Process for the physical separation of multilayer material comprising at least one PVDC layer

Abstract

The present invention relates to a process for separating a polyvinylidene chloride (PVDC) layer from a polymer layer adhered to the PVDC layer by an adhesion layer, in a multilayer material comprising at least one PVDC layer, at least one adhesion layer and at least one polymer layer different from PVDC and different from adhesion layer, comprising soaking the multilayer material in a liquid until the PVDC layer and the polymer layer are separated from each other.

Description

SSPI 2025 / 002Process for the physical separation of multilayer material comprising at least one PVDC layerCross reference

[0001] This application claims priority to application No.202511017604 filed in India on 27 February 2025, the whole content of this application being incorporated herein by reference for all purposes.Technical field

[0002] The present invention relates to a process for separating a polyvinylidene chloride (PVDC) layer from a polymer layer adhered to the PVDC layer by an adhesion layer, in a multilayer material comprising at least one PVDC layer, at least one adhesion layer and at least one polymer layer different from PVDC and different from adhesion layer.Background

[0003] Copolymers based on vinylidene chloride typically comprising vinyl chloride, alkyl acrylates, ethylene, acrylonitrile or mixtures thereof are often used as a coating onto plastic films to ensure to the later excellent barrier properties either against oxygen or against water vapor.

[0004] Such coated films are used mainly in food or pharmaceutical packaging applications like blister packs for drugs.

[0005] In such applications, most films are made of polyvinyl chloride (PVC). Indeed, PVC rigid film with a thickness of e.g. 250 pm can be easily thermoformed to prepare the plastic part of the package. Beforehand, PVC films are typically coated by polyvinylidene chloride (PVDC) copolymers latexes and the resulting coated substrate is further dried to obtain the film having the desired barrier properties. PVC films coated by polyvinylidene chloride (PVDC) copolymers latexes are known as Duplex multilayer structures.

[0006] Generally, to enhance the adhesion of the PVDC coating to the PVC substrate, PVC films are first coated with an anchor agent or primer that can be selected from polyacrylic acid resins, polyurethane resins, isocyanate resins, polyestersSSPI 2025 / 002resins, oxazoline resins and carbodiimide resins. Therefore, PVC / PVDC coated films can be considered as multilayer films.

[0007] Those multilayer films generally comprise up to 30 wt % of PVDC.

[0008] Other multilayer structures, also known as Triplex structures, comprise polyethylene (PE) layers in addition to PVDC and PVC layers generally in the following design PVC / PE / PVDC.

[0009] Polyvinylidene chloride (PVDC) copolymers are also used as barrier layers in multilayer shrink films for meat and cheese packaging. These PE / PVDC multilayer films contain typically 10-25% w / w PVDC and can include ethylene vinyl acetate (EVA) up to 50 % w / w. In such multilayer films, the EVA layer acts as the adhesion layer between the PVDC layer and PE layer. The five-layer LDPE / EVA / PVDC / EVA / LDPE (Low-Density Polyethylene) structure is highly diffused in the market.

[0010] The recycling of blister package wastes is complex due to the layered structure of plastic parts and the presence of aluminum lidding in the case of end-of-life wastes.

[0011] Although aluminum lidding is present in end-of-life waste and likely present in post-industrial waste, it can be efficiently separated from the plastic part by methods well known to the skilled person, for example through dissolving aluminum foil with a hydrochloric acid solution.

[0012] Shulka et al. in Separation and Purification Technology 348 (2024) 127760, explore the recycling of aluminum from waste pharmaceutical blister packages (WPBs) using phosphoric acid. The study highlights a hydrometallurgical process to recover secondary aluminum, aiming to reduce environmental impact. Phosphoric acid is effective for aluminum extraction from WPBs and added hydrogen peroxide achieves complete extraction in a few hours. Aluminum is recovered as aluminum phosphate.

[0013] Capkin et al. in JOM 75 (2023) 4672-4679 investigate the recycling potential of aluminum-rich waste pharmaceutical blisters (WPBs), which consist of multilayered structures of aluminum and polymers. The study focuses on separation methods to recover both metal and plastic, emphasizing hydrometallurgicalSSPI 2025 / 002processes. Acetone and other solvents can be used to separate aluminum and polymers.

[0014] The recycling of polymers in blister package wastes is complex due to the layered structure of plastic parts.

