Recycling method of a porous substrate with a thermoplastic coating

Abstract

A method for recycling a porous substrate coated with a thermoplastic coating composition is disclosed. The method comprises the steps of shredding the coated porous substrate, dissolving the coating composition, and separating the dissolved coating composition and the substrate.

Description

[0001] Recycling method of a porous substrate with a thermoplastic coating

[0002] Background of the Invention

[0003] Field of the Invention

[0004] The present invention concerns a method for recycling a porous substrate coated with a thermoplastic coating composition. In particular, the present invention concerns a method that enables recycling and re-use of both the porous substrate and the thermoplastic coating composition.

[0005] Description of Related Art

[0006] Different functional properties, such as protective and repelling properties, are required in many applications, and when the substrate itself do not possess such properties, those are usually provided by different kinds of coating layers. In particular, various porous substrates typically have poor repelling properties, wherein protective coatings are required to improve the product life and overall properties of the product. Improved properties obtained by coatings enable applications where the substrate needs protection e.g. from water, light and oxygen. For example, textile coatings are commonly used to provide preferred properties, such as dirt, wind, fire, oil and water resistance, to the textile.

[0007] Porous substrates requiring repelling properties typically have a polymeric coating layer to improve its physical properties. Most typically this coating layer is made of fossil-based plastics. Porous substrates made from fibrous material, such as natural fibres, are known to be coated with common coating materials such as polyvinyl chloride (PVC), acrylic resins or polyurethane. There materials have many desired properties, however, all of these have the drawback of being toxic and / or fossil-based. PVC comprises various dangerous chemicals and additives that are harmful for both human and environment. Acryl is a better alternative from this point view, however, it is also fossil-based and, further, it does not provide as good properties as PVC in terms of tactile properties and dirt resistance, for example. Also manufacture of polyurethane requires use of harmful chemicals. Use of biopolymers is an attractive option to replace these plastic coatings, and thus biobased or at least partially bio-based laminate films have been researched for coating different porous substrates.

[0008] However, such functional products based on porous substrates are challenging to recycle, in the case of both fossil -based polymer coatings and biopolymer coatings. Separation of the coating and the substrate is generally difficult and, in particular, it is difficult to recover those in re-usable forms. There are some recycling methods for recycling of polymers based on dissolution, however, these are only limited to certain (fossil-based) polymers, such as polyvinyl chloride (PVC), polyethylene terephthalate (PET), polypropylene (PP), low density polyethylene (LDPE), high density polyethylene (HDPE) and polystyrene (PS), and those methods typically utilize harmful chemicals, and especially, do not relate to porous substrate coatings. Further, such polymers are generally not suitable, functional and / or desired coating materials for porous substrates, such as textiles.

[0009] Thus, there does not exist a functional recycling method for porous substrates coated with thermoplastic coatings, in particular with biobased or at least partially bio-based thermoplastic polymer coatings.

[0010] Summary of the Invention

[0011] The present invention aims at solving at least some of the problems of the prior art. In particular, the present invention provides a more environmentally friendly alternative for the prior art solutions.

[0012] It is an object of the present invention to provide a new kind of recycling method for porous substrates, especially for fiber-based porous substrates, coated with a thermoplastic coating composition.

[0013] Thus, the present invention relates to a method for recycling a porous substrate coated with a thermoplastic coating composition. According to one aspect the method comprises the steps of shredding a coated porous substrate, dissolving the coating composition, and separating the dissolved coating composition and the undissolved porous substrate. In particular, the present invention relates to a method for recycling a porous substrate coated with a thermoplastic coating composition that is preferably bio-based or at least partly bio-based and recyclable. The present invention provides an efficient recycling method for porous substrates coated with a coating composition providing improved properties for porous substrates in terms of both functional and environmental aspects.

[0014] Thus, the present invention is based on dissolution of a thermoplastic coating composition, wherein the coating composition can be separated from a substrate, and both the coating composition and the substrate can be recycled for further use. In particular, the dissolved coating composition is preferably further separated from the solvent used for the dissolution and brought into a solid form, wherein it can for example be re-used as a coating material. Also, the solvent used in the present method can be recovered and recycled. In particular, the recycling method is suitable for recycling of porous substrates coated with at least partly bio-based thermoplastic coating compositions.

[0015] In particular, the present invention is characterized by what is stated in the independent claim. Some specific embodiments are defined in the dependent claims.

