Method for manufacturing PVC products

Abstract

Method for manufacturing PVC products, comprising: - providing a batch of material obtained from recycling post-consumer and / or post-industrial waste, wherein said material comprises particles having a composition of PVC and at least one or more additives chosen from the list consisting of filler, stabilizer, processing aid and impact modifier; - defining an indicative composition of the particles contained in said batch of material; - providing a malleable PVC composition by compounding a portion of said batch of material with an amount of one or more of a filler, a stabilizer, a processing aid and an impact modifier, wherein said amount is adjusted on the basis of said indicative composition; - molding or extruding said malleable PVC composition to yield said PVC products.

Description

[0001] Method for manufacturing PVC products.

[0002] The present invention relates to a method for manufacturing PVC products. In particular the present invention relates to a method for manufacturing such products using a batch of material obtained from recycling post-consumer and / or post-industrial waste. The invention is of particular interest for the manufacturing of board or sheet material that serves as a substrate layer of a decorative panel, such as a floor panel.

[0003] It is known, for example from WO 2019 / 086,566, to provide such substrate layer with a decorative top layer for example comprising a printed pattern. The method disclosed in WO ‘566 comprises the step of compounding a PVC composition and the step of extruding said PVC composition using an extruder, and a slot nozzle die linked to the outlet of said extruder. WO 2017 / 133804 discloses the use of PVC from a recycled source in an extrusion process for providing such substrate layer. WO‘804 may use pigment, impact modifier, lubricant, stabilizer, wax, and / or an aid processing agent as an additive. These additives appear to be entirely based on virgin materials.

[0004] JP 2006 / 249423 discloses that additives can be recuperated from waste PVC materials by means of a solvent extraction process. Although such process would allow for valorization of additives contained in waste PVC materials, the process is intensive and costly. The use of solvent may be disadvantageous for the environment.

[0005] JP 2016 / 216558 discloses a method for manufacturing PVC window sashes including recycling used PVC window sashes. The old PVC window sashes are pulverized to produce recycled powder and additives are added to the recycled powder. The additive type to be added is determined based on the results of a property evaluation of a molded article obtained from the recycled powder. The amount and type of the respective additive to be added in case of lack of certain properties is predefined. Properties such as impact resistance and thermal stability are evaluated, and the evaluation is aimed at judging whether the old window sashes have not changed their composition too much over time. As JP ‘558 recycles old products into same new products, in this case window sashes into window sashes, no complications are to be expected regarding compositions of the PVC to be recycled that would be significantly different than the compositions of the PVC desired for the new product. The aging of the old window sashes can only bring about marginal changes in the composition of the PVC. For example, the amount of filler type additives and / or plasticizer type additives will be largely similar in old and new window sashes, such that at least the properties to be evaluated are not expected to fluctuate due to a changing filler and / or plasticizer content. In such cases the standard seasoning of the recycled powder with a predefined amount of additives of a certain type, as taught in JP ‘558, may be sufficient. The profile extrusion of JP ‘558 is typically demanding less consistency in the raw material than for example an extrusion through a slot nozzle die linked to an extruder, wherein said slot nozzle die has a slot opening of limited height, for example 6mm or less, and a significant width, for example 1 m or more. Such extrusion through a slot nozzle die may be used for example to manufacture floor or wall covering products that are highly filled.

[0006] The present invention in the first place aims at providing an alternative method for manufacturing PVC products using e.g. material obtained from recycling post-consumer and / or post-industrial waste, wherein, in accordance with preferred embodiments, solutions are offered for one or more of the problems with the methods form the state of the art. According to some embodiments a more fluent and / or less intensive and / or more economic valorization of additives contained in waste PVC materials may be obtained. According to some embodiments the invention allows to take in post-consumer and / or post-industrial waste having a wide range of different compositions, in particular a wide range of different filler and / or plasticizer content within a same batch of material or in between batches of material.

[0007] With the above goal, the present invention, in accordance with its first independent aspect is a method for manufacturing PVC products, wherein said method comprises at least the following steps:

[0008] - the step of providing at least one batch of material preferably obtained from recycling post-consumer and / or post-industrial waste, wherein said material comprises particles having a composition of PVC and at least one additive, or a mix of two or more additives, chosen from the list consisting of filler, stabilizer, processing aid and impact modifier;

[0009] - the step of defining an indicative composition of the particles contained in said batch of material;

[0010] - the step of providing a malleable PVC composition by compounding a portion of said batch of material with an amount of one or more of a filler, a stabilizer, a processing aid and an impact modifier, wherein said amount is adjusted on the basis of said indicative composition;

[0011] - the step of at least molding or extruding said malleable PVC composition to yield said PVC products.

[0012] More particularly, the invention in accordance with its first independent aspect is a method for manufacturing PVC products, wherein said PVC products comprise a first composition of PVC and a first amount of at least one additive type chosen from the list consisting of filler, stabilizer, plasticizer, processing aid and impact modifier, or an amount equivalent to said first amount in that it brings about essentially the same functionality as said first amount, wherein said method comprises at least the following steps:

[0013] - the step of providing at least one batch of material preferably obtained from recycling post-consumer and / or post-industrial waste, wherein said material comprises particles having a second composition, or a second composition in average, of PVC and a second amount of at least said one additive type;

[0014] - the step of defining said second amount of at least said one additive type, or an amount equivalent to said second amount in that it brings about essentially the same functionality as said second amount;

[0015] - the step of providing a malleable PVC composition by compounding at least a portion of said batch of material with a third amount of said one additive type, wherein said third amount is defined on the basis of said second amount, or on the basis of said amount equivalent to said second amount, such that the total amount of said one additive type in said malleable PVC composition equals or approximates said first amount and / or such that the total amount of said one additive type is equivalent or approximately equivalent to said first amount in that it brings about essentially the same functionality as said first amount;

[0016] - the step of at least molding or extruding said malleable PVC composition to yield said PVC products.

[0017] Said equivalent amounts are preferably expressed taking the additive forming said third amount as a basis. For example, if the additive forming said third amount has twice the effectivity of the additive forming said second amount in said second composition, then half the second amount is considered to be the equivalent amount, because such equivalent amount of said additive forming said third amount would bring about essentially the same functionality as the second amount of the additive in said second composition.

[0018] Preferably, said one additive type is filler type additive and / or plasticizer type additive. Of course, the method of the invention may comprise the step of defining an amount of a plurality of additive types, such as at least filler type additive and at least plasticizer type additive. By at least defining the amount or average amount of filler type additive in said second composition an important additive leading to different mechanical and / or thermal properties is identified and may be taken into account when providing said malleable PVC composition. In the case of plasticizer type additive, an amount equivalent to said second amount may be defined, in that it brings about an equivalent plasticizing effect. For defining amounts equivalent to available second amounts of plasticizer type additives in said second composition, one may for example take the plasticizer type additive used in said step of compounding, i.e. the additive forming said third amount, as a basis, and define said amount equivalent to said second amount as an amount of said plasticizer type additive used in said step of compounding which brings about an equivalent, or essentially same, functionality in said second composition when it would replace said second amount. In an analogous way equivalent amounts of other additive types may be defined.

[0019] It is clear that said batch of material can originate from PVC products having a plurality of different compositions. In such case said particles are considered to have a second composition that is an average composition of the PVC products in said batch. Preferably, the step of defining said indicative composition or second amount, or amount equivalent to said second amount, is based on a mix, preferably a uniform mix, of particles comprised in said batch. In so doing, the average composition, or average second amount, or average amount equivalent to said average second amount, of the respective additive type can be defined, and taken into account in said step of providing the malleable PVC composition.

[0020] Preferably, said second composition or average second composition is significantly different from said first composition. For example, the amount of filler type additive in said second composition may be, or be in average, at least 10 phr lower, or at least 100 phr lower, than the amount of filler type additive in said first composition. For example, a second composition of particles from a batch may comprise about 35 phr of filler or less, while a first composition may comprise 250 phr of filler or more, or even 300 phr of filler or more. Such batch of material may originate from window frames and sashes. Such first composition may be suitable for manufacturing such PVC products as floor or wall covering products. According to another example, the amount of plasticizer type additive in said second composition may be, or be in average, at least 10 phr higher, or at least 20 phr higher, than the amount of plasticizer type additive in said first composition. For example, a second composition of particles from a batch may comprise about 35 phr of plasticizer or more, while a first composition may comprise 10 phr or less of plasticizer, 5 phr of plasticizer or less, preferably comprises 1 phr of plasticizer or less to no plasticizer. Such batch of material may originate from medical materials, such as bloodbags, while such first composition may be suitable for manufacturing rigid PVC flooring panels.

[0021] In general, said PVC product may be a floor or wall covering product, while said postconsumer and / or post-industrial waste originates from PVC products different from floor and wall products. For example, said post-consumer and / or post-industrial waste originates from PVC window frames or sashes, PVC door frames, PVC pipes, PVC medical materials and / or PVC textiles. It is clear that a batch of said post-consumer and / or post-industrial waste may originate from a plurality of different sources as well. Preferably said indicative composition or second amount, or amount equivalent to said second amount, includes an indication about the content, or respectively includes the amount, of filler materials, heavy metals, plasticizers, impact modifiers and / or stabilizing agents of said particles. Additives like fillers, plasticizers, impact modifiers and / or stabilizing agents in waste materials can to a large extent, if not wholly, be functional again in said malleable PVC composition. Some degeneration is not to be excluded, but may be mostly marginal.

[0022] Due to the present invention, wherein the indicative composition, or said second amount, or equivalent amount, of at least one additive type, of the batch of recycled material is taken into account in the final malleable PVC composition, the additives in the recycled material can be valorized without the need of extracting them.

[0023] It is clear that said adjustment is preferably such that the sum of said amount or third amount of a filler, a stabilizer, a processing aid and an impact modifier, and the respective indicative content or second amount, or equivalent amount, of the same or same-type additive in the particles of said batch is kept substantially constant between batches of said malleable PVC composition, and thus between batches of said PVC products. Alternatively, the adjustment or addition of said third amount is such that mechanical and thermal properties, such as thermal degradation and / or the modulus of elasticity, remain substantially constant. In other words, the total amount of the respective one additive type is equivalent or approximately equivalent to said first amount in that it brings about essentially the same functionality as the first amount. With “same-type additives” are meant additives having the same function in said malleable PVC composition. For example plasticizers, independent of their actual chemical formula, are all same-type additives, i.e. they all have a plasticizing function. For example impact modifiers, independent of their actual chemical formula, are all same-type additives. For example stabilizers, independent of their actual chemical formula, are all same-type additives. For example fillers, independent of their actual formula, are all same-type additives. Fillers that may be used in the present context include talcum, sand, chalk, limestone and other inorganic and / or mineral materials, whether or not comprising calcium carbonate. Coloring or whitening pigments, such as TiO2, are also considered to be filler type additives.

[0024] Plasticizers that may be used in the present context include

[0025] - High Molecular Weight Ortho Phthalates, such as Diisononyl phthalate (DINP), Bi s(2 -propylheptyl) phthalate (DPHP), Diisodecyl phthalate (DIDP),

[0026] Diisoundecyl phthalate (DIUP), Ditridecyl phthalate (DTDP);

[0027] Terephthalates, such as Bis(2-ethylhexyl) terephthalate (DEHT; Dioctyl terephthalate, DOTP), Diisopentyl terephthalate (DiPT), Dibutyl terephthalate (DBT)(EDOTP);

[0028] Trimellitates, such as Tri(2-ethylhexyl)trimellitate (TEHTM) (TOTM, Trioctyl Trimellitate plasticizer), Tri(isononyl)trimellitate (TINTM), Tri(isodecyl)trimellitate (TIDTM), Tri(isotridecyl)trimellitate (TITDTM);

[0029] Adipates & Sebacates, such as Bis(2-ethylhexyl)adipate (DEHA, dioctyl adipate plasticizer), Dibutyl sebacate (DBS), Di(2-ethylhexyl)sebacate, Di-octyl Sebacate (or DOS plasticizer);

[0030] Organophosphates, such as Tricresyl phosphate (TCP) and 2-Ethylhexyl diphenyl phosphate;

[0031] 1,2-Cyclohexane dicarboxylic acid diisononyl ester (DINCH);

[0032] Bis(2-ethylhexyl) cyclohexane-l,4-dicarboxylate (DEHCH);

[0033] Alkyl sulphonic acid phenyl ester (ASE);

[0034] Triethylene glycol di-2ethylhexanoate (TEG-EH); and / or

[0035] Glycerol triacetate (Triacetin), Acetyltributylcitrate and Epoxidized soybean oil.

[0036] Impact modifiers that may be used in the present context include CPE (chlorinated polyethylene), polyethylene, acrylics, styrene-acrylics, methacrylate butadiene styrene (MBS) and maleic anhydride-modified polyolefins. Such product may lead to an enhanced impact strength due to its presence as micro particles dispersed within the molecular structure of PVC. Stabilizers that may be used in the present context include Calcium / Zinc stabilizers, Sodium / Zinc stabilizers, that are preferably stearic acid based.

[0037] The wide range of possible fillers, stabilizers, plasticizers and impact modifiers results from the many possible sources of said batch of waste material.

[0038] Said batch of material may be provided in a comminuted form, for example with a particle size distribution having a D90 percentile value of 5 mm or less, preferably 1 mm or less, for example a D90 value between 0.1 and 1 mm.

[0039] Preferably, the recycled post-consumer or post-industrial waste used for preparing said batch of material has been purified and / or washed to remove any dirt, glue or other materials that are not PVC or typical additives to PVC, such as fillers, plasticizers, impact modifiers, processing agent, stabilizers. Preferably, the recycled post-consumer or postindustrial waste has been treated exclusively at temperatures below 100°C, below 80°C or below 60°C. Thermal stress on the PVC and / or the additives comprised in the composition of the waste can thus be limited or avoided, and potentially resultant degeneration of the PVC and / or additives largely prevented. Preferably, the recycled post-consumer or post-industrial waste has exclusively been purified and / or washed, and been comminuted mechanically. A high potential for valorization of PVC and the present additives from said waste is maintained.

[0040] Preferably, said step of extruding said malleable PVC composition comprises extruding said malleable PVC composition through a slot nozzle die linked to an extruder, wherein said slot nozzle die has a slot opening with a height of 8 mm or less, or 6 mm or less, and a width of Im or more. This step allows for forming PVC products of small thickness, for example with a thickness of 2 to 8 mm, preferably from 3 to 6 mm, at a convenient width, for example a width of 1 to 1.5 m, or about 1.3 m, in a continuous manner. Such step is convenient for extruding a substrate layer for use in manufacturing a floor panel, however requires the malleable PVC composition to maintain a substantially uniform composition, or at least substantially uniform thermal and / or mechanical properties, throughout the extrusion process. Adjusting the amount of stabilizers and impact modifiers taking into account the indicative composition or second amount of at least one additive type, preferably at least the filler type additive, of particles from said batch of recycled material can bring about a more repeatable and more reliable extrusion process.

[0041] Preferably, said malleable PVC composition is obtained by compounding a portion of said batch of material with a mix of additives or additive types comprising at least two, or all of the list consisting of plasticizer, impact modifier, filler and stabilizer, wherein, preferably, the amount of each additive or additive type is adjusted or defined on the basis of said indicative composition or its defined amount, or equivalent amount, within said second composition. For each additive type, the total amount of the respective additive type in said malleable PVC composition can equal or approximate the amount of the respective additive type in said first composition. Alternatively, the total amount of the respective additive type is equivalent or approximately equivalent to said amount of the respective additive type in said first composition in that it brings about essentially the same functionality. PVC compositions with such a mix of additives or additive types are of particular importance in the production of substrate layers for floor or wall panels. These substrate layers may have a limited thickness for example between 2 and 8 mm, or between 3 and 6 mm, and / or such panels may at at least two opposite edges comprise coupling parts that are formed in one piece with the panel material, for example essentially in the substrate layer. Herein, it preferably concerns coupling parts that allow to obtain a locking between adjacent panels at the respective edges in a vertical direction perpendicular to the plane of the coupled panels, and in a horizontal direction in the plane of the coupled panels, and perpendicular to the respective edges. For PVC compositions used in the substrate layer of such panels, it is important that the amount of filler, plasticizer, stabilizer and / or impact modifier is closely guarded, since a too low or too high content of these additives may have a considerable negative influence on the obtained mechanical properties of the flooring, more particularly of the coupling parts. In accordance with a particularly preferred embodiment, said PVC composition is used in the substrate layer of such panels, and said PVC composition is mechanically and / or chemically foamed. In the case of mechanical foaming this may concern the introduction of CO2 or N2 gas in the PVC composition, for example in the extrusion process in the extruder barrel, in the slot nozzle die, or in any part connecting the extruder outlet with the slot nozzle die.

[0042] Preferably, said malleable PVC composition, said first composition and / or said PVC product comprises 100 parts by weight of PVC, 3 to 12 parts by weight of stabilizer, and 3 to 10 parts by weight of impact modifier. It is in particular with such PVC compositions or PVC products that the invention is of importance. The valorization of additives from the batch of recycled material can maximally be exploited in that case. This composition may be used for a substrate layer of a floor or wall panel having coupling parts as described above.

[0043] Preferably, said malleable PVC composition, said first composition and / or said PVC product comprises 100 parts by weight of PVC and at least 150 parts by weight of filler, or at least 300 parts by weight of filler. This composition may be used for a substrate layer of a floor or wall panel having coupling parts as described above.

[0044] Preferably, said adjusting, or said defining said third amount, results in said malleable PVC composition or first composition having a constant amount of stabilizers and impact modifiers within a tolerance of + / - 2 parts by weight per 100 weight parts of the PVC, or within a tolerance of -0.5 / +1.5 parts by weight per 100 weight parts of the PVC. Such tolerance ranges are acceptable when working with extrusion through a slot nozzle die, even if the slot nozzle opening has a height of 8 mm or less, or 6 mm or less, and a width of 1 m or more. As mentioned herein, preferably a slight overdosing is preferred in order to compensate for potential partial ineffectiveness or degradation of available additives in the batch of waste material. In such case a tolerance of +0.1 / + 1.5 parts by weight per 100 parts of the PVC may be obtained.

[0045] Said step of defining an indicative composition, or said second amount, or said amount equivalent to said second amount, of a respective additive type, of said batch of material may be implemented in a variety of different manners of which here below some three possibilities are mentioned without desiring to be exhaustive. In accordance with a first possibility, preferably, said step of defining said second amount, an amount equivalent thereto, or an indicative composition of said batch of material at least includes the substep of identifying and / or using the origin of said material to define an indicative composition or a composition of said batch of material. For example, when it is known that the batch of material mainly stems from PVC window frames, pipes or other PVC profiles, the textbook composition of such products can be used as composition or indicative composition to adjust the amount of filler, plasticizer, impact modifier and / or stabilizer to be added in order to obtain the desired first composition of the malleable PVC composition.

[0046] In accordance with a second possibility, preferably, said step of defining said second amount, amount equivalent thereto, or an indicative composition of said batch of material at least includes

[0047] - the substep of using a portion of said batch for making one or more test samples;

[0048] - the substep of mechanically and / or thermally stressing said test samples and recording their behaviour;

[0049] - the substep of comparing said behaviour to the behaviour of reference samples, wherein said reference samples have varying defined compositions of PVC and an amount of at least one or more of said additives or additive types;

[0050] - the substep of using said comparison to define said second amount, an amount equivalent thereto, or an indicative composition of said batch of material, for example by defining said indicative composition or said second amount, or said amount equivalent thereto, as comprising, respectively being, the amount of said one or more additives that is comprised in the composition of the reference sample whose behaviour best compares to the behaviour of the one or more test samples.

[0051] Preferably, said substep of mechanically and / or thermally stressing said test sample comprises performing one or more of a thermal stability test, a mechanical impact test and a mechanical bending test. Here below some example test methods are mentioned without desiring to be exhaustive. According to a first example, thermally stressing said test sample includes performing a Congo Red test, preferably in accordance with SATRA TM 324. Herein, a test sample of the batch material is heated at a defined temperature, for example 180°C, 200°C or 210°C. The time taken for the material to degrade, indicated by evolution of hydrogen chloride is determined by a change of color in a Congo Red test paper. In this test, the test sample preferably comprises particles taken from said batch of waste material, and so no further operations are done on said particles for making said test sample. This thermal stress test enables to define an amount, equivalent amount, or an indicative content of stabilizer in the test sample, by comparing its behaviour, i.e. the time taken for degradation, to the respective behaviour of reference test samples, for example test samples having a known amount of a stabilizer type additive.

[0052] According to a second example, the test sample is a strip of PVC made from said particles, for example by extrusion using a lab extruder. The thermal stability of said strip of PVC is tested by putting it in a hot-air oven and gradually transporting the test sample lengthwise out of the hot-air oven (e.g. so-called Mathis LTE-T oven from Mathis AG). The strips may have a length of 420 mm. The hot-air oven is at a set temperature, for example of 200°C. The transport speed may be set at 1 cm / min. The dwelling time in the hot air oven with a strip length of 420 mm varies between 5 s for the start of the strip that almost instantaneously leaves the oven and 42 min for the end of the strip. In so doing the degradation of the test samples varies along the length of the PVC strip. Again the behaviour can be compared to the behaviour of reference samples put to the same test conditions. This thermal stress test enables defining an amount, equivalent amount, or an indicative content of stabilizer in the test sample, by comparing its behaviour, i.e. the time taken for degradation, to the respective behaviour of reference test samples, for example test samples having a known amount of a stabilizer type additive.

[0053] According to a third example, a rotational rheometer is applied for measuring the viscosity of a test sample. The temperature, shear stress and compressive stress on the sample is kept constant during the test for a long period of time. Due to the gradual degradation of the test sample, the molecules of the PVC will tend to become larger and a higher viscosity will be measured over time. This stress test enables defining an amount, equivalent amount or indicative content of stabilizer in the test sample, by comparing its behaviour, i.e. the time taken for reaching a defined viscosity, to the respective behaviour of reference test samples. This test may also serve to obtain indications about the Fikentscher K value (referenced in DIN EN ISO 1628-1) of the PVC.

[0054] According to a fourth example, a Charpy impact test may be performed on a test sample, for example in accordance with ISO 179-2:2020. In a Charpy test a pendulum crashes into a V-notched test sample. The energy lost in the pendulum’s swing because of breaking the test sample is recorded. This mechanical stress test enables defining an amount, equivalent amount, or an indicative content of impact modifier and / or stabilizer in the test sample, by comparing its behaviour, i.e. the energy lost in breaking the test sample, to the respective behaviour of reference test samples, for example test samples having a known amount of a stabilizer type additive and / or an impact modifier type additive.

[0055] According to a fifth example, a three point bending test may be performed on a test sample, for example in accordance with ISO 178:2019 (Charpy single V EN ISO 179 / leA). In a three point bending test, a force is exerted in the middle of a sample that is supported at its free ends. The stress-strain diagram may be recorded, preferably including the Young’s modulus, the maximum strain and stress at break, the maximum strain and stress in the elastic regime, and / or the stress at 0.2% strain. This mechanical stress test enables defining an amount, equivalent amount, or indicative content of impact modifier and / or plasticizer and / or stabilizer in the test sample, by comparing its behaviour, i.e. the stress-strain diagram or certain values thereof, such as the maximum stress at breakage, to the respective behaviour of reference test samples, for example test samples having a known amount of a stabilizer type additive and / or an impact modifier type additive and / or a plasticizer type additive.

[0056] According to a sixth example, a test sample is burnt and the weight of the ash content measured. In this test, the test sample preferably comprises particles taken from said batch of waste material, and so no further operations are needed on said particles for making said test sample. This thermal stress test enables defining an amount, equivalent amount, or indicative content of fillers and coloring pigments in the test sample. A comparison to reference sample is not necessary in this case.

[0057] It is remarked that many more standardized or non-standardized tests may be used to stress the test samples and the reference samples. A comparison between the respective behaviours may lead to an indicative content or said second amount, or an amount equivalent thereto, of any or all of the additives or additive types in the batch of waste material.

[0058] Preferably, said one or more test samples include test samples made from said particles without addition of additives and / or test samples made from said particles with addition of, preferably a defined amount of, one or more of said additives or additive types, i.e. one or more of a filler, a plasticizer, an impact modifier and a stabilizer. In the latter case, the substep of using said comparison may define said indicative composition or second amount or equivalent amount as comprising, respectively being, the amount of said one or more additives that is comprised in the composition of the reference sample whose behaviour best compares to the behaviour of the one or more test samples, minus the defined amount that was added to prepare the respective test sample.

[0059] Preferably, said one or more test samples do include test samples made from said particles with addition of one or more of said additives or additive types.

[0060] In mechanically and / or thermally stressing test samples, the effectivity of the function of the available additives is put to the test. Any degeneration of the available additives is automatically taken into account, as the comparison leads to an indicative composition or a second amount, or an amount equivalent thereto, showing only the amount of a respective additive that is effective, or an equivalent amount that brings about essentially the same functionality.

[0061] According to a third possibility, preferably, said step of defining an indicative composition of said batch of material at least includes the substep of using X-ray, infrared or other types of radiation to define an indicative composition or second amount, or amount equivalent thereto, of said at least one additive type of said batch of material and / or of test samples made from using a portion of said batch. An XRF (X-ray fluorescence) may be used to determine a level of heavy metal, or other harmful components, in the batch of waste material. The use of radiation may enable a very quick and accurate characterization of the respective batch of material. An economic industrially applicable process of recycling post-consumer and / or post-industrial waste may be obtained. With such techniques said batch of material may even be split in a plurality of portions, or sub batches, to enable a more detailed characterization of each portion, or sub batch, and a definition or adaptation of said third amount in said step of compounding in accordance with the indicative composition of the respective portion, or sub batch, being compounded. The speedy characterization may even be done in the transport of said portion or sub batch to a vessel where said step of compounding is taking place, for example in the transport to a hot-and-cold mixer, or to a compounding screw. The addition of said third amount may be automatically controlled on the basis of said characterization of incoming material from said batch of material.

[0062] It is clear that a plurality of said batches of material may be provided, wherein for each batch said indicative composition or said second amount, or amount equivalent thereto, of at least one additive type is defined separately. According to an alternative, a uniform mix of the material from two or more batches may be created, wherein an indicative composition of, or second amount, or amount equivalent thereto, of the at least one additive type within, the mixed batch is defined in accordance with the methods described herein. Mixing of batches may lead to a reduction of fluctuations in said indicative composition or second amount, or amount equivalent thereto, and the subsequent adjustments needed in the amounts of filler, stabilizer, impact modifier and plasticizer to be added for providing said malleable PVC composition.

[0063] As already mentioned above, said malleable PVC composition is preferably at least obtained by compounding a portion of said batch of material with a mix of additives comprising at least plasticizer, impact modifier, filler and stabilizer, wherein, preferably, the amount of each additive is adjusted on the basis of said indicative composition or said second amount, or amount equivalent thereto, of the respective additive type. The compounding may also include a portion of virgin PVC, and / or a portion of a composition comprising virgin PVC and / or virgin additives. Alternatively said malleable PVC composition is obtained essentially or exclusively from a portion of said batch of material and said mix of additives at said adjusted or third amount. It should be noted that the adjustment may lead to a zero addition for one, some or all of the additives or additive types in said mix. Preferably, however, at least one of filler, stabilizer and impact modifier is added in an adjusted amount or third amount larger than zero, for example at least at 0.5 parts by weight per 100 parts of the PVC.

[0064] 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 the particle size distribution 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 may need to be brought in a loose state, and can be dispersed in a liquid, such as water.

[0065] It is clear that the present invention also concerns a PVC product obtained with a method in accordance with the first independent aspect and / or the preferred embodiments thereof. Further the invention also concerns a floor or wall covering product, with as a characteristic that said floor or wall covering product comprises such a PVC product, wherein said floor or wall covering is a laminated product comprising a single- or multilayered substrate and a single- or multilayered top layer applied on top of said substrate, wherein said PVC product essentially forms said substrate or a layer thereof, or, essentially forms said top layer or a layer thereof.

[0066] With the aim of still further illustrating the features of the invention, here below, an example of the method of the invention and the results obtained are listed. Example:

[0067] A batch of material obtained from recycling post-industrial waste is provided. The material consists of particles having a composition of PVC and a mix of additives. The post-industrial waste originates from the window frame industry and has been comminuted to particles having a particle size distribution having a DIO percentile of 106 pm, a D50 percentile of 298 pm and a D95 percentile of 467 pm.

[0068] PVC compositions in window frames are quite standardized with the exception of the filler content, which may vary. A standard PVC composition for window frames may include 5.6 parts of stabilizer, 0.56 parts of processing aid, 5.5 parts of an acrylic impact modifier and 5 parts of whitening pigment (TiCh) by weight per 100 weight parts of PVC.

[0069] As a preliminary step, a test sample taken from the particles of said batch of material is burnt and the weight of the ash content measured. It was obtained that 20.05% of the weight of the particles was formed by the ash. The expected components of the ash are the filler and the whitening pigment. The remaining, burnt, portion of 79,95% is assumed to be made up by 100 parts by weight of PVC, 5.6 parts of stabilizer, 0.56 parts of processing aid, 5.5 parts of impact modifier. This means that an indicative composition or second amount in relation to the additive types and the PVC can be defined as 71.60 wt% PVC, 4.01 wt% stabilizer, 0.4 wt% processing aid, 3,94 wt% impact modifier, 3.58 wt% of whitening pigment and 16.4 wt% of filler (about 23 parts by weight per 100 weight parts of PVC). This indicative composition or second composition can be used to adjust the amount of additives or additive types to be added in the step of providing said malleable PVC composition. At least the content of filler may be taken into account for the adjustment of the amount of additional filler to be used in providing said malleable PVC composition. The amount of whitening pigment may also be taken into account as filler content when adjusting the malleable PVC composition. With regard to the impact modifier and stabilizer, it is preferred that further steps are taken to define their content on the basis of their effectiveness, as described herein below. Such method will take better into account any degradation that occurred or the remaining quality of the used respective additive.

[0070] In a further step, an analysis is made to define a content of heavy metals and other harmful components by means of at least XRF. It was found that a test sample taken from said batch of material contained 0.95 wt% of lead stabilizer. On the basis of this measurement, it can be calculated to which extent the particles from the batch must be mixed with virgin materials or a batch of material containing less lead stabilizer to fulfil the prevailing regulations on the allowed content of lead stabilizer in PVC products.

[0071] In a further step, the behaviour of test samples of four different compositions are compared with a reference sample in the Congo Red test, in accordance with the first example mentioned in the introduction. The reference sample 1 comprises 9 parts by weight of stabilizer, which is the normal composition, or first composition, of the PVC products aimed at. The used additional stabilizer is Ca / Zn stearic acid based. Test samples in the form of strips of the same four different compositions are tested in a hotair oven in accordance with the second example mentioned in the introduction. In the Congo Red test the time in minutes until full degradation of the sample was recorded. In the hot-air oven the dwelling time until discoloration, and the dwelling time until full degradation was recorded. The results are shown in the below table, where sample 1 is the reference sample. In test sample 2, no valorization at all was made of the stabilizer content available in the particles of the batch of waste material. Instead an amount of stabilizer was added as if all the available PVC were virgin, i.e. 9 phr. The times until full degradation or discoloration obtained in the Congo Red test and in the hot-air oven test however show that the thermal stability of the test sample 2 are unnecessarily high, i.e. far higher than the reference sample. Sample 5 shows that also on itself the particles from the batch of waste material are extremely well stabilized, since they provide for an even higher time to degradation or discoloration. In test sample 3 and 4 the amount of stabilizer is adjusted from 9 in the reference sample to 6.75, respectively 5 parts per hundred (phr) of the PVC. This resulted in times to discoloration and degradation that are more comparable to the reference sample. The compositions of reference sample 3 and 4 appear to put forward an interesting valorization of the available stabilizer content in the particles of the batch of waste material, and in the step of providing a malleable PVC composition the amount of stabilizer to be added can therefor be adjusted similarly, i.e., in this case, from 9 to 6.75 or even to 5 phr.

[0072] In a further step, the behaviour of test samples of three different compositions are compared with a reference sample in the Charpy test, in accordance with the fourth example mentioned in the introduction. The reference sample 1 comprises 6 parts by weight of impact modifier (chlorinated polyethylene) and 9 parts by weight of stabilizer (Ca / Zn stearic acid based), which is the normal composition, or first composition, of the PVC products aimed at. In the Charpy test the energy consumed in breaking the samples was recorded, averaged out over 10 identical samples. The results are shown in the below table, where sample 1’ is the reference sample. The range listed in the below table indicates the deviation of the results over the 10 experiments, i.e. the difference between the maximally and minimally obtained energy in breaking the 10 samples.

[0073] The test results do, in this case, not show any statistically significant differences.

[0074] In a further step, samples having the same composition as samples 1 ’ to 4’ are tested in accordance with said fifth example mentioned in the introduction, i.e. in a three point bending test. The modulus of elasticity or Young’s modulus was recorded as shown in the below table. The results show that the amount of impact modifier can be adjusted from 6 phr in the reference sample to 4.6 phr in the step of providing said malleable composition, without compromising the elasticity of the material of the obtained PVC product. The present example shows the advantage of the valorization of the additives contained in PVC waste material in that the amount of fillers, stabilizers and impact modifiers can be adjusted, i.e. lowered, while maintaining significant mechanical and thermal properties of PVC products made from such a malleable PVC composition. It is noted that similar tests, or additional test samples, may be needed when the valorization of the available additives in said batch of material is aimed at foamed PVC products, as these are commonly more demanding. Defining an indicative composition, or a second amount of at least one additive type, in the case of foamed PVC products is therefor of still greater importance.

[0075] Preferably, the samples 1’ to 4’ used in the Charpy test and / or the three point bending test comprise, like was the case in the above experiments, an amount of filler of 300 parts by weight per 100 parts of the PVC, hereby taking into consideration the filler content of the particles from the batch of recycled material, that was indicatively defined as 20.05% or 28 parts by weight per hundred parts of PVC. In the below table the composition of the samples 1’ to 4’ has been completed with the filler content.

[0076] It is remarked that, in the context of the invention, it is not excluded that the adjustment of the amount of additives to the malleable PVC composition is such that no amount of one, two or more, or all of the additives is added for providing the malleable PVC composition, such depending on said indicative composition. Preferably, at least filler is added in said adjusted or third amount. It is clear that, within the context of the invention, it is possible that for providing said malleable PVC composition exclusively particles from said batch of recycled material are used, with addition of additives or additive types in said adjusted or third amounts, which as above stated, may lead to a zero addition of one, some or all of the additives or additive types.

[0077] Where in the above an amount is said to approximate another amount, this amount is preferably in a range of + / - 10% around the respective another amount, and more preferably in a range of + / - 5% around the respective another amount.

[0078] Where in the above an amount is said to be approximately equivalent to another amount, this amount preferably leads to a time to degradation in the Congo Red Test or hot-air oven, as described by means of the first respectively second example test method, which is in a range of + / - 10%, or + / - 5%, around the time to degradation in the Congo Red Test, respectively hot-air oven, of the respective another amount, with other parameters kept constant; a time taken to reach a defined viscosity in a rotational rheometer, in accordance with said third example test method, which is in a range of + / - 10%, or + / - 5%, around the time to reach the same viscosity for the respective another amount, with other parameters kept constant; and / or an energy loss in breaking a test sample in the Charpy impact test, in accordance with said fourth example test method, which is in a range of + / - 10%, or + / - 5%, around the energy loss in breaking a test sample with the respective another amount, with other parameters kept constant. a Young’s modulus, maximum strain and stress at break, maximum stress and strain in the elastic regime and / or stress at 0.2% strain, as measured in accordance with said fifth example test method, which is in a range of + / - 10% around the respective values for the respective another amount, with other parameters kept constant. The invention further relates to the following independent aspects and embodiments as defined by means of the below numbered paragraphs.

[0079] 1.- Method for manufacturing PVC products, wherein said method comprises at least the following steps:

[0080] - the step of providing at least one batch of material, preferably obtained from recycling post-consumer and / or post-industrial waste, wherein said material comprises particles having a composition of PVC and at least one additive, or a mix of two or more additives, chosen from the list consisting of filler, stabilizer, processing aid and impact modifier;

[0081] - the step of defining an indicative composition of the particles contained in said batch of material;

[0082] - the step of providing a malleable PVC composition by compounding a portion of said batch of material with an amount of one or more of a filler, a stabilizer, a processing aid and an impact modifier, wherein said amount is adjusted on the basis of said indicative composition;

[0083] - the step of at least molding or extruding said malleable PVC composition to yield said PVC products.

[0084] 2.- Method according to numbered paragraph 1, characterized in that said step of defining an indicative composition of said batch of material at least includes the substep of identifying and / or using the origin of said material to define an indicative composition of said batch of material.

[0085] 3.- Method according to numbered paragraph 1 or 2, characterized in that said step of defining an indicative composition of said batch of material at least includes

[0086] - the substep of using a portion of said batch for making one or more test samples;

[0087] - the substep of mechanically and / or thermally stressing said test sample and recording its behaviour;

[0088] - the substep of comparing said behaviour to the behaviour of reference samples, wherein said reference samples have a defined composition of PVC and at least one or more of said additives; - the substep of using said comparison to define an indicative composition of said batch of material.

[0089] 4.- Method according to numbered paragraph 3, characterized in that said substep of mechanically and / or thermally stressing said test sample comprises performing one or more of a thermal stability test, a mechanical impact test and a mechanical bending test.

[0090] 5.- Method according to numbered paragraph 3 or 4, characterized in that said one or more test samples include test samples made from said particles without addition of additives.

[0091] 6.- Method according to any of numbered paragraphs 3 to 5, characterized in that said one or more test samples include test samples made from said particles with addition of one or more of said additives.

[0092] 7.- Method according to any of numbered paragraphs 1 to 6, characterized in that said step of defining an indicative composition of said batch of material at least includes the substep of using X-ray, infrared or other types of radiation to define an indicative composition of said batch of material and / or of test samples made from using a portion of said batch.

[0093] 8.- Method according to any of the preceding numbered paragraphs, characterized in that a plurality of said batches of material are provided, wherein for each batch said indicative composition is defined separately.

[0094] 9.- Method according to any of the preceding numbered paragraphs, characterized in that said indicative composition includes an indicative content of filler materials, heavy metals, plasticizers, impact modifiers and / or stabilizing agents.

[0095] 10.- Method according to any of the preceding numbered paragraphs, characterized in that said malleable PVC composition is obtained by compounding a portion of said batch material with a mix of additives comprising at least plasticizer, impact modifier, filler and stabilizer, wherein, preferably, the amount of each additive is adjusted on the basis of said indicative composition.

[0096] 11.- Method according to any of the preceding numbered paragraphs, characterized in that said PVC product comprises 100 parts by weight of PVC, 3 to 12 parts by weight of stabilizer, and 3 to 10 parts by weight of impact modifier.

[0097] 12.- Method according to any of the preceding numbered paragraphs, characterized in that said PVC product comprises 100 parts by weight of PVC and at least 150 parts by weight of filler, or at least 300 parts by weight of filler.

[0098] 13.- Method according to any of the preceding numbered paragraphs, characterized in that said adjusting results in said malleable PVC composition having a constant amount of stabilizers and impact modifiers within a tolerance of 2 parts by weight per 100 weight parts of the PVC.

[0099] 14.- Method according to any of the preceding numbered paragraphs, characterized in that said step of extruding said malleable PVC composition comprises extruding said malleable PVC composition through a slot nozzle die linked to an extruder, wherein said slot nozzle die has a slot opening with a height of 6 mm or less, and a width of Im or more.

[0100] 15.- PVC product obtained with a method in accordance with any of the preceding numbered paragraphs.

[0101] 16.- Floor or wall covering product, characterized in that said floor or wall covering product comprises a PVC product in accordance with numbered paragraph 15, wherein said floor or wall covering is a laminated product comprising a single- or multilayered substrate and a single- or multilayered top layer applied on top of said substrate, wherein said PVC product essentially forms said substrate or a layer thereof, or, said top layer or a layer thereof. The present invention is not limited to the examples described here above, but such methods, PVC products and floor or wall covering products may be realized according to several variants without leaving the scope of the invention.

Claims

Claims:1.- Method for manufacturing PVC products, wherein said PVC products comprise a first composition of PVC and a first amount of at least one additive type chosen from the list consisting of filler, stabilizer, processing aid and impact modifier, or an amount equivalent to said first amount in that it brings about essentially the same functionality as said first amount, wherein said method comprises at least the following steps:- the step of providing at least one batch of material, preferably obtained from recycling post-consumer and / or post-industrial waste, wherein said material comprises particles having a second composition of PVC and a second amount of at least said one additive type;- the step of defining said second amount of at least said one additive type, or an amount equivalent to said second amount in that it brings about essentially the same functionality as said second amount;- the step of providing a malleable PVC composition by compounding at least a portion of said batch of material with a third amount of said one additive type, wherein said third amount is defined on the basis of said second amount, or on the basis of said amount equivalent to said second amount, such that the total amount of said one additive type in said malleable PVC composition equals or approximates said first amount and / or such that the total amount of said one additive type is equivalent or approximately equivalent to said first amount in that it brings about essentially the same functionality as said first amount;- the step of at least molding or extruding said malleable PVC composition to yield said PVC products.2.- Method according to claim 1, characterized in that said at least one additive type is filler type additive.3.- Method according to claim 1 or 2, characterized in that the amount of filler type additive in said second composition is, or is in average, at least 10 phr lower, or at least 100 phr lower, than the amount of filler type additive in said first composition.4.- Method according to claim 3, characterized in that said second composition comprises about 35 phr of filler or less and said first composition comprises 150 phr of filler or more, 250 phr of filler or more, preferably 300 phr of filler or more.5.- Method according to any of the preceding claims, characterized in that the amount of plasticizer type additive in said second composition is, or is in average, at least 10 phr higher, or at least 20 phr higher, than the amount of plasticizer type additive in said first composition.6.- Method according to claim 5, characterized in that said second composition comprises about 35 phr or more of plasticizer and said first composition comprises 10 phr of plasticizer or less, 5 phr of plasticizer or less, preferably comprises 1 phr of plasticizer or less to no plasticizer.7.- Method according to any of the preceding claims, characterized in that said step of defining said second amount at least includes the substep of identifying and / or using the origin of said material to define a composition of said batch of material.8.- Method according to any of the preceding claims, characterized in that said step of defining said second amount, or said amount equivalent to said second amount, at least includes- the substep of using a portion of said batch for making one or more test samples;- the substep of mechanically and / or thermally stressing said test sample and recording its behaviour;- the substep of comparing said behaviour to the behaviour of reference samples, wherein said reference samples have a defined composition of PVC and said at least one additive type;- the substep of using said comparison to define said second amount or said amount equivalent to said second amount.9.- Method according to claim 8, characterized in that said substep of mechanically and / or thermally stressing said test sample comprises performing one or more of a thermal stability test, a mechanical impact test and a mechanical bending test.10.- Method according to claim 8 or 9, characterized in that said one or more test samples include test samples made from said particles without addition of additives.11.- Method according to any of claims 8 to 10, characterized in that said one or more test samples include test samples made from said particles with addition of one or more of said additive types.12.- Method according to any of the preceding claims, characterized in that said step of defining said second amount at least includes the substep of using X-ray, infrared or other types of radiation to define a composition of said batch of material and / or of test samples made from using a portion of said batch.13.- Method according to any of the preceding claims, characterized in that a plurality of said batches of material are provided, wherein for each batch said second amount, or said amount equivalent to said second amount, is defined separately.14.- Method according to any of the preceding claims, characterized in that said second composition comprises one or more additive types including filler materials, heavy metals, plasticizers, impact modifiers and / or stabilizing agents.15.- Method according to any of the preceding claims, characterized in that said malleable PVC composition is obtained by compounding a portion of said batch material with a mix of additive types comprising at least plasticizer, impact modifier, filler and stabilizer, wherein, preferably, the amount of each additive type is defined on the basis of its defined amount within said second composition, such that, for each additive type, the total amount of the respective additive type in said malleable PVC composition equals or approximates the amount of the respective additive type in said first composition and / or such that the total amount of the respective additive type is equivalentor approximately equivalent to said amount of the respective additive type in said first composition in that it brings about essentially the same functionality.16.- Method according to any of the preceding claims, characterized in that said first composition comprises 100 parts by weight of PVC, 3 to 12 parts by weight of stabilizer, and 3 to 10 parts by weight of impact modifier.17.- Method according to any of the preceding claims, characterized in that said first composition comprises 100 parts by weight of PVC and at least 150 parts by weight of filler, or at least 300 parts by weight of filler.18.- Method according to any of the preceding claims, characterized in that said malleable PVC composition has an amount of stabilizers and impact modifiers equal to the amount of the respective additive type in said first composition within a tolerance of 2 parts by weight per 100 weight parts of the PVC.19.- Method according to any of the preceding claims, characterized in that said step of extruding said malleable PVC composition comprises extruding said malleable PVC composition through a slot nozzle die linked to an extruder, wherein said slot nozzle die has a slot opening with a height of 6 mm or less, and a width of Im or more.20.- Method in accordance with any of the preceding claims, characterized in that said PVC product is a floor or wall covering product, while said batch of material is obtained from post-consumer and / or post-industrial waste originating from PVC products different from floor and wall products.21.- Method in accordance with claim 20, characterized in that said post-consumer and / or post-industrial waste originates from PVC window frames or sashes, PVC door frames, PVC pipes, PVC medical materials and / or PVC textiles.22.- PVC product obtained with a method in accordance with any of the preceding claims.23.- Floor or wall covering product, characterized in that said floor or wall covering product comprises a PVC product in accordance with claim 22, wherein said floor or wall covering is a laminated product comprising a single- or multilayered substrate and a single- or multilayered top layer applied on top of said substrate, wherein said PVC product essentially forms said substrate or a layer thereof, or, said top layer or a layer thereof.

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