[0015] For example, mechanical recycling of PVDC / PVC plastic material from pharmaceutical blisters in PVC composition suitable for extrusion and injection molding applications is rendered difficult since PVDC and PVC heat stabilities are different. Indeed, the thermal degradation of PVDC occurs at a lower temperature than PVC thermal degradation and at a higher rate for a given temperature. Accordingly, a small amount of PVDC copolymer in a PVC-based composition is detrimental to the thermal stability of such a compound, and suitable stabilization is required for use in some applications requiring temperatures above 170°C. Generally, thermal degradation results in the loss of mechanical properties and in turning to yellow up to dark brown color.

[0016] US5726234 raises the problem of recycling multilayer films comprising PVDC in PVC compositions for applications requiring processing temperatures above 170°C. The solution provided by US5726234 is a stabilized PVDC-containing PVC composition comprising inorganic compounds of the series of metal oxides, metal hydroxides, or metal carbonates wherein metals are preferably barium (Ba), calcium (Ca), magnesium (Mg), zinc (Zn), titanium (Ti), lead (Pb), tin (Sn), and manganese (Mn). However, the stability of these compositions is rather limited as revealed by the coloration of samples submitted to temperatures exceeding 170°C.

[0017] All the above highlights that there is a need for a delamination process to separate the PVC layer, PVDC layer and eventually the PE layer present in the plastic part of the blister for drug packaging to recycle separately each material.

[0018] Delamination processes between polymer layers present in the plastic part of blister packaging for drugs or food have already been studied and disclosed; however, none have involved multilayer materials comprising at least one PVDC layer.SSPI 2025 / 002

[0019] US2024 / 0207795 discloses a separation fluid useful for swelling, degrading, or fully dissolving adhesives such as polyurethane-based, polyester-based, or acrylic-based adhesives, which can be present to ensure adhesion between different polymer layers of a multilayer packaging film. The separation fluid according to US2024 / 0207795 comprises a solvent that contains at least one aromatic group and at least one hetero-atom, and water. Cited multilayer packaging films include, among others, PE, PP, PET, PVC, PVOH, or PS. PVDC is not mentioned. Examples are conducted onto adhesive strips soaked into separation fluid. There is no example involving multilayer material and separation fluid.

[0020] IN202411001193 discloses a method for separating polymers and aluminium metal from medicine blister packaging. It involves treating the packaging with a solvent to enable layer delamination, followed by solvent recovery and controlled drying of polymers like PVC, PET, and EVA. The dried polymers are collected, and solvent vapours are condensed for recycling. PVDC is not mentioned. The use of acetone as a separation agent has proven to be effective, reliable, cost-efficient, and efficient in separating individual layers, namely PVC, EVA, and aluminium, from medicine blister packaging. However, extended exposure of the multilayer material with acetone leads to the dissolution of PVC and or EVA and thus makes separation of the two polymers difficult to achieve.

[0021] CA2116217 discloses a process for treating at least two materials joined to one another by an adhesion promoter where said adhesion promoter is dissolved by an acetone-water mixture containing 1-20 % by weight of water. In the process, the acetone-water mixture does not dissolve the materials and therefore allows their separation from one another. Exemplified materials are aluminium, and PVC comprised in pharmaceutical blisters. PVDC is not mentioned.

[0022] The aforementioned points emphasize the necessity for a delamination process to separate the PVDC layers and other polymer layers in the plasticSSPI 2025 / 002components of blister packaging used for drugs or for food. This separation is essential to enable the recycling of each material individually.

[0023] There is a need for a delamination process to separate the PVDC and PVC layers in the plastic components of blister packaging to enable the recycling of PVDC and PVC individually.

[0024] There is a need for a delamination process to separate the PVDC and PE layers in the plastic components of blister packaging to enable the recycling of PVDC and PE individually.

[0025] There is a need for a delamination process to separate the PVDC and PVC and optionally PE layers in the plastic components of blister packaging to enable the recycling of PVDC, PVC and PE individually.

[0026] There is a need for a delamination process to separate the PVDC layers, other polymer layers and optionally metal layer in blister packaging used for drugs or for food. This separation is essential to enable the recycling of each material individually.

