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] Using a F1 multi-layer system

[0016] The present invention relates to the use of 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: a composition (a1) of styrene block copolymers comprising at least one elastomer block; one or more tackifying resins (a2);

[0019] - 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, for preparing a recycled article.

[0020] F1 Multi-Layer System

[0021] The multilayer system F1 necessarily includes at least these three layers C1, C2 and Ad.

[0022] In the context of the present invention, the terms “article”, “structure” and “system” are used equivalently.

[0023] The F1 multilayer system can be a laminate, a complex, a film.

[0024] Advantageously, the F1 multi-layer system is mechanically recyclable.

[0025] 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.

[0026] 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.

[0027] 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 comprises at least one mechanical crushing step. In the context of the invention, the terms "recycled" and "recyclate" refer to a material originating at least in part from either post-consumer waste or industrial waste. Post-consumer waste concerns objects that have been used by the consumer at least once already (i.e. they have served their initial purpose), whereas industrial waste concerns manufacturing residues that do not reach the consumer.Manufacturing residues can be, for example, offcuts from multi-layer complex reels when they are cut after production to prepare packaging.

[0028] 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.

[0029] Layers C1 and C2

[0030] Layer C1 may comprise a polypropylene or a mixture of polypropylenes. Layer C2 may comprise a polypropylene or a mixture of polypropylenes. Layers C1 and C2 may comprise one or more polypropylenes having different physicochemical characteristics.

[0031] 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.

[0032] 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.

[0033] Layers C1 and C2 may comprise one or more identical or different polypropylenes.

[0034] 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).

[0035] Polypropylenes can be prepared by various methods, such as polymerization in the presence of a Ziegler-Natta catalyst or metallocene catalyst.

[0036] 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. The thickness of the C1 layer can vary from 10 to 120 pm, preferably from 10 to 100 pm.

[0037] The thickness of the C2 layer can vary from 10 to 120 pm, preferably from 10 to 100 pm.

[0038] 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.

[0039] 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).

[0040] The two aforementioned layers C1 and C2 are preferably bonded together by the adhesive layer Ad.

[0041] Each of the layers C1 and C2, independently of one another, may comprise at least one layer chosen from aluminum oxides (AIOx), silicon oxides (SiOx), a metallization layer, and mixtures thereof.

[0042] 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 the C1 and / or C2 layer).

[0043] 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.

[0044] If they are present on the C1 and / or C2 layers, these layers (AIOx, SiOx or metallization) can be in direct contact with the adhesive layer.

[0045] Ad adhesive layer / CA hot melt adhesive composition

[0046] 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.

[0047] For the purposes of the present invention, 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.

[0048] Unless otherwise indicated, the standards referred to throughout the application are those in force on the date of filing of the application. Composition (a1) of styrenic block copolymers comprising at least one elastomer block

[0049] The styrenic block copolymers used in composition (a1) have a weight-average molar mass Mw generally between 50 kDa and 500 kDa.

[0050] These styrenic block copolymers consist of blocks of different polymerized monomers including at least one polystyrene block, and are prepared by radical polymerization techniques.

[0051] Unless otherwise indicated, the weight-average molar masses M w which are given in this text are expressed in daltons (Da) and are determined by Gel Permeation Chromatography, the column being calibrated with polystyrene standards.

[0052] Triblock copolymers consist of two polystyrene blocks and one elastomer block. They can have various structures: linear, star-shaped (also called radial), branched, or comb-shaped. Diblock copolymers consist of one polystyrene block and one elastomer block.

[0053] Triblock copolymers have the general formula:

[0054] ABA (I) in which:

[0055] - A represents a non-elastomeric styrenic (or polystyrene) block, and

[0056] - B represents an elastomer block which can be:

[0057] - polyisoprene. The block copolymer then has the structure: polystyrene-polyisoprene-polystyrene, and the name: SIS;

[0058] - polyisoprene followed by a polybutadiene block. The block copolymer then has the structure: polystyrene-polyisoprene-polybutadiene-polystyrene, and the name: SIBS

[0059] - polybutadiene. The block copolymer then has the structure: polystyrene-polybutadiene-polystyrene, and the name: SBS;

[0060] - fully or partially hydrogenated polybutadiene. The block copolymer then has the structure: polystyrene-poly(ethylenebutylene)-polystyrene and the name: SEBS; - fully or partially hydrogenated polyisoprene. The block copolymer then has the structure: polystyrene-poly(ethylenepropylene)-polystyrene and the name: SEPS.

