Method for extracting additives from polyvinyl chloride or polyvinyl butyral products.

Abstract

Method for extracting one or more additives from polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products (1), characterized in that said method comprises the step (S1) of comminuting said PVC or PVB products (1) into particulate material (2) and the step (S2) of subjecting said particulate material (2) to an extraction by means of a solvent (3) in one or more extraction vessels (4), characterized in that - the bulk density of said particulate material (2) while being subjected to said solvent-based extraction is at least 300 kilograms per cubic meter, preferably at least 500 kilograms per cubic meter and / or - said extraction comprises using a first amount of said solvent (3) to extract additives from a first and second batch of particulate material (2) in a first and second extraction vessel (4A-4B) subsequently.

Description

[0001] Method for extracting additives from polyvinyl chloride or polyvinyl butyral products.

[0002] The present invention relates to recycling polyvinyl chloride (PVC) or polyvinyl butyral products. In particular, the invention relates to recycling polyvinyl chloride products such that the polymer and potentially its additives obtained from these products may be used for the production of new products. More in particular, the invention may relate to recycling floor or wall coverings.

[0003] Although polyvinyl chloride and polyvinyl butyral are thermoplastic polymers, recycling of these products is often conceived as being difficult or problematic. This is mainly due to the additives and / or contaminants that such products may contain. It is particularly common for most polyvinyl chloride and polyvinyl butyral products to contain plasticizers. In the state of the art, a class of plasticizers which has been abundantly used are phthalates and their derivatives. Recently however, phthalates have been associated with public health related issues, and in particular with regard to the emission of volatile organic compounds (VOCs). Furthermore, such products may contain, among others, fillers (for example calcium carbonate), dyes and / or heavy metals, which may contribute to making recycling even more difficult. As the composition of polyvinyl chloride and polyvinyl butyral products strongly depends on their specific application, recycling the products at their end-of-life stage may be particularly complex.

[0004] The prime object of the present invention is to provide a method for recycling polyvinyl chloride products and / or polyvinyl butyral products, with various preferred embodiments offering a solution for the problems associated with the recycling methods of the state of the art. In particular, the invention aims to provide a better and more widely applicable method for recycling polyvinyl chloride and / or polyvinyl butyral products, wherein the recycled polymer may be used to produce new products.

[0005] JP 2006 / 249423A discloses a method for recovering material from soft polyvinyl chloride products. Crushed soft polyvinyl chloride products are treated with an alcoholic solvent and a non-alcoholic solvent. The non-alcoholic solvent may be carbon dioxide. The non-alcoholic solvent may be in a supercritical state. The extraction may be repeated several times with fresh solvent until the rate of recovering additives falls below a threshold. JP 2007 / 092035 A discloses a similar method for recovering material from lead-containing soft polyvinyl chloride material. The method disclosed in these documents are experimental and / or at small scale. The example in JP’423 concerns recovery of material from a sample of a PVC film, weighing 10 grams. Such films are notoriously differently composed than flooring materials in general. For example, films may be free of filler materials, such as talcum, chalk or other calcium carbonate based materials, while flooring materials are generally highly filled. Fillers may render the extraction process ineffective. Films have a uniform composition while flooring materials are generally composed of laminated together portions of a mutually different composition.

[0006] There is a lack of a method for recovering or separating material from waste polyvinyl chloride or polyvinyl butyral at an industrial scale, particularly from filled or highly filled products.

[0007] WO 2024 / 134371 discloses an industrial process for extracting additives from highly filled polyvinyl chloride products. WO ’371 amongst others proposes to comminute the PVC products to be recycled into granules having a particle size distribution with a D90 of less than 2.5 mm. Subjecting small granules to extraction by means of a solvent may allow for improved extraction. Further WO ’371 proposes extraction with at least two consecutive steps, where prior, to the second step of two consecutive steps, the particle size of the PVC products may be further reduced. Different types of solvents may be used in each step to further optimize the extraction.

[0008] The present invention in the first place aims at an alternative method for separating additives or contaminants for polyvinyl chloride products or polyvinyl butyral products, wherein, in accordance with preferred embodiments, solutions are offered to one or more of the problems with the methods of the prior art. To this aim, a first independent aspect of the present invention is a method for extracting one or more additives from polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products, with as a characteristic that said method comprises the step of comminuting said PVC or PVB products into particulate material and the step of subjecting said particulate material to an extraction by means of a solvent, preferably in one or more extraction vessels, characterized in that the bulk density of said particulate material while being subjected to said solvent-based extraction is at least 300 kilograms per cubic meter, preferably at least 500 kilograms per cubic meter. The bulk density of particulate material obtained from the PVC or PVB products may in itself be about 250 kilograms per cubic meter. The inventors have found that raising the bulk density of the particulate material, for example by compression, does not necessarily reduce the efficiency of the extraction process. Preferably, however, the bulk density is below a level where the efficiency could be significantly reduced. Therefore, preferably, said bulk density is between 300 and 1000 kilograms per cubic meter, preferably between 500 and 750 kilograms per cubic meter.

[0009] As stated, said method preferably comprises a step of compressing said particulate material prior to or during said solvent-based extraction. Prior to the extraction the particulate material may be compressed by introducing it into the extraction vessel, and increasing the bulk density of the particulate material by compacting it by means of a plunger. A compression or compaction during said solvent-based extraction may be similarly obtainable, for example by means of a plunger compacting the particulate material in the sealed extraction vessel. In the latter case, the compaction or bulk density of the particulate material may be altered at multiple times, or even continuously, during said extraction, in order to create optimal extraction efficiency. Indeed the efficiency may be different from batch to batch and an initial compaction prior to, or at the start of, the extraction may be suboptimal. In a special preferred embodiment, the content of one or more additives in the solvent is monitored during the extraction, and on this basis the compaction may be altered. The content of the additives in the solvent may be monitored by using near infrared spectroscopy, e.g. within the extraction vessel, or within a separate vessel or tube connected to the extraction vessel, or through a transparent part of such vessel or tube. It is clear that the monitoring of the quality of the solvent is of importance independent of the actual bulk density of the particulate material. Therefore, the present invention, in accordance with a special independent aspect, is a method for extracting one or more additives from polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products, characterized in that said method comprises the step of comminuting said PVC or PVB products into particulate material and the step of subjecting said particulate material to an extraction by means of a solvent, preferably in one or more extraction vessels, with as a characteristic that the content of additives in said solvent is monitored during said extraction, preferably using near infrared spectroscopy. Preferably, the extraction time, the bulk density of said particulate material, the amount of solvent, the temperature of said solvent, the pressure of said solvent and / or the evacuation of said solvent is controlled on the basis of said monitoring.

[0010] Preferably, at least 5kg of particulate material is present in said one or more extraction vessels during said solvent-based extraction, or at least 10 kg or at least 100 kg of PVC products. Herein it is meant that said solvent and said PVC products are brought into contact with each other in an extraction vessel that at each time comprises at least 5 kg, at least 10 kg or at least 100 kg of PVC products. The method may be performed in a discontinuous manner, i.e. batch per batch, or in a continuous manner, wherein PVC product is continuously fed into said extraction vessel, and extracted material is continuously transported out of said extraction vessel.

[0011] Preferably, said particulate material has an average surface to volume ratio of 1:10 or higher as expressed in 1 / mm.