[0027] There is a need for a delamination process to separate the PVDC layers, other polymer layers and optionally metal layer in blister packaging that is easily performed and thus cost-effective.Summary of the invention

[0028] With the aim of fulfilling the above needs, the Applicant faced the problem of providing a delamination process to separate the PVDC layers, other polymer layers and optionally metal layer present in multilayer materials.

[0029] Thus, the present application relates to a process for separating a polyvinylidene chloride (PVDC) layer from a polymer layer adhered to the PVDC layer by an adhesion layer, in a multilayer material comprising at least one PVDC layer, at least one adhesion layer and at least one polymer layer different from PVDC and different from adhesion layer, comprising soaking the multilayer material in a liquid at a temperature of 10°C to 40°C, for a duration ranging from 10 seconds to 10 hours, until the PVDC layer and the polymer layer are separated from each other, wherein at the given temperature and for the given duration:SSPI 2025 / 002- the liquid causes the adhesion layer to swell up to at least 100% by weight or causes the complete dissolution of the adhesion layer, and- the liquid optionally causes the PVDC layer and / or the polymer layer to swell up to at most 20% by weight.

[0030] Without being limited to any specific theory, the liquid suitable for this invention serves two purposes. Firstly, it swells or dissolves the adhesion layer that binds the PVDC layer to the polymer layer, facilitating their separation. Secondly, when the liquid swells the PVDC or polymer layer, it does so only up to a maximum of 20% by weight. This moderate swelling, or complete absence of swelling, does not compromise the mechanical properties of either the PVDC or polymer layers, making the separated layers easy to handle.

[0031] This process provides an opportunity to recycle multilayer films containing PVDC from blister packs, whether they originate from end-of-life waste or postindustrial waste, into PVDC-rich and other polymer-rich fractions.Detailed description

[0032] The inventors have found that delamination processes as described in prior art are generally not devoted to the recycling of multilayer materials comprising at least one PVDC layer.

[0033] Moreover, the inventors have observed that processes as described in prior art are generally not suitable to separate the PVDC layers and other polymer layers in the plastic components of blister packaging used for drugs or for food and therefore are not suitable for the recycling of each material individually.

[0034] The present application relates to a process for separating a polyvinylidene chloride (PVDC) layer from a polymer layer adhered to the PVDC layer by an adhesion layer, in a multilayer material comprising at least one PVDC layer, at least one adhesion layer and at least one polymer layer different from PVDC and different from adhesion layer, comprising soaking the multilayer material in a liquid at a temperature of 10°C to 40°C, for a duration ranging from 10 seconds to 10 hours, until the PVDC layer and the polymer layer are separated from each other, wherein at the given temperature and for the given duration:SSPI 2025 / 002- the liquid causes the adhesion layer to swell up to at least 100% by weight or causes the complete dissolution of the adhesion layer, and- the liquid optionally causes the PVDC layer and / or the polymer layer to swell up to at most 20% by weight.

[0035] Generally, the multilayer material is soaked in the liquid at a temperature of 10°C to 40°c, preferably at a temperature of 10°C to 30°C. Good results were obtained at room temperature i.e. at 25°C.

[0036] It is advantageous to be able to carry out the process according to the invention at such low temperatures.

[0037] In the process according to the invention, soaking is generally conducted for a duration ranging from 10 seconds to 10 hours. Sometimes, soaking is conducted for a duration ranging from 30 seconds to 5 hours. Often, soaking is conducted for a duration ranging from 1 minute to 3 hours.

[0038] Soaking the multilayer material can be carried out in any container that can be filled with the appropriate liquid. The container may be equipped with a stirring device, as well as a heating system and temperature control.

[0039] The container can be an open or closed container. For example, a closed container can be used to prevent liquid dissipation into the atmosphere. It is advantageous because it makes it possible to recycle the liquid after use.

[0040] In some embodiments the process is conducted under inert atmosphere e.g.under nitrogen, argon or mixture thereof atmosphere. In some other embodiments it is conducted under air.

[0041] In some embodiments, soaking is conducted under stirring of the mixture composed of the appropriate liquid and of the multilayer material.

[0042] The multilayer material to be treated using the process described in the invention can be introduced into the container either as a film or as flakes resulting from shredding. Therefore, it can be soaked in the liquid either as a film or as flakes resulting from shredding.

[0043] The multilayer material can be shredded using machines well known by the skilled person equipped with rotating blades or cutting tools, like rotary or horizontal shredders.SSPI 2025 / 002

[0044] During the process according to the invention, the liquid causes the adhesion layer to swell by at least 100% by weight or leads to the complete dissolution of the adhesion layer. Swelling by at least 100% by weight means that a layer composed of the adhesive, when soaked in the appropriate liquid at the given temperature and for the specified duration, will have its weight increased by 100% at least. For example, a strip of adhesive weighing 1g will weigh at least 2g after soaking. Typically, the weight after soaking is obtained by weighing the strip that has been wiped beforehand e.g. with absorbing paper.

[0045] It is assumed that during the process, a highly swollen adhesion layer will no longer ensure adhesion between the PVDC and the polymer layer, which will consequently separate. Obviously, the separation is also observed when the liquid causes complete dissolution of the adhesion layer.

[0046] Similarly, during the process according to the invention, the liquid optionally causes the PVDC layer and / or the polymer layer to swell up to at most 20% by weight. Swelling by at most 20% by weight means that a layer composed of PVDC and / or the layer composed of the polymer layer, when soaked in the appropriate liquid at the given temperature and for the specified duration, will have its weight increased by 20% at most. For example, a strip of PVDC and / or of the polymer weighing 1 g will weigh 1 ,2g at most after soaking.

[0047] It has been observed that during the process, a moderately swollen or not swollen at all PVDC layer and / or polymer layer, i.e. , swollen by at most 20%, retains sufficient mechanical properties to be easily separated. This moderate swelling does not compromise the mechanical properties of either the PVDC or polymer layers, making the separated layers easy to handle.

[0048] Accordingly, the choice of the liquid is crucial. A liquid that causes significant swelling of the PVDC and / or the polymer would make separation impossible, especially if soaking is performed under stirring. Highly swollen PVDC and / or polymer will have very poor mechanical properties and will disintegrate into small pieces dispersed in the liquid, making them extremely difficult to recover and separate.SSPI 2025 / 002

[0049] In the present invention, the term PVDC encompasses copolymers based on vinylidene chloride typically comprising vinyl chloride, acrylonitrile, acrylates, or ethylene as comonomers.

[0050] In the present invention, the term at least one polymer encompasses polymers generally used in packaging application. The polymer can be selected from the list consisting of polyvinyl chloride (PVC), polyethylene (PE), Polyethylene terephthalate (PET), polyamide (PA) and polypropylene (PP). Preferably the polymer is selected from polyvinyl chloride (PVC) and polyethylene (PE).

[0051] In some embodiments, at least one polymer layer different from PVDC is at least one polyvinyl chloride (PVC) layer.

[0052] Therefore, any multilayer material comprising at least one PVDC layer, at least one adhesion layer and at least one PVC layer can be treated by the process according to the invention.

[0053] In some embodiments, the multilayer material is pharmaceutical blister packaging waste coming from end-of-life waste or post-industrial waste.

[0054] In particular, PVC / PVDC blister flakes of duplex structure, with 40 grams per square meter (gsm) of PVDC, containing about 11 wt% of PVDC with regards to the total weight of PVDC and PVC or PVC / PVDC blister flakes of duplex structure, with 120 grams per square meter (gsm) of PVDC, containing about 25 wt% of PVDC with regards to the total weight of PVDC and PVC can be treated by the process according to the invention.

[0055] Generally, to ensure the adhesion of the PVDC layer to the PVC layer, PVC films are first coated with an adhesion layer that can be selected from polyacrylic acid resins, polyurethane resins, isocyanate resins, polyester resins, oxazoline resins and carbodiimide resins.

[0056] When the multilayer material comprises at least one PVDC layer, at least one adhesion layer and at least one PVC layer, the liquid may be any liquid that satisfies at the given temperature and for the specified duration:

[0057] - swelling up to at least 100% by weight or completely dissolving the adhesion layer, andSSPI 2025 / 002

[0058] - optionally swelling the PVDC layer and / or the PVC layer up to at most 20% by weight.

[0059] In some embodiments, the liquid consists of acetone and water with a volume ratio of 50 / 50 to 80 / 20, preferably 70 / 30 to 80 / 20.

[0060] Good results were obtained at 25 °C for a duration of 1 hour 50 minutes with an acetone / water v / v ratio of 70 / 30. Good results were also obtained at 25 °C for a duration of 1 hour 40 minutes with an acetone / water v / v ratio of 75 / 25.

[0061] This acetone-water composition is critical because if there is a higher relative amount of water, the adhesion layer does not swell sufficiently, preventing separation. Conversely, if there is a higher amount of acetone, the swelling of the PVDC and PVC layers becomes so significant that these layers lose their mechanical properties, disintegrating into small pieces dispersed in the liquid, making recovery and separation extremely difficult, if not impossible.

[0062] Acetone in combination with water is advantageous because it can be easily recovered by distillation due to its low boiling point at atmospheric pressure and thus recycled in the process.

[0063] In some other embodiments, the liquid consists of methyl ethyl ketone (MEK) saturated with water or mixture of diethyl ketone (DEK) saturated with water.

[0064] In some other embodiments, at least one polymer layer different from PVDC is at least one polyethylene (PE) layer.

[0065] Therefore, any multilayer material comprising at least one PVDC layer, at least one adhesion layer and at least one PE layer can be treated by the process according to the invention.

[0066] In some embodiments, the multilayer material is food blister packaging waste coming from end-of-life waste or post-industrial waste.

[0067] In particular, multilayer shrink films for meat and cheese packaging. These PE / PVDC multilayer films contain typically 10-25% w / w of PVDC and can include ethylene vinyl acetate (EVA) up to 50 % w / w. In such multilayer films, the EVA layer acts as the adhesion layer between the PVDC layer and the PE layer. The five-layer LDPE / EVA / PVDC / EVA / LDPE (Low-Density Polyethylene) structure is highly diffused in the market.SSPI 2025 / 002

[0068] Generally, to ensure the adhesion of the PVDC layer to the PE layer, an adhesion layer that can be selected from ethylene vinyl acetate copolymers (EVA).

[0069] In some embodiments, the adhesion layer is the EVA copolymer layer.

[0070] When the multilayer material comprises at least one PVDC layer, at least one adhesion layer and at least one PE layer, the liquid may be any liquid that satisfies at the given temperature and for the specified duration:- swelling up to at least 100% by weight or completely dissolving the adhesion layer, and- optionally swelling the PVDC layer and / or the PE layer up to at most 20% by weight.

[0071] Generally, the liquid is selected from the list consisting of toluene, xylene, ethyl acetate, chloroform, dichloromethane and mixtures thereof.

[0072] Good results were obtained at 25°C, for a duration of 2 minutes using toluene as the liquid.

[0073] Other multilayer structures, also known as Triplex structures, comprise polyethylene (PE) layers in addition to PVDC and PVC layers generally in the following design PVC / PE / PVDC can be treated by the process according to the invention.

[0074] In some embodiments, the multilayer material further comprises a metal layer adhered either on the PVDC layer or the polymer layer. It is generally the case when the material originates from end-of-life waste.

[0075] The process according to the invention may further comprise the steps of:- isolating the separated PVDC, polymer and optionally metal layer from the liquid- optionally drying the isolated PVDC, polymer and optionally metal layer - sorting the PVDC, polymer and optionally metal layer to recover fractions rich in PVDC, polymer and optionally metal.

[0076] Isolating the PVDC, the polymer and optionally the metal from the liquid can be made by filtration of these solid materials. Further to the filtration rinsing or washing can be made with fresh liquid or by water.SSPI 2025 / 002

[0077] When required, PVDC, polymer and optionally metal can be dried at relevant temperatures and pressure using equipment well-known by the skilled person. Generally, drying is conducted at a temperature below the lowest glass transition temperature of the materials being considered.

[0078] Finally, the sorting of PVDC, the polymer, and optionally the metal can be performed using techniques well known in the field of polymer recycling, such as density flotation sorting or wind shifting sorting.

[0079] Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

[0080] The invention will be now described with reference to the following examples, whose purpose is merely illustrative and not intended to limit the scope of the invention.Figure

[0081] Figure 1: PVDC / PE food multilayer film delamination process using toluene bathExperimental section

[0082] Raw materials

[0083] Liveo and ACG PVC / PVDC blister flakes of duplex structure, with 40 grams per square meter (gsm) of PVDC and containing 11 wt% of PVDC with regards to the total weight of PVDC and PVC were used (Duplex (A)).

[0084] Liveo and ACG PVC / PVDC blister flakes of duplex structure, with 120 grams per square meter (gsm) of PVDC and containing 29 wt% of PVDC with regards to the total weight of PVDC and PVC were also used successfully (Duplex (B)).

[0085] Table 1 : Pharmaceutical blisters structure and compositionSSPI 2025 / 002

[0086] Sealed Air France multilayer film PE / EVA / PVDC / EVA / PE containing 14.35 wt% of PVDC with regards to the total weight of PVDC, EVA and PE was also used (PVDC / PE film).

[0087] Table 2: Food multilayer film structure and composition (PVDC / PE film)

[0088] Sodium bromide (NaBr), acetone, ethyl acetate and toluene were obtained from Aldrich.

[0089] Separation process

[0090] Pharmaceutical blisters delamination study

[0091] PVDC / PVC pharmaceutical blister films of thickness 275 pm (Duplex (A)) or 340pm (Duplex (B)) were shredded to get flakes of 1.9 mm X 8 mm. 5g of the shredded material was placed into a glass bottle containing 100 ml of the separation liquid at 25°C.

[0092] Separation was conducted under gentle stirring using a stirring bar. Results with acetone and ethyl acetate as separation liquids are reported in table 3.

[0093] Table 3: Delamination of pharmaceutical blister Duplex (A)

[0094] From table 3, one can see that, at 25°C, acetone and ethyl acetate cause rather swift delamination of PVDC and PVC layers. However, separation isSSPI 2025 / 002accompanied with consequent swelling of the PVC (>100wt%) layer which renders this layer fragile and impossible to handle easily.

[0095] Separation at 25°C was also conducted with different liquid compositions based on acetone and water mixtures. Results are reported in table 4.

[0096] Table 4: Delamination of pharmaceutical blister Duplex (A)><<

[0097] From table 4, it is clear that the addition of water to acetone reduces the swelling of the PVC layer. However, the amount of water must be fine-tuned for separation to occur while swelling of PVC is kept acceptable. A good tradeoff between separation time and degree of swelling of the PVC layer was obtained for acetone / water compositions in volumes of 75 / 25 and 70 / 30.

[0098] Pharmaceutical blister separation on a larger scale

[0099] Suitable liquid compositions as described above were used on a larger scale to be able to achieve a meaningful material balance.

[0100] Step I: Delamination / separation process

[0101] Into a 10L jacketed glass vessel equipped with an overhead stirrer and bottom drain valve, 5L of acetone / water (75 / 25 v / v) and 500 g of shredded PVDC / PVC film (Duplex A) were introduced. The content was slowly stirred at low rpm at 25°C. After 2h delamination of the PVDC / PVC was noticed. Then, the liquid was removed from the bottom valve, and the delaminated material was washed with water. All the water washings were collected and distilled out to recover acetone and water. 96 wt% of water and more than 98 wt% of acetone was recovered.SSPI 2025 / 002

[0102] Duplex B was treated with a similar process involving 2L of acetone / water (70 / 30 v / v) and 200 g of shredded PVDC / PVC film (Duplex B).

[0103] The delaminated PVDC and PVC were recovered as per the process described in step II.

[0104] Step II: Recovery process of separated materials by flotation

[0105] A 40 w% aqueous sodium bromide (NaBr) solution at 20°C with a density of 1.41 g / cm3was used for PVDC and PVC separation by flotation. Indeed, at this temperature the density of PVC is 1.38 g / cm3while the density of PVDC is 1.68 g / cm3.

[0106] The wet mixture of delaminated PVDC and PVC from step I was introduced into 2L of 40 w% aqueous NaBr solution. Floating PVC flakes were removed with a skimmer and sinking PVDC flakes were recovered by elimination of supernatant. Flakes were separately washed with water to remove the salt and dried under vacuum at 40°C until constant weight was obtained. The yield of recovered PVDC and PVC are reported in table 5 and table 6.

[0107] Table 5: Delamination of pharmaceutical blister Duplex (A) with acetone / water 75 / 25 v / v material balance after flotation and drying

[0108] Table 6: De amination of pharmaceutical blister Duplex (B) with acetone / water 70 / 30 v / v material balance after flotation and drying

[0109] The results reported in table 5 and 6 show that treating the PVDC / PVC multilayer material with a suitable liquid composed of acetone-water allows for recovery in high yield of very pure PVDC and PVC fractions by flotation.SSPI 2025 / 002

[0110] Very good results were also obtained by the inventors using a wind shifting process conducted on delaminated flakes of PVDC and PVC with a fluidized bed riser coupled to a cyclone separator.