[0016] Several advantages are reached using the present invention. First of all, the method of the present invention enables recycling of porous substrates coated with a thermoplastic coating composition. In particular, the present method is suitable for recycling of porous substrates coated with a coating composition that is preferably fully or at least partly made of renewable and / or biodegradable raw materials and that does not comprise any harmful chemicals. The recycling method enables recycling and re-use of both the substrate and the coating composition, as well as the used solvent.

[0017] The method of the present invention enables efficient separation of the substrate and the coating composition, wherein the substrate and the coating composition, as well as the used solvent, are recovered as pure as possible, the impurity / residue levels being less than 5 wt.%, preferably less than 1 wt.%, more preferably less than 0,1 wt.%, calculated from the total weight of the recovered substrate / coating composition / solvent. Thus, the recovered materials serve as a good quality raw materials for further use. Further, the method generally comprises use of environmentally friendly materials, such as at least partly bio-based polymer coatings and non-harmful chemicals for dissolution. In a preferred embodiment ethyl acetate having low toxicity is used as a solvent. Preferably, also the substrate is bio-based, biodegradable, recyclable and / or compostable porous substrate, thus ensuring the recyclability of the entire material in accordance with the requirements of circular economy, especially with chemical recycling methods.

[0018] Thus, the invention provides a recycling method for porous materials with a coating composition having good protective / repelling properties, thus the coated porous substrate being durable, washable, repellent and flexible, and thus having an improved service life.

[0019] Next, embodiments will be discussed in more detail.

[0020] Embodiments

[0021] As used herein, the term “about” refers to a value which is ± 5% of the stated value.

[0022] As used herein, the term “about” refers to the actual given value, and to an approximation to such given value that would reasonably be inferred to one of ordinary skill in the art, including approximations due to the experimental and / or measurement conditions for such given value.

[0023] In the present context, the term “biodegradable”, when used in connection of a material, such as polyester or a coating composition, and applied in particular to the organic part thereof, has the conventional meaning of the material being capable of degrading (breaking down) by the action of microorganisms, such as bacteria or fungi or both. Degradation can proceed through aerobic and anaerobic processes and will at the end typically yield carbon dioxide of the organic material. Biodegradation generally takes place in the present of water. Biodegrading the organic matter can be influenced by temperature and pH of the ambient and can take from days to months to even years to completion.

[0024] The present invention relates to a method for recycling a porous substrate coated with a thermoplastic coating composition. The method comprises dissolving the coating composition, whereafter it can be separated from the substrate. Dissolution is more efficient if the coated substrate is first shredded in smaller pieces to enable the used solvent to have an effect on a larger surface area of the coated substrate.

[0025] Thus, according to one embodiment, the method comprises the steps of shredding the coated porous substrate, dissolving the coating composition, and separating the dissolved coating composition and the undissolved porous substrate.

[0026] In one embodiment, the first step of the present method is shredding the coated porous substrate. Shredding provides a shredded coated porous substrate. Shredding may be carried out by using any conventional method, such as chopping, cutting, grinding and / or pulverizing.

[0027] According to one embodiment a shredded coated porous substrate comprises fibers having a fiber length of less than 20 mm. In one embodiment, a shredded coated porous substrate comprises fibers having a fiber length of at least 10 mm, preferably at least 12 mm, in particular at least 12.3 mm, in particular fibers having a fiber length in the range of 10 to 20 mm, such as in the range of 12.3 to 18 mm. This applies especially to fibers that are recycled as such by spinning. Thus, a desired fiber length is typically selected based on the further use of the recycled substrate. Fiber spinning for example typically requires lightly longer fibers, whereas also shorter fibers are suitable for thermomechanical recycling, such as melt spinning, in which fiber length is not relevant.

[0028] In one embodiment, the second step of the present method is dissolving the coating composition. Thus, the coating composition is preferably dissolved after shredding the coated porous substrate. If the coating comprises several different coating layers, all coating layers are preferably dissolved.

[0029] A solvent is used for dissolving the coating composition. Any solvent suitable to dissolve the used coating composition can be used. Preferably, a non-toxic solvent is used.

[0030] In one embodiment, the coating composition is insoluble in water.

[0031] According to one embodiment the coating composition is dissolved by a solvent selected from the group of ethyl acetate, acetone, methyl ethyl ketone, propylene glycol monoethyl ether acetate, n-butyl propionate, n-propyl acetate, butyl diglycol acetate, n-propyl propanoate, n-butyl acetate, dibasic esters, methyl acetate, tetrahydrofuran, iso-propyl acetate, n-amyl acetate, butyl glycol acetate, isoamyl acetate and mixtures thereof. In particular embodiment, the solvent comprises ethyl acetate, wherein at least 50, 60, 70, 80, 90, 95 or 99 wt.% of the solvent is ethyl acetate, calculated from the total weight of the solvent.

