Layering of multilayer films using water / organic emulsions

Abstract

A process for layering a multilayer film having a polyolefin: metal: polyolefin structure by treating the multilayer film with water / organic emulsion.

Description

Technical Field

[0001] The present invention relates to delamination processes utilizing emulsion delamination agent systems for processing multilayer films containing polyolefin recycle streams, and the use of such systems to achieve simple delamination or combined delamination / demetallization, depending on the characteristics of the aqueous phase of the emulsion. Background Art

[0002] Over the past decade, concerns have grown about plastics and their environmental sustainability at current usage levels. This has led to new legislation regarding the disposal, collection and recycling of polyolefins. In addition, many countries have made efforts to increase the percentage of plastic materials that are recycled rather than sent to landfills.

[0003] In Europe, plastic waste accounts for approximately 27 million tonnes of waste per year; in 2016, 7.4 million tonnes of this amount were disposed of in landfills, 11.27 million tonnes were incinerated (to produce energy), and about 8.5 million tonnes were recycled. Polypropylene-based materials are a particular problem, as these are widely used for packaging. Considering the huge amount of waste collected compared to the amount of waste that is recycled back into the stream (which only accounts for about 30%), there is still great potential for the intelligent reuse of plastic waste streams and for the mechanical recycling of plastic waste.

[0004] Take the automotive industry as an example: In Europe, the end of life (ELV) directive from the European Union stipulates that 85% / 95% of the materials from a vehicle should be recyclable or recoverable. The current recycling rate of automotive components is significantly below this target. On average, a vehicle consists of 9% by weight of plastic, of which only 3% by weight is currently recycled. Therefore, there is still a need to be met if the goals for recycling plastics in the automotive industry are to be achieved. However, due to cost reasons, poor mechanical properties and poor processing properties, waste streams containing cross-linked polyolefins are usually used for energy recovery (e.g. incineration in district heating plants or for heat generation in the cement industry), and are less often recycled into new products.

[0005] A major trend in the polyolefin field is the use of recycled materials from a wide variety of sources. Durable goods streams such as those from waste electrical equipment (WEE) or end-of-life vehicles (ELV) contain a wide variety of plastics. These materials can be processed to recycle acrylonitrile butadiene styrene (ABS), high impact polystyrene (HIPS), polypropylene (PP) and polyethylene (PE) plastics. Separation can be performed using density separation in water followed by further separation based on fluorescence, near infrared absorption or Raman fluorescence.

[0006] The better the quality of the recycled polyolefin, i.e. the higher the purity, the more expensive the material. In addition, the recycled polyolefin material will usually be cross-contaminated with non-polyolefin materials such as polyethylene terephthalate, polyamide, polystyrene or non-polymeric substances such as wood, paper, glass or aluminum. In addition, polyolefin films are generally multilayer structures, which combine the barrier properties and sealing properties of (multiple) layers. In addition to the main polyolefin, these multilayer structures can contain other polyolefins and even non-polyolefin materials in addition.

[0007] Additionally, recycled polyolefin-rich materials typically have much inferior properties than virgin materials unless the amount of recycled polyolefin added to the final compound is extremely low.

[0008] Packaging materials are often formed from multi-layer laminates. Such laminates are difficult to recycle because they often contain multiple polymer layers and / or other non-polymer materials that contaminate the polymer output of the recycling process, which is preferably a single polyolefin (e.g., polypropylene or polyethylene).

[0009] Removing such membranes from mixed polyolefin recycle streams is the simplest way to remove these sources of contamination; however, this option is wasteful and fails to recover potentially useful polyolefins.

[0010] Many delamination procedures are known in the art, which typically employ highly engineered delamination agent solutions. While these procedures can help recover more of the desired polyolefin from a particular polyolefin recycling process, from a process economics perspective, it is undesirable to incorporate additional steps into the process.

[0011] Therefore, a process in which the delamination step can be combined with an existing step (such as washing or deodorization) using cheap, readily available delamination agents is very useful for minimizing waste in recycling processes in an economical manner. Summary of the invention

[0012] The present invention is based on the discovery that a simple washing / demixing step involving an organic / aqueous emulsion can achieve these goals.

[0013] In a first aspect, the present invention relates to a process for treating a polyolefin recycle stream (A) comprising the following steps in the given order:

[0014] i) providing a polyolefin recycle stream (A) comprising at least 50 wt.-% of a multilayer film (F) relative to the total weight of the polyolefin recycle stream (A), the multilayer film (F) comprising the following layers:

[0015] (a) an outer layer consisting of a composition comprising at least 90% by weight of one or more polyolefins (PO);

[0016] (b) a metal layer in contact with the outer layer (a); and

[0017] (c) one or more further layers, wherein at least one of the one or more further layers is in contact with the metal layer (b), wherein the one or more further layers may contain a non-polyolefin material or one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), provided that the further layers in contact with the metal layer (b) contain one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a),

[0018] ii) contacting the polyolefin recycle stream (A) with an emulsion (E), said emulsion (E) comprising:

[0019] (a) an aqueous phase; and

[0020] (b) an organic phase,

[0021] Thereby a suspended polyolefin recycle stream (B) is obtained,

[0022] iii) subjecting said suspended polyolefin recycle stream (B) to agitation by ultrasonic treatment, thereby obtaining a treated recycle stream (C) dispersed in said emulsion (E),

[0023] iv) removing the emulsion (E) from said treated recycle stream (C), and

[0024] v) optionally recycling one or both of the aqueous phase and the organic phase.