[0111] Multilayer material for food delamination

[0112] Multilayer film PE / EVA / PVDC / EVA / PE (PVDC / PE film) containing 14.35 wt% of PVDC with regards to the total weight of PVDC, EVA and PE were treated in the following conditions.

[0113] Multilayer film was soaked in a toluene bath (400 ml) for 2 to 30 minutes at 25°C. The resulting PVDC and PE layers were then collected on the rollers mechanism (see figure 1), washed with toluene / ethyl acetate mixture (65:35) and dried under vacuum at 40°C until a constant weight was obtained.

[0114] Toluene bath and washing fractions were gathered and EVA was recovered by evaporation. The presence of EVA copolymer was confirmed by differential scanning calorimetry (DSC) and FTIR spectroscopy.

[0115] The material balance of the process is reported in table 7.

[0116] Table 7: Delamination of food multilayer film with toluene material balance after washing and drying

[0117] Results reported in table 7, show that the process according to the invention allows the delamination of PE / EVA / PVDC / EVA / PE multilayer film and recovery with a high yield of pure materials.

Claims

SSPI 2025 / 002ClaimsClaim 1. A process for separating a polyvinylidene chloride (PVDC) layer from a polymer layer adhered to the PVDC layer by an adhesion layer, in a multilayer material comprising at least one PVDC layer, at least one adhesion layer and at least one polymer layer different from PVDC and different from adhesion layer, comprising soaking the multilayer material in a liquid at a temperature of 10°C to 40°C, for a duration ranging from 10 seconds to 10 hours, until the PVDC layer and the polymer layer are separated from each other, wherein at the given temperature and for the specified duration:- the liquid causes the adhesion layer to swell up to at least 100% by weight or causes the complete dissolution of the adhesion layer, and- the liquid optionally causes the PVDC layer and / or the polymer layer to swell up to at most 20% by weight.Claim 2. The process according to claim 1, wherein soaking is conducted for a duration ranging from 30 seconds to 5 hours, or from 1 minute to 3 hours.Claim 3. The process according to claim 1 or 2 wherein soaking is performed under stirring.Claim 4. The process according to any one of claims 1 to 3, wherein the multilayer material is soaked in the liquid either as a film or as flakes resulting from shredding. Claim 5. The process according to any one of claims 1 to 4, wherein the at least one polymer layer different from PVDC is selected from the list consisting of polyvinyl chloride (PVC), polyethylene (PE), Polyethylene terephthalate (PET), polyamide (PA) and polypropylene (PP).Claim 6. The process according to any one of claims 1 to 5, wherein the at least one polymer layer different from PVDC is at least one polyvinyl chloride (PVC) layer. Claim 7. The process according to claim 6, wherein the liquid consists of acetone and water with a volume ratio of 50 / 50 to 80 / 20, preferably of 70 / 30 to 80 / 20.Claim 8. The process according to claim 6, wherein the liquid consists of methyl ethyl ketone (MEK) saturated with water or of diethyl ketone (DEK) saturated with water.SSPI 2025 / 002Claim 9. The process according to any one of claims 5 to 8, wherein the multilayer material is pharmaceutical blister packaging waste.Claim 10. The process according to any one of claims 1 to 6, wherein the at least one polymer layer different from PVDC is at least one polyethylene (PE) layer. Claim 11. The process according to claim 10, wherein the adhesion layer is EVA copolymer layer.Claim 12. The process according to claims 10 to 11, wherein the liquid is selected from the list consisting of toluene, xylene, ethyl acetate, chloroform, dichloromethane and mixtures thereof.Claim 13. The process according to claims 10 to 12, wherein the multilayer material is food blister packaging waste.Claim 14. The process according to any one of the preceding claims, wherein the multilayer material further comprises a metal layer adhered either on the PVDC layer or the polymer layer.Claim 15. The process according to any one of the preceding claims, further comprising the steps of:- isolating the separated PVDC, polymer and optionally metal layer from the liquid - optionally drying the isolated PVDC, polymer and optionally metal layer- sorting the dried PVDC, polymer and optionally metal layer to recover fractions rich in PVDC, polymer and optionally metal.Claim 16. The process according to claim 15, wherein sorting is made by flotation or by wind shifting.

Images