[0032] According to a preferred embodiment, the coating composition is dissolved by ethyl acetate. Ethyl acetate is relatively environmentally friendly solvent and also highly recyclable in terms of purity and yield. Ethyl acetate has found to be highly efficient solvent in the context of the present invention by providing rapid dissolution at relatively low temperatures. Further, the coating composition remains especially well dissolved during filtration when using ethyl acetate, wherein the separation from the substrate is easier. In particular, ethyl acetate enables selective dissolution of the coating composition without affecting / weakening the substrate.

[0033] According to one embodiment, the weight ratio of the coating composition to the solvent, preferably ethyl acetate, in the dissolving step is in the range of 1 :3 to 1 :7, preferably in the range of 1 :4 to 1 :6, such as 1 :5.

[0034] The dissolving step can be facilitated by performing it at an elevated temperature. Thus, the dissolution is preferably performed at a temperature of at least 50 °C, 60 °C, 70 °C or 90 °C. In one embodiment, the dissolution is performed at a temperature in the range of 50 to 120 °C, preferably in the range of 60 to 80 °C, more preferably at about 70 °C.

[0035] However, the dissolution may also be performed at room temperature. Room temperature may be better for example for more sensitive substrates.

[0036] In one embodiment, the dissolution is continued for at least 60 minutes, such as for at least 70, 80, 90, 100, 110 or 120 or 150 or 180 or 200 or 220 minutes, preferably for at least 100 minutes, such as for about 120 minutes. In one embodiment, lower dissolution temperature may require longer dissolution time. For example, if the dissolution is performed at room temperature, in one embodiment the dissolution may be continued for at least 150, 200 or 220 minutes, such as for 240 minutes. In one embodiment, the dissolution occurs in a reactor, preferably while stirring the mixture. According to one embodiment, vigorous stirring is used, preferably a stirring speed of at least 50, 100, 150 or 200 rpm, such as a stirring speed of 50 to 250 rpm. Vigorous stirring enables movement of the materials efficient enough to obtain efficient and proper dissolution. The solvent can be added all at once or gradually.

[0037] After the dissolution, the coating composition is in dissolved form whereas the substrate remains undissolved, i.e. solid.

[0038] In one embodiment, the third step of the present method is separating the dissolved coating composition and the undissolved porous substrate. According to one embodiment, the dissolved coating composition and the undissolved porous substrate are separated by filtration. Any known filtration method can be used. Generally, the used filtration method can be selected based on the type and composition of the substrate and the coating composition. For example, coarse filtration or fine filtration can be used.

[0039] In one embodiment, the separation step may comprise one or more filtration steps, for example two or three filtrations. Thus, the filtration can for example comprise the combination of coarse and fine filtration. First, a coarse filtration can be used to filtrate bigger solid particles (for example particles having a particle size of 1 to 2 mm), after which a fine filtration can be used to filtrate possible smaller particles / impurities (for example particles having a particle size of 1 to 50 um) from the dissolved coating composition. The amount and pore size of the filtration typically depends on the desired purity level.

[0040] According to one embodiment, the separation step is performed while the mixture of the dissolved coating composition and the undissolved porous substrate still being warm, i.e. at a temperature of at least 40 °C, preferably at least 50 °C, more preferably at least 60 °C, such as at a temperature in the range of 40 to 120 °C or 50 to 80 °C. This facilitates the separation since the coating composition remains better dissolved while being warm.

[0041] The dissolved coating composition and the substrate are recovered from the separation step. The recovered substrate can optionally be directed to one or several washing step(s) in order to remove possible residues of the solvent and / or the coating composition. The washing can for example comprise further dissolution of the porous substrate with a solvent, preferably with the same solvent that was used in the dissolution of the coating composition. In one embodiment, the recovered substrate is washed with ethyl acetate at 70 °C for 120 minutes while stirring, followed by filtration.

[0042] The recovered, i.e. the separated and optionally washed, substrate can then be further directed to a separate recycling process, such as mechanical recycling process of textile fibers, to be processed into re-usable form. Such mechanical recycling process can be for example sorting, grinding or spinning. In one exemplary embodiment, mechanical recycling comprises a tearing process where the fibers are separated by tearing apparatus equipped with drums, pins or blades. Separated the fibers are sieved by length by airflow or mechanically, wherein longer reusable fibers isolate from microfibers or particulate waste. Longer fibers are then further processed by carding or combing, wherein the fibers are cleaned and aligned to improve their suitability for further processes.