[0012] Preferably, said particulate material has a bulk density lower than 300 kilograms per cubic meter, or lower than 275 kilograms per cubic meter, without compaction. Such bulk density is obtainable when said particulate material has an average surface to volume ratio of 1:10 or higher as expressed in 1 / mm and / or when the D90 value of the particle size distribution is 2.5 mm or below, and preferably the D50 value is 0.5 mm or above.

[0013] Preferably, said PVC products are polyvinyl chloride (PVC) floor or wall coverings. With the same aim as in said first independent aspect, the present invention, in accordance with a second independent aspect is a method for extracting one or more additives from polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products, with as a characteristic that said method comprises the step of comminuting said PVC or PVB products into two or more batches of particulate material and the step of subjecting two or more amounts, or two or more batches, of said particulate material to an extraction by means of a solvent, preferably in two or more extraction vessels or in two or more compartments of an extraction equipment, with as a characteristic that said extraction comprises using a first amount of said solvent to extract additives from a first and second batch of particulate material in a first and second extraction vessel subsequently. The inventors have noted that extraction efficiency diminishes with lapsing time, presumably because less additives or contaminants remain to be extracted and because the extraction solvent is partially satisfied with said additives of contaminants, and thus becomes less effective. Gains in efficiency may be obtained with the present second independent aspect, e.g. by using a partially satisfied solvent for extraction of fresh particulate material, i.e. material that had not been subjected to extraction before. On the other hand, the further extraction of the same particulate material may then be executed by means of a fresh amount of said solvent to more effectively extract the remaining additives and contaminants. In so doing, the speed or efficiency of extraction may be averaged and become more uniform.

[0014] It is clear that, preferably, said first amount of particulate material has previously been subjected to another amount of said solvent, or to another solvent, while said second amount of particulate material is subjected to a solvent-based extraction for the first time, or has been subjected to a solvent-based extraction for fewer times than said first amount of particulate material has been.

[0015] Preferably, said method comprises a step of pressurizing said first amount of solvent, preferably to a pressure of at least 10 MPa, or at least 30 MPa, e.g. about 40 or 41 MPa, prior to using said solvent for extracting additives from said first amount of particulate materials. Preferably, said first amount of solvent is allowed to expand to a lower pressure, preferably atmospheric pressure, only after using said solvent for extracting additives from said second amount of particulate material.

[0016] Preferably, the extraction by means of said first amount of solvent of said first and second batch is immediately subsequent to each other. Preferably the method is devoid of steps for treatment of said first amount of said solvent in between the extraction of said first and second batches, wherein these treatments would change the effectiveness of said solvent after extraction of said first batch. For example, no washing, forced expansion to lower pressure, separation of additives or contaminants and / or flaring, takes place before said solvent has finished its portion of the extraction of said second batch.

[0017] Preferably, the particulate material in said first and second batch are similar, i.e. substantially composed of a same amount of PVC or PVB, or a same mix of PVC and PVB, i.e. substantially having a same particle size distribution, substantially having a same amount of additives and contaminants prior to any extraction, substantially having a same bulk density during extraction.

[0018] It is noted, that the method of the second aspect and its preferred embodiments may be practiced in combination with the features of the first aspect and its preferred embodiments, i.e. for extracting particulate material that has a bulk density of at least 300 kilograms per cubic meter, or at least 500 kilograms per cubic meter, though, preferably less than 1000 or less than 750 kilograms per cubic meter.

[0019] The invention in accordance with said second independent aspect is in particular suitable for a batch process. However, it is clear that the general idea of having a fresh amount of solvent first treating an already partially extracted batch of particulate material, and afterwards using the same amount of solvent for treating a fresh batch of particulate material is also of benefit to a continuous extraction process. Therefore, with the same aim as in said first and second independent aspect, the present invention, in accordance with its third independent aspect is a method for extracting one or more additives from polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products, with as a characteristic that said method comprises the step of comminuting said PVC or PVB products into particulate material and the step of subjecting said particulate material to an extraction by means of a solvent, with as a characteristic that said extraction takes place with the particulate material moving in a first direction, while said solvent is flowing in a direction substantially opposite to said first direction. In this way, the solvent that enters the extraction equipment will meet particulate material that has already been subjected to a partial extraction and move onwards to the more freshly entering particulate material. Preferably, the extraction equipment comprises a vessel or barrel, wherein a transporting mechanism is moving the particulate material for an inlet to an outlet of said vessel or barrel. The transporting mechanism may be a screw, for example an Archimedes screw or an extruder screw. In both cases the pressure or compaction of the particulate material may be made to change along the respective screw.

[0020] Here below, some preferred embodiments will be listed that may be practiced in combination with any of the above aspects and their respective preferred embodiments.

[0021] Preferably said extraction comprises extracting at least one component from the polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products, said component is chosen from the group of plasticizers, heavy metals, polar components, acrylic resins, organic components, pigments, additives, or combinations thereof.

[0022] Preferably, said solvent comprises supercritical carbon dioxide (CO2). Preferably, said particulate material is brought into contact with supercritical carbon dioxide (CO2) at a temperature of between 20 and 100 °C, preferably of between 50 and 95 °C, more preferably of between 75 and 90 °C, for example about 80°C or about 88°C. Preferably, said particulate material is brought into contact with supercritical carbon dioxide (CO2) at a pressure of between 20 and 50 MPa, preferably of between 30 and 50 MPa, for example about 40 MPa or about 41 MPa.

[0023] The inventors have found that particulate material having a bulk density of 300 to 750, or from 500 to 750 kilogram per cubic meter can be efficiently extracted with supercritical CO2 at a temperature of 75 to 90°C and a pressure of 30 to 50 MPa, preferably 35 to 45 MPa. The batch size of the particulate material being extracted is preferably at least 5 kg, and the particle size distribution preferably has a D90 value of 2.5 millimeters or below. Preferably, the method in accordance with the second aspect is applied, wherein a same amount of supercritical C02 subsequently extracts additives and / or contaminants subsequently from two separate batches of particulate material, wherein preferably the second of the two consecutive batches is a batch of fresh particulate material, i.e. particulate material that had not been subjected to extraction yet at all. The total extraction time for one batch is preferably 60 minutes or more, for example up to 100 minutes, or about 90 minutes. Preferably one batch is treated with two separate amounts of solvent subsequently, wherein a first time it is treated with a solvent that is partially satisfied with additives and contaminants from the partial extraction of another batch, while a second time it is treated with a solvent, preferably a same type solvent, e.g. again supercritical CO2, that is fresh, or, in other words, has not taken up additives and contaminants from extraction of another batch. With the above features in combination, a very effective industrially applicable method for extracting additives and / or contaminants from PVC or PVB products can be obtained. The method can be used for treating incoming post-consumer waste of such products. In such case, the composition of the incoming waste may be largely unknown, and the methods of the present invention may be used to separate harmful additives or contaminants form the PVC or PVB polymer. The retrieved PVC or PVB polymer may then be reused in the manufacturing of new products, as are separated additives that are not considered harmful.

[0024] Preferably, between 10 and 20 kg, preferably between 13 and 18 kg, e.g. about 14 kg, of supercritical dioxide (CO2) is used in said extraction per kg of particulate material. This amount of solvent has shown to lead to an acceptable extraction speed, in particular at a pressure of 30 to 50 MPa, e.g. 40 or 41 MPa and a temperature of 75 to 90°C, e.g. about 80 or about 88°C. The bulk density can herein be increased to 500 or to 750 kilograms per cubic meter without negatively affecting the extraction efficiency.

[0025] In accordance with a variant, which may also be combined with supercritical CO2, said solvent comprises an ionic liquid. Preferably, said particulate material is brought into contact with the ionic liquid at a temperature of at least 100 °C, preferably of at least 150 °C.

[0026] Generally, and in particular when working with supercritical CO2, said particulate material is brought into contact with said solvent during a contact time of between 30 and 120 minutes, preferably of between 60 and 120 minutes, more preferably of between 75 and 100 minutes, e.g. about 90 minutes.

[0027] Preferably, said particulate material has a particle size D90 of less than 2.5 mm, preferably of less than 1 mm, more preferably of less than 0.5 mm.

[0028] Preferably, the method is used to separate additives or contaminants from PVC products. The PVC products may comprise PVC in an amount of between 20 and 100 wt.%.

[0029] Preferably, said polyvinyl chloride (PVC) products or polyvinyl butyral products comprise filler, preferably mineral filler, in an amount of between 0 and 85 wt.%. The presence of fillers generally negatively decrease the effectiveness of the extraction process, especially when the amount of fillers is above 50 wt%. However, the methods of the different aspects of the present invention and their respective preferred embodiments bring a relieve and are able to offer an economical industrially applicable method for separating additives and contaminants also from such products, such that highly filled PVC or PVB products may be effectively recycled. A clean, or essentially clean, PVC polymer or PVB polymer stream may be obtained using one or more of the methods of the invention.

[0030] Preferably said polyvinyl chloride or polyvinyl butyral products that are subjected to solvent-based extraction at least comprise polyvinyl chloride, respectively polyvinyl butyral, and a filler, for example talcum and / or calcium carbonate, such as chalk and / or limestone. Preferably said products comprises filler at a filler to PVC, or filler to PVB, weight ratio of at least 1 : 1, or of at least 3:1. In light of the invention, the term “solvent-based extraction” need to be interpreted as the separation of one or more components, in particular additives, from a mixture by dissolving said one or more components in a suitable solvent. More in particular, one or more soluble components may be separated from one or more insoluble components in a mixture.

[0031] By preference, said solvent-based extraction comprises extracting at least one additive from the polyvinyl chloride (PVC) products, said additive is chosen from the group of plasticizers, heavy metals, polar components, acrylic resins, organic components, pigments, additives, or combinations thereof.

[0032] According to some embodiments, said additive is a plasticizer. In light of the invention, the term “plasticizer” need to be interpreted as a substance which may be added to a material, in particular a synthetic material, with the goal of making said material softer, more flexible, to increase its plasticity, to decrease its viscosity, and / or to improve handling of said material during a manufacturing process, e.g. by decreasing friction of the material in a manufacturing line. More in particular, a distinction may be made between phthalate based plasticizers and non-phthalate based plasticizers. On one hand, phthalate based plasticizers are to be interpreted as plasticizers having a chemical structure in accordance with formula I, wherein R and R’ may be the same or may be different, and wherein R and / or R’ are chosen from the group of CnHin+i, wherein n is an integer between 1 and 15, while non-phthalate based plasticizers have a chemical structure which is not in accordance with formula I.

[0033]

[0034] Extracting plasticizers upon recycling PVC or PVB products according to one or more of the methods of the invention is particularly advantageous as the resulting clean PVC or PVB polymer stream may be used more efficiently for manufacturing new PVC products. More in particular, in making said new PVC products, a specific target amount of plasticizer may be easier controlled when starting from a substantially plasticizer-free PVC or PVB polymer stream.

[0035] According to some embodiments, said plasticizer is a phthalate based plasticizer in accordance with formula I. It is noted that especially those phthalate based plasticizers having a high molecular weight, such as plasticizers having a chemical structure in accordance with formula I wherein n is 5 or more, may be of high relevance in light of potential VOC emissions and the related public health concerns. More by preference, said phthalate based plasticizer is chosen from the group of diisononyl phthalate (DINP), di-(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), diisoheptyl phthalate (DIHP), di-n-octyl phthalate (DOP), diisooctyl phthalate (DIOP), diisodecyl phthalate (DIDP), or combinations thereof. A method for extracting additives from PVC or PVB products according to the invention is particularly interesting as it allows to efficiently extract hazardous phthalate based plasticizers from PVC or PVB products to be recycled, such that new PVC or PVB products may be safely manufactured based upon the resulting clean PVC or PVB polymer stream. Furthermore, upon making new PVC or PVB products from the clean PVC, respectively PVB, polymer stream, one may specifically target the use of non-hazardous plasticizers.

[0036] According to a further or another embodiment, said component may be a non-phthalate based plasticizer not in accordance with formula I. More by preference, said non-phthalate based plasticizer is chosen from the group of benzoate esters, adipate esters, citrate esters, cyclohexanoate esters, or combinations thereof. Extraction of non-hazardous, non-phthalate based plasticizers from the PVC or PVB products allows to obtain a clean PVC or PVB polymer stream which can be more efficiently used in making new PVC or PVB products, thereby accurately controlling the composition during manufacturing of said new products. According to some embodiments, a mixture of one or more phthalate based plasticizers and one or more non-phthalate plasticizers may be extracted from a batch of particulate material.

[0037] According to some embodiments, said additive may be a heavy metal. By preference, said heavy metal is chosen from the group of antimony (Sb), arsenic (As), bismuth (Bi), cadmium (Cd), cerium (Ce), chromium (Cr), cobalt (Co), copper (Cu), gallium (Ga), gold (Au), iron (Fe), lead (Pb), manganese (Mn), mercury (Hg), nickel (Ni), platinum (Pt), silver (Ag), tellurium (Te), thallium (Tl), tin (Sn), uranium (U), vanadium (V), and zinc (Zn), or combinations thereof. More by preference, said heavy metal may be chosen from the group of copper (Cu), iron (Fe), lead (Pb), nickel (Ni), zinc (Zn), or combinations thereof.

[0038] According to some embodiments, said additive may be a polar component. According to some embodiments, said additive may be an acrylic resin. According to some embodiments, said additive may be an organic component. According to some embodiments, said additive may be a pigment, such as carbon black.

[0039] Clearly, said solvent-based extraction comprises bringing said polyvinyl chloride or polyvinyl butyral product into contact with at least one solvent. Said at least one solvent may herein bring the one or more additives into solution, while leaving the polyvinyl chloride or polyvinyl butyral unaltered, thereby achieving physical separation of said one or more additives from the polyvinyl chloride or polyvinyl butyral.

[0040] By preference, said polyvinyl chloride or polyvinyl butyral product is brought into contact with at least one liquid solvent. This has the advantage that the liquid solvent may better penetrate the product, thus making better contact with the one or more additives, thereby improving solution of said one or more additives into said liquid solvent.

[0041] According to some embodiments, said polyvinyl chloride or polyvinyl butyral product may be brought into contact with a single solvent. According to some other embodiments, said polyvinyl chloride or polyvinyl butyral product may be brought into contact with two or more different solvents. It may herein be possible that one or more additives are soluble in a first solvent, while one or more other additives are soluble in a second solvent. Alternatively, said two or more different solvents may bring a synergistic effect in that said one or more additives may be better soluble in the presence of the combination of the two or more solvents, than in the presence of just one of said two or more solvents. According to some embodiments, said polyvinyl chloride or polyvinyl butyral product may be brought into contact with a solvent and an anti-solvent, thereby further improving the physical separation of said one or more additives from the polyvinyl chloride or polyvinyl butyral product. Herein, the solvent may have particular affinity towards one or more additives to be extracted, while the anti-solvent has affinity with the polyvinyl chloride or polyvinyl butyral material. By combining these diverging affinities in a solvent / anti -solvent system, obtaining good separation between the one or more additives and the polyvinyl chloride or polyvinyl butyral material may be easier. In the case where two or more different solvents are used they may be used as a mixture, or, alternatively, be used serially during separate extraction steps, wherein then one or more these extraction steps are in accordance with one or more of the methods of the invention.

[0042] According to a first preferred embodiment, said solvent comprises supercritical carbon dioxide (CO2). In light of the invention, supercritical carbon dioxide may be regarded as a liquid solvent, more in particular, it concerns a supercritical fluid state. Using supercritical carbon dioxide as a solvent may be particularly useful for the extraction of plasticizers.

[0043] Said polyvinyl chloride or polyvinyl butyral product is by preference brought into contact with supercritical carbon dioxide (CO2) at a temperature of between 20 and 100 °C. More by preference, said product is brought into contact with supercritical carbon dioxide (CO2) at a temperature of between 50 and 95 °C. More by preference, said product is brought into contact with supercritical carbon dioxide (CO2) at a temperature of between 75 and 90 °C. The inventors have found that such temperature is particularly advantageous for extracting additives from larger batches of polyvinyl chloride or polyvinyl butyral products, in particular when these products comprise filler, for example at a filler to PVC or PVB weight ratio of 1 : 1 or above, or even of 3 : 1 or above.

[0044] According to a further or another embodiment, said polyvinyl chloride or polyvinyl butyral product is brought into contact with supercritical carbon dioxide (CO2) at a pressure of between 20 and 50 MPa. By preference, said product is brought into contact with supercritical carbon dioxide (CO2) at a pressure of between 30 and 50 MPa. More by preference, said product is brought into contact with supercritical carbon dioxide at a pressure of between 35 and 45 MPa. The inventors have found that such pressure is particularly advantageous for extracting components from larger batches of polyvinyl chloride or polyvinyl butyral products, in particular when these products comprise filler, for example at a filler to PVC or PVB weight ratio of 1:1 or above, or even of 3:1 or above.

[0045] In the cases where supercritical carbon dioxide is used as a solvent, it may be used in combination with a cosolvent. The cosolvent preferably has affinity to phthalates and / or is chosen from the list consisting of water, methanol, ethyl acetate, methylene chloride. Other possibilities are cosolvents that lead to a swelling of the PVC or PVB material and / or is chosen from the list consisting of CHCh, acetone, cyclohexanone and tetrahydrofuran (THF).

[0046] According to a second preferred embodiment, said solvent comprises an ionic liquid. In light of the present invention, the term “ionic liquid” may be interpreted as liquids which consist of both organic and / or inorganic ions, and which may contain more than one cation or anion. Another way to describe “ionic liquid” may thus be “liquid salt”. Using an ionic liquid as a solvent may be particularly useful for the extraction of heavy metals. A particular kind of ionic liquids are “natural deep eutectic solvents” (NADES), which are mixtures of natural compounds, namely, organic acids and bases, amino acids, sugars, sugar alcohols, and polyalcohols that interact through hydrogen bonding and liquefy if combined in specific molar ratios. Said polyvinyl chloride of polyvinyl butyral product is by preference brought into contact with the ionic liquid at a temperature of at least 100 °C. More by preference, said product is brought into contact with the ionic liquid at a temperature of at least 150 °C.

[0047] According to a further or another embodiment, said ionic liquid may comprise one or more of l-butyl-3 -methyl imidazolium tetrafluoroborate ([BMIM][BF4]), l-butyl-3-methyl imidazolium hexafluorophosphate ([BMIM][PF6]), 2,4-bis(2-hydroxypropyl)-1,1,3,3-tetramethyl guanidinium tetrafluoroborate ([TMGHPO2][BF4]), and tetramethyl guanidine lactate (TMGL).

[0048] According to a further or another embodiment, said ionic liquid is chosen from the group of l-octyl-3 -methyl imidazolium tetrafluoroborate ([C8mim][BF4]), l-octyl-3 -methyl imidazolium hexafluorophosphate ([C8mim][PF6]), tri ethylammonium hydrogen sulphate ([HNEt3][HSO4]).

[0049] It is clear that the cosolvents mentioned in connection to extraction with supercritical CO2 may also be used in combination with an extraction executed by means of ionic liquids in accordance with the second preferred embodiment.

[0050] It is noted that solvent extraction, especially when practiced with liquid or supercritical CO2 whether or not in combination with a cosolvent, tends to extract all additives that are liquid at room temperature. The obtained liquid fraction could hence comprise plasticizers, stabilizers, dispersants and other additives.

[0051] According to some embodiments, said polyvinyl chloride or polyvinyl butyral product is brought into contact with supercritical carbon dioxide (CO2) and / or the ionic liquid, wherein said polyvinyl chloride has a surface to volume ratio of 1:10 (as expressed in 1 / mm) or higher, for example between 1:10 and 10:1 (as expressed in 1 / mm) or between 1:5 and 5:1 (as expressed in 1 / mm). It is not excluded that the surface to volume ratio would be between 1:1 and 1:10 (as expressed in 1 / mm). By preference, the product is brought into contact with supercritical carbon dioxide and / or the ionic liquid, wherein said product has a surface to volume ratio of between 3:1 and 10:1 (as expressed in 1 / mm). According to an alternative the surface to volume ratio is between 1:3 and 1:10 (as expressed in 1 / mm).

[0052] In a more particular embodiment, the polyvinyl chloride or polyvinyl butyral product is brought into contact with supercritical CO2 at a temperature of between 20 and 100 °C, at a pressure of between 20 and 50 MPa, during a contact time of between 5 and 120 minutes, and preferably with a surface to volume ratio of 1 : 10 (as expressed in 1 / mm) or higher, for example between 1:10 and 10:1 (as expressed in 1 / mm), or between 1:5 and 5:1. It is not excluded to work with PVC or PVB having a surface to volume ratio between 1 : 1 and 1 : 10 (as expressed in 1 / mm). More preferably, the polyvinyl chloride or polyvinyl butyral product is brought into contact with supercritical CO2 at a temperature of between 50 and 95 °C, at a pressure of between 30 and 50 MPa, during a contact time of between 60 and 100 minutes, and wherein said product preferably has a surface to volume ratio of at least 3:1, for example between 3:1 and 10:1. According to an alternative the surface to volume ratio is between 1:3 and 1:10 (as expressed in 1 / mm).

[0053] In an alternative particular embodiment, the polyvinyl chloride or polyvinyl butyral product is brought into contact with the ionic liquid at a temperature at least 100 °C, during a contact time of between 5 and 60 minutes, and wherein said product preferably has a surface to volume ratio of 1:10 (as expressed in 1 / mm) or higher, for example between 1:10 and 10:1 (as expressed in 1 / mm), or between 1:5 and 5:1 (as expressed in 1 / mm). It is not excluded to work with PVC or PVB having a surface to volume ratio between 1:1 and 1:10 (as expressed in 1 / mm). More preferably, the product is brought into contact with the ionic liquid at a temperature of at least 150 °C, during a contact time of between 10 and 45 minutes, and preferably with a surface to volume ratio of at least 3 : 1, for example between 3 : 1 and 10:1. According to an alternative the surface to volume ratio is between 1:3 and 1:10 (as expressed in 1 / mm).

[0054] A minimal surface to volume ratio of the products, more particularly the particulate material, for example at least 0.5, or at least 1, or at least 3 (as expressed in 1 / mm), is advantageous for providing a high enough surface for the respective solvent to interact with the product and for this solvent to be efficient in extracting the respective component. The surface to volume ratio of the products is preferably kept below a maximum value, for example below 10 (as expressed in 1 / mm) to prevent clogging of the system and / or to avoid agglomeration of the particulate material. The range of surface to volume ratio between 1:10 and 10:1, or between 1:1 and 10:1, is of particular importance to extraction at an industrial scale, namely when the batch size of PVC or PVB product is at least 5 kg, at least 10 kg or at least 100 kg, and / or, when said products comprise filler, for example at a filler to PVC or PVB weight ratio of 1:1 or above, or even of 3 : 1 or above.

[0055] As stated, said method, prior to the step of subjecting said polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products to the solvent-based extraction, comprises the step of comminuting said products into particulate material. Preferably said particulate material has a particle size distribution percentile D90 value of less than 2,5 mm and / or a D50 percentile value or less than 1,75 mm.

[0056] In general it is remarked that, wherever particle size percentile D90 or D50 values are described herein, the particle size may be measured by various techniques known in the art. Particularly for larger granules, the particle size may possibly be determined by sieving techniques. The particle size of smaller particles may be determined by laser granulometry, in particular, the particle size percentile D90 or D50 may be determined using laser granulometry, which may be performed in accordance with ISO 13320:2020. This is a dynamic light scattering technique using a laser with an emission wavelength of 632.8 nm, measuring at a scattering angle of 90 degrees. This technique may be performed, for example, with a Malvern® Mastersizer 2000 or with a Malvern® Mastersizer 3000. To perform the measurement of the particle size distribution, the respective particles need to be brought in a loose state, and can be dispersed in a liquid, such as water.

[0057] It is further remarked that the surface to volume ratio of the polyvinyl chloride products may be determined as being equal to 6 / D50 and expressed in 1 / mm, with the D50 percentile of the particle size distribution being determined as explained above. According to some preferred embodiments, said polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products are comminuted into particulate material having a particle size distribution with a D90 percentile value of less than 2 mm, more by preference of less than 1,5 mm, of less than 1 mm, most by preference of less than 0,5 mm.

[0058] According to some embodiments, the solvent-based extraction may be brought about in multiple steps. In particular, said polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products may first be comminuted into granules having a first particle size, for example a particle size D90 value of less than 2 mm, and may subsequently be subjected to a first solvent-based extraction step. Thereafter, the products may be comminuted into granules having a second particle size which is smaller than the first particle size, for example a particle size D90 of less than 0,5 mm, and may subsequently be subjected to a second solvent-based extraction step. As PVC or PVB material with a low amount of plasticizers is generally more brittle, it may be easier to comminute said material into small granules. Hence, a multi-step process as described herein may have the advantage that plasticizer content is gradually lowered, thereby allowing comminuting the PVC or PVB into still smaller granules. In its turn, subjecting small granules to solvent-based extraction may allow improved extraction altogether. It may be possible that two consecutive steps are performed, or that even three or more consecutive steps are performed. The used solvents in each of the steps may be the same, or may be different. For example, supercritical carbon dioxide extraction may be performed in a first step on larger particle sizes, while ionic liquid extraction may be performed in the second step on still smaller particles. In any case at least one of the steps practices a method in accordance with any of the mentioned aspects of the invention.

[0059] Said method, prior to the step of subjecting said products to the solvent-based extraction or, prior to the step of comminuting said products, may according to some embodiments also comprise the step of mechanically separating non-polyvinyl chloride (non-PVC) and / or non-polyvinyl butyral (non-PVB) material from polyvinyl chloride (PVC) and / or polyvinyl butyral (PVB) material. As PVC or PVB products may also comprise a lot of non-PVC or non-PVB material, this may render recycling said products more difficult. Said separating may improve the recycling thereof. Examples of non-PVC or non-PVB material include polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), or polyurethane (PU). In particular where the PVC products concern floor or wall coverings, said non-PVC material may for example include a non-PVC backing layer, a non-PVC top layer, a non-PVC pad-attached, or combinations thereof.

[0060] Additionally or alternatively, prior to the step of subjecting said polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products to the solvent-based extraction or, prior to the step of comminuting said products into granules, said method may according to some embodiments also comprise the step of mechanically separating polyvinyl chloride (PVC) or polyvinyl butyral (PVB) material which comprises contaminants from polyvinyl chloride (PVC) material or polyvinyl butyral (PVB) material which does not comprise contaminants. For example, material comprising heavy metals may be mechanically separated from material not comprising heavy metals. According to some embodiments, said mechanical separation may be performed by means of infrared (IR) or near-infrared spectroscopic techniques.

[0061] According to some embodiments, said method, after said step of subjecting said polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products to the solvent-based extraction, may also comprise the step of washing said post-extraction polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products.

[0062] According to a further or another embodiment, said method, after said step of subjecting said polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products to the solvent-based extraction, may comprise the step of purifying the extracted additive. Obtaining a higher purity of the extracted additive may allow subsequent processing or reuse of said additive.

[0063] According to a further or another embodiment, said method, after said step of subjecting said products to the solvent-based extraction, thereby extracting at least said plasticizers, may comprise the step of separating non-phthalate plasticizers from phthalate plasticizers. Said step of purifying and / or said step of separating may be performed by using one or more pressurized and potentially heated tanks. In such tank the liquid fraction of the extracted material or part thereof may be tapped off. Depending on the pressure and temperature conditions in such tank, different components may be available in the tapped off liquid fraction. The extracted material may subsequently be passed through several tanks operating at mutually different temperature and pressure conditions, and at one or more of these tanks the obtained liquid fraction may be tapped off. The different temperature and pressure conditions may lead to liquid fractions having different compositions.

[0064] According to the most preferred embodiment, said step of solvent-based extraction is performed by mixing CO2, preferably supercritical CO2, and potentially a cosolvent, e.g methanol or another cosolvent, with PVC or PVB particulate material obtained from scrap PVC or PVB material in a first vessel, the so-called extractor vessel. The extracted material is transported from the extractor vessel by a plurality of subsequent separator vessels operating at least at different pressures and potentially at different temperature. At at least one, and preferably at each of said separator vessels a respective liquid fraction is removed. The removal may happen at a time when the pressure is released from the respective vessel. This embodiment may conveniently lead to a separation of mutually different fractions as a part of the extraction process, preferably each having a different main component or extracted additive.

[0065] According to a further or another embodiment, said method, after said step of subjecting said products to the solvent-based extraction, may comprise the step of converting phthalate plasticizers to non-phthalate plasticizers, preferably by means of a transesterification and / or hydrogenation reaction. For example, diisononyl phthalate (DINP) may be converted to 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH). In each case, substances which may be considered to be harmful may be converted into substances which are considered at least less harmful, to even unharmful with respect to current regulations. According to some embodiments, said method, after said step of subjecting said products to the solvent-based extraction, comprises the step of supplementing said post-extraction products with virgin polyvinyl chloride (PVC) or virgin polyvinyl butyral (PVB), plasticizers, compatibilizers, or combinations thereof. This may be particularly useful in that reactivity and / or quality of the post-extraction polymer may be improved, such that it may be more suitable for manufacturing new PVC or PVB products.

[0066] According to a preferred embodiment, said polyvinyl chloride (PVC) products are floor or wall coverings, preferably floor or wall panels. Preferably said polyvinyl chloride (PVC) products are composed of a plurality of layers, wherein a majority of said layers are preferably comprising PVC and one or more of said components. Two or more of the composing layers of such product may have a mutually different composition, for example a mutually different filler content and / or plasticizer content. For example, said polyvinyl chloride (PVC) products may comprise a substrate of a filled PVC (for example calcium carbonate to PVC weight ratio of at least 3:1), which for example comprises 5 phr or less of plasticizer, an applied thereon printed PVC film, which for example also comprises 5 phr of plasticizer or less but is free or essentially free from fillers, and a PVC wear layer applied to said printed PVC film, which for example comprises 15 phr or more of plasticizer and is essentially free of fillers. The thickness of the composing layers may be substantially different. For example, the substrate may be 1 to 5 mm thick, while the printed PVC film has a thickness of 50 to 100 micron, and the PVC wear layer has a thickness of 0.2 to 1 mm. A method of extraction using one or more solvents as described herein is particularly advantageous for the treatment of waste having such non-uniform composition. In particular the use of supercritical CO2 and / or an ionic liquid as solvent, preferably in combination with a co-solvent has proven to provide a very versatile extraction method in these cases. Also the surface to volume ratio above 1:10 or above 1:1 is of interest in such case, since it may expose all composing layers to a satisfactory extent.

[0067] Said polyvinyl chloride (PVC) products may comprise, according to some embodiments, PVC in an amount of between 20 and 100 wt.%. More by preference, polyvinyl chloride may be present in an amount of between 20 and 40 wt.%. In some embodiments, said polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products may also comprise filler, preferably mineral filler, in an amount of between 0 and 80 wt.%. More by preference, filler may be present in an amount of between 60 and 80 wt.%.

[0068] According to some embodiments, said polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products comprise plasticizers, preferably phthalate-based plasticizers, in an amount of between 1 and 50 phr, more preferably between 10 and 25 phr.

[0069] According to some embodiments, the solvent-based extraction may be performed in a reactor, that forms said vessel. Alternatively or additionally, the solvent-based extraction may be performed in an extruder.

[0070] Additionally or alternatively, said solvent may comprise water and / or an additional extraction step using water as a solvent may be implemented in the method according to the invention.

[0071] Additionally or alternatively, the method may also comprise a complexation step, wherein the polyvinyl chloride (PVC) or polyvinyl butyral products are brought into contact with one or more complexing agents, such as ethylene diamine tetra-acetic acid (EDTA). The use of EDTA may be particularly beneficial for the extraction of heavy metals. Bringing the products into contact with one or more complexing agents, may be performed in an extruder. Alternatively, said step may be performed in a reactor.

[0072] Additionally or alternatively, use may be made a melt filtration step. In this particular case, it is noted that a certain amount of plasticizer may be required in the polyvinyl chloride (PVC) or polyvinyl butyral (PVB) material in order to allow efficiently performing said melt filtration step. In such a case, plasticizer may be purposefully added to the material, for example in an amount of between 10 and 25 phr, to allow melt extraction. Subsequently, said plasticizer may be extracted again using solvent-based extraction according to the invention. Additionally or alternatively, use may be made of microwave-assisted extraction. Additionally or alternatively, use may be made of ultrasonic extraction.

[0073] It is clear that the invention further is a method for manufacturing polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products, comprising the step of providing polyvinyl chloride (PVC) or polyvinyl butyral (PVB) material, wherein said material is obtained by recycling existing polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products by means of solvent-based extraction, and / or wherein said material is obtained by a method according to any of the mentioned aspects of the invention.

[0074] By preference, said polyvinyl chloride (PVC) product is a floor or wall panel. According to a variant, said polyvinyl chloride (PVC) product is a sheet flooring product, such as a so-called cushion vinyl. Cushion vinyl is a multilayered flooring product, and may be built up starting from a liner having a foamed PVC layer applied thereto, i.e. the actual cushion vinyl layer. Said foamed layer may comprise two or more sublayers, and is usually obtained from applying PVC plastisol to said liner, and subsequently foaming the plastisol. On top of the foamed layer a printed decor is positioned. The printed decor may be applied as a prefabricated and preprinted foil, such as a printed PVC foil, or it may be formed directly on the foamed layer, e.g. with the intermediary of suitable primers and other base layers, such as layers on the basis of PVC plastisol. A transparent layer is applied on top of said printed decor in order to protect from abrasion and other wear. The transparent layer may also be based on PVC. Possibly, at the surface of said transparent layer a superficial lacquer layer may be present, such as an acrylate-, urethane acrylate- or polyurethane based lacquer layer.

[0075] According to some embodiments, said method comprises the steps of forming a substrate on the basis of said polyvinyl chloride (PVC) material, providing a decorative layer onto an upper surface of said substrate, and providing a wear layer onto an upper surface of said decorative layer. Forming a substrate on the basis of said polyvinyl chloride (PVC) material may be performed by means of an extrusion operation, a scattering operation, or an operation including gelling of a plastisol. According to some embodiments, the substrate may be single-layered or comprising a plurality of substrate layers, preferably an uneven number of substrate layers. The substrate, whether single-layered or multi-layered, preferably forms at least half the thickness and / or half the weight of said panel and / or is at least available at a central location within the thickness of said panel. According to some embodiments, the decorative layer is a thermoplastic decorative layer. Preferably, said thermoplastic decorative layer is a thermoplastic decorative film, said thermoplastic decorative layer comprising a print. According to some embodiments, the wear layer is a transparent and / or translucent thermoplastic wear layer. Preferably, said transparent and / or translucent thermoplastic wear layer is a thermoplastic film. According to some embodiments, a lacquer layer is present onto an upper surface of said wear layer.

[0076] The floor or wall panel of the invention preferably has a total thickness between 2 and 8 mm, and even better between 3 and 6 mm. The substrate, whether multi-layered or single layered, preferably has a thickness between 2 mm and 5 mm. In the case of a sheet flooring product, that too may have a total thickness between 2 and 5 mm.

[0077] The floor or wall panel of the invention may be provided on at least two opposite edges with coupling parts, allowing that two such panels at the respective edges can be coupled to each other, wherein, in the coupled condition, a locking is obtained in a vertical direction perpendicular to the plane of coupled panels, and in a horizontal direction in the plane of coupled panels and perpendicular to said edges.

[0078] With the intention of better showing the characteristics according to the invention, in the following, as an example without limitative character, several embodiments are described, with reference to the accompanying drawings, wherein

[0079] - Figure 1 illustrates some steps in a method for extracting additives from PVC or PVB products in accordance with amongst others the first aspect of the invention; - Figure 2 illustrates some steps in a method for extracting additives from PVC or PVB products in accordance with the second aspect of the invention;

[0080] - Figure 3 illustrates some steps in a method for extracting additives from PVC or PVB products in accordance with the third aspect of the invention; and - Figure 4 shows the area indicated with F4 on figure 3, though for a variant.

[0081] Figure 1 illustrates a method for recycling PVC or PVB products 1, wherein the method comprises the step SI of comminuting said PVC or PVB products 1 into particulate material 2 and the step S2 of subjecting said particulate material 2 to an extraction by means of a solvent 3 in one or more extraction vessels 4. During said step S2 of extraction at least 5 kg of particulate material 2 is present in said extraction vessel 4. In this case, even 20 kg or more of particulate material 2 is present in said extraction vessel 4. Preferably said particulate material 2 has a particle size D90 of less than 2.5 mm.