[0025] In a second aspect, the present invention relates to the use of an emulsion (E1) comprising an organic phase and a substantially neutral aqueous phase having a pH in the range of 5.0 to 9.0, more preferably in the range of 6.0 to 8.0, most preferably in the range of 6.5 to 7.5, for achieving the delamination of a multilayer film (F) comprising the following layers:

[0026] (a) an outer layer consisting of a composition comprising at least 90% by weight of one or more polyolefins (PO);

[0027] (b) a metal layer in contact with the outer layer (a); and

[0028] (c) one or more further layers, wherein at least one of the one or more further layers is in contact with the metal layer (b), wherein the one or more further layers may contain a non-polyolefin material or one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), provided that the further layers in contact with the metal layer (b) contain one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a),

[0029] To provide a metallized film comprising layers (a) and (b) and an additional film derived from layer (c), the additional film may be a single layer film or a multilayer film.

[0030] In a third aspect, the present invention relates to the use of an emulsion (E2) comprising an organic phase and an acidic aqueous phase having a pH in the range of 0.0 to 5.0, more preferably in the range of 0.0 to 3.0, most preferably in the range of 0.0 to 1.0, for achieving delamination and demetallization of a multilayer film (F) comprising:

[0031] (a) an outer layer consisting of a composition comprising at least 90% by weight of one or more polyolefins (PO);

[0032] (b) a metal layer in contact with the outer layer (a); and

[0033] (c) one or more further layers, wherein at least one of the one or more further layers is in contact with the metal layer (b), wherein the one or more further layers may contain a non-polyolefin material or one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), provided that the further layers in contact with the metal layer (b) contain one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a),

[0034] To provide a monolayer film derived from layer (a) and an additional film derived from layer (c), the additional film may be a monolayer film or a multilayer film.

[0035] In a final aspect, the present invention relates to the use of an emulsion (E3) comprising an organic phase and an alkaline aqueous phase having a pH in the range of 9.0 to 14.0, more preferably in the range of 11.0 to 14.0, most preferably in the range of 12.0 to 14.0, for achieving delamination and demetallization of a multilayer film (F) comprising:

[0036] (a) an outer layer consisting of a composition comprising at least 90% by weight of one or more polyolefins (PO);

[0037] (b) a metal layer in contact with the outer layer (a); and

[0038] (c) one or more further layers, wherein at least one of the one or more further layers is in contact with the metal layer (b), wherein the one or more further layers may contain a non-polyolefin material or one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), provided that the further layers in contact with the metal layer (b) contain one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a),

[0039] To provide a monolayer film derived from layer (a) and an additional film derived from layer (c), the additional film may be a monolayer film or a multilayer film.

[0040] definition

[0041] Those skilled in the art know that pH values ​​greater than 14.0 and less than 0.0 are theoretically possible; however, they also know that it is very difficult to determine such pH values ​​using conventional pH probes. Therefore, in the context of the present invention, an aqueous solution having an effective pH greater than 14.0 is considered to have a pH of 14.0, while an aqueous solution having an effective pH less than 0.0 is considered to have a pH of 0.0.

[0042] The term logP refers to the partition function between two solvents, which are considered to be octanol and water unless otherwise stated. The logP of a given compound is calculated according to the following formula:

[0043]

[0044] Among them, the value [compound] 辛醇 and [compound] 水 denotes the concentration of a given compound in the octanol phase or the water phase of a two-phase octanol / water system, respectively. Although those skilled in the art know how to measure this property according to well-known methods, values ​​for many compounds have been tabulated and can be found in "James Sangster, Octanol-Water Partition Coefficients of simple organic compounds. J. Phys. Chem. Ref. Data, 1989, Vol. 18, No 3, 1111-1226", which means that those skilled in the art usually do not have to determine logP experimentally.

[0045] The term "fully saturated" means that the compound (typically an organic compound) does not have any double or triple bonds, i.e., all bonds present in the molecule are single (sigma) bonds. Fully saturated compounds may be linear, branched or cyclic. Fully saturated compounds are typically less reactive than unsaturated compounds due to the presence of fewer reactive functional groups in the compound.

[0046] An "inorganic oxyacid" is any compound in which an acidic hydrogen is bonded to an oxygen atom, wherein the acid does not contain a hydrocarbon chain or ring structure (i.e., an organic moiety). These inorganic oxyacids typically have H m XO n The general formula of the type, wherein X is the atom that acts as the central atom, and the parameters m and n depend on the oxidation state of the element X. In most cases, the element X is a nonmetal, but some metals, such as chromium and manganese, can also form oxoacids when present in their highest oxidation state. Due to the generally high oxidation state of the central atom X, the conjugate base of such an oxoacid can act as an oxidant.

[0047] In the context of the present invention, the term "rinsing" is used to indicate the addition of a solvent, typically water, which is used to remove foreign matter or residual liquid from the polyolefin surface. Compared to a "washing" step which typically requires longer time and agitation, this can be achieved in a very short time (i.e., less than 5 minutes, typically less than 1 minute) to remove adhering foreign matter from the polyolefin surface and potentially extract volatile organic compounds from the polyolefin.

[0048] Post-consumer waste refers to objects that have completed at least their first cycle of use (or life cycle), ie have served their first purpose, whereas post-industrial waste refers to manufacturing waste that does not normally reach the consumer.

[0049] The recycling stream may contain both articles for recycling and fragments of articles for recycling (e.g. flakes). In the context of the present invention, the contents of the recycling stream will be referred to as pieces, regardless of whether these pieces are whole articles, fragments thereof, or flakes thereof. In some embodiments, the pieces may be flakes, while in other embodiments, the pieces may be larger objects that may be converted into flakes at a later stage.