[0061] In the above triblock copolymer, the A blocks on either side of B may be the same or different, for example they may each have a different length.

[0062] Diblock copolymers have the general formula:

[0063] AB (II) in which A and B are as defined previously.

[0064] When the composition (a1) comprises several styrenic triblock copolymers, the latter being chosen from the group comprising SIS, SBS, SEPS, SIBS, SEBS, it is understood that said triblocks may belong to one or more of these 5 families of copolymers. The same applies, mutatis mutandis, to diblock copolymers.

[0065] It is preferred to use a composition (a1) comprising a triblock copolymer and a diblock copolymer having the same elastomer block, in particular due to the fact that such mixtures are commercially available.

[0066] Preferably, the composition (a1) of styrenic block copolymers comprising at least one elastomer block is constituted, on the basis of its total weight:

[0067] - from 10 to 90% by weight of at least one diblock copolymer chosen from the group comprising SI, SBI, SIB, SB, SEB, and SEP, and

[0068] - from 10 to 90% by weight of at least one triblock copolymer chosen from the group comprising SIS, SIBS, SBS, SEBS and SEPS.

[0069] Preferably, the content of composition (a1) in the hot-melt self-adhesive composition CA ranges from 30% to 80% by weight, preferably from 40% to 70% by weight, relative to the total weight of said composition CA.

[0070] The total styrenic unit content of said composition (a1) preferably varies from 10 to 40% by weight based on the total weight of (a1).

[0071] According to a particularly preferred embodiment variant, the content of diblock copolymer in the composition (a1) can vary from 15 to 80%, preferably from 50 to 80%. Preferably, the composition (a1) consists of a triblock copolymer SIS and a diblock copolymer SI. In this case, the total content of styrene units in the composition (a1) preferably varies from 10 to 25%.

[0072] The triblock copolymers included in composition (a1) preferably have a linear structure.

[0073] Styrenic block copolymers with elastomeric block, in particular of type SI and SIS, usable in composition (a) are commercially available, often in the form of triblock / diblock mixtures.

[0074] Kraton® D1111 from Kraton, Quintac® 3520 and Quintac® 3433 N from Zeon Chemicals are examples of compositions (a1) consisting of SIS and SL

[0075] Kraton® D1111 is a composition with an overall styrenic unit content of 22%, consisting of 82% linear SIS triblock copolymer of M w approximately 250 kDa, and 18% SI diblock copolymer of M w about 100 kDa.

[0076] Quintac® 3520 is a composition that consists of, respectively, 22% and 78% of linear SIS triblock (M wapproximately 300 kDa) and diblock SI (M w approximately 130 kDa), and whose total content of styrenic units is 15%.

[0077] Quintac® 3433 N is a composition that consists of, respectively, 44% and 56% of linear SIS triblock (M w approximately 220 kDa) and diblock SI (M w approximately 110 kDa), and whose total content of styrenic units is 16.5%.

[0078] Tackifying resins (a2)

[0079] The tackifying resin(s) (a2) that can be used have weight-average molar masses M w generally between 300 and 5000 Da and are chosen in particular from:

[0080] - (i) rosins of natural or modified origin, such as, for example, rosin extracted from pine gum, wood rosin extracted from tree roots and their derivatives hydrogenated, dehydrogenated, dimerized, polymerized or esterified by monoalcohols or polyols such as glycerol;

[0081] - (ii) resins obtained by hydrogenation, polymerization or copolymerization (with an aromatic hydrocarbon) of mixtures of unsaturated aliphatic hydrocarbons having approximately 5, 9 or 10 carbon atoms derived from petroleum fractions; - (iii) terpene resins generally resulting from the polymerization of terpene hydrocarbons such as, for example, mono-terpene (or pinene) in the presence of Friedel-Crafts catalysts, possibly modified by the action of phenols;

[0082] - (iv) copolymers based on natural terpenes, for example styrene / terpene, alpha-methyl styrene / terpene and vinyl toluene / terpene.

[0083] The softening temperature (or point) of the tackifying resins usable in the composition according to the invention can vary from 5 to 140 °C. 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 resin to be tested in the molten state. 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 phase of temperature rise of the bath 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.

[0084] Preferably, the resin (a2) is chosen from aliphatic resins belonging to categories (ii) or (iii). Examples of commercially available resins include:

[0085] (ii) Escorez® 1310 LC available from Exxon Chemicals, which is a resin obtained by polymerization of a mixture of unsaturated aliphatic hydrocarbons having about 5 carbon atoms, and which has a softening temperature of 94°C and a weight average molar mass Mw of about 1800 Da; Escorez® 5400 also available from Exxon Chemicals, which is a resin obtained by polymerization, then hydrogenation of a mixture of unsaturated aliphatic hydrocarbons having about 9 or 10 carbon atoms and which has a softening temperature of 100°C and a Mw of about 570 Da; Regalite® R1125 available from Eastman, which is a hydrogenated resin which has a softening temperature of 123°C and a weight average molar mass Mw of about 1200 Da.

[0086] (iii) Dercolyte® S115 available from the company “Dérivés Résiniques et Terpéniques” or DRT) which is a terpene resin with a softening temperature of 115°C and an Mw of approximately 2300 Da.

[0087] CA hot melt self-adhesive composition Preferably, the CA hot melt self-adhesive composition comprises:

[0088] - from 40 to 70% by weight of a composition (a1) of styrene block copolymers comprising at least one elastomer block, said composition (a1) being constituted, on the basis of its total weight:

[0089] - from 10 to 90% by weight of at least one diblock copolymer chosen from the group comprising SI, SBI, SIB, SB, SEB, and SEP, and

[0090] - from 10 to 90% by weight of at least one triblock copolymer chosen from the group comprising SIS, SIBS, SBS, SEBS and SEPS; the total content of styrenic units in said composition (a1) varying from 10 to 40% by weight based on the total weight of (a1); and

[0091] - from 30 to 60% by weight of one or more tackifying resins (a2).

[0092] More preferably, the CA composition comprises or consists essentially of:

[0093] - from 50 to 70% of the composition (a1) of styrenic block copolymers; And

[0094] - from 30 to 50% of at least one tackifying resin (a2) having a softening temperature of between 5 and 140°C.

[0095] The hot melt adhesive composition CA may also comprise, in addition to composition (a1) and the tackifying resin(s) (a2), from 0.1 to 2% of one or more stabilizers (or antioxidants). These compounds are 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. The 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.

[0096] The CA composition may also include a plasticizer, but in an amount not exceeding 5%. Paraffinic and naphthenic oil (such as Primol® 352 from ESSO) may be used as a plasticizer, possibly including aromatic compounds (such as Nyflex 222B).

[0097] The CA composition can finally include mineral or organic fillers, pigments or dyes. F1 multi-layer system

[0098] The multi-layer system F1 may further comprise one or more additional layers (in addition to the aforementioned layers C1, Ad and C2).

[0099] These may be barrier layers (e.g. protein-based layers, layers 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.

[0100] The total thickness of the multilayer system F1 may be likely to vary within a wide range, for example from 20 to 500 pm.

[0101] 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.

[0102] The F1 multilayer system can be obtained anywhere by any method known in the field.

[0103] 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.

[0104] 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:

[0105] - the fusion, in separate extruders, of the compositions and materials constituting the layers Ad, C1 and C2, then

[0106] - 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

[0107] - radial expansion (relative to the annular die) and stretching (in the axial direction) of the bubble, then

[0108] - cooling of the bubble.

[0109] 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 further description of the bubble-blowing co-extrusion process. Recycled article

[0110] The recycled article can be a single-layer film, a laminate, a complex (multi-layer), a molded article, preferably a molded article.

[0111] 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.

[0112] 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.

[0113] The recycled article is preferably obtained by mechanical recycling of the multilayer system F1 according to the invention.

[0114] The recycled article preferably comprises less than 5% by weight of styrenic block copolymers relative to the total weight of said recycled article.

[0115] The styrenic block copolymer content can be determined by Gel Permeation Chromatography (GPC), with an appropriate standard.

[0116] 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.

[0117] 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.

[0118] 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 1 A, specimen dimensions 80 x 10 x 4, tensile speed 50 mm / min).

[0119] The recycled article advantageously has an impact resistance (Charpy method) greater than or equal to 5.0, preferably greater than or equal to 5.5, 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).

[0120] 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).

[0121] 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.

[0122] 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 15%, 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) and devoid of 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.

[0123] Impact resistance is measured according to the standard mentioned above.

[0124] The recycled article is preferably prepared according to the process described below.

[0125] 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.

[0126] The elongation at break is measured according to the standard mentioned above.

[0127] 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 5%, 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) and devoid of 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.