[0043] Thus, in one embodiment, the porous substrate is textile and it can be recycled back to a textile product after the separation from the coating composition. Thus, the present invention enables the fibers of the substrate to remain undamaged, wherein those can be reused as a textile.

[0044] The dissolved coating composition obtained from the separation step also comprises the solvent. In one embodiment, the coating composition is further separated from the solvent to recover the coating composition and the solvent. Any known separation method can be used. In one embodiment, the coating composition and the solvent are separated by evaporation, precipitation and / or filtration, to recover the solvent and the coating composition. Preferably the coating composition is recovered in solid form. In one specific embodiment, the coating composition and the solvent are separated by evaporation, in particular by using a shower shovel evaporator or spray evaporator.

[0045] According to one embodiment, the recovered solvent is directed back to the dissolution of the coating composition of the present method, wherein it can be re-used there as a solvent. Alternatively, the recovered solvent can be re-used in any other process. The recovered, preferably solid, coating composition can be further processed and / or reused as a raw material in other processes. In particular embodiment, the recovered coating composition, especially in solid form, can be processed to be re-used as a coating material, especially by means of melt processing. The recovered coating composition can be further processed and / or used as a raw material as such, for example to produce a coating material consisting 100 % of the recycled coating composition, or it can be mixed with a virgin material. For example, at least 20 wt.%, preferably at least 50 wt.%, more preferably at least 80 wt.% of the used raw material consists of the recovered, i.e. recycled, coating composition.

[0046] In one embodiment, the recycled substrate and / or coating composition can be re-used as such without further processing.

[0047] The porous substrate can be any porous material. According to the present invention the term “porous” relates to a material that is permeable to gas, liquid, oils or fats or combinations thereof. Typically, the porous material is provided in the form of a sheet, board, plate, or web.

[0048] In one embodiment, the porous materials comprise fibrous materials, typically in the form of sheets, boards, plates, or webs. Examples of porous materials for use in embodiments of the present technology include textiles, such as tablecloth, clothe, protective textile, interior textile, consumer device, for example watch strep or heat rate belt. Textile as a porous substrate of the present invention can be made of natural or man-made fiber, preferably natural fiber.

[0049] According to a preferred embodiment the substrate is a woven or non-woven fabric or sheet, especially made of natural fibres, such as vegetable fibres (e.g. cellulose, cotton, hemp, flax, ramie, jute, coconut), or animal fibres (e.g. wool, silk).

[0050] Thus, the substrate is preferably bio-based. “Bio-based substrates” are materials generally obtained from biological materials, such as biomass (e.g. carbohydrate materials, lignocellulosic materials, in particular in the form of fibrous materials), proteinaceous materials, and lipid-containing materials and combinations thereof. Typically, such materials can be biodegradable, recyclable, repulpable and / or compostable. In one embodiment, the porous material comprises natural fibers, such as lignocellulosic or cellulosic fibers or combinations thereof.

[0051] In one embodiment, the substrate comprises 50 to 100 % by weight, in particular at least 60, 65, 70, 75, 80, 85, 90 or 95 % by weight, such as 75 to 100 % by weight of natural fibers, such as cellulosic or lignocellulosic fibers or combinations thereof, calculated from the total weight of fibrous matter in the substrate, preferably calculated from the total weight of the substrate.

[0052] In one embodiment, the substrate material comprises a combination of natural and manmade fibres. Examples of man-made fibres include synthetic fibres such as polyesters and acrylics as well as regenerated fibres, such as fibres made by the viscose process, or Lyocell process or other synthetic fibres comprising materials derived from polysaccharides. In one embodiment, the substrate comprises 10 to 75 % by weight of natural fibres and 90 to 25 % by weight of man-made fibres, calculated from the total weight of the substrate.

[0053] In one embodiment, the porous substrate comprises plastic, i.e. thermoplastic, materials.

[0054] In a preferred embodiment, the porous substrate is a textile substrate, preferably a textile made of cotton, polyester, regenerated cellulose fiber or a mixture thereof.

[0055] Any thermoplastic coating composition suitable for porous substrates can be used in the present invention. However, preferably a bio-based or at least partly bio-based coating composition is used.

[0056] In the present context, the term “coating composition” refers to a composition suitable to be used as a coating composition. Such coating composition can be applied onto the substrate by any known method, especially by traditional coating methods in which the coating composition is formed into a layer only on the surface of the substrate, i.e. provided on the substrate in molten form and then cooled, or as a laminate. Terms “coating” and “coating layer” are used as synonyms referring to the layer formed from the coating composition on the porous substrate. The coating of the present invention can have any thickness, and the coating layer can be single layer or a multi-layer coating. Preferably the coating is as thin as possible still capable to provide the desired properties for the substrate. In a preferred embodiment, the coating has a thickness of less than 100 pm, more preferably less than 80 pm, such as less than 50 pm. The thickness can be for example 20 to 100 pm. However, for some applications, such as artificial leather type textiles, thicker coating may be desired. Thus, in one embodiment, the coating has a thickness of at least 150, 200, 250 or 300 pm. The thickness can be for example 200 to 500 pm. The coating layer formed by the coating composition of the present invention can be single layer or a multi-layer coating

[0057] In the context of the present invention the terms “bio” and “bio-based” relates to polymers or compositions produced from natural sources either chemically synthesized from a biological material or entirely biosynthesized by living organisms.

[0058] According to one embodiment, the thermoplastic coating composition is at least 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 or 95 wt.% bio-based. In a preferred embodiment, the coating composition is 40 to 80 wt.%, more preferably 50 to 100 wt.%, such as 60 to 90 wt.%, biobased. The amounts being calculated from the total weight of the coating composition. Bio-based content can result from different raw materials of the composition, such as polymers, fillers, plasticizers or additives, preferably all of these being bio-based. In one embodiment, the coating composition comprises only bio-based thermoplastic polymers. In one embodiment, the above-mentioned bio-based contents are calculated from the total weight of the thermoplastic polymers.

[0059] In general, thermoplastic coatings are composed of polymers that do not undergo a chemical change during curing. Those are typically highly durable materials that melt and flow when heated. In order to provide a thermoplastic coating, at least one of the polymers of the coating composition must be thermoplastic and be able to provide thermoplasticity throughout the material. In one embodiment, the coating composition comprises at least 75, 80, 85, 90, 95 or 99 wt.%, preferably 80 to 100 wt.%, of thermoplastic polymer(s), calculated from the total weight of the coating composition. However, in a preferred embodiment, the coating composition comprises only thermoplastic polymers. According to one embodiment, the thermoplastic coating composition comprises polyester, in particular bio-polyester, cellulose ester, thermoplastic polyurethane (TPU) or any mixture thereof. These polymers are generally toxicologically harmless and can all be provided in bio-based form. In on embodiment, the total amount of polyester, cellulose ester and / or thermoplastic TPU is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 wt.%, calculated from the total weight of the coating composition. Preferably, the total amount of polyester, cellulose ester and / or thermoplastic TPU is 60 to 99 wt.%, such as 70 to 95 wt.%, calculated from the total weight of the coating composition.

[0060] In one embodiment, the coating composition comprises one or more thermoplastic polymers(s) selected from the group of polyester, such as polybutylene succinate (PBS) or polybutylene succinate adipate (PBSA), cellulose ester and thermoplastic polyurethane (TPU).

[0061] In one embodiment, the coating composition comprises a mixture of thermoplastic polyester, in particular bio-based polyester, cellulose ester and thermoplastic polyurethane (TPU), in particular bio-based TPU.

[0062] According to one preferred embodiment, the optional polyester is at least 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 or 95 wt.% bio-based, i.e. polyester is 35 to 100 % bio-based. Preferably, possibly used polyester is 100 % bio-based. The amount being calculated from the total weight of the polyester.

[0063] In one embodiment, the coating composition comprises a polyester that can be any polyester, especially biodegradable polyester. It can either be a commercial grade polyester or manufactured using well known polymerization routes. According to a preferred embodiment, the polyester is thermoplastic polyester. Polyester especially provides mechanical strength to the composition.

[0064] One or more polyesters can be used in the present invention. For example, two different polyesters can be used in the coating composition. In an embodiment, the polyester(s) is selected from the group of polylactic acid, polylactide, polybutylene succinate, polybutylene succinate adipate, poly hydroxy alkanoate, polyhydroxybutyrate, poly (3- hydroxybutyrate-co-3 -hydroxy valerate), poly(3 -hydroxybutyrate-co-3 -hydroxyhexanoate), poly (butylene adipate-co-terephthalate), polyethylene furanoate, polycaprolactone, and combinations thereof. These compositions may provide advantageous biodegradability, and flexibility of the composition, and barrier properties to the composition. In case of two or more polyesters, those can be independently selected from the above mentioned groups of polyesters. Having two or more polyesters may provide advantageous biodegradability, and flexibility of the composition, and barrier properties to the composition.

[0065] According to a preferred embodiment, polyester is polybutylene succinate (PBS) and / or polybutylene succinate adipate (PBSA), especially PBSA. Preferably, at least 80 wt.%, more preferably at least 90 wt.% of the polyesters are polybutylene succinates and / or polybutylene succinate adipates.

[0066] According to one embodiment the coating composition comprises at least 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 or 95 wt.% of polyester calculated from the total weight of the composition.

[0067] According to one embodiment the composition comprises up to 95, 90, 85, 80, 75, 70, 65, 60, 55 or 50 wt.% of polyester calculated form the total weight of the composition.

[0068] In a preferred embodiment, the composition comprises 40 to 95 wt.%, preferably 45 to 85 wt.%, more preferably 50 to 70 wt.%, of polyester calculated from the total weight of the composition.

[0069] In another preferred embodiment, the composition comprises 30 to 95 wt.%, preferably 30 to 65 wt.%, more preferably 30 to 50 wt.%, of polyester calculated from the total weight of the composition.

[0070] In one embodiment, the coating composition comprises a cellulose ester that can be any cellulose ester. According to a preferred embodiment, the cellulose ester is selected from the group of cellulose acetate (CA), cellulose acetate butyrate (CAB), cellulose acetate propionate (CAP) or mixtures thereof. In a preferred embodiment the cellulose ester is CAP or CAB or a combination thereof. Cellulose ester can be especially used to increase transparency and mechanical properties, such as flexibility or durability, of the composition.

[0071] According to one embodiment the composition comprises at least 10, 15, 20, 25, 30, 35, 40 or 45 wt.% of cellulose ester calculated from the total weight of the composition.

[0072] According to one embodiment the composition comprises up to 45, 40, 35, 30, 25, 20, 15 or 10 wt.% of cellulose ester calculated form the total weight of the composition.

[0073] In a preferred embodiment, the composition comprises 10 to 60 wt.%, preferably 20 to 50 wt.%, more preferably 25 to 45 wt.%, for example 30 to 40 wt.%, of cellulose ester calculated form the total weight of the composition.

[0074] In one embodiment, the coating composition comprises a thermoplastic polyurethane (TPU), preferably bio-based TPU. According to one embodiment, the coating composition comprises TPU at most 50 wt.% or at most 25 wt.%, or 5 - 50 wt.%, 25 - 50 wt.%, or 1 - 20 wt.%, more preferably 5 - 10 wt.%, of the total weight of the coating composition. TPU can be used to further increase the adhesion of the composition to the substrate, elasticity, mechanical properties, processability, wash-resistance and rub durability, optical and haptic properties, and / or thermal stability, and combinations thereof, of the composition of the composition.

[0075] According to one embodiment, the coating composition also comprises a polymer selected from the group of polyethylene (PE), preferably biobased PE, or polyethylene terephthalate (PET), preferably biobased PET, or polypropylene (PP), preferably biobased PP, or a polyamide (PA), preferably a biobased PA, or a mixture thereof. Preferably, amount of the PE, PET, PP, PA, or a mixture thereof in the coating composition is at most 50 wt.%, preferably less than 50 wt.%, or at most 25 wt.%, or at most 10 wt.%, for example 1 - 20 wt.%, more preferably 5 to 10 wt.%, of the total weight of the coating composition. PE, PET, PP and / or PA can be used to further increase elasticity and mechanical properties of the composition. PE, PET, PP, TPU and / or PA may be used to further increase the adhesion of the composition to the substrate, processability, wash-resistance and rub durability, optical and haptic properties, and / or thermal stability, and combinations thereof, of the composition. According to one embodiment, the composition of the present invention further comprises an additive, especially a plasticizer, such as glycerol, polyethylene glycol, triethyl citrate, tributyl citrate, acetyl tributyl citrate, vegetable oil, such as soybean oil, linseed oil, tall oil, castor oil, canola, or their modification, such as maleated, acrylated, vinylated, succinated, epoxidized, hydroxylated vegetable oil or other vegetable ester oil or resin including epoxidized soybean oil, maleated soybean oil, epoxidized linseed oil, or any combination thereof. Plasticizer especially increases flexