Recycling a multilayer system

Abstract

The present invention relates to a multilayer system F1 comprising: a layer C1 comprising at least one polypropylene, an adhesive layer Ad made up of a hot-melt self-adhesive composition CA, and a layer C2 comprising at least one polypropylene, said multilayer system F1 comprising at least 80% by weight of polypropylene or a mixture of polypropylenes relative to the total weight of said system. The invention also relates to the use of said system F1 for producing a recycled item.

Description

[0001] Recycling a multi-layer system

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a method for recycling a multi-layer system.

[0004] The present invention also relates to the use of a hot melt self-adhesive composition or a multi-layer system for preparing a recycled article.

[0005] TECHNOLOGICAL BACKGROUND

[0006] Multi-layer articles (or laminated articles) are used in many fields for packaging a wide variety of products, particularly in the food, cosmetics, and detergent industries. Depending on the requirements, these articles can be flexible or rigid. These include flexible packaging. These articles are generally made of different materials (composite multi-layer articles). The materials can be chosen from paper, metal, or thermoplastic polymers. Thermoplastic polymers can be chosen from polyethylene (PE), polypropylene (PP), ethylene vinyl acetate copolymers (EVA), polyamide (PA), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polymers derived from lactic acid (PLA), a polyhydroxyalkanoate (PHA), or their mixtures.

[0007] An individual layer of material can itself be made of several materials. For example, it can be a layer of thermoplastic polymers obtained by coextrusion of two polymers (there is then no glue between the coextruded layers), the individual layers of thermoplastic polymer can be additionally coated with a substance (for example based on aluminum oxide or silicon oxide), a protein layer or metallized (metallization with aluminum particles) to add an additional barrier effect.

[0008] The characteristics and properties of multi-layer articles will depend in particular on the materials used to obtain the layers. Thus, it is common to combine layers comprising different materials in order to obtain multi-layer articles, very generally composite multi-layer articles, combining the characteristics and properties of the different individual layers and therefore having particular characteristics and properties, for example in terms of visual appearance, gas and moisture barrier properties, safety or lack of toxicity for users, inertness with respect to packaged products, chemical resistance to packaged products and / or physical, mechanical, thermal and chemical resistance to manufacturing and packaging processes.

[0009] The layers can be assembled by lamination or co-extrusion. The lamination processes can be implemented using adhesive compositions or suitable devices.

[0010] Among the multi-layer articles, there are resealable trays that are used in the food industry and large-scale distribution to package foodstuffs, particularly fresh produce. Such packaging is described by US patent 4673601 and patent application EP 1053952. These trays are based on hot-melt self-adhesive compositions typically comprising tackifying resins and styrene block copolymers. Hot-melt adhesive compositions are also commonly referred to as HMPSA, corresponding to the initials of the English translation "Hot Melt Pressure Sensitive Adhesive". These are substances that are solid at room temperature and contain neither water nor solvent.Applied in the molten state, they solidify upon cooling, thus forming an adhesive layer which ensures the bond between the 2 thin layers of thermoplastic polymer material to be assembled, while providing the corresponding packaging with advantageous opening and reclosing properties.

[0011] Today, there is a wide variety of multi-layered articles with characteristics and properties suitable for multiple uses. However, these articles generally have the disadvantage of being single-use and generating waste. In order to meet the climate challenge, reduce environmental pollution, conserve natural resources, and adapt to more stringent regulations, it is imperative to develop recycling and recovery channels for this waste.

[0012] Despite the development of various recycling and recovery channels, many multi-layer articles are difficult to recycle, whether for reasons of yield, technical feasibility, performance, cost, etc. Thus, for example, the recycled materials obtained do not necessarily have the characteristics and properties required to obtain new articles such as molded articles: deterioration of mechanical and / or physical properties, incompatibility, cloudiness, etc.

[0013] There is therefore a need for new solutions to at least partially overcome these drawbacks.

[0014] There is therefore a real need to provide multi-layer articles that can be recycled, particularly mechanically, to lead to recycled articles having satisfactory mechanical and physicochemical properties and characteristics. DESCRIPTION OF THE INVENTION

[0015] F1 Multi-Layer System

[0016] The present invention relates to a multilayer system F1 comprising:

[0017] - a layer C1 comprising at least one polypropylene,

[0018] - an adhesive layer Ad consisting of a hot-melt self-adhesive composition CA comprising:

[0019] - i) from 40% to 80% by weight of at least one copolymer A comprising more than 80% by weight of units derived from but-1-ene;

[0020] - ii) optionally at least one copolymer T comprising more than 50% by weight of units derived from propylene;

[0021] - iii) at least one non-hydrogenated tackifying resin obtained by polymerization, or copolymerization with an aromatic hydrocarbon, of mixtures of unsaturated aliphatic hydrocarbons having from 4 to 6 carbon atoms derived from petroleum fractions;

[0022] - a layer C2 comprising at least one polypropylene, said multilayer system F1 comprising at least 80% by weight of polypropylene or a mixture of polypropylenes relative to the total weight of said system.

[0023] The multilayer system F 1 necessarily includes at least these three layers C1, C2 and Ad.

[0024] In the context of the present invention, the terms “article”, “structure” and “system” are used equivalently.

[0025] The F1 multilayer system can be a laminate, a complex, a film.

[0026] Advantageously, the F1 multi-layer system is mechanically recyclable.

[0027] The term “mechanically recyclable” is used to indicate that the F1 multi-layer system can be converted into a new article via a mechanical recycling process.

[0028] Mechanical recycling has been around for many years. From an environmental perspective, mechanical recycling (compared to chemical recycling) is the most energy-efficient and generates little waste. Chemical recycling is defined by ISO-15270 as the conversion into monomers or the production of new raw materials by modifying the chemical structure of plastic waste through cracking, gasification, or depolymerization, with the exception of energy recovery and incineration.

[0029] In the context of the invention, "mechanical recycling" means the definition given in the ISO-15270 standard, namely the processing of plastic waste into secondary raw material or products, without significant modification of the chemical structure of the material, for example without modification of the chemical functions and repeating patterns. Mechanical recycling includes at least one mechanical crushing step.

[0030] In the context of the invention, the terms "recycled" and "recyclate" refer to a material derived at least in part from either post-consumer waste or industrial waste. Post-consumer waste relates to objects that have been used by the consumer at least once already (i.e., they have served their initial purpose), while industrial waste relates to manufacturing residues that do not reach the consumer. Manufacturing residues may be, for example, offcuts from rolls of multi-layer laminates when they are cut after production to prepare packaging.

[0031] For the purposes of the invention, the term “virgin” refers to newly produced materials and / or articles prior to their first use and which have not been recycled.

[0032] Layers C1 and C2

[0033] Layer C1 may comprise a polypropylene or a mixture of polypropylenes. Layer C2 may comprise a polypropylene or a mixture of polypropylenes.

[0034] Layers C1 and C2 may comprise one or more polypropylenes having different physicochemical characteristics.

[0035] An example of polypropylene of the same chemical nature (same chemical composition) but different physicochemical characteristics is: layer C1 comprises a polypropylene having an MFI < 10 g / 10 min, layer C2 comprises a polypropylene having an MFI > 10 g / 10 min. Thus, the chemical nature is identical: polypropylene, but the physicochemical characteristics such as the MFI are different.

[0036] The physicochemical characteristics of layers C1 and C2 may be different, for example due to differences in the molecular weight of the polypropylene(s), the degree of branching of the polypropylene(s), the MFI, the density of the polypropylene(s), the thickness of the layer, etc.

[0037] Layers C1 and C2 may comprise one or more identical or different polypropylenes.

[0038] The term "polypropylene" covers homopolymers and copolymers prepared from propylene, said copolymers comprising at least more than 50 mol % of units derived from propylene monomer(s).

[0039] Polypropylenes can be prepared by different methods, such as polymerization in the presence of a Ziegler-Natta catalyst or a metallocene catalyst.

[0040] There are also commercial polypropylenes, such as RC2472 available from HMC Polymers; RD226CF available from BOREALIS; ELTEX P available from INEOS; PPR 3260 available from TOTAL; RD204CF (static copolymer MFI = 8 g / 10 min at 230°C / 2.16 kg) available from BOREALIS.

[0041] The thickness of the C1 layer can vary from 10 to 120 pm, preferably from 10 to 100 pm.

[0042] The thickness of the C2 layer can vary from 10 to 120 pm, preferably from 10 to 100 pm.

[0043] Each of the layers C1 and C2, independently of one another, may comprise one or more additives, for example chosen from the group consisting of slip agents, pigments, inks, fillers, thermal stabilizers, UV stabilizers, antistatic agents, and mixtures thereof.

[0044] Preferably, each of the layers C1 and C2, independently of one another, comprises more than 80% by weight of polypropylene, more preferably more than 90% by weight, and even more preferably more than 99% by weight of a polypropylene (or a mixture of polypropylenes) relative to the total weight of said layer C1 (or C2 respectively).

[0045] The two aforementioned layers C1 and C2 are preferably bonded together by the adhesive layer Ad.

[0046] Each of the layers 01 and 02, independently of one another, may comprise at least one layer chosen from aluminum oxides (AIOx), silicon oxides (SiOx), a metallization layer, and mixtures thereof.

[0047] The metallization layer is well known in the field, and corresponds to a very thin layer of aluminum, typically having a thickness of less than 100 nm, preferably ranging from 3 to 60 nm. The layer can be conventionally made by vapor deposition on the surface of the substrate (of layer 01 and / or 02).

[0048] The AIOx and SiOx layers are typically less than 500 nm, preferably less than 200 nm, for example in the order of 5 to 150 nm.

[0049] If they are present on layers 01 and / or 02, these layers (AIOx, SiOx or metallization) can be in direct contact with the adhesive layer.

[0050] Ad adhesive layer / CA hot melt adhesive composition

[0051] The thickness of the adhesive layer Ad may be between 1 and 50 μm, preferably between 5 and 35 μm, and even more preferably between 5 and 25 μm. The percentages by weight of the ingredients are relative to the total weight of said hot-melt self-adhesive composition CA.

[0052] As used herein, the term "copolymer" refers to a polymer obtained by the polymerization of at least two different monomers. The term "copolymer" includes terpolymers that comprise three different types of monomers. Unless otherwise indicated, the standards referred to throughout the application are those in effect on the date of filing of the application.

[0053] Copolymer A

[0054] The hot-melt self-adhesive composition CA preferably comprises from 45% to 80% by weight of copolymer(s) A, even more preferably from 50% to 80% by weight relative to the total weight of said composition. Even more preferably, the composition CA comprises from 50% to 70% by weight of copolymer(s) A relative to the total weight of said composition.

[0055] Copolymer A may have a lower density ranging from 0.800 to 0.899 g / cm 3 , preferably from 0.850 to 0.895 g / cm 3 , and even more preferably from 0.860 to 0.880 g / cm 3 .

[0056] Density can be measured according to ISO 1183-1.

[0057] Copolymer A may have a Shore A hardness less than or equal to 90, preferably less than or equal to 70, and even more preferably less than or equal to 65.

[0058] Shore A hardness can be measured according to ISO 868.

[0059] Copolymer A may have a polydispersity index (Mw / Mn) less than or equal to 3, preferably ranging from 2 to 3.

[0060] The polydispersity index can be measured by size exclusion chromatography (SEC), for example using a polystyrene standard.

[0061] Copolymer A preferably comprises more than 82% by weight of units derived from but-1-ene, and even more preferably more than 90% by weight of units derived from but-1-ene.

[0062] Copolymer A comprises units derived from an alpha-olefin preferably selected from ethylene, propylene, pentene, hexene, heptene, nonene, and mixtures thereof.

[0063] Copolymer A may comprise at most 20% by weight of units derived from alpha-olefin, preferably at most 18% by weight, and even more preferably at most 10% by weight of units derived from alpha-olefin, and more preferably from ethylene.

[0064] Preferably, copolymer A is a but-1-ene-ethylene copolymer.

[0065] The percentages by weight of monomer units are relative to the total weight of said copolymer A.

[0066] The weight percentage of monomeric units can be determined by any known method, such as for example by NMR.

[0067] Copolymer A is preferably obtained by polymerization in the presence of metallocene type catalysts which are well known in the art.

[0068] Copolymer A may also be commercially available. For example, the Koattro KT MR06 polymer marketed by LYONDELLBASELL may be cited, which is a C2 / C4 copolymer having an MFI at 190°C, 2.16 kg of 1.3 g / 10 min and comprising a mass content of C2 ethylene of approximately 8.3%.

[0069] Copolymer T

[0070] Preferably, the hot melt self-adhesive composition CA comprises copolymer T.

[0071] The hot-melt self-adhesive composition CA preferably comprises from 1.5% to 4.5% by weight of copolymer(s) T, preferably from 1.8 to 4.3% by weight of copolymer(s) T, more preferably from 2.0 to 4.0%, and even more preferably from 2.0 to 3.5% by weight relative to the total weight of said composition CA.

[0072] Copolymer T can be obtained by polymerization in the presence of metallocene or Ziegler-Natta type catalysts which are well known in the field.

[0073] A T copolymer may also be commercially available, such as ADSYL 7622 XCP marketed by LYONDELLBASELL comprising more than 50% by weight of propylene-derived units and having a melting temperature of 132°C as well as an MFI at 230°C, 2.16kg of 5.6 g / 10 min.

[0074] The copolymer T preferably comprises more than 60% by weight of units derived from propylene, more preferably more than 70% by weight of units derived from propylene, and even more preferably more than 80% by weight of units derived from propylene.

[0075] Preferably, the copolymer T is a propylene-ethylene-butene copolymer T.

[0076] The copolymer T may comprise from 1% to 25% by weight of units derived from ethylene, preferably from 1% to 10% by weight of units derived from ethylene, and even more preferably from 1% to 5% by weight of units derived from ethylene.

[0077] The copolymer T may comprise from 1% to 25% by weight of units derived from butene, preferably from 2% to 15% by weight of units derived from butene, and even more preferably from 5% to 12% by weight of units derived from butene.

[0078] The percentages by weight of monomer units are relative to the total weight of said copolymer T.

[0079] The weight percentage of monomeric units can be determined by any known method, such as for example by NMR.

[0080] Copolymer T is preferably crystalline.

[0081] Copolymer T preferably has a melting temperature measured by DSC (“Differential Scanning Calorimetry”) ranging from 130°C to 160°C.

[0082] Copolymer T preferably has a flow index (or MFI) ranging from 0.6 to 10 g / 10 min, preferably from 2 to 10 g / 10 min, and even more preferably from 4 to 8 g / 10 min. The flow index (or Melt Flow Index MFI) of copolymer T is measured at 230°C and under a total weight of 2.16 kg, in accordance with condition d) of standard ISO 1133. The MFI is the mass of composition (previously placed in a vertical cylinder) which flows in 10 minutes through a die of fixed diameter, under the effect of pressure exerted by a loaded piston having the total weight of 2.16 kg.

[0083] Tackifying resin iii)

[0084] The hot-melt self-adhesive composition CA comprises at least one non-hydrogenated tackifying resin iii) obtained by polymerization (or copolymerization with an aromatic hydrocarbon) of mixtures of unsaturated aliphatic hydrocarbons having from 4 to 6 carbon atoms (preferably approximately 5 carbon atoms) from petroleum fractions.

[0085] When the tackifying resin is obtained by copolymerization of mixtures of unsaturated aliphatic hydrocarbons having from 4 to 6 carbon atoms with an aromatic hydrocarbon, these are in particular aromatic modified aliphatic resins. It is well known to those skilled in the art that the content of aliphatic radicals is higher than that of aromatic radicals in aromatic modified aliphatic resins.

[0086] Preferably, the non-hydrogenated tackifying resin iii) is obtained by polymerization of mixtures of unsaturated aliphatic hydrocarbons having from 4 to 6 carbon atoms derived from petroleum fractions.

[0087] The tackifying resin iii) may have a softening temperature (or point) ranging from 25° to 150°C, preferably from 30° to 130°C, more preferably from 50°C to 120°C, and even more preferably from 90° to 120°C.

[0088] The softening temperature is determined in accordance with the standardized test ASTM E 28, the principle of which is as follows. A brass ring with a diameter of approximately 2 cm is filled with the molten resin to be tested. After cooling to room temperature, the ring and the solid resin are placed horizontally in a thermostatically controlled glycerin bath, the temperature of which can vary by 5°C per minute. A steel ball with a diameter of approximately 9.5 mm is centered on the solid resin disc. The softening temperature is - during the bath temperature rise phase at a rate of 5°C per minute - the temperature at which the resin disc creeps by a height of 25.4 mm under the weight of the ball.

[0089] The tackifying resin iii) may have a weight-average molar mass M w generally between 300 and 5000 Da, preferably between 1000 and 2000 Da.

[0090] Among the tackifying resins iii), we can for example cite Escorez® 1310LC marketed by EXXONMOBIL CHEMICAL (Softening temperature of 94°C and a Mw of approximately 1800 Da) or Wingtack 98 marketed by CRAY VALLEY (Softening temperature of 98°C and a Mw of approximately 2000 Da). The composition according to the invention can comprise a total content of tackifying resin(s) iii) ranging from 18.5 to 58.5% by weight, preferably from 18.5 to 53.5% by weight, preferentially from 18.5 to 48.5% by weight, and even more preferentially from 28.5% to 48.5% relative to the total weight of said composition.

[0091] The hot melt self-adhesive composition CA may comprise a tackifying resin iii) as defined above, or a mixture of tackifying resins iii) as defined above.

[0092] Optional tackifying resin iv)

[0093] The hot-melt self-adhesive composition CA may also further comprise one or more tackifying resin(s) iv) different from resin iii) as defined above.

[0094] The tackifying resin iv) may be chosen from those having a weight-average molar mass M w between 300 and 5000 Da.

[0095] The tackifying resin(s) iv) may be chosen in particular from:

[0096] - iv-a) rosins of natural or modified origin, such as, for example, rosin extracted from pine gum, wood rosin extracted from tree roots and their hydrogenated, dehydrogenated, dimerized, polymerized or esterified derivatives with monoalcohols or polyols such as glycerol;

[0097] - iv-b) resins obtained by hydrogenation, polymerization or copolymerization (with an aromatic hydrocarbon) of mixtures of unsaturated aliphatic hydrocarbons having approximately 9 or 10 carbon atoms from petroleum fractions.

[0098] Among the tackifying resins (iv-a), we can for example cite Sylvalite® RE 100S from the company Kraton Polymers (rosin and pentaerythritol ester with a softening temperature of approximately 100°C).

[0099] Among the tackifying resins (iv-b), we can for example cite Escorez® 5400 marketed by the company ExxonMobil Chemical which is a resin obtained by polymerization, then hydrogenation of a mixture of unsaturated aliphatic hydrocarbons having approximately 9 or 10 carbon atoms and which has a softening temperature of 100°C and an Mw of approximately 570 Da.

[0100] Preferably, the hot-melt self-adhesive composition of the invention does not comprise a tackifying resin chosen from terpene resins (terpene resins).

[0101] Terpene resins include unmodified terpene resins, terpene resins modified by the action of phenols (terpene-phenol resins) and terpene resins resulting from copolymerization (for example styrene / terpene). Terpene resins can result from the polymerization of terpene hydrocarbons such as mono-terpene (or pinene), in the presence of Friedel-Crafts catalysts. Among the terpene resins, Dercolyte® S115 available from DRT (terpene resin with a softening temperature of 115°C and an Mw of approximately 2300 Da) and Sylvares® TR7115 from Kraton Polymers are known.

[0102] According to a preferred embodiment, the composition according to the invention does not comprise any tackifying resin other than the aforementioned tackifying resin(s) iii).

[0103] According to a preferred embodiment, the hot melt adhesive composition CA does not comprise C9 hydrogenated aromatic resins.

[0104] Additional / optional components

[0105] Preferably, the hot-melt self-adhesive composition CA comprises less than 0.1% by weight of styrenic block copolymer (SBC), even more preferably less than 0.05% by weight relative to the total weight of said composition. Even more advantageously, the hot-melt self-adhesive composition does not comprise styrenic block copolymer.

[0106] Styrenic block copolymers consist of blocks of different polymerized monomers including at least one polystyrene block, and are typically prepared by free radical polymerization techniques.

[0107] Preferably, the hot melt self-adhesive composition CA comprises:

[0108] - i) from 40% to 80% by weight of at least one but-1-ene-ethylene copolymer A, said copolymer comprising more than 80% by weight of units derived from but-1-ene;

[0109] - ii) from 1.5% to 4.5% by weight of at least one propylene-ethylene-butene copolymer T, said copolymer T comprising more than 50% by weight of units derived from propylene;

[0110] - iii) at least one non-hydrogenated tackifying resin obtained by polymerization, or copolymerization with an aromatic hydrocarbon, of mixtures of unsaturated aliphatic hydrocarbons having from 4 to 6 carbon atoms derived from petroleum fractions.

[0111] According to one embodiment, the aforementioned hot-melt self-adhesive CA composition consists of:

[0112] - i) from 45% to 80% by weight of at least one copolymer A as defined above;

[0113] - ii) from 1.5% to 4.5% by weight of at least one copolymer T as defined above;

[0114] - iii) at least one non-hydrogenated tackifying resin obtained by polymerization, or copolymerization with an aromatic hydrocarbon, of mixtures of unsaturated aliphatic hydrocarbons having from 4 to 6 carbon atoms derived from petroleum fractions;

[0115] - from 0% to 5% by weight of additional component chosen from the group consisting of stabilizers (antioxidants), plasticizers, anti-caking agents, pigments, dyes, organic fillers, mineral fillers, and mixtures thereof.

[0116] The total amount of additional component(s) may range from 0.01% to 2% by weight, preferably from 0.1% to 2% by weight relative to the total weight of said composition. Antioxidants may typically be introduced to protect the composition from degradation resulting from a reaction with oxygen which is likely to form by the action of heat, light or residual catalysts on certain raw materials such as tackifying resins. These compounds may include primary antioxidants which scavenge free radicals and are generally substituted phenols such as Irganox® 1010 from BASF. Primary antioxidants may be used alone or in combination with other antioxidants such as phosphites such as Irgafos® 168 also from BASF, or with UV stabilizers such as amines.

[0117] Anti-caking agents may be chosen from talc, calcium carbonate, calcium stearate, silica (natural or synthetic) or mixtures thereof.

[0118] Paraffinic and naphthenic oil (such as Primol® 352 from EXXONMOBIL) can be used as a plasticizer, possibly including aromatic compounds (such as Nyflex 222B).

[0119] According to a preferred embodiment, the aforementioned CA hot melt self-adhesive composition comprises:

[0120] - i) from 45% to 80% by weight of at least one copolymer A as defined above;

[0121] - ii) from 2.0% to 4.0% by weight of at least one copolymer T as defined above;

[0122] - iii) at least one non-hydrogenated tackifying resin obtained by polymerization, or copolymerization with an aromatic hydrocarbon, of mixtures of unsaturated aliphatic hydrocarbons having from 4 to 6 carbon atoms derived from petroleum fractions;

[0123] - from 0% to 5% by weight of additional component chosen from the group consisting of stabilizers (antioxidants), plasticizers, anti-caking agents, pigments, dyes, organic fillers, mineral fillers, and mixtures thereof.

[0124] Composition

[0125] The hot-melt self-adhesive composition CA may have a total polymer content (copolymer A + copolymer T) ranging from 41.5% to 84.5%, preferably from 46.8% to 84.3%, more preferably from 52% to 84%, and even more preferably from 52% to 73.5%.

[0126] The hot-melt self-adhesive composition CA may comprise a mass ratio of polymers (copolymer A + copolymer T): Tackifying resin(s) iii) ranging from 40:60 to 90:10, preferably from 45:55 to 85:15, even more preferably from 50:50 to 70:30.

[0127] The hot-melt self-adhesive composition CA according to the invention may have a flow index (or MFI) ranging from 5 to 50 g / 10 min, preferably from 5 to 20 g / 10 min, and even more preferably from 5 to 15 g / 10 min.

[0128] The Melt Flow Index (MFI) of the CA hot-melt self-adhesive composition is measured at 190°C and under a total weight of 2.16 kg, in accordance with condition d) of ISO 1133. The MFI is the mass of composition (previously placed in a vertical cylinder) which flows in 10 minutes through a die of fixed diameter, under the effect of pressure exerted by a loaded piston having a total weight of 2.16 kg. Unless otherwise stated, the MFI values ​​indicated in this text were measured under these same conditions.

[0129] The hot-melt self-adhesive composition CA according to the invention is preferably in the form of ellipsoidal granules whose average dimensions of the major axis and the minor axis are advantageously as follows:

[0130] - average dimension of the major axis between 1 and 10 mm, preferably between 2 and 6 mm;

[0131] - average dimension of the minor axis between 1 and 10 mm, preferably between 2 and 6 mm.

[0132] Average dimensions are typically calculated by averaging over ten measurements.

[0133] The measurement of the dimensions of the major axis and minor axis of the granules can be done using a caliper.

[0134] The CA hot melt self-adhesive composition may be prepared in this form by a process which comprises:

[0135] - a step of mixing the ingredients hot, between 150°C and 220°C, using a twin-screw extruder equipped with a tool for cutting the extruded product of the underwater cutting type at the outlet of the die, then

[0136] - a drying and cooling step, for example at room temperature (23°C).

[0137] The method may comprise a step of hot pre-mixing of the copolymers A and T as defined above, then said step of mixing the ingredients (of the pre-mix with the other ingredients such as for example the tackifying resin) hot between 150°C and 250°C, by means of a twin-screw extruder equipped with a tool for cutting the extruded product of the underwater cutting type at the outlet of the die.

[0138] F1 Multi-Layer System

[0139] The multi-layer system F1 may further comprise one or more additional layers (in addition to the aforementioned layers C1, Ad and C2).

[0140] These may be barrier layers (e.g. protein-based layer, layer based on aluminum oxides (AIOx), silicon oxides (SiOx), aluminum, PVOH (PolyVinyl Alcohol), ethylene and vinyl alcohol copolymers (EVOH), ethylene and alkyl acrylate copolymers, ethylene and vinyl acetate copolymers (EVA)...), tie layers (called intermediate layers or "tie layers" in English), printable layers, receptacle layers, etc. The total thickness of the multilayer system F1 may be likely to vary in a wide range, for example from 20 to 500 μm.

[0141] Preferably, the multilayer system F1 comprises at least 80%, preferably at least 85% by weight, and even more preferably at least 90% by weight of polypropylene or a mixture of polypropylenes relative to the total weight of said system.

[0142] The F1 multilayer system can be obtained anywhere by any method known in the field.

[0143] The method may comprise a step of co-extrusion of the hot-melt self-adhesive composition CA and the materials constituting the layers C1 and C2 and, where appropriate, the additional layers.

[0144] The co-extrusion device may be a bubble blown co-extrusion device (also known as “sheath blown co-extrusion”). As known to those skilled in the art, this method comprises:

[0145] - the fusion, in separate extruders, of the compositions and materials constituting the layers Ad, C1 and C2, then

[0146] - the passage of the corresponding flows through a set of annular and concentric dies, so as to form a tubular bubble with several layers, in the order corresponding to that desired for the final structure, then

[0147] - radial expansion (relative to the annular die) and stretching (in the axial direction) of the bubble, then

[0148] - cooling of the bubble.

[0149] The geometric characteristics of the dies, as well as the process parameters such as the radial expansion rate and the stretching speed are set so as to obtain the desired thickness for the different constituent layers of the multilayer film. Reference is made in particular to patent application US2013 / 0029553 for a more detailed description of the bubble-blowing co-extrusion process.

[0150] Uses of CA Adhesive Composition / F1 Multi-Layer System

[0151] The present invention also relates to the use of the hot melt self-adhesive composition CA comprising:

[0152] - i) from 40% to 80% by weight of at least one copolymer A comprising more than 80% by weight of units derived from but-1-ene;

[0153] - ii) optionally at least one copolymer T comprising more than 50% by weight of units derived from propylene;

[0154] - iii) at least one non-hydrogenated tackifying resin obtained by polymerization, or copolymerization with an aromatic hydrocarbon, of mixtures of unsaturated aliphatic hydrocarbons having from 4 to 6 carbon atoms derived from petroleum fractions; to prepare a recycled article.

[0155] The description, embodiments and preferred modes described above for the CA hot melt adhesive composition apply for use without the need to repeat them.

[0156] Preferably, the present invention relates to the use of the hot melt self-adhesive composition CA comprising:

[0157] - i) from 40% to 80% by weight of at least one but-1-ene-ethylene copolymer A, said copolymer comprising more than 80% by weight of units derived from but-1-ene;

[0158] - ii) from 1.5% to 4.5% by weight of at least one propylene-ethylene-butene copolymer T, said copolymer T comprising more than 50% by weight of units derived from propylene;

[0159] - iii) at least one non-hydrogenated tackifying resin obtained by polymerization, or copolymerization with an aromatic hydrocarbon, of mixtures of unsaturated aliphatic hydrocarbons having from 4 to 6 carbon atoms derived from petroleum fractions; to prepare a recycled article.

[0160] The present invention relates to the use of the hot-melt self-adhesive composition CA as defined above for preparing a recycled article comprising at least 2% by weight of a recycled multilayer system F1 comprising said adhesive composition CA, preferably at least 5% by weight relative to the total weight of said recycled article.

[0161] The present invention also relates to the use of the multilayer system F1 as defined above, said system F1 preferably comprising:

[0162] - a layer C1 comprising at least one polypropylene,

[0163] - an adhesive layer Ad consisting of a hot-melt self-adhesive composition CA comprising:

[0164] - i) from 40% to 80% by weight of at least one but-1-ene-ethylene copolymer A, said copolymer comprising more than 80% by weight of units derived from but-1-ene;

[0165] - ii) from 1.5% to 4.5% by weight of at least one propylene-ethylene-butene copolymer T, said copolymer T comprising more than 50% by weight of units derived from propylene;

[0166] - iii) at least one non-hydrogenated tackifying resin obtained by polymerization, or copolymerization with an aromatic hydrocarbon, of mixtures of unsaturated aliphatic hydrocarbons having from 4 to 6 carbon atoms derived from petroleum fractions;

[0167] - a layer C2 comprising at least one polypropylene, said multilayer system F1 comprising at least 80% by weight of polypropylene or a mixture of polypropylenes relative to the total weight of said system; to prepare a recycled article. The description, embodiments and preferred modes described above for the multilayer system F1 apply for use without the need to repeat them.

[0168] Recycled item

[0169] The recycled article can be a single-layer film, a laminate, a complex (multi-layer), a molded article, preferably a molded article.

[0170] The molded article may be a blow-molded or injection-molded article. The molded article is preferably an injection-molded article. Injection molding is well known. It is typically a process in which a thermoformable material is melted and injected at high pressure into a mold to form an article of a given size and shape.

[0171] In the context of the invention, the term “single-layer film” means a film comprising a single layer, and is thus distinguished from multi-layer films.

[0172] The recycled article is preferably obtained by mechanical recycling of the multilayer system F1 according to the invention.

[0173] The recycled article preferably comprises less than 5% by weight of a copolymer A as described in the present application relative to the total weight of said recycled article.

[0174] The content of copolymer A can be determined by Gel Permeation Chromatography (GPC), for example with a trichlorobenzene (TCB) standard.

[0175] The recycled article preferably comprises at least 90%, more preferably at least 95%, even more preferably at least 97% by weight of polypropylene or a mixture of polypropylenes relative to the total weight of said recycled article.

[0176] The recycled article preferably comprises at least 2% by weight of the multilayer system F1 as defined in the present application, preferably at least 5% by weight, relative to the total weight of said recycled article.

[0177] The recycled article advantageously has a breaking strength greater than or equal to 20 MPa, preferably greater than or equal to 22 MPa, measured according to standard ISO 527-1 (type 1A, specimen dimensions 80 x 10 x 4, tensile speed 50 mm / min).

[0178] The recycled article advantageously has an impact resistance (Charpy method) greater than or equal to 5.0, preferably greater than or equal to 5.2, measured according to standard ISO 179-2 1 eA at 23°C (specimen dimensions 80 x 10 x 4 mm, speed of 2.9 m / s).

[0179] The recycled article advantageously has an elongation at break greater than or equal to 7 MPa, preferably greater than or equal to 8 MPa, measured according to standard ISO 527-1 (type 1 A), test piece dimensions 80 x 10 x 4 mm, tensile speed 50 mm / min).

[0180] The present invention also relates to the use of the hot-melt self-adhesive composition CA according to the invention for improving the impact resistance of a recycled article, preferably a recycled article based on polypropylene. More particularly, the use of the hot-melt self-adhesive composition CA of the invention advantageously makes it possible to improve by at least 2%, preferably by at least 5%, even more preferably by at least 10%, the impact resistance of a recycled article comprising said hot-melt self-adhesive composition, compared to a control article consisting of 100% polypropylene (preferably recycled polypropylene, even more preferably having an MFR of approximately 8.95 g / 10 min at 230°C / 2.16 kg) and lacking said hot-melt self-adhesive composition. It goes without saying that the recycled article and the control article have similar sizes and shapes for a suitable comparison.

[0181] Impact resistance is measured according to the standard mentioned above.

[0182] The recycled article is preferably prepared according to the process described below.

[0183] The present invention also relates to the use of the hot-melt self-adhesive composition CA according to the invention for improving the elongation at break of a recycled article, preferably of a recycled article based on polypropylene.

[0184] The elongation at break is measured according to the standard mentioned above.

[0185] More particularly, the use of the hot-melt self-adhesive composition CA of the invention advantageously makes it possible to increase by at least 2%, preferably by at least 4%, and even more preferably by at least 15% the elongation at break of a recycled article comprising said hot-melt self-adhesive composition, compared to a control article consisting of 100% polypropylene (preferably recycled polypropylene, even more preferably having an MFR of approximately 8.95 g / 10 min at 230°C / 2.16 kg) and lacking said hot-melt self-adhesive composition. It goes without saying that the recycled article and the control article have similar sizes and shapes for a suitable comparison.

[0186] The recycled article is preferably prepared according to the process described below.

[0187] Process for preparing a recycled article

[0188] The present invention also relates to a process for preparing a recycled article, said process comprising: a) providing the multilayer system F1 as described in the present invention; b) converting the multilayer system F1 into chips; c) optionally mixing the chips obtained in step b) with recycled or virgin polypropylene; d) converting the chips of step b) or the mixture of step c) into a recycled article.

[0189] The description, embodiments and preferred modes described above for the multilayer system F1 apply to the present process for preparing a recycled article without it being necessary to repeat them. Step b) is preferably a grinding step advantageously leading to chips (also called "flakes" in English). It can be carried out at 23°C.

[0190] The method may comprise an optional washing step b-1) of the chips obtained in step b), and a drying step b-3).

[0191] The washing step b-1) can be carried out with water, possibly in the presence of additives, possibly with stirring.

[0192] The washing step b-1) advantageously makes it possible to remove residues present in the packaging such as, for example, food waste or cosmetic residues from cosmetic packaging, or to remove any inks or other materials that may be present.

[0193] Washing step b-1) can be carried out at a temperature ranging from 20°C to 25°C.

[0194] The method may comprise a flotation step b-2) between step b-1) and step b-3). This step may be carried out by any means known to those skilled in the art.

[0195] The chips from the washing step iii-1) can be placed during the washing step or after the washing step in a stirred tank. After stopping the stirring, the flotation / separation step advantageously makes it possible to separate the products which float from those (preferably impurities) which settle at the bottom of the stirring tank. The flotation step is typically a density separation step. Polyolefins typically have a density of less than 1g / cm 3 , which generally allows them to be recovered on the surface.

[0196] Drying step b-3) can be carried out by any known method. It can be done at a temperature ranging from 50°C to 100°C.

[0197] In the context of the invention, and unless otherwise stated, the term “virgin polypropylene” means newly produced polypropylene that has not been recycled.

[0198] The method may comprise a step b') of densifying the chips from step b), to form granules. The subsequent steps are then typically carried out on these granules.

[0199] Step c) may comprise mixing the chips obtained in step b) with recycled or virgin polypropylene in a chips:recycled (or virgin) PP ratio ranging from 1:99 to 99:1, preferably from 5:95 to 95:5, for example from 5:95 to 50:50.

[0200] The recycled or virgin polypropylene from step c) may be in the form of chips or granules, preferably in the form of chips.

[0201] Step d) may be an extrusion, co-extrusion, molding step, for example injection molding.

[0202] Extrusion (co-extrusion) advantageously allows the preparation of recycled films, while molding advantageously allows the preparation of molded articles.

[0203] Preferably, step d) is an injection molding step. The method advantageously allows transformation of the multilayer system F1 into chips or granules that can be reused to manufacture a new article.

[0204] Recycled item

[0205] The description, embodiments, and preferred modes previously disclosed for the recycled article apply in the present method without the need to repeat them.

[0206] The present invention also relates to a recycled article obtainable by the process for preparing a recycled article as defined above.

[0207] The present invention also relates to the use of the recycled article for the automotive field.

[0208] In the context of the invention, by "between x and y", or "ranging from x to y", is meant an interval in which the limits x and y are included. For example, the range "between 0% and 25%" includes in particular the values ​​0% and 25%.

[0209] The invention is now described in the following exemplary embodiments which are given purely for illustrative purposes and should not be interpreted to limit its scope.

[0210] The following compounds were used in the examples:

[0211] Escorez® 1310 LC: Non-hydrogenated tackifying resin obtained by polymerization of a mixture of unsaturated aliphatic hydrocarbons having approximately 5 carbon atoms from petroleum fractions. It has a softening temperature of 94°C (supplier EXXONMOBIL CHEMICAL)

[0212] SONGNOX® 1010 (SONGWON supplier): Primary antioxidant

[0213] KOATTRO KT MR06: C2 / C4 copolymer having an MFI at 190°C, 2.16 kg of 1.3 g / 10 min and comprising a mass content of C2 ethylene of approximately 8.3% (supplier LYONDELL BASELL)

[0214] Terpolymer T: C2 / C3 / C4 comprising about 3% by weight C2, 9% by weight C4, the remainder being C3 and having an MFI at 230°C under 2.16 kg of 5.50 g / 10 min preparation of a hot melt adhesive composition

[0215] The adhesive composition (see Table 1) is first prepared in the form of ellipsoidal granules whose major axis and minor axis respectively have an average dimension of between 1 and 10 mm, preferably between 2 and 6 mm, by mixing their ingredients at a temperature ranging from 150°C to 200°C using a 2-screw extruder, extruding through a die and then cutting the product using a granulation tool such as an underwater cutter, then drying and cooling to room temperature (23°C). Table 1 indicates percentages by weight.

[0216] Table 1:

[0217] Example 2: Preparation of a multilayer film

[0218] We prepare a film consisting of:

[0219] - a first polypropylene film (RD204CF from Borealis) with a thickness of 30 pm;

[0220] - an adhesive layer between the two films, from example 1 of 14 pm;

[0221] - a second polypropylene film (RD204CF from Borealis) with a thickness of 15 pm.

[0222] This three-layer film is manufactured using a continuously operating bubble-blowing co-extrusion pilot plant, in which 3 extruders are fed:

[0223] - for one, by the composition of example 1; and

[0224] - for the other 2, by polypropylene.

[0225] Several usual parameters were set, namely a radial bubble expansion rate of 3.18, a stretching speed of 7 m / minute and an overall flow rate of 11 kg / hour.

[0226] The resulting three-layer film has a total thickness of 59 μm, a length of 50 m and is packaged in the form of a 250 mm wide reel. The different materials were introduced into each extruder, in order to fill the screws and form the polymer bubble at the outlet of the extrusion die. After 30 minutes of purging, the thicknesses and stability of the bubble being checked, 50 m of film were wound onto mandrels. process for preparing recycled articles

[0227] Grinding step 1

[0228] The multi-layer complex of Example 2 PP / adhesive / PP is ground using an MDS 340 / 150 shredder, 8 mm die to obtain chips. This grinding step results in a mixture of chips.

[0229] Step 2: Mix with a reference

[0230] Then, the chips from step 1 are mixed with recycled polypropylene granules (Reference, PP marketed by PreZero) in a ratio of 95:5 and 70:30 (Reference: recycled multilayer film from step 1). The mixture is introduced into a Berstorff ZE 25, 36 L / D twin-screw extrusion line, melted at a temperature above their melting temperatures, and then extruded. At the end of this step, granules are obtained.

[0231] Recycled polypropylene (Reference) has an MFR of 8.95 g / 10 min at 230°C for a weight of 2.16 kg. mechanical and thermal properties of molded articles

[0232] Strength at break / elongation at break

[0233] The breaking strength is measured according to ISO 527-1 (type 1A) on injection molded samples by tensile testing was carried out according to the protocol described below.

[0234] The principle of the measurement consists of stretching in a tensile testing machine, whose movable jaw moves at a constant speed equal to 50 mm / minute, a standard specimen made up of the granules obtained in step 2 (or reference) and recording, at the moment when the specimen ruptures, the applied tensile stress (in MPa) as well as the elongation of the specimen (in %). The standard specimen is dumbbell-shaped, as illustrated in the international standard ISO 527. The narrow part of the dumbbell used has a length of 80 mm, a width of 10 mm and a thickness of 4 mm. Impact strength (Charpy)

[0235] Impact resistance is measured according to the method DI N EN ISO 179-2 1 eA at 23°C on ISO test specimens type 1, with dimensions 80 x 10 x 4 mm (speed of 2.9 m / s). The mechanical properties of the various prepared articles are described in the following table:

[0236]

[0237] Nd: not determined

[0238] N / A: not applicable

[0239] Articles 4.2 and 4.3 advantageously present breaking forces almost similar to those obtained for the reference article (control 4.1) which does not contain recycled granules from example 3.

[0240] Articles 4.2. and 4.3 advantageously have a higher elongation at break than that of the reference article (control 4.1). It is also higher for article 4.3. Articles 4.2. and 4.3 advantageously have a higher impact resistance than that of the reference article (control 4.1). It is also higher for article 4.3.

[0241] Article 4.3 (invention) differs from Article 4.4. in that it includes within it the hot-melt self-adhesive composition derived from the recycled film of Example 2. The results in the table demonstrate that advantageously the presence of the self-adhesive composition does not negatively impact the thermal and mechanical properties. On the contrary, the elongation at break and the impact resistance are advantageously improved compared to an Article 4.4. without adhesive composition.

[0242] The MFR is described in the following table:

[0243] Articles 4.2 and 4.3 advantageously have an MFR close to reference 4.1. This advantageously allows the use of injection molding conditions similar to the reference, without requiring additional adjustments.

Claims

CLAIMS 1. F1 multi-layer system comprising: - a layer C1 comprising at least one polypropylene, - an adhesive layer Ad consisting of a hot-melt self-adhesive composition CA comprising: - i) from 40% to 80% by weight of at least one copolymer A comprising more than 80% by weight of units derived from but-1-ene; - ii) optionally at least one copolymer T comprising more than 50% by weight of units derived from propylene; - iii) at least one non-hydrogenated tackifying resin obtained by polymerization, or copolymerization with an aromatic hydrocarbon, of mixtures of unsaturated aliphatic hydrocarbons having from 4 to 6 carbon atoms derived from petroleum fractions; - a layer C2 comprising at least one polypropylene, said multilayer system F1 comprising at least 80% by weight of polypropylene or a mixture of polypropylenes relative to the total weight of said system.

2. Multilayer system F1 according to claim 1, characterized in that the hot-melt self-adhesive composition CA comprises from 45% to 80% by weight of copolymer(s) A, preferably from 50% to 80% by weight, even more preferably from 50% to 70% by weight of copolymer(s) A relative to the total weight of said composition.

3. Multilayer system F1 according to any one of claims 1 or 2, characterized in that the copolymer A comprises more than 82% by weight of units derived from but-1-ene, and even more preferably more than 90% by weight of units derived from but-1-ene.

4. Multilayer system F1 according to any one of claims 1 to 3, characterized in that the copolymer A is a but-1-ene-ethylene copolymer.

5. Multilayer system F1 according to any one of claims 1 to 4, characterized in that the hot-melt self-adhesive composition CA comprises from 1.5% to 4.5% by weight of copolymer(s) T, preferably from 1.8 to 4.3% by weight of copolymer(s) T, more preferably from 2.0 to 4.0%, and even more preferably from 2.0 to 3.5% by weight relative to the total weight of said composition CA.

6. Multilayer system F1 according to any one of claims 1 to 5, characterized in that the copolymer T is a propylene-ethylene-butene copolymer T.

7. Multilayer system F1 according to any one of claims 1 to 6, characterized in that the copolymer T comprises from 1% to 25% by weight of units derived from ethylene, preferably from 1% to 10% by weight of units derived from ethylene, and even more preferably from 1% to 5% by weight of units derived from ethylene.

8. Multilayer system F1 according to any one of claims 1 to 7, characterized in that the total content of tackifying resin(s) iii) ranges from 18.5 to 58.5% by weight, preferably from 18.5 to 53.5% by weight, preferentially from 18.5 to 48.5% by weight, and even more preferentially from 28.5% to 48.5% relative to the total weight of said composition CA.

9. Multilayer system F1 according to any one of claims 1 to 8, characterized in that the hot-melt self-adhesive composition consists of: - i) from 40% to 80% by weight of at least one copolymer A; - ii) from 1.5% to 4.5% by weight of at least one copolymer T; - iii) at least one non-hydrogenated tackifying resin obtained by polymerization, or copolymerization with an aromatic hydrocarbon, of mixtures of unsaturated aliphatic hydrocarbons having from 4 to 6 carbon atoms derived from petroleum fractions; - from 0% to 5% by weight of additional component chosen from the group consisting of stabilizers (antioxidants), plasticizers, anti-caking agents, pigments, dyes, organic fillers, mineral fillers, and mixtures thereof.

10. Multilayer system F1 according to any one of claims 1 to 9, characterized in that it comprises at least 80%, preferably at least 85% by weight, and even more preferably at least 90% by weight of polypropylene or a mixture of polypropylenes relative to the total weight of said system.

11. Use of a multilayer system F1 as defined in any one of claims 1 to 10, or of a hot melt self-adhesive composition CA as defined in any one of claims 1 to 10, for preparing a recycled article.

12. Use according to claim 11, characterized in that the recycled article is a single-layer film, a laminate, a complex (multilayer), a molded article, preferably a molded article.

13. Use according to any one of claims 11 or 12, characterized in that the recycled article comprises at least 90%, more preferably at least 95%, even more preferably at least 97% by weight of polypropylene or a mixture of polypropylenes relative to the total weight of said recycled article.

14. Use of the hot-melt self-adhesive composition CA according to any one of claims 1 to 10, for improving the impact resistance of a recycled article, preferably of a recycled article based on polypropylene.

15. Use according to claim 14, to improve by at least 2%, preferably by at least 5%, and even more preferably by at least 10% the impact resistance of a recycled article comprising said hot-melt self-adhesive composition CA, compared to a control article made of 100% polypropylene and devoid of said hot-melt self-adhesive composition.

16. A method of preparing a recycled article, said method comprising: a) providing the multilayer system F1 according to any one of claims 1 to 10; b) converting the multilayer system F1 into chips; c) optionally mixing the chips obtained in step b) with recycled or virgin polypropylene; d) converting the chips of step b) or the mixture of step c) into a recycled article.

17. Recycled article obtainable according to the process as defined in claim 16.

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