[0050] Polyolefin films are typically composed of one or more polyolefin thin layers, which means that one dimension of the film will be very small, while the other two dimensions can be many orders of magnitude larger. The same is true for flakes, which can be formed by films or similar thin products (such as plastic bags). In the context of the present disclosure, the term "in the form of flakes" or "flakes" or "flake-like" refers to the shape of an object, wherein, like a film, one dimension of the flake is very small, while the other two dimensions can be many orders of magnitude larger. In the context of the present invention, any complex product with a defined shape, such as a plastic bag with a clearly defined outer surface and inner surface, is not considered to be a film or flake, although these products can be converted into flakes of any size by methods known to those skilled in the art.

[0051] In the context of the present invention, the sheet surface area is defined as the surface area of ​​one face of the polyolefin in sheet form. This surface area is approximately half of the total surface area of ​​the sheet, which has two such faces and a very small amount of surface area from the edges of the sheet. The sheets according to the present invention typically have a surface area of ​​between 50 and 2500 mm 2 In the range of 100 to 1600 mm, more preferably in the range of 100 to 1600 mm 2 In the range of 150 to 900 mm, most preferably 2 within the range.

[0052] The unit % v / v (volume / volume) refers to the volume concentration of a specific solvent in a mixture, ie the volume of one component of the mixture divided by the volume of the entire mixture.

[0053] When the term "comprising" is used in the present description and claims, it does not exclude other unspecified elements of major or minor functional importance. For the purposes of the present invention, the term "consisting of" is regarded as a preferred embodiment of the term "comprising..." If a group is defined below as comprising at least a certain number of elements, this is also understood to disclose a group that preferably consists of only these elements.

[0054] When an indefinite or definite article is used when referring to a singular noun, for example "a", "an", "the", this includes a plural of that noun unless something else is specifically stated. DETAILED DESCRIPTION

[0055] Technology

[0056] In a first aspect, the present invention relates to a process for treating a polyolefin recycle stream (A) comprising the following steps in the given order:

[0057] i) providing a polyolefin recycle stream (A) comprising at least 50 wt.-% of a multilayer film (F) relative to the total weight of the polyolefin recycle stream (A), the multilayer film (F) comprising the following layers:

[0058] (a) an outer layer consisting of a composition comprising at least 90% by weight of one or more polyolefins (PO);

[0059] (b) a metal layer in contact with the outer layer (a); and

[0060] (c) one or more further layers, wherein at least one of the one or more further layers is in contact with the metal layer (b), wherein the one or more further layers may contain a non-polyolefin material or one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), provided that the further layers in contact with the metal layer (b) contain one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a),

[0061] ii) contacting the polyolefin recycle stream (A) with an emulsion (E), said emulsion (E) comprising:

[0062] (a) an aqueous phase; and

[0063] (b) an organic phase,

[0064] Thereby a suspended polyolefin recycle stream (B) is obtained,

[0065] iii) subjecting said suspended polyolefin recycle stream (B) to agitation by ultrasonic treatment, thereby obtaining a treated recycle stream (C) dispersed in said emulsion (E),

[0066] iv) removing the emulsion (E) from said treated recycle stream (C), and

[0067] v) optionally recycling one or both of the aqueous phase and the organic phase.

[0068] Step v) is an optional step, which means that the process according to the invention may comprise the following steps in the given order:

[0069] i) providing a polyolefin recycle stream (A) comprising at least 50 wt.-% of a multilayer film (F) relative to the total weight of the polyolefin recycle stream (A), the multilayer film (F) comprising the following layers:

[0070] (a) an outer layer consisting of a composition comprising at least 90% by weight of one or more polyolefins (PO);

[0071] (b) a metal layer in contact with the outer layer (a); and

[0072] (c) one or more further layers, wherein at least one of the one or more further layers is in contact with the metal layer (b), wherein the one or more further layers may contain a non-polyolefin material or one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), provided that the further layers in contact with the metal layer (b) contain one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a),

[0073] ii) contacting the polyolefin recycle stream (A) with an emulsion (E), the emulsion (E) comprising

[0074] (a) an aqueous phase; and

[0075] (b) an organic phase,

[0076] Thereby a suspended polyolefin recycle stream (B) is obtained,

[0077] iii) subjecting said suspended polyolefin recycle stream (B) to agitation by ultrasonic treatment, thereby obtaining a treated recycle stream (C) dispersed in said emulsion (E),

[0078] iv) removing the emulsion (E) from said treated recycle stream (C).

[0079] Alternatively, the process according to the invention may comprise the following steps in the order given:

[0080] i) providing a polyolefin recycle stream (A) comprising at least 50 wt.-% of a multilayer film (F) relative to the total weight of the polyolefin recycle stream (A), the multilayer film (F) comprising the following layers:

[0081] (a) an outer layer consisting of a composition comprising at least 90% by weight of one or more polyolefins (PO);

[0082] (b) a metal layer in contact with the outer layer (a); and

[0083] (c) one or more further layers, wherein at least one of the one or more further layers is in contact with the metal layer (b), wherein the one or more further layers may contain a non-polyolefin material or one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), provided that the further layers in contact with the metal layer (b) contain one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a),

[0084] ii) contacting the polyolefin recycle stream (A) with an emulsion (E), said emulsion (E) comprising:

[0085] (a) an aqueous phase; and

[0086] (b) an organic phase,

[0087] Thereby a suspended polyolefin recycle stream (B) is obtained,

[0088] iii) subjecting said suspended polyolefin recycle stream (B) to agitation by ultrasonic treatment, thereby obtaining a treated recycle stream (C) dispersed in said emulsion (E),

[0089] iv) removing the emulsion (E) from said treated recycle stream (C), and

[0090] v) recycling one or both of the aqueous phase and the organic phase.

[0091] Step i) involves providing a polyolefin recycle stream (A).

[0092] The polyolefin recycle stream (A) comprises at least 50 wt.-%, more preferably at least 60 wt.-%, still more preferably at least 70 wt.-%, still more preferably at least 80 wt.-%, still more preferably at least 90 wt.-%, relative to the total weight of the polyolefin recycle stream (A), of a multilayer film (F) comprising the following layers:

[0093] (a) an outer layer consisting of a composition comprising at least 90% by weight of one or more polyolefins (PO);

[0094] (b) a metal layer in contact with the outer layer (a); and

[0095] (c) one or more other layers, wherein at least one of the one or more other layers is in contact with the metal layer (b), wherein the one or more other layers may contain non-polyolefin materials or one or more polyolefins that may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), provided that the other layer in contact with the metal layer (b) contains one or more polyolefins that may be the same as or different from the one or more polyolefins (PO) of the outer layer (a).

[0096] In a particular embodiment, the polyolefin recycle stream (A) consists of a multilayer membrane (F) as defined above.

[0097] It is particularly preferred that the metal layer (b) is a vapor-deposited metal layer, wherein the metal layer has been vapor-deposited on the outer layer (a).

[0098] The one or more other layers (c) may comprise any material, either polyolefin or non-polyolefin, provided that the layer in contact with the metal layer (b) contains one or more polyolefins.

[0099] The polyolefin recycle stream (A) is preferably derived from post-consumer waste, post-industrial waste, or a combination thereof, most preferably from post-consumer waste.

[0100] The polyolefin recycle stream (A) is usually obtained by sorting a mixed polyolefin recycle stream using known sorting techniques. Suitable methods include near IR spectroscopy, mid IR spectroscopy, high speed laser spectroscopy, Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and sorting by color. Particularly preferred is near IR spectroscopy.

[0101] The precise form of the article of multilayer film (F) is not critical; however, it is preferred that the multilayer film (F) is provided in the form of a sheet.

[0102] Although providing in the form of flakes is not believed to be critical to achieving demixing using the emulsions of the present invention, providing in the form of flakes is necessary for most conventional pre- or post-classification steps and furthermore allows easier processing of the polyolefin recycle stream (A), the suspended recycle stream (B) and the treated recycle stream (C).

[0103] Step ii) involves contacting the polyolefin recycle stream (A) with an emulsion (E), said emulsion (E) comprising:

[0104] (a) an aqueous phase; and

[0105] (b) an organic phase,

[0106] A suspended polyolefin recycle stream (B) is thus obtained.

[0107] The definition of said emulsion is defined in more detail below.

[0108] Step iii) involves subjecting said suspended polyolefin recycle stream (B) to agitation by ultrasonic treatment, thereby obtaining a treated recycle stream (C) dispersed in said emulsion (E).

[0109] As will be appreciated by those skilled in the art, all polyolefins typically contain fractions soluble in organic solvents, and many polyolefins are characterized by their hexane soluble content or xylene soluble content. Although a small amount of polyolefin dissolution can be tolerated, it is best not to dissolve too much recycled polyolefin. Therefore, it will be appreciated by those skilled in the art that they need to avoid using excessive organic solvents in the emulsion (E). From an economic point of view, it is also advantageous to minimize the amount of the organic solvent employed.

[0110] Preferably, the polyolefin recycle stream (A) and the emulsion (E) are present in step iii) in a weight ratio in the range of 5:95 to 67:33, most preferably in the range of 5:95 to 45:55.

[0111] Preferably, step iii) is performed for a period of time in the range of 1 minute to 4 hours, more preferably in the range of 5 minutes to 2 hours, most preferably in the range of 10 minutes to 1 hour.

[0112] It is also preferred that step iii) is carried out at a temperature in the range of 20 to 95°C, more preferably in the range of 40 to 90°C, most preferably in the range of 50 to 85°C.

[0113] In addition to agitation by ultrasonic treatment, other agitation methods such as mechanical mixing, mechanical grinding or a pump around loop may be used in combination with ultrasonic treatment.

[0114] Step iv) involves removing the emulsion (E) from the treated recycle stream (C). Although the process is relatively simple to achieve by decanting and / or filtering the mixture, trace amounts of the emulsion (E) and / or any of the aqueous or organic phases may remain on the surface of the recycled polyolefin. These trace amounts of the emulsion (E) and / or any of the aqueous or organic phases may contain dissolved organic compounds, so it is advantageous to remove all traces of the emulsion (E).

[0115] This may be achieved by using a flushing step whereby any foreign matter and / or aqueous solution is flushed from the surface of the recycled polyolefin.

[0116] Therefore, it is preferred that the process comprises a further step iv.i) of flushing the residual emulsion (E) and / or any other foreign matter and / or degradation products thereof from the recycled polyolefin, which is performed after step iv).

[0117] In addition to or as an alternative to the washing step iv.i), it is preferred that the process comprises a further step iv.ii): drying the treated recycle stream after step iv) has been carried out, or after step (iv.i) if step (iv.i) is present. The drying step removes any residual aqueous phase, organic phase, or washing solution that may be present on the surface of the recycled polyolefin.

[0118] Depending on the nature of the emulsion introduced in step ii), the product of the process will either comprise a mixture of a metallized film comprising layers (a) and (b) and further films derived from layer (c), which may be monolayer films or multilayer films, or a mixture of a monolayer film derived from layer (a) and further films derived from layer (c), which may be monolayer films or multilayer films.

[0119] The product mixture may be sorted to produce sorted streams comprising metallized films of layers (a) and (b) and / or a monolayer film derived from layer (a) and other films derived from layer (c).

[0120] This sorting can be carried out by any method known to those skilled in the art. Suitable methods include near IR spectroscopy, mid IR spectroscopy, high speed laser spectroscopy, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy and sorting by color. Particularly preferred is near IR spectroscopy.

[0121] Emulsion (E)

[0122] The emulsion (E) of the present invention comprises

[0123] aqueous phase; and

[0124] Organic phase.

[0125] The skilled person will appreciate that the emulsion may include other phases that are immiscible with the aqueous and organic phases as described above, and indeed the present invention does not exclude such composite emulsions. These composite emulsions may have advantages in removing particularly specific volatile organic compounds; however, in the context of the present invention, it is preferred that the emulsion (E) consists of an aqueous and organic phase as described above, as this results in an operationally simple process.

[0126] The emulsion (E) of the present invention may be preformed before contacting with the polyolefin recycle stream (A) in step ii), or alternatively the aqueous phase and the organic phase are separately added to the polyolefin recycle stream (A) and the emulsion (E) is generated during step ii).

[0127] Two-phase emulsions comprising an aqueous phase and an organic phase can be classified as either oil-in-water emulsions or water-in-oil emulsions, depending on which component forms the dispersed phase and which component forms the continuous phase, which can generally be predicted from the relative amounts (ie, ratio) of the phases.

[0128] In the following discussion, the terms "oil" and "water" are equivalent to "organic phase" and "aqueous phase", respectively.

[0129] The relative contents of the organic phase and the aqueous phase are not particularly limited in the present invention. Preferably, the ratio of water to oil is in the range of 1:99 to 99:1, more preferably in the range of 5:95 to 99:5.

[0130] In one embodiment, the emulsion (E) of the present invention is an oil-in-water emulsion, wherein the ratio of water to oil is in the range of 50:50 to 99:1, more preferably in the range of 75:25 to 95:5.

[0131] In an alternative embodiment, the emulsion (E) of the present invention is a water-in-oil emulsion, wherein the ratio of oil to water is in the range of 50:50 to 99:1, more preferably in the range of 75:25 to 95:5.

[0132] Although the exact ratio between water and oil in the emulsion (E) is not critical to achieving effective removal of volatile organic compounds, certain ratios also have other advantages. In particular, ratios between 75:25 and 95:5 are very useful if recycling of the main components is to be achieved. In addition, although the organic phase is relatively cheap, it is more expensive to use than water due to waste stream management considerations. Therefore, from an economic point of view, especially if it is desired to recycle the aqueous phase, an embodiment in which the ratio of water to oil is in the range of 75:25 to 95:5 is particularly preferred. In addition, this embodiment is also advantageous for avoiding excessive polyolefin dissolution in the organic phase.

[0133] The organic phase of the emulsion (E), besides being highly stable, is advantageously non-reactive towards both the aqueous phase and the polyolefin recycle stream (A). Furthermore, the polarity is advantageously such that an emulsion is formed with the aqueous phase.

[0134] Preferably, the organic phase comprises at least 90% v / v of one or more fully saturated organic solvents having a logP value in the range of 1.0 to 10.0, more preferably in the range of 2.0 to 8.0, most preferably in the range of 3.0 to 6.0.

[0135] Preferably, the organic phase comprises at least 95% v / v of one or more fully saturated organic solvents having a logP value in the range of 1.0 to 10.0, more preferably at least 98% v / v, most preferably the organic phase consists of one or more fully saturated organic solvents having a logP value in the range of 1.0 to 10.0.

[0136] In a particularly preferred embodiment, the organic phase comprises at least 90% v / v, more preferably 95% v / v, still more preferably at least 98% v / v of a single fully saturated organic solvent having a logP value in the range of 1.0 to 10.0, and the organic phase most preferably consists of a single fully saturated organic solvent having a logP value in the range of 1.0 to 10.0.

[0137] It is particularly preferred that the one or more fully saturated organic solvents are selected from linear and branched alkanes and ethers (ie containing only carbon, hydrogen and optionally oxygen), most preferably linear and branched alkanes (ie containing only carbon and hydrogen).

[0138] In the broadest sense, the aqueous phase may be any aqueous solution or simply pure water.

[0139] In all embodiments, the aqueous phase may include detergent in an amount ranging from 0.1 wt % to 1.0 wt % relative to the total weight of the aqueous phase.

[0140] The detergent (one or more) can be a commercially available detergent mixture, or can be composed in any manner known to those skilled in the art. Suitable detergents include TUBIWASH SKP, TUBIWASH GFN, TUBIWASH EYE and TUBIWASH TOP commercially available from CHT, KRONES colclean AD 1004, KRONES colclean AD 1002 and KRONES colclean AD1008 from KICK RONES, and P3-stabilon WT, P3 stabilon AL from ECOLAB Ltd.

[0141] Basically neutral emulsion (E1)

[0142] In one embodiment of said emulsion (E1 ), said aqueous phase is a substantially neutral aqueous phase having a pH in the range of 5.0 to 9.0, more preferably in the range of 6.0 to 8.0, most preferably in the range of 6.5 to 7.5.