[0082] In the represented case post-industrial and / or post-consumer flexible PVC products 1 comprising plasticizer at a rate of 5 phr or more are comminuted into particulate material 2 and provided in an extraction vessel 4. In this case, the step S2 of extraction is performed by means of a mix of supercritical CO2 and a cosolvent, e.g. methanol.

[0083] The method, as illustrated, comprises a step S3. In this step S3, the extracted material 5 is transported from the extractor vessel 4 to one or more separator vessels 6, in this case only one extractor vessel 4 is represented. At the separator vessel 6, in a substep S3B, a base liquid fraction 7 may be removed, which may or may not be further subjected to purification before being reused in a new product, e.g. a sheet vinyl flooring. In step S3, more particularly in substep S3 A, the thus extracted particulate material 2A is removed from the extractor vessel 4 as well, and may be directly used, or further processed for example by milling e.g. down to a particle size distribution with a D90 value of 500pm or less and subsequently reused, in a PVC product, such as in a sheet vinyl flooring 6.

[0084] The thus obtained base liquid fraction 7 may be formed for at least 75 wt% of plasticizers and can be used without further purification as plasticizer for example in a PVC plastisol.

[0085] The bulk density of the granulate material 2 during said step S2 of extraction is about 600 kilograms per cubic meter. For reaching this bulk density, the illustrated method comprises a step S4 of compressing said particulate material 2 prior to said step S2 of extraction by means of a plunger 8. The solvent 3, more particularly the mixture of supercritical C02 and the cosolvent, is at a pressure of 40 to 41 MPa. This pressure has been by means of a compressor or pump 9 prior to circulating the solvent 3 by means of the pump 10 in said step of extraction S2. The temperature of the solvent 3 is preferably 75 to 90°C. The step S2 of extraction can be performed during 30 to 120 minutes. As illustrated here, during said step S2 of extraction the solvent 3 is not refreshed. Only after completion of the predefined duration of extraction, the extracted material 5 is transported from the extractor vessel 4 to one or more separator vessels 6, as described above.

[0086] Alternatively, as illustrated in figure 1, the content of additives or contaminants in said solvent 3 may be monitored during said step S2 of extraction. In this case near infrared spectroscopy 11 is used to monitor the solvent 3 that is being circulated. For this reason a probe 12 is mounted internally in the circulation tubes 13. In such case, the direction of extraction may be controlled on the basis of said monitoring. For example, when the solvent 3 becomes satisfied with additives or contaminants, or otherwise becomes ineffective, the step S2 of extraction may be finished or interrupted, for example for refreshing the solvent 3.

[0087] Figure 2 illustrates how a batch process that comprises at least three extraction vessels 4A-4B-4C may efficiently be run in subsequent time intervals T1-T2-T3-T4.

[0088] In a first time interval extraction vessel 4B is being provided with fresh particulate material 2. Although not represented here, this particulate material 2 may be subjected to a step of compressing by means of e.g. a plunger. In extraction vessel 4A, previously loaded particulate material 2 is being subject to a step S2B of extraction by means of a freshly provided solvent 3A. In extraction vessel 4C, previously loaded particulate material 2 is being subjected to a step S2A of extraction by means of a partially satisfied solvent 3B. The partially satisfied solvent 3B had been used in a previous time-interval, not illustrated here, for extraction or partial extraction of another batch of particulate material. The particulate material 2 in vessel 4 A had in a previous time interval, not illustrated here, already been subjected to partial extraction by means of another solvent. At or towards the end of time interval Tl, the extracted material 5, more particularly the satisfied or partially satisfied solvent 3B, is transported from the extractor vessel 4C to one or more separator vessels 6, for separation of a liquid fraction 7 in a step S3B.

[0089] In a subsequent time interval T2, the thus extracted particulate material 2A is removed from vessel 4A, which subsequently is being replenished with fresh particulate material 2. The fresh solvent 3 A, which has now become a partially satisfied solvent 3B due to its use in extraction step S2B in time interval Tl in vessel 4A, is transported to vessel 4B where it will be used during time interval T2 for a step S2A of extraction of the particulate material 2 that had been freshly provided in vessel 4B in time interval Tl. In extraction vessel 4C, previously loaded and partially extracted particulate material 2 is in time interval T2 being subjected to a step S2B of extraction by means of a solvent 3 A that is freshly provided. At or towards the end of time interval T2, the extracted material 5, more particularly the satisfied or partially satisfied solvent 3B, is transported from the extractor vessel 4B to one or more separator vessels 6, for separation of a liquid fraction 7 in a step S3B.

[0090] In a subsequent time interval T3, the thus extracted particulate material 2A is removed from vessel 4C, which subsequently is being replenished with fresh particulate material 2. The fresh solvent 3 A, which has now become a partially satisfied solvent 3B due to its use in extraction step S2B in time interval T2 in vessel 4C, is transported to vessel 4A where it will be used during time interval T3 for a step S2A of extraction of the particulate material 2 that had been freshly provided in vessel 4A in time interval T2. In extraction vessel 4B, previously loaded and partially extracted particulate material 2 is in time interval T3 being subjected to a step S2B of extraction by means of a solvent 3 A that is freshly provided. At or towards the end of time interval T3, the extracted material 5, more particularly the satisfied or partially satisfied solvent 3B, is transported from the extractor vessel 4A to one or more separator vessels 6, for separation of a liquid fraction 7 in a step S3B.

[0091] In a subsequent time interval T4, the thus extracted particulate material 2A is removed from vessel 4B, which subsequently is being replenished with fresh particulate material 2. The fresh solvent 3A, which has now become a partially satisfied solvent 3B due to its use in extraction step S2B in time interval T3 in vessel 4B, is transported to vessel 4C where it will be used during time interval T4 for a step S2A of extraction of the particulate material 2 that had been freshly provided in vessel 4C in time interval T3. In extraction vessel 4A, previously loaded and partially extracted particulate material 2 is in time interval T4 being subjected to a step S2B of extraction by means of a solvent 3 A that is freshly provided. At or towards the end of time interval T4, the extracted material 5, more particularly the satisfied or partially satisfied solvent 3B, is transported from the extractor vessel 4C to one or more separator vessels 6, for separation of a liquid fraction 7 in a step S3B.

[0092] The skilled person will notice that in time interval T4 a situation similar to time interval T1 is reached. After time interval T4, the actions described in connection with subsequent time intervals T2-T3-T4 can be repeated one or more times.

[0093] It is clear that figure 2 illustrates that an amount of solvent 3A is being used to extract additives from a first and second batch of particulate material 2 in a first and second extraction vessel 4A-4B-4C subsequently. For example, the amount of fresh solvent 3A added to extraction vessel 4A and used for the step S2B of extraction in time interval Tl, is used as a partially satisfied solvent 3B during time interval T2 for the step S2A of extraction of particulate material 2 in extraction vessel 4B. It is clear that no intermediate treatment steps in between the extraction in time interval Tl and T2 that would change the effectiveness of the solvent 3B have been executed. The respective amount of solvent is allowed to expand to a lower pressure only after said time interval T2, more particularly in said step S3B.

[0094] Figure 3 illustrates a step S2 of extraction in a continuous extraction process. Herein the extraction takes place with the particulate material 2 generally moving in a first direction DI, while said solvent is generally flowing in a direction D2, substantially opposite to said first direction DI. The fresh solvent 3 A that enters the extraction equipment 4D meets particulate material 2A that has already been subjected to a partial or essentially full extraction. The fresh solvent 3 A moves on to meet more and more fresh particulate material 2 at the inlet 14. In doing so, the fresh solvent 3A more and more becomes satisfied with additives and contaminants extracted from the particulate material 2, and may be removed with the extracted material 5 from the extractor equipment 4D to one or more separator vessels 6, where the liquid fraction 7 may be obtained in a step S3B. It is possible that a plurality of inlets for fresh solvent 3A are provided at one or more locations along the extractor equipment. Also a plurality of outlets for extracted material 5 can be provided along one or more locations along the extractor equipment. At the outlet 15 of the extraction equipment 4D, extracted particulate material 2A is obtained in may be further processed in a step S3 A as described above.

[0095] Preferably, the extraction equipment 4D comprises, as is the case here, a barrel 16 and at least a screw 17. Preferably, said screw 17 is configured for compressing or compacting said particulate material 2. In such case, said step S4 of compressing said particulate material 2 is executed during said step S2 of extracting, by means of said screw 17.

[0096] Figure 4 shows an example where an amount of fresh solvent 3 has been used twice to perform an extraction on two separate amounts of particulate material 2. In this case, it relates to a continuous extraction equipment 4D with a barrel 16 and screw 17 as described in connection to figure 3. Such screw 17 whether or not together with the barrel 16 and the particulate material 2 may essentially form compartments, and said solvent 3A may be made to extract one or several of such compartments subsequently. In this case, the solvent 3 A extracts the particulate material 2 in at least one such compartment, before being circulated as a partially satisfied solvent 3B by means of the pump 10 to a compartment of particulate material 2 that is more upstream in relation to the direction DI of moving particulate material 2. It can be seen in the figure 4, that the extraction equipment 4D has been provided, for this purpose, with multiple inlets for fresh solvent 3 A, and multiple outlets for extracted material 5.

[0097] The present invention is by no means limited to the embodiments described above, however such methods may be realized according to various variants without departing from the scope of the present invention.

Claims

Claims.1.- Method for extracting one or more additives from polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products (1), characterized in that said method comprises the step (SI) of comminuting said PVC or PVB products (1) into particulate material (2) and the step (S2) of subjecting said particulate material (2) to an extraction by means of a solvent (3) in one or more extraction vessels (4), characterized in that the bulk density of said particulate material (2) while being subjected to said solvent-based extraction is at least 300 kilograms per cubic meter, preferably at least 500 kilograms per cubic meter.2.- Method according to claim 1, characterized in that said bulk density is between 300 and 1000 kilograms per cubic meter, preferably between 500 and 750 kilograms per cubic meter.3.- Method according to claim 1 or 2, characterized in that said method comprises a step (S3) of compressing said particulate material (2) prior to or during said solvent-based extraction.4.- Method according to any of the preceding claims, characterized in that at least 5kg of particulate material (2) is present in said one or more extraction vessels (4) during said solvent-based extraction.5.- Method according to any of the preceding claims, characterized in that said particulate material (2) has an average surface to volume ratio of 1:10 or higher as expressed in 1 / mm.6.- Method according to any of the preceding claims, characterized in that said PVC products (1) are polyvinyl chloride (PVC) floor or wall coverings.7.- Method for extracting one or more additives from polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products, characterized in that, said method comprises the step(SI) of comminuting said PVC or PVB products (1) into two or more batches of particulate material (2) and the step of subjecting two or more batches of said particulate material (2) to an extraction by means of a solvent in two or more extraction vessels (4A-4B), characterized in that said extraction comprises using a first amount of said solvent (3) to extract additives from a first and second batch of particulate material (2) in a first extraction vessel (4A) and a second extraction vessel (4B) subsequently.8.- Method according to claim 7, characterized in that said first amount of particulate material (2) has previously been subjected to another amount of said solvent (3), or to another solvent (3), while said second amount of particulate material (2) is subjected to a solvent-based extraction for the first time, or has been subjected to a solvent-based extraction for fewer times than said first amount of particulate material (2) has been.9.- Method according to claim 7 or 8, characterized in that said method comprises a step of pressurizing said first amount of solvent (3), preferably to a pressure of at least 10 MPa, prior to using said solvent (3) for extracting additives from said first amount of particulate materials (2).10.- Method according to claim 9, characterized in that said first amount of solvent (3) is allowed to expand to a lower pressure, preferably atmospheric pressure, only after using said solvent (3) for extracting additives from said second amount of particulate material (2).11.- Method for extracting one or more additives from polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products, characterized in that said method comprises the step (SI) of comminuting said PVC or PVB products (1) into particulate material (2) and the step (S2) of subjecting said particulate material (2) to an extraction by means of a solvent (3), characterized in that said extraction takes place with the particulate material (2) moving in a first direction (DI), while said solvent (3) is flowing in a direction (D2) substantially opposite to said first direction (DI).12.- Method for extracting one or more additives from polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products, characterized in that said method comprises the step (SI) of comminuting said PVC or PVB products (1) into particulate material (2) and the step (S2) of subjecting said particulate material (2) to an extraction by means of a solvent (3) in one or more extraction vessels (4), characterized in that the content of additives in said solvent (3) is monitored during said extraction, preferably using near infrared spectroscopy.13.- Method according to claim 12, characterized in that the extraction time, the bulk density of said particulate material (2), the amount of solvent (3), the temperature of said solvent (3), the pressure of said solvent (3) and / or the evacuation of said solvent (3) is controlled on the basis of said monitoring.14.- Method according to any of the preceding claims, characterized in that said extraction comprises extracting at least one additive from the polyvinyl chloride (PVC) or polyvinyl butyral (PVB) products (1), said additive is chosen from the group of plasticizers, heavy metals, polar components, acrylic resins, organic components, pigments, or combinations thereof.15.- Method according to any of the preceding claims, characterized in that said solvent (3) comprises supercritical carbon dioxide (CO2).16.- Method according to claim 15, characterized in that said particulate material (2) is brought into contact with supercritical carbon dioxide (CO2) at a temperature of between 20 and 100 °C, preferably of between 50 and 95 °C, more preferably of between 75 and 90 °C.17.- Method according to claim 15 or 16, characterized in that said particulate material (2) is brought into contact with supercritical carbon dioxide (CO2) at a pressure of between 20 and 50 MPa, preferably of between 30 and 50 MPa.18.- Method according to any of claims 15 to 17, characterized in that between 10 and 20 kg, preferably between 13 and 18 kg, of supercritical dioxide (CO2) is used in said extraction per kg of particulate material.19.- Method according to any of the preceding claims, characterized in that said solvent (3) comprises an ionic liquid.20.- Method according to claim 19, characterized in that said particulate material (2) is brought into contact with the ionic liquid at a temperature of at least 100 °C, preferably of at least 150 °C.21.- Method according to any of the preceding claims, characterized in that said particulate material (2) is brought into contact with said solvent (3) during a contact time of between 30 and 120 minutes, preferably of between 60 and 120 minutes, more preferably of between 75 and 100 minutes.22.- Method according to any of the preceding claims, characterized in that said particulate material (2) has a particle size D90 of less than 2.5 mm, preferably of less than 1 mm, more preferably of less than 0.5 mm.23.- Method according to any of the preceding claims, characterized in that said polyvinyl chloride (PVC) products (1) comprise PVC in an amount of between 20 and 100 wt.%.24.- Method according to any of the preceding claims, characterized in that said polyvinyl chloride (PVC) products or polyvinyl butyral (PVB) products comprise filler, preferably mineral filler, in an amount of between 0 and 80 wt.%.

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