesive, said first substrate comprising a support coated with a silicone coating suitable for food contact, said adhesive being inserted between the two substrates and being in contact with the silicone coating of said first substrate, characterized in that said adhesive is a structural silicone adhesive, suitable for food contact obtained by crosslinking a silicone composition crosslinkable by polyaddition reaction.

[0015] The present invention also relates to a method for manufacturing an article suitable for food contact, said method comprising the steps of:

[0016] - providing a first substrate and a second substrate, the first substrate comprising a support coated with a silicone coating suitable for food contact,

[0017] - depositing on the silicone coating of said first substrate a silicone composition crosslinkable by polyaddition reaction suitable for food contact,

[0018] - assembling the second substrate with the first substrate so that said silicone composition is between the two substrates,

[0019] - crosslink or allow said silicone composition to crosslink to obtain the bonding of the two substrates by a structural silicone adhesive.

[0020] Finally, the present invention also relates to the use of a structural silicone adhesive, suitable for food contact, obtained by crosslinking a crosslinkable silicone composition by polyaddition reaction for the manufacture of an article suitable for food contact.

[0021] Detailed description of the invention

[0022] Unless otherwise indicated, all viscosities of the silicone oils discussed in this disclosure correspond to a dynamic viscosity quantity at 25°C known as “Newtonian”, i.e. the dynamic viscosity which is measured, in a manner known per se, with a Brookfield viscometer at a shear rate gradient sufficiently low so that the measured viscosity is independent of the rate gradient.

[0023] The present invention therefore relates to an article suitable for food contact comprising a first substrate and a second substrate joined by an adhesive. Said adhesive is a structural silicone adhesive.

[0024] For the purposes of this text, an adhesive may be described as “structural” provided that said adhesive is not the weak point of said assembly.

[0025] It is important to note that the structural silicone adhesive as defined herein is not a PSA (pressure sensitive adhesive). A PSA forms a bond with a substrate simply by contact or by applying slight pressure to join the adhesive with the substrate surface. Physical bonds are created because the PSA adhesive is soft enough to wet the substrate surface, but also hard enough to resist flow when pressure is applied to the bonding area. When the adhesive and the substrate surface are in close proximity, Van Der Waals-type molecular interactions can contribute significantly to the strength of the bond. A PSA therefore forms a physical, not a chemical, bond with the substrate surface. A chemical bond can be defined as a bond between reactive chemical groups at the adhesive-substrate interface.In contrast, a physical bond can be defined as a non-chemical, temporary or reversible bond created by a physical interaction between the adhesive and the substrate. Silicone PSA compositions generally consist of a hydroxylated silicone resin of the MQ(OH) type and a linear silicone gum in solution in an organic solvent, typically toluene and / or xylene.

[0026] In contrast, without however wishing to be bound by this theory, the structural silicone adhesive according to the present invention, which is not a PSA, can form a chemical bond with the substrate, and can thus guarantee good adhesion between two substrates. Preferably, the failure between the two substrates assembled with the structural silicone adhesive according to the present invention is a cohesive failure. In the present text, the expression "cohesive failure" designates the failure which occurs in the body of the material, as opposed to the "adhesive failure" which occurs at the interface between the adhesive and the substrate.

[0027] The silicone adhesive according to the present invention must be suitable for food contact. The suitability of an object for food contact, in the field of food packaging, means that the material from which it is made meets regulatory or normative requirements guaranteeing that there is no risk of toxicity induced, for food or drinks, by this object.

[0028] In Europe, reference may be made to Regulation (EC) 1935 / 2004, which sets out general requirements for all materials intended to come into contact with foodstuffs. More specifically, recommendations from the BfR in Germany, or Title 21 CFR of the FDA in the United States, may be taken into consideration.

[0029] Under normal conditions of use, the materials used must not release to the food constituents in quantities likely to present a danger to human health or to cause an unacceptable change in the composition of the food, with or without an alteration of its organoleptic characteristics.

[0030] The silicone adhesive according to the present invention, which is not a PSA, is obtained by crosslinking a silicone composition crosslinkable by polyaddition reaction. Preferably, the silicone composition crosslinkable by polyaddition reaction comprising:

[0031] - at least one organopolysiloxane A having, per molecule, at least two C2-C12 alkenyl groups linked to silicon,

[0032] - at least one organopolysiloxane B having, per molecule, at least two SiH units,

[0033] - a catalytically effective amount of at least one polyaddition catalyst C, preferably a platinum-based polyaddition catalyst, and

[0034] - possibly at least one crosslinking inhibitor D.

[0035] Organopolysiloxane A having, per molecule, at least two alkenyl groups, C2-C12 linked to silicon, may preferably be a linear organopolysiloxane formed:

[0036] - at least two siloxyl units of the following formula: Y a R 1 bSiO(4-ab) / 2 in which Y represents a C2-C12 alkenyl group, preferably a vinyl group; R 1represents a monovalent hydrocarbon group having from 1 to 12 carbon atoms, preferably selected from alkyl groups having from 1 to 8 carbon atoms such as methyl, ethyl, propyl groups, cycloalkyl groups having from 3 to 8 carbon atoms and aryl groups having from 6 to 12 carbon atoms; a = 1 or 2, b = 0, 1 or 2 and the sum a+b = 2 or 3, and

[0037] - possibly patterns of the following formula: R 1 c SiO(4-o / 2 in which R 1 has the same meaning as above and c = 2 or 3.

[0038] It is understood in the above formulas that, if several R groups 1 are present, they can be the same or different from each other.

[0039] Preferably, said organopolysiloxanes A are oils with a dynamic viscosity of between 100 mPa.s and 100,000 mPa.s, preferably between 1,000 mPa.s and 100,000 mPa.s. According to a preferred embodiment, the silicone composition according to the present invention does not comprise linear silicone gum.

[0040] The linear organopolysiloxane A having, per molecule, at least two alkenyl groups, C2-C12 linked to silicon, may preferably be essentially constituted of siloxyl units “D” chosen from the group consisting of the siloxyl units R^SiCLa, YR 1 SiO2 / 2 and Y2SiO2 / 2, and terminal “M” siloxyl units chosen from the group consisting of the siloxyl units YR^SiOi^, Y2R 1 SiOi / 2 and R' ;SiOi 2. The symbols Y and R 1 are as described above.

[0041] Examples of terminal “M” units include trimethylsiloxy, dimethylphenylsiloxy, dimethylvinylsiloxy or dimethylhexenylsiloxy groups.

[0042] Examples of “D” units include dimethylsiloxy, methylphenylsiloxy, methylvinylsiloxy, methylbutenylsiloxy, methylhexenylsiloxy, methyldecenylsiloxy or methyldecadienylsiloxy groups.

[0043] Examples of linear organopolysiloxanes which may be an organopolysiloxane A according to the invention are:

[0044] - a poly(dimethylsiloxane) with dimethylvinylsilyl ends;

[0045] - a poly(dimethylsiloxane-co-methylphenylsiloxane) with dimethylvinylsilyl ends;

[0046] - a poly(dimethylsiloxane-co-methylvinylsiloxane) with dimethylvinylsilyl ends; and

[0047] - a poly(dimethylsiloxane-co-methylvinylsiloxane) with trimethylsilyl ends.

[0048] Preferably, the organopolysiloxane A contains terminal dimethylvinylsilyl units and even more preferably the organopolysiloxane A is a poly(dimethylsiloxane) with dimethylvinylsilyl ends.

[0049] Preferably, the organopolysiloxane compound A has a mass content of alkenyl unit of between 0.001% and 30%, preferably between 0.01% and 10%, preferably between 0.02% and 5%.

[0050] The silicone composition preferably comprises from 50% to 95% by weight of organopolysiloxane A, even more preferably from 60% to 90% by weight of organopolysiloxane A.

[0051] According to one embodiment, it is possible that the silicone composition according to the present invention contains a branched organopolysiloxane or resin comprising C2-C12 alkenyl units. Branched organopolysiloxanes, also called resins, contain “T” siloxyl units (R 1SiCLn) and / or siloxyl units “Q” (SiOj 2). The symbols R 1 are as described above. Examples of branched organopolysiloxanes are:

[0052] - a poly(dimethylsiloxane)(methylsiloxane) with trimethylsilyl and dimethyl-vinylsilyl ends, consisting of “M” trimethylsiloxy, “M” dimethylvinylsiloxy, “D” dimethylsiloxy and “T” methylsiloxy units;

[0053] - a resin consisting of “M” trimethylsiloxy, “M” dimethylvinylsiloxy and “Q” units; and

[0054] - a resin consisting of “M” trimethylsiloxy, “D” methylvinylsiloxy and “Q” units.

[0055] However, according to a preferred embodiment, the silicone composition does not comprise branched organopolysiloxanes or resins comprising C2-C12 alkenyl units.

[0056] Organopolysiloxane B is an organopolysiloxane having, per molecule, at least two SiH units. It is therefore an organohydrogenpolysiloxane compound. Preferably, compound B comprises at least three SiH units. According to a preferred embodiment, the silicone composition of the invention comprises one or more organopolysiloxane B in mixtures.

[0057] According to a preferred embodiment, the silicone composition according to the invention comprises at least one organopolysiloxane having, per molecule, two SiH units, and at least one organopolysiloxane having, per molecule, three or more SiH units.

[0058] According to one embodiment of the invention, the silicone composition comprises at least one linear organopolysiloxane B having, per molecule, at least two SiH units and an organopolysiloxane B having a branched structure such as a silicone resin.

[0059] Organopolysiloxane B may advantageously be an organopolysiloxane comprising at least two, preferably at least three, siloxyl units of the following formula: H d R 2 e SiO(4-de) / 2 in which R 2 represents a monovalent radical having from 1 to 12 carbon atoms, d = 1 or 2, e = 0, 1 or 2 and d+e = 1, 2 or 3; and optionally other units of the following formula: R 2 fSiO<4-f) / 2 in which R 2 has the same meaning as above, and f = 0, 1, 2, or 3.

[0060] It is understood that, if several R groups 2 are present in the above formulas, they can be the same or different from each other.

[0061] Preferably, R 2may represent a monovalent radical selected from the group consisting of alkyl groups having 1 to 8 carbon atoms, optionally substituted by at least one halogen atom such as chlorine or fluorine, cycloalkyl groups having 3 to 8 carbon atoms and aryl groups having 6 to 12 carbon atoms. R 2 may advantageously be selected from the group consisting of methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl.

[0062] The symbol d is preferably equal to 1.

[0063] Organopolysiloxane B may have a linear, branched, or cyclic structure. The degree of polymerization is preferably greater than or equal to 2. Generally, it is less than 5000. Preferably, the viscosity of organopolysiloxane B is between 1 mPa.s and 5000 mPa.s, more preferably between 1 mPa.s and 2000 mPa.s, and even more preferably between 5 mPa.s and 1000 mPa.s.

[0064] When it comes to linear polymers, these are essentially made up of siloxyl units “D” chosen from the R units 2 2SiO2 / 2 and R 2 HSiC>2 / 2, and terminal “M” siloxyl units chosen from the R units 2 3SiOi / 2 and R 2 2HSiOi / 2, where R 2 has the same meaning as above.

[0065] Examples of linear organohydrogenpolysiloxanes which may be compounds B according to the invention are:

[0066] - a poly(dimethylsiloxane) with hydrogenodimethylsilyl ends;

[0067] - a poly(dimethylsiloxane-co-methylhydrogensiloxane) with trimethylsilyl ends; - a poly(dimethylsiloxane-co-methylhydrogensiloxane) with hydrogenodimethylsilyl ends;

[0068] - a poly(methylhydrogensiloxane) with trimethylsilyl ends; and

[0069] - a cyclic poly(methylhydrogensiloxane).

[0070] In one embodiment, the organopolysiloxane B according to the silicone composition of the invention comprises a linear organohydrogenpolysiloxane or several linear organohydrogenpolysiloxanes in mixtures.

[0071] In one embodiment, the organopolysiloxane B according to the silicone composition of the invention comprises an organohydrogenpolysiloxane B which is a poly(dimethylsiloxane-co-methylhydrogensiloxane) with hydrogenodimethylsilyl ends and an organohydrogenpolysiloxane B which is a poly(methylhydrogensiloxane) with trimethylsilyl ends.

[0072] When the organohydrogenpolysiloxane B has a branched structure, it is preferably chosen from the group consisting of silicone resins of the following formulae:

[0073] - M'Q where the hydrogen atoms linked to silicon atoms are carried by the M groups;

[0074] - MM'Q where the hydrogen atoms linked to silicon atoms are carried by a part of the M patterns;

[0075] - MD'Q where the hydrogen atoms linked to silicon atoms are carried by the D groups;

[0076] - MDD'Q where the hydrogen atoms linked to silicon atoms are carried by part of the D groups;

[0077] - MM'TQ where the hydrogen atoms linked to silicon atoms are carried by part of the M motifs;

[0078] - MM'DD'Q where the hydrogen atoms linked to silicon atoms are carried by part of the M and D motifs;

[0079] - and their mixtures, with M = siloxyl unit of formula R 2 3SiOi / 2, M' = siloxyl unit of formula R 2 2HSiOi / 2, D = siloxyl unit of formula R 2 2SiO2 / 2, D' = siloxyl unit of formula R 2 HSiC>2 / 2, T = siloxyl unit of formula R 2 3SiOi / 2 and Q = siloxyl unit of formula SiOjn- where R 2 has the same meaning as above.

[0080] In one embodiment, the organopolysiloxane B according to the silicone composition of the invention comprises one or more linear organohydrogenpolysiloxane mixtures, and a silicone resin.

[0081] In one embodiment, the organopolysiloxane B according to the silicone composition of the invention comprises an organohydrogenpolysiloxane B which is a poly(dimethylsiloxane-co-methylhydrogensiloxane) with hydrogenodimethylsilyl ends, an organohydrogenpolysiloxane B which is a poly(methylhydrogensiloxane) with trimethylsilyl ends and a silicone resin.

[0082] Preferably, the organopolysiloxane B has a mass content of Si-H hydrogenosilyl functions of between 0.2% and 91%, more preferably between 3% and 80% and even more preferably between 15% and 70%. Advantageously, the molar ratio of the Si-H hydrogenosilyl functions of the organopolysiloxanes B to the alkene functions of the organopolysiloxanes A is between 0.01 and 20, preferably between 0.1 and 10, preferably between 0.5 and 5, more preferably between 1 and 5, and even more preferably between 1 and 3.

[0083] The silicone composition according to the invention preferably comprises from 0.1% to 20% by weight, more preferably from 0.1% to 10%, and even more preferably from 0.5% to 5% by weight, of organopolysiloxane B.

[0084] The hydrosilylation catalyst C may in particular be chosen from platinum and rhodium compounds but also from silicon compounds such as those described in patent applications WO 2015 / 004396 and WO 2015 / 004397, germanium compounds such as those described in patent applications WO 20160 / 75414 or nickel, cobalt or iron complexes such as those described in patent applications WO 2016 / 071651, WO 2016 / 071652 and WO 2016 / 071654. The catalyst C is preferably a compound derived from at least one metal belonging to the platinum group. These catalysts are well known. In particular, it is possible to use the complexes of platinum and an organic product described in US patents 3,159,601, US 3,159,602, US 3,220,972 and European patents EP 0.057.459, EP 0.188.978 and EP 0.190.530, the complexes of platinum and vinyl organosiloxanes described in US patents 3,419,593, US 3,715,334, US 3,377,432 and US 3,814,730.Alternatively, a photo-activatable hydrosilylation catalyst may be used. Said catalyst may be activated by irradiation, in particular by UV radiation.

[0085] Preferably, catalyst C is a compound derived from platinum. In this case, the weight quantity of catalyst C, calculated as the weight of platinum metal, is generally between 2 ppm and 400 ppm by mass, more preferably between 50 ppm and 300 ppm, and even more preferably between 70 ppm and 200 ppm, based on the total weight of the silicone composition. Alternatively, the weight quantity of catalyst C, calculated as the weight of platinum metal, may be between 5 ppm and 200 ppm by mass, more preferably between 20 ppm and 200 ppm,

[0086] Preferably, catalyst C is a Karstedt platinum.

[0087] The silicone composition according to the invention may optionally contain a crosslinking inhibitor D. Crosslinking inhibitors are designed to slow down the crosslinking reaction and are also called retarders. Crosslinking inhibitors are well known in the prior art. Examples include the cyclic polymethylvinylsiloxanes and acetylenic alcohols described in US Patent 3,923,705, the acetylenic alcohols described in US Patent 3,445,420, the heterocyclic amines described in US Patent 3,188,299, diallyl maleate and other dialkyl esters described in US Patent 4,256,870, the olefinic siloxanes described in US Patent 3,989,667, and the dialkyl ethynedicarboxylates described in US Patent 4,347,346.The following classes of inhibitors may also be mentioned: hydrazines, triazoles, phosphines, mercaptans, organic nitrogen compounds, acetylenic alcohols, silylated acetylenic alcohols, maleates, fumarates, ethylenically or aromatically unsaturated amides, ethylenically unsaturated isocyanates, olefinic siloxanes, unsaturated hydrocarbon monoesters and diesters, conjugated eneynes, hydroperoxides, nitriles and diaziridines.The crosslinking inhibitor D is preferably selected from 1,3,5,7-tetramethyl-1,3,5,7-tetravinyl-cyclotetrasiloxane, 1-ethynyl-1-cyclohexanol (ECH), 3-methyl-1-butyn-3-ol, 2-methyl-3-butyn-2-ol, 3-butyn-1-ol, 3-butyn-2-ol, propargyl alcohol, 2-phenyl-2-propyn-1-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynylcyclopentanol, 1-phenyl-2-propynol, 3-methyl-1-penten-4-yn-3-ol, 3-methyl-1-dodecyne-3-ol, 3,7,1-trimethyl-1-dodecyne-3-ol, diphenyl-1,1-propyne-2-ol-1, 3,6-diethyl-1-nonyne-3-ol, 3-methyl-1-pentadecyne-3-ol, and mixtures thereof. Acetylenic alcohols are highly preferred crosslinking inhibitors D according to the invention, and very particularly 1-ethynyl-1-cyclohexanol (ECH). According to one embodiment, the silicone composition D comprises between 1 ppm and 1000 ppm of crosslinking inhibitor D, preferably between 20 ppm and 500 ppm, relative to the total weight of the silicone composition.

[0088] The silicone composition crosslinkable by polyaddition reaction may optionally comprise a filler. According to one embodiment, the silicone composition comprises between 5% and 40% by weight of filler relative to the total weight of the silicone composition. Advantageously, the silicone composition comprises between 10% and 30% by weight of filler.

[0089] The filler that may be provided is preferably mineral. The filler may be a very finely divided product with an average particle diameter of less than 0.1 μm. The filler may be siliceous in particular. In the case of siliceous materials, they may act as reinforcing or semi-reinforcing fillers. The reinforcing siliceous fillers are chosen from colloidal silicas, combustion and precipitation silica powders or mixtures thereof. These powders have an average particle size generally less than 0.1 μm (micrometers) and a BET specific surface area greater than 30 m2 / g, preferably between 30 m 2 / g and 350 m 2 / g. Semi-reinforcing siliceous fillers such as diatomaceous earth or ground quartz may also be used. These silicas may be incorporated as such or after being treated with organosilicon compounds commonly used for this purpose. These compounds include methylpolysiloxanes such as hexamethyldisiloxane, octamethylcyclotetrasiloxane, methylpolysilazanes such as hexamethyldisilazane, hexamethylcyclotrisilazane, tetramethyldivinyldisilazane, chlorosilanes such as dimethyldichlorosilane, trimethylchlorosilane, methylvinyldichlorosilane, dimethylvinylchlorosilane, alkoxysilanes such as dimethyldimethoxysilane, dimethylvinylethoxysilane, trimethylmethoxysilane, and mixtures thereof. As for non-siliceous mineral materials, they can be used as semi-reinforcing or bulking mineral fillers.Examples of these non-siliceous fillers that can be used alone or in mixtures are calcium carbonate, possibly surface-treated with an organic acid or an ester of an organic acid, calcined clay, rutile-type titanium oxide, iron, zinc, chromium, zirconium, magnesium oxides, different forms of alumina (hydrated or not), boron nitride, lithopone, barium metaborate, barium sulfate and glass microbeads. These fillers are coarser, generally with an average particle diameter greater than 0.1 μm and a specific surface area generally less than 30 μm. 2 / g. These charges may have been surface modified by treatment with the various organosilicon compounds usually used for this purpose.

[0090] Preferably, the filler is silica, and even more preferably combustion silica. Advantageously, the silica has a BET specific surface area of ​​between 75 m 2 / g and 410 m 2 / g.

[0091] The silicone composition according to the present invention may also comprise other functional additives usual in silicone compositions. As families of usual functional additives, mention may be made of: adhesion promoters, adhesion modulators, additives for increasing consistency, additives for thermal resistance, oil resistance or fire resistance, for example metal oxides, virucides, bactericides, anti-abrasion additives, and pigments (organic or mineral).

[0092] However, some common additives in silicone compositions are not compatible with use in food contact. It is therefore preferable that the silicone composition does not contain any additional additives.

[0093] Typically, an adhesion promoting compound may be an organosilicon compound comprising an adhesion promoting functional group. In particular, it may be an organosilicon compound comprising:

[0094] - one or more hydrolyzable groups linked to the silicon atom, generally alkoxy groups linked to the silicon atoms, and

[0095] - one or more organic groups chosen from mercaptan groups, the urea group, the isocyanurate group, (meth)acrylate, epoxy, and alkenyl radicals.

[0096] Examples of compounds that may be mentioned include, alone or in mixtures: vinyltrimethoxysilane (VTMO), 3-glycidoxypropyl-trimethoxy silane (GLYMO), methacryloxypropyltrimethoxy silane (MEMO), [H2N(CH2)3]Si(OCH2CH2CH3)3, [H2N(CH2)3]Si(OCH3)3, [H2N(CH2)3]Si(OC2H5)3, [H2N(CH2)4]Si(OCH3)3, [H2NCH2CH(CH3)CH2CH2]SiCH3(OCH3)2, [H2NCH2]Si(OCH3)3, [n-C4H9- HN-CH2]Si(OCH3)3, [H2N(CH2)2NH(CH2)3] Si(OCH3)3, H2N(CH2)2NH(CH2)3]Si(OCH2CH2OCH3)3, [CH3NH(CH2)2NH(CH2)3]Si(OCH3)3, [H(NHCH2CH2)2NH(CH2)3]Si(OCH3)3, HS(CH2)3Si(OCH3)3, NH2CONH2(CH2)3Si(OCH3), or polyorganosiloxane oligomers, containing for example from 2 to 100 silicon atoms, containing such organic groups at a content greater than 20%. Mention may also be made specifically of organosilicon compounds comprising at least one, preferably at least two, alkoxy groups bonded to a silicon atom and at least one epoxy group.Furthermore, an adhesion promoting compound may be an organic titanium compound, preferably a titanium chelate or a metal alkoxide of formula Ti(OR)4 where R is selected from linear or branched C1-C8 alkyl groups, alkoxyalkyl groups or acyl groups. Even more preferably, the organic titanium compound is selected from titanium alkoxides such as butyl titanate, isopropyl titanate, methyl titanate and octyl titanate. Even more preferably, the organic titanium compound is butyl titanate (TBOT).

[0097] According to a preferred embodiment, the silicone composition according to the present invention does not contain any adhesion promoting compound. In particular, the silicone composition according to the present invention preferably does not contain any of the adhesion promoting compounds cited individually above.

[0098] Furthermore, the silicone composition according to the present invention preferably does not contain an organic solvent, typically no toluene or xylene.

[0099] According to a preferred embodiment, the silicone composition crosslinkable by polyaddition reaction according to the invention comprises, based on the total weight of the silicone composition:

[0100] - from 50% to 95%, preferably from 60% to 90%, of an organopolysiloxane A having, per molecule, at least two C2-C12 alkenyl groups linked to silicon,

[0101] - from 0.1% to 20%, preferably from 0.5% to 5%, of an organopolysiloxane B having, per molecule, at least two SiH units,

[0102] - from 1 ppm to 400 ppm, preferably from 2 ppm to 200 ppm, of a hydrosilylation catalyst C (calculated by weight of metal),

[0103] - optionally, from 1 ppm to 1000 ppm, preferably from 20 ppm to 500 ppm, of a crosslinking inhibitor D,

[0104] - optionally, from 5% to 40%, preferably from 10% to 30%, of a silica filler.

[0105] According to a particular embodiment, the silicone composition crosslinkable by polyaddition reaction according to the invention comprises, based on the total weight of the silicone composition:

[0106] - from 50% to 95%, preferably from 60% to 90%, of an organopolysiloxane A having, per molecule, at least two C2-C12 alkenyl groups linked to silicon,

[0107] - from 0.1% to 20%, preferably from 0.5% to 5%, of an organopolysiloxane B having, per molecule, at least two SiH units, and an organopolysiloxane B having a branched structure such as a silicone resin,

[0108] - from 1 ppm to 400 ppm, preferably from 2 ppm to 200 ppm, of a hydrosilylation catalyst C (calculated by weight of metal),

[0109] - optionally, from 1 ppm to 1000 ppm, preferably from 20 ppm to 500 ppm, of a crosslinking inhibitor D,

[0110] - optionally, from 5% to 40%, preferably from 10% to 30%, of a silica filler. The silicone composition crosslinkable by polyaddition reaction according to the invention preferably has a viscosity greater than 5000 mPa.s, more preferably between 10000 mPa.s and 100000 mPa.s.

[0111] According to one embodiment, the silicone composition according to the invention can be prepared from a two-component system characterized in that it is presented in two distinct parts intended to be mixed to form said silicone composition, and in that one of the parts comprises catalyst C and does not comprise organopolysiloxane B, while the other part comprises organopolysiloxane B and does not comprise catalyst C.

[0112] The silicone composition may be prepared by mixing all of the different components as described above. Mixing may be carried out with mixers suitable for such compositions, for example mixers or planetary mixers under inert gas atmospheres. Alternatively, the two parts of the composition may be stored in a two-component adhesive cartridge, with mixing being carried out at the cartridge outlet by a static mixer.

[0113] After crosslinking, the silicone composition according to the invention forms a structural silicone adhesive allowing the assembly of several substrates.

[0114] The food contact article according to the present invention comprises a first substrate and a second substrate, these two substrates being joined by the adhesive as described above. The first substrate comprises a support coated with a food contact silicone coating.

[0115] The support is preferably a fibrous support. Among the fibrous supports, we can cite various varieties of paper (such as Kraft paper whose degree of refinement can be any, glassine paper, greaseproof papers), cardboards, vegetable parchment, papers coated with polyethylene or carboxymethylcellulose, cellulose sheets. Very preferably, the support is chosen from papers and cardboards. In the case of a paper support, we can select a paper preferably having a Bendtsen porosity of between 0.1 mL / min and 500 mL / min according to the ISO 5636-3 standard and a COBB value in water of between 5 and 30 according to the ISO 535 method.

[0116] Alternatively, the support may be a polymeric material, for example a sheet of polymeric materials such as polyethylene, polypropylene, polyethyl terephthalate, polyester or even natural polymer.

[0117] Alternatively, the support may be made of metal, for example a metal sheet.

[0118] According to one embodiment, the support according to the present invention is a flexible support. In this text, the term "flexible support" means a support that can be bent or folded by human force alone without breaking or being damaged. In contrast, according to another embodiment, the support according to the present invention is a rigid or semi-rigid support. In this text, the term "rigid or semi-rigid support" means a support that cannot be bent or folded easily by human force alone without breaking or being damaged.

[0119] Preferably, the support is in the form of a sheet or a film. However, any other form is possible within the scope of the present invention.

[0120] According to the present invention, the support of said first substrate is coated with a silicone coating suitable for food contact. The silicone coating may be present on one side of the support or on both sides. Such coatings are known to those skilled in the art. Typically, the silicone coating suitable for food contact may be obtained by coating the support and then crosslinking a silicone composition. Said silicone composition may be a silicone emulsion or a solvent-free silicone composition. For silicone emulsions, reference may in particular be made to European patent application EP 0253747 and international applications WO 99 / 35181 and WO 2018 / 178321. For solvent-free silicone compositions, reference may for example be made to international application WO 2005 / 059039.

[0121] Preferably, a suitable silicone coating consists of a water-repellent and non-stick coating or film obtained by coating the support and then crosslinking a silicone emulsion. Said silicone emulsion can crosslink via polycondensation chemistry or via polyaddition chemistry. Preferably, said silicone emulsion is an aqueous silicone emulsion crosslinkable into a silicone elastomer by polyaddition reactions. Generally, polyaddition chemistry is preferred for reasons of suitability for food contact, since certain tin-based polycondensation catalysts cannot be used. Furthermore, without wishing to be bound by this theory, it is believed that a silicone coating obtained by polyaddition reactions could have residual chemical functions on the surface, potentially available to serve as an anchor point for the structural silicone adhesive which involves the same crosslinking chemistry.

[0122] It may in particular be an aqueous silicone emulsion, crosslinkable into a silicone elastomer by polyaddition reactions, comprising:

[0123] - at least one organopolysiloxane having per molecule at least two unsaturated functional groups of C2-C6 alkenyl type, linked to silicon,

[0124] - at least one organopolysiloxane having per molecule at least three hydrogen atoms bonded to silicon,

[0125] - at least one polyaddition catalyst,

[0126] - at least one emulsifying agent,

[0127] - water,

[0128] - possibly at least one crosslinking inhibitor,

[0129] - optionally at least one pH fixing agent chosen so as to maintain the pH of the emulsion between 5 and 9, preferably between 5.5 and 8.5 and even more preferably between 6 and 8, - optionally at least one formulation additive, such as for example a bactericidal agent such as for example sorbic acid, an antifreeze and / or wetting agent such as for example glycols such as propylene or ethylene glycol, an antifoam, a filler, preferably mineral, chosen from siliceous or non-siliceous materials, siliceous fillers being more particularly preferred, a colorant or pigment, an acidifier such as for example acetic acid.

[0130] However, some common additives in silicone compositions are not compatible with use in food contact. It is therefore preferable that the silicone composition does not contain any additional additives.

[0131] The manufacture of the support coated with a silicone coating according to the present invention, in particular silicone paper, can typically be carried out by in-line coating, that is to say directly on the machine manufacturing the support once the sheet has been formed.

[0132] The silicone coating preferably has a thickness of between 0.05 g / m 2 and 1 g / m 2 . However, the amount of silicone emulsion coated on the substrate must be adapted considering the penetration of the silicone into the substrate. For example, if the penetration of the silicone into the paper is between 0% and 50% and the paper is coated on both sides, then the total amount of silicone per m 2 of paper is preferably between 0.1 g / m 2 and 4 g / m 2 .

[0133] According to a first embodiment, the second substrate according to the present invention is identical to the first substrate. For example, the first substrate and the second substrate may be a single silicone sheet folded on itself. The second substrate therefore comprises a support coated with a silicone coating suitable for food contact. The support and the silicone coating may be as described previously for the first substrate. In this configuration, the structural silicone adhesive is preferably inserted between the two substrates and is in contact with the silicone coatings of the two substrates.

[0134] According to a second embodiment, the second substrate according to the present invention is different from the first substrate. The second substrate may be a support as described above without a silicone coating. For example, the second substrate may be a transparent sheet of polymeric material. In this configuration, the structural silicone adhesive is preferably inserted between the two substrates and is in contact with the silicone coating of the first substrate, the second substrate not necessarily having a silicone coating.

[0135] The article suitable for food contact according to the invention can be obtained by a process comprising the steps of:

[0136] - providing a first substrate and a second substrate, the first substrate comprising a support coated with a silicone coating suitable for food contact,

[0137] - depositing on the silicone coating of said first substrate a silicone composition crosslinkable by polyaddition reaction suitable for food contact,

[0138] - assembling the second substrate with the first substrate so that said silicone composition is between the two substrates,

[0139] - crosslink or allow said silicone composition to crosslink to obtain the bonding of the two substrates by a structural silicone adhesive.

[0140] The deposition of the crosslinkable silicone composition by polyaddition reaction suitable for food contact on the silicone coating of said first substrate can be carried out according to methods known to those skilled in the art. The deposition can typically be carried out by casting, by brush, by doctor blade, by immersion or by extrusion. According to one embodiment, the deposition of the silicone composition is carried out continuously on a portion of the silicone coating of the first substrate. Thus, the silicone coating of the first substrate is covered for example by a strip of silicone composition. This embodiment is advantageous if it is desired to obtain a continuous and waterproof bond between the first and the second substrate.

[0141] However, it is also possible within the framework of the present invention to deposit the silicone composition discontinuously, on certain areas only or for example in points, when a watertight bond is not desired.

[0142] The quantity of silicone composition deposited on the silicone coating of the first substrate may be between 1 g / m 2 and 50 g / m 2 , preferably between 5 g / m 2 and 20 g / m 2 .

[0143] Prior to the deposition of the crosslinkable silicone composition by polyaddition reaction, the method may comprise an optional step of surface treatment of the silicone coating of said first substrate, for example a Corona treatment.

[0144] The assembly of the second substrate with the first substrate can be carried out continuously using contacting cylinders and doctor blades.

[0145] The silicone composition can crosslink without external intervention if the reactivity between the parts brought into contact beforehand is sufficient. However, it is preferable to thermally activate the crosslinking reaction. The means for thermal activation of the crosslinking are conventionally ovens (for example tunnel ovens), heated laminating rollers, or infrared sources. This thermal activation can be supplemented by actinic activation and / or by electron bombardment. The crosslinking temperature can be greater than 120°C, without exceeding the degradation temperature of the support, preferably between 160°C and 200°C. The duration of this thermal activation step of the crosslinking can be between 0.1 s and 30 s, preferably between 0.1 s and 5 s.

[0146] Alternatively, the crosslinking reaction can be activated by irradiation, for example by UV. For this, a person skilled in the art can choose a photo-activatable polyaddition catalyst, and possibly appropriate photosensitizing additives. Advantageously, the steps of manufacturing the article suitable for food contact as described above can be carried out continuously, using devices known to a person skilled in the art, in particular using packaging manufacturing machines.

[0147] After crosslinking, the final thickness of the structural silicone adhesive may be between 1 pm and 50 pm, preferably between 5 pm and 20 pm.

[0148] The article suitable for food contact according to the present invention may advantageously be food packaging. It may for example be chosen from:

[0149] - flexible packaging: bags, pouches and pouches, in particular for waterproof packaging, with the possible presence of a ventilation valve, sandwich bags, bags with or without transparent window, bloomer bags, etc.

[0150] - semi-rigid packaging: boxes, meal boxes, pastry boxes, hamburger boxes, cases, cones, trays, pots with or without lids, cups, shells, cartons, bricks, etc.

[0151] - rigid packaging: corrugated cardboard box (pizza box type).

[0152] The article according to the present invention has properties which make it particularly interesting for food packaging professionals, and for the final consumer:

[0153] - It is suitable for food contact and meets the requirements of current regulations. Silicone, when correctly formulated and implemented, is known for its non-toxicity and inertness with respect to food products. In addition, thanks to the use of a polyaddition silicone adhesive, the product does not contain tin-based catalysts.

[0154] - Thanks to the silicone coating and silicone adhesive, the product is able to withstand significant temperature variations, typically from -30°C to +250°C or from -70°C to +250°C. The product can be used for both freezing and cooking. It is particularly suitable for microwave cooking. The product has water barrier properties. It is also non-stick and water-repellent: food does not stick to its packaging even after storage.

[0155] - The choice of structural silicone adhesive allows the substrates to be joined cohesively and permanently. It is therefore possible to produce a waterproof assembly useful for long-term food preservation.

[0156] - Finally, from an implementation point of view, the manufacture of the article suitable for food contact according to the invention is possible at high speed, preferably with standard industrial tools in the packaging field. The speed of crosslinking of the adhesive is compatible with high industrial speeds. The viscosity of the adhesive is also compatible with industrial application tools. Finally, the crosslinking of the adhesive is carried out without the release of odor. The present invention also relates to the use of a structural silicone adhesive, suitable for food contact, obtained by crosslinking a silicone composition crosslinkable by polyaddition reaction for the manufacture of an article suitable for food contact.

[0157] Other details or advantages of the invention will appear more clearly from the examples given below for information purposes only.

[0158] Examples

[0159] Manual coating tests

[0160] A5-sized silicone baking paper was manually coated with a silicone compound. A second baking paper, identical to the first, was manually applied over the coating and the assembly was crosslinked as detailed below.

[0161] The silicone compositions tested are as follows:

[0162] PSA 1: Silicone PSA consisting of polydimethylsiloxane gum and MQ(OH) hydroxylated resin in toluene. Dry matter content: 60%. Viscosity: 80000 mPa.s

[0163] PSA 2: Silicone PSA consisting of polydimethylsiloxane gum and MQ(OH) hydroxylated resin in toluene. Dry matter content: 60%. Viscosity: 70000 mPa.s

[0164] Adhesive 1: RTV2 type silicone composition, in 2 parts, crosslinking by polyaddition.

[0165] Part A:

[0166] For 100 games:

[0167] -74.38 parts of polydimethylsiloxane oil with Si(CH3)2CH=CH2 ends with a viscosity of 1500 mPa.s

[0168] -2.11 parts of organopolysiloxane oils B consisting of a polydimethylsiloxane oil with Si(CH3)2H ends, and a polymethylhydrogenosiloxane oil with Si(CH3)3 ends, -23.48 parts of a treated combustion silica, 1

[0169] -0.03 parts of ethynyl-l-cyclohexanol (ECH).

[0170] Part B:

[0171] For 100 games:

[0172] -99 parts of polydimethylsiloxane oil with Si(CH3)2CH=CH2 ends having a viscosity of 100,000 mPa.s,

[0173] - 1 part of a Karstedt platinum catalyst (10 ppm relative to the total weight of the composition). Parts A and B are mixed to obtain a mass ratio of part A to part B equal to 10.

[0174] Viscosity of adhesive 1: 40000 mPa.s.

[0175] Adhesive 2 (Modif 3): RTV2 type silicone composition, in 2 parts, crosslinking by polyaddition.

[0176] Part A:

[0177] For 100 games:

[0178] -75.04 parts of polydimethylsiloxane oil with Si(CH3)2CH=CH2 ends with a viscosity of 1500 mPa.s

[0179] -1.25 parts of organopolysiloxanes B consisting of a MM'Q type resin where the hydrogen atoms linked to silicon atoms are carried by the M groups, of a polymethylhydrogensiloxane oil with Si(CH3)3 ends, and of a poly(dimethylsiloxane-co-methylhydrogensiloxane) oil with Si(CH3)2H ends,

[0180] -23.68 parts of treated combustion silica,

[0181] -0.03 parts of l-ethynyl-1-cyclohexanol (ECH).

[0182] Part B:

[0183] -99 parts of polydimethylsiloxane oil with Si(CH3)2CH=CH2 ends having a viscosity of

[0184] 100,000 mPa.s,

[0185] -1 part of a Karstedt platinum catalyst (10 ppm relative to the total weight of the composition). Parts A and B are mixed to obtain a mass ratio of part A to part B equal to 10.

[0186] Viscosity of adhesive 2: 40000 mPa.s.

[0187] Adhesive 3 (Modif 7): RTV2 type silicone composition, in 2 parts, crosslinking by polyaddition.

[0188] Part A:

[0189] For 100 games:

[0190] -75.06 parts of polydimethylsiloxane oil with Si(CH3)2CH=CH2 ends with a viscosity of 1500 mPa.s

[0191] -1.22 parts of organopolysiloxane oils B consisting of polymethylhydrogensiloxane oil with Si(CH3)3 ends and a poly(dimethylsiloxane-co-methylhydrogensiloxane) oil with Si(CH3)2H ends.

[0192] -23.69 parts of treated combustion silica,

[0193] -0.03 parts of l-ethynyl-1-cyclohexanol (ECH).

[0194] Part B:

[0195] For 100 games:

[0196] -99 parts of polydimethylsiloxane oil with Si(CH3)2CH=CH2 ends having a viscosity of 100,000 mPa.s, - 1 part of a Karstedt platinum catalyst (10 ppm relative to the total weight of the composition).

[0197] Parts A and B are mixed to obtain a mass ratio of part A to part B equal to 10.

[0198] Viscosity of adhesive 3: 40000 mPa.s.

[0199] Adhesive 4 (Comparative): RTV2 type silicone composition, in 2 parts, crosslinking by polyaddition. Part A: polydimethylsiloxane oils with Si(CH3)2CH=CH2 ends, polydimethylsiloxane oil with Si(CH3)3H ends, poly(methylhydrogensiloxane-co-dimethylsiloxane) oil with Si(CH3)3 ends, treated combustion silica, 1-ethynyl-l-cyclohexanol (ECH), 3-glycidoxypropyl-trimethoxysilane (GLYMO).

[0200] Part B: Si(CH3)2CH=CH2 end-coated polydimethylsiloxane oils, treated combustion silica, Karstedt platinum catalyst (10 ppm based on total composition weight), butyl titanate (TBOT).

[0201] Parts A and B are mixed to obtain a mass ratio of part A to part B equal to 10. Viscosity of adhesive 4: 40000 mPa.s.

[0202] This composition is unsuitable for food contact due to the presence of adhesion promoters such as 3-glycidoxypropyl-trimethoxy silane (GLYMO) or butyl titanate (TBOT).

[0203] Adhesive 5 (Comparison): RTV1 type silicone composition, in 1 part, crosslinking by polycondensation.

[0204] Formulation: Hydroxy-terminated polydimethylsiloxane oils, treated combustion silica, methyltriacetoxy silane, tetra-n-butyl titanate (polycondensation catalyst).

[0205] The quality of the adhesion was evaluated on a dynamometer using a T-peel method, inspired by the ASTM D1876 standard. Particular attention was paid to the fracture surface of the specimens, which must be cohesive (tearing of the paper during the test) to guarantee optimal assembly performance.

[0206] The results are reported in Table 1 below:

[0207] The results obtained with PSA-type compositions are not conclusive and clearly lag behind structural adhesives. The adhesives of the present invention 1, 2 and 3, which are each a silicone composition crosslinking by polyaddition, make it possible to obtain satisfactory adhesion, while being suitable for food contact and not presenting any major drawback in terms of formability (for example odor).

[0208] Unlike Comparative Example (Adhesive 4), the adhesives of the present invention (1, 2 and 3) do not require the presence of an adhesion promoter to obtain satisfactory adhesion results. In addition, Comparative Example 5 is an adhesive that crosslinks by polycondensation and thus has the disadvantage of releasing acetic acid.

[0209] Furthermore, adhesives 2 and 3 of the present invention lead to satisfactory results despite a low thickness of coated adhesive. Thus, these embodiments are particularly advantageous on an industrial scale. Coating test with cylinders

[0210] A coating tool with two cylinders and a heated doctor blade was used. This tool is shown in Figure 1: a first substrate (1) and a second substrate (2) were fixed on cylinders. An adhesive composition was applied by a dispensing means (3). A heated metal doctor blade (4) was brought into contact with the second support, before the assembly passed between two heated metal laminating cylinders (5). The air gap (6) was set at 0.1 mm between the two cylinders. The travel in the tool is manual and estimated at approximately 10 m / min. The set temperature of the doctor blade and the two metal cylinders is electronically regulated.

[0211] Substrate: Commercial silicone-coated baking paper

[0212] Composition of the silicone adhesive as described above for adhesive 1.

[0213] The crosslinking assessment is visual and carried out by the scissor blade fouling test: Immediately after crosslinking, a cutting test is carried out with a guillotine or scissors to estimate the fouling of the blade. The blade of the cutting tool must not become fouled and must remain free of silicone.

[0214] Adhesion is assessed manually: Immediately after crosslinking, the two parts of the assembly are firmly held together during a shear test. The assembly must be able to withstand the constraints imposed by the production tool.

[0215] The results are presented in Table 2 below:

[0216] [Table 2]

[0217] The assemblies obtained as described above were placed in a cold environment (-17°C) in a food freezer for 2 hours, then removed and immediately mechanically tested. Others were placed in a hot environment (+230°C) in a laboratory oven for 2 hours, then removed and immediately mechanically tested. In both cases, a preservation of the mechanical performance of the assembly was observed.

Claims

DEMANDS 1. Article suitable for food contact comprising a first substrate and a second substrate joined by an adhesive, said first substrate comprising a support coated with a silicone coating suitable for food contact, said adhesive being inserted between the two substrates and being in contact with the silicone coating of said first substrate, characterized in that said adhesive is a structural silicone adhesive, suitable for food contact obtained by crosslinking a silicone composition crosslinkable by polyaddition reaction.

2. Article according to claim 1, characterized in that the polyaddition reaction crosslinkable silicone composition comprises: - at least one organopolysiloxane A having, per molecule, at least two alkenyl groups in C2-C12 bonded to silicon, - at least one organopolysiloxane B having, per molecule, at least two SiH motifs, - a catalytically effective amount of at least one C polyaddition catalyst, preferably a platinum-based polyaddition catalyst, and - possibly at least one D crosslinking inhibitor.

3. Article according to claim 1 or claim 2, characterized in that the silicone composition crosslinkable by polyaddition reaction comprises between 5% and 40% by weight of filler relative to the total weight of the silicone composition.

4. Article according to any one of claims 1 to 3, characterized in that the silicone composition does not contain any organic solvent, typically no toluene or xylene.

5. Article according to any one of claims 1 to 4, characterized in that the silicone composition crosslinkable by polyaddition reaction has a viscosity greater than 5000 mPa.s, more preferably between 10000 mPa.s and 100000 mPa.s.

6. Article according to any one of claims 1 to 5, characterized in that the support is a fibrous support, preferably the support is chosen from papers and cardboards.

7. Article according to any one of claims 1 to 6, characterized in that the food-contact silicone coating consists of a water-repellent and non-stick coating or film obtained by coating the support and then cross-linking a silicone emulsion, preferably an aqueous silicone emulsion cross-linkable into a silicone elastomer by polyaddition reactions.

8. Article according to any one of claims 1 to 7, characterized in that said article is a food packaging, preferably selected from: - Flexible packaging: bags, pouches and bags, especially for waterproof packaging, possibly with a ventilation valve, sandwich bags, bags with or without a transparent window, bloomer bags... - Semi-rigid packaging: boxes, meal boxes, pastry boxes, hamburger boxes, cases, cones, trays, pots with or without lids, cups, shells, cartons, bricks... - rigid packaging: corrugated cardboard box (pizza box type).

9. A process for manufacturing an article suitable for food contact, said process comprising the steps of: - to provide a first substrate and a second substrate, the first substrate comprising a support coated with a food-grade silicone coating, - to deposit onto the silicone coating of said first substrate a food-contact-compatible silicone composition crosslinkable by polyaddition reaction, - to assemble the second substrate with the first substrate so that said silicone composition is between the two substrates, - to crosslink or allow the said silicone composition to crosslink in order to obtain the bonding of the two substrates by a structural silicone adhesive.

10. Use of a structural silicone adhesive suitable for food contact obtained by crosslinking a crosslinkable silicone composition by polyaddition reaction for the manufacture of an article suitable for food contact.

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