[0143] Acid emulsion (E2)

[0144] In an alternative embodiment of the emulsion (E2), the aqueous phase is an acidic aqueous phase having a pH in the range of 0.0 to 5.0, more preferably in the range of 0.0 to 3.0, most preferably in the range of 0.0 to 1.0.

[0145] Preferably, the acidic aqueous phase is an inorganic oxygen-containing acid solution.

[0146] Preferably, the inorganic oxygen-containing acid is selected from disulphuric acid (pyrosulfuric acid), sulfuric acid, phosphoric acid, nitric acid, perchloric acid, and mixtures thereof.

[0147] In a particularly preferred embodiment, the inorganic oxygen-containing acid is sulfuric acid.

[0148] Preferably, the pKa of the inorganic oxoacid is in the range of -5.0 to 5.0, preferably in the range of -5.0 to 0.0.

[0149] It is also preferred that the amount of inorganic oxygen-containing acid in aqueous solution A is in the range of 40 to 100 wt % (equivalent to a molar concentration of sulfuric acid of 5.3 to 18.65 M), more preferably in the range of 70 to 98 wt % (equivalent to 11.5 M to 18.4 M), and most preferably in the range of 94 to 98 wt % (equivalent to 17.8 M to 18.4 M).

[0150] The acidic aqueous phase may comprise more than one inorganic oxygen-containing acid. The above concentrations and pKa values ​​refer to each individual acid.

[0151] It is particularly preferred that the aqueous solution A is an aqueous solution of sulfuric acid having a concentration in the range of 94 to 98% by weight.

[0152] Alkaline emulsion (E3)

[0153] In other alternative embodiments of the emulsion (E3), the aqueous phase is an alkaline aqueous phase having a pH in the range of 9.0 to 14.0, more preferably in the range of 11.0 to 14.0, most preferably in the range of 12.0 to 14.0.

[0154] Preferably, the alkaline aqueous phase comprises the base in an amount ranging from 0.05 to 10 wt. %, more preferably ranging from 0.10 to 7 wt. %, most preferably ranging from 0.50 to 5 wt. %, relative to the total weight of the alkaline aqueous solution.

[0155] The choice of base is not critical, however it is preferred that the basic aqueous phase is an aqueous solution of a base selected from the group consisting of calcium hydroxide, potassium hydroxide, magnesium hydroxide, lithium hydroxide, sodium bicarbonate, sodium hydroxide, and mixtures thereof.

[0156] It is particularly preferred that the base is sodium hydroxide.

[0157] use

[0158] In a second aspect, the present invention relates to the use of an emulsion (E1) comprising an organic phase and a substantially neutral aqueous phase having a pH in the range of 5.0 to 9.0, more preferably in the range of 6.0 to 8.0, most preferably in the range of 6.5 to 7.5, for achieving the delamination of a multilayer film (F) comprising:

[0159] (a) an outer layer consisting of a composition comprising at least 90% by weight of one or more polyolefins (PO);

[0160] (b) a metal layer in contact with the outer layer (a); and

[0161] (c) one or more further layers, wherein at least one of the one or more further layers is in contact with the metal layer (b), wherein the one or more further layers may contain a non-polyolefin material or one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), provided that the further layers in contact with the metal layer (b) contain one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a),

[0162] To provide a metallized film comprising layers (a) and (b) and an additional film derived from layer (c), the additional film may be a single layer film or a multilayer film.

[0163] In this particular application, the selection of a substantially neutral aqueous phase has the following consequence: layer (b) will separate from layer (c) to provide a metallized film comprising layers (a) and (b), and further films derived from layer (c), which may be monolayer films or multilayer films. Demetallization of the metallized film comprising layers (a) and (b) is avoided, which may enable more efficient separation of the resulting film before demetallization is achieved in a subsequent step.

[0164] In a third aspect, the present invention relates to the use of an emulsion (E2) comprising an organic phase and an acidic aqueous phase having a pH in the range of 0.0 to 5.0, more preferably in the range of 0.0 to 3.0, most preferably in the range of 0.0 to 1.0, for achieving delamination and demetallization of a multilayer film (F) comprising:

[0165] (a) an outer layer consisting of a composition comprising at least 90% by weight of one or more polyolefins (PO);

[0166] (b) a metal layer in contact with the outer layer (a); and

[0167] (c) one or more further layers, wherein at least one of the one or more further layers is in contact with the metal layer (b), wherein the one or more further layers may contain a non-polyolefin material or one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), provided that the further layers in contact with the metal layer (b) contain one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a),

[0168] To provide a monolayer film derived from layer (a) and an additional film derived from layer (c), the additional film may be a monolayer film or a multilayer film.

[0169] In a final aspect, the present invention relates to the use of an emulsion (E3) comprising an organic phase and an alkaline aqueous phase having a pH in the range of 9.0 to 14.0, more preferably in the range of 11.0 to 14.0, most preferably in the range of 12.0 to 14.0, for achieving delamination and demetallization of a multilayer film (F) comprising:

[0170] (a) an outer layer consisting of a composition comprising at least 90% by weight of one or more polyolefins (PO);

[0171] (b) a metal layer in contact with the outer layer (a); and

[0172] (c) one or more further layers, wherein at least one of the one or more further layers is in contact with the metal layer (b), wherein the one or more further layers may contain a non-polyolefin material or one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), provided that the further layers in contact with the metal layer (b) contain one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a),

[0173] To provide a monolayer film derived from layer (a) and an additional film derived from layer (c), the additional film may be a monolayer film or a multilayer film.

[0174] In the third and final aspect, the emulsion used is able to effect both demixing and demetalling, avoiding the need for a separate demetalling step.

[0175] All alternatives and preferred embodiments provided in the process and emulsion sections above are applicable mutatis mutandis to the second, third and final uses.

[0176] Example

[0177] Determination method:

[0178] pH: The pH of the solution was determined potentiometrically using a Metrohm 867 pH module commercially available from Metrohm AG with a Unitrode

[0179] logP: Calculate log P according to the following formula:

[0180]

[0181] Among them, the value [compound] 辛醇 and [compound] 水 The concentrations of a given compound in the octanol phase or the aqueous phase of a biphasic octanol / water system measured by the shake flask method are shown in Table 1.

[0182] Experimental part:

[0183] In the following experiments, various washing systems were used to treat post-industrial waste membranes (PIW) and post-consumer waste membranes (PCW). The washing systems used were as follows:

[0184] Neutral emulsion: an emulsion formed by water and heptane (organic phase with pH 7.0)

[0185] Alkaline emulsion: an emulsion formed from a 1.8 wt% aqueous NaOH solution and heptane (organic phase with a pH of 14.0)

[0186] Acidic emulsion: Emulsion of concentrated sulfuric acid (i.e. 96 wt%) and heptane (pH 0.0 organic phase) Water wash: Water only (pH 7.0)

[0187] Heptane wash: Use only heptane

[0188] Alkaline wash solution: Use only 3.0% NaOH aqueous solution (pH 14.0)

[0189] Each emulsion was formed from 80% v / v aqueous phase and 20% v / v organic phase (ie heptane).

[0190] Post-industrial waste membrane (PIW) has the following layers:

[0191] (a) 50 μm polypropylene layer,

[0192] (b) 0.03 μm aluminum layer;

[0193] (c) A 25 μm multilayer film comprising three layers having the following composition:

[0194] (c1) 5 μm polypropylene tie layer comprising an oxygen-containing compound

[0195] (c2) 15 μm polypropylene layer

[0196] (c3) 5 μm polypropylene tie layer comprising an oxygen-containing compound

[0197] Wherein the aluminum layer (b) is formed via vapor deposition onto the polypropylene layer (a) and the order of the layers is (a): (b): (c1): (c2): (c3).

[0198] The post-consumer waste film (PCW) has the same structure as the post-industrial waste film (PIW), except that the final layer (c3) has an ink layer on the outer surface, ie the surface facing away from layer (c2).

[0199] The results of the delamination experiments are given in Table 1. The experiments were conducted at both room temperature (RT) and 80°C, with a weight ratio of PIW or PCW to emulsion (E) of 30:70. Note whether separation (i.e. delamination) occurred between layers (b) and (c), and whether demetallization had occurred, providing a demetallized film consisting of layer (a). For the PCW samples, further note whether the ink was removed from layer (c).

[0200] Table 1 Layered experimental results

[0201]

[0202]

[0203] As can be seen from Table 1, all three emulsions used were successfully separated at room temperature and 80 °C.

[0204] On the other hand, water and heptane washes were ineffective in achieving delamination or demetallization at both room temperature and 80°C. Alkaline washes were able to achieve combined demetallization-delamination, albeit only after very long reaction times. It is believed that the mechanism by which the alkaline wash achieves delamination is via demetallization that works slowly from the edge to the center of the flakes.

[0205] Neutral emulsions affect delamination without accompanying demetallization, so the mechanisms of delamination must be different. It is believed that alkaline and acidic emulsions achieve delamination / demetallization via an initial delamination (as for neutral emulsions), exposing the metal layer to the alkaline / acidic emulsion, which can affect demetallization much faster than would be possible using an alkaline wash solution alone once the surface of the metal layer is exposed to the emulsion. Although delamination of large films (not in flaky form) is not possible using an alkaline wash solution, it is possible using an emulsion according to the invention.

[0206] Alkaline and acidic emulsions are useful when complete delamination / demetallization is desired, improving the economics of the process; however, further control can be achieved by first effecting delamination with a neutral emulsion and then effecting demetallization of the (a):(b) film by any method known in the art, prior to separating the (a):(b) metallized film from (c). Although the process involves more steps, if layers (c) and (a) are similar in composition, this two-step process will make it much easier to separate the layers at an intermediate stage (since it is much more straightforward to separate a metallized film from a non-metallized film).

[0207] Experiments involving PCW also showed that the acidic and alkaline emulsions were also able to remove ink and / or adhesive layers while affecting delamination / demetallization.

Claims

1. A process for treating a polyolefin recycle stream (A) comprising the following steps in the given order: i) providing a polyolefin recycle stream (A) comprising at least 50 wt.-% of a multilayer film (F) relative to the total weight of the polyolefin recycle stream (A), the multilayer film (F) comprising the following layers: (a) an outer layer consisting of a composition comprising at least 90% by weight of one or more polyolefins (PO); (b) a metal layer in contact with the outer layer (a); and (c) one or more further layers, wherein at least one of the one or more further layers is in contact with the metal layer (b), wherein the one or more further layers may contain a non-polyolefin material or one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), provided that the further layers in contact with the metal layer (b) contain one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), ii) contacting the polyolefin recycle stream (A) with an emulsion (E), said emulsion (E) comprising: (a) aqueous phase; and (b) an organic phase, Thereby a suspended polyolefin recycle stream (B) is obtained, iii) subjecting said suspended polyolefin recycle stream (B) to agitation by ultrasonic treatment, thereby obtaining a treated recycle stream (C) dispersed in said emulsion (E), iv) removing the emulsion (E) from said treated recycle stream (C), v) optionally recycling one or both of the aqueous phase and the organic phase.