[0128] The recycled article is preferably prepared according to the process described below.

[0129] Uses of CA Hot Melt Adhesive Composition

[0130] The present invention also relates to the use of the hot-melt self-adhesive composition CA comprising: a composition (a1) of styrene block copolymers comprising at least one elastomer block; one or more tackifying resins (a2); for preparing a recycled article.

[0131] The description, embodiments and preferred modes described above for the CA hot melt adhesive composition apply for use without the need to repeat them.

[0132] 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. Process for preparing a recycled article

[0133] 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.

[0134] The description, embodiments and preferred modes described above for the multilayer system F1 apply to the present method of preparing a recycled article without it being necessary to repeat them.

[0135] Step b) is preferably a grinding step advantageously leading to chips (also called “flakes” in English). It can be carried out at 23°C.

[0136] The method may comprise an optional washing step b-1) of the chips obtained in step b), and a drying step b-3).

[0137] The washing step b-1) can be carried out with water, possibly in the presence of additives, possibly with stirring.

[0138] 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.

[0139] Washing step b-1) can be carried out at a temperature ranging from 20°C to 25°C.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] In the context of the invention, and unless otherwise stated, the term "virgin polypropylene" means newly produced polypropylene that has not been recycled. The process 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.

[0144] 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.

[0145] The recycled or virgin polypropylene from step c) may be in the form of chips or granules, preferably in the form of chips.

[0146] Step d) may be an extrusion, co-extrusion, molding step, for example injection molding.

[0147] Extrusion (co-extrusion) advantageously allows the preparation of recycled films, while molding advantageously allows the preparation of molded articles.

[0148] Preferably, step d) is an injection molding step.

[0149] The process advantageously allows transformation of the F1 multilayer system into chips or granules that can be reused to manufacture a new article.

[0150] Recycled item

[0151] The description, embodiments, and preferred modes previously disclosed for the recycled article apply in the present method without the need to repeat them.

[0152] The present invention also relates to a recycled article obtainable by the process for preparing a recycled article as defined above.

[0153] The present invention also relates to the use of the recycled article for the automotive field.

[0154] 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%.

[0155] 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. Examples:

[0156] The following compounds were used in the examples:

[0157] Kraton® D1111 marketed by KRATON: composition with an overall styrenic unit content of 22%, and which is made up of 82% linear SIS triblock copolymer of M w approximately 250 kDa, and 18% SI diblock copolymer of M w about 100 kDa

[0158] Quintac® 3520 marketed by Zeon Chemicals: composition consisting, respectively, of 22% and 78% of linear SIS triblock (M w approximately 300 kDa) and diblock SI (M w approximately 130 kDa), and whose total content of styrenic units is 15%

[0159] Quintac® 3433 N marketed by Zeon Chemicals: composition consisting, respectively, of 44% and 56% of linear SIS triblock (M w approximately 220 kDa) and diblock SI (M w approximately 110 kDa), and whose total content of styrenic units is 16.5%

[0160] Escorez® 1310 LC available from Exxon Chemicals: a resin obtained by polymerization of a mixture of unsaturated aliphatic hydrocarbons having about 5 carbon atoms, and which has a softening temperature of 94°C and a weight average molar mass Mw of about 1800 Da

[0161] Regalite® R1125 available from Eastman: hydrogenated resin which has a softening temperature of 123°C and a weight average molar mass Mw of approximately 1200 Da.

[0162] Example 1: Preparation of hot-melt adhesive compositions

[0163] The adhesive compositions (see Table 1) are first prepared in the form of granules of approximately 4 mm diameter, by mixing their ingredients using a twin-screw extruder, extruding them 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 shows percentages by weight.

[0164] Table 1: Adhesive compositions preparation of a multilayer film

[0165] We prepare a film consisting of:

[0166] - a first polypropylene film (RD204CF from Borealis) with a thickness of 30 pm;

[0167] - an adhesive layer between the two films, derived from composition A1 of example 1 of 14 pm;

[0168] - a second polypropylene film (RD204CF from Borealis) with a thickness of 15 pm.

[0169] This three-layer film is manufactured using a continuously operating bubble-blowing co-extrusion pilot plant, in which 3 extruders are fed:

[0170] - for one, by composition A1 of example 1; and

[0171] - for the other 2, by polypropylene.

[0172] 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.

[0173] The resulting three-layer film has a total thickness of 59 pm, a length of 50 m and is packaged in the form of a 250 mm wide reel.

[0174] The different materials were introduced into each extruder, in order to fill the screws and form the polymer bubble at the exit of the extrusion die. After 30 minutes of purging, the thickness and stability of the bubble were checked, 50m of film was wound onto mandrels. process for preparing recycled articles

[0175] Step 1 of brovage

[0176] 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.

[0177] Step 2: Mix with a reference

[0178] 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. The 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

[0179] Strength at break / elongation at break

[0180] 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.

[0181] The principle of the measurement consists of stretching in a tensile machine, whose movable jaw moves at a constant speed equal to 50 mm / minute, a standard test piece made up of the granules obtained in step 2 (or reference) and recording, at the moment when the test piece breaks, the tensile stress applied (in MPa) as well as the elongation of the test piece (in %). The standard test piece 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.

[0182] Impact resistance is measured according to the DI N EN ISO 179-2 1 eA method at 23°C on ISO test specimens of type 1, with dimensions 80 x 10 x 4 mm (speed of 2.9 m / s).

[0183] The mechanical properties of the various prepared articles are described in the following table:

[0184] d: not determined / A: not applicable

[0185] 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.

[0186] 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.

[0187] 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.

[0188] The MFR is described in the following table:

[0189] 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 . Use of a multi-layer system F1 comprising: - a layer C1 comprising at least one polypropylene, - an adhesive layer Ad consisting of a hot-melt self-adhesive composition CA comprising: o a composition (a1) of styrene block copolymers comprising at least one elastomer block; o one or more tackifying resins (a2); - 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, for preparing a recycled article. Use according to claim 1, characterized in that the composition (a1) of styrene block copolymers comprising at least one elastomer block is constituted, on the basis of its total weight: - from 10 to 90% by weight of at least one diblock copolymer chosen from the group comprising SI, SBI, SIB, SB, SEB, and SEP, and - from 10 to 90% by weight of at least one triblock copolymer chosen from the group comprising SIS, SIBS, SBS, SEBS and SEPS. . Use according to any one of claims 1 or 2, characterized in that the content of composition (a1) in the hot-melt self-adhesive composition CA ranges from 30% to 80% by weight, preferably from 40% to 70% by weight, relative to the total weight of said composition CA. . Use according to any one of claims 1 to 3, characterized in that the total content of styrenic units in said composition (a1) varies from 10 to 40% by weight based on the total weight of (a1). . Use according to any one of claims 1 to 4, characterized in that the content of diblock copolymer in the composition (a1) varies from 15 to 80%, preferably from 50 to 80%. . Use according to any one of claims 1 to 5, characterized in that the hot-melt self-adhesive composition CA comprises: - from 40 to 70% by weight of a composition (a1) of styrene block copolymers comprising at least one elastomer block, said composition (a1) being constituted, on the basis of its total weight: - from 10 to 90% by weight of at least one diblock copolymer chosen from the group comprising SI, SBI, SIB, SB, SEB, and SEP, and - from 10 to 90% by weight of at least one triblock copolymer chosen from the group comprising SIS, SIBS, SBS, SEBS and SEPS; the total content of styrenic units in said composition (a1) varying from 10 to 40% by weight based on the total weight of (a1); and - from 30 to 60% by weight of one or more tackifying resins (a2).

7. Use according to any one of claims 1 to 6, characterized in that the composition (a1) consists of a triblock copolymer SIS and a diblock copolymer SI.

8. Use according to any one of claims 1 to 7, characterized in that 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.

9. Use according to any one of claims 1 to 8, characterized in that the recycled article is a single-layer film, a laminate, a complex (multilayer), a molded article, preferably a molded article.

10. Use according to any one of claims 1 to 9, 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.

11. Use of the hot-melt self-adhesive composition CA as defined according to any one of claims 1 to 10, for preparing a recycled article.

12. Use of the hot-melt self-adhesive composition CA as defined according to any one of claims 1 to 11, for improving the impact resistance of a recycled article, preferably of a recycled article based on polypropylene. Use according to claim 12, for improving by at least 5%, preferably by at least 15%, the impact resistance of a recycled article comprising said hot-melt self-adhesive composition CA, compared to a control article consisting of 100% polypropylene and lacking said hot-melt self-adhesive composition. A process for preparing a recycled article, said process comprising: a) providing the multilayer system F1 as defined 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 from step b) or the mixture from step c) into a recycled article. A recycled article obtainable according to the process as defined in claim 14.