2. The process according to claim 1, wherein step iii) is carried out for a period of time in the range of 1 minute to 4 hours, more preferably in the range of 5 minutes to 2 hours, most preferably in the range of 10 minutes to 1 hour.

3. A process according to claim 1 or claim 2, wherein step iii) is carried out at a temperature in the range of 20 to 95°C, more preferably in the range of 40 to 90°C, most preferably in the range of 50 to 85°C.

4. A process according to any one of the preceding claims, wherein the organic phase comprises at least 90% v / v of one or more fully saturated organic solvents having a logP value in the range of 1.0 to 10.0, preferably wherein the one or more fully saturated organic solvents are selected from linear and branched alkanes and ethers, most preferably linear and branched alkanes.

5. The process according to any one of the preceding claims, wherein the aqueous phase is a substantially neutral aqueous phase having a pH in the range of 5.0 to 9.0, more preferably in the range of 6.0 to 8.0, most preferably in the range of 6.5 to 7.

5.

6. The process according to any one of claims 1 to 4, wherein the aqueous phase is an acidic aqueous phase having a pH in the range of 0.0 to 5.0, more preferably in the range of 0.0 to 3.0, most preferably in the range of 0.0 to 1.

0.

7. The process according to claim 6, wherein the acidic aqueous phase is an inorganic oxygen-containing acid solution, preferably wherein the inorganic oxygen-containing acid is selected from disulfuric acid, sulfuric acid, phosphoric acid, nitric acid, perchloric acid, and mixtures thereof, most preferably sulfuric acid.

8. The process according to any one of claims 1 to 4, wherein the aqueous phase is an alkaline aqueous phase having a pH in the range of 9.0 to 14.0, more preferably in the range of 11.0 to 14.0, most preferably in the range of 12.0 to 14.

0.

9. The process according to any one of the preceding claims, wherein the alkaline aqueous phase is an aqueous solution of a base selected from the group consisting of calcium hydroxide, potassium hydroxide, magnesium hydroxide, lithium hydroxide, sodium bicarbonate, sodium hydroxide, and mixtures thereof, preferably sodium hydroxide.

10. The process according to any of the preceding claims, wherein the amount of base in the alkaline aqueous phase is in the range of 0.05 to 10 wt.-%, more preferably in the range of 0.10 to 7 wt.-%, most preferably in the range of 0.50 to 5 wt.-%, relative to the total weight of the alkaline aqueous phase.

11. The process according to any one of the preceding claims, wherein the aqueous phase comprises a detergent in an amount ranging from 0.1% to 1.0% by weight relative to the total weight of the aqueous phase.

12. The process according to any one of the preceding claims, wherein the metal layer (b) is a vapour deposited metal layer, wherein the metal layer has been vapour deposited on the outer layer (a).

13. Use of an emulsion (E1) comprising an organic phase and a substantially neutral aqueous phase having a pH in the range of 5.0 to 9.0, more preferably in the range of 6.0 to 8.0, most preferably in the range of 6.5 to 7.5, for achieving the delamination of a multilayer film (F) comprising: (a) an outer layer consisting of a composition comprising at least 90% by weight of one or more polyolefins (PO); (b) a metal layer in contact with the outer layer (a); and (c) one or more further layers, wherein at least one of the one or more further layers is in contact with the metal layer (b), wherein the one or more further layers may contain a non-polyolefin material or one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), provided that the further layers in contact with the metal layer (b) contain one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), To provide a metallized film comprising layers (a) and (b) and an additional film derived from layer (c), the additional film may be a single layer film or a multilayer film.

14. Use of an emulsion (E2) comprising an organic phase and an acidic aqueous phase having a pH in the range of 0.0 to 5.0, more preferably in the range of 0.0 to 3.0, most preferably in the range of 0.0 to 1.0, for achieving delamination and demetallization of a multilayer film (F) comprising: (a) an outer layer consisting of a composition comprising at least 90% by weight of one or more polyolefins (PO); (b) a metal layer in contact with the outer layer (a); and (c) one or more further layers, wherein at least one of the one or more further layers is in contact with the metal layer (b), wherein the one or more further layers may contain a non-polyolefin material or one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), provided that the further layers in contact with the metal layer (b) contain one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), To provide a monolayer film derived from layer (a) and an additional film derived from layer (c), the additional film may be a monolayer film or a multilayer film.

15. Use of an emulsion (E3) comprising an organic phase and an alkaline aqueous phase having a pH in the range of 9.0 to 14.0, more preferably in the range of 11.0 to 14.0, most preferably in the range of 12.0 to 14.0, for achieving delamination and demetallization of a multilayer film (F) comprising: (a) an outer layer consisting of a composition comprising at least 90% by weight of one or more polyolefins (PO); (b) a metal layer in contact with the outer layer (a); and (c) one or more further layers, wherein at least one of the one or more further layers is in contact with the metal layer (b), wherein the one or more further layers may contain a non-polyolefin material or one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), provided that the further layers in contact with the metal layer (b) contain one or more polyolefins which may be the same as or different from the one or more polyolefins (PO) of the outer layer (a), To provide a monolayer film derived from layer (a) and an additional film derived from layer (c), the additional film may be a monolayer film or a multilayer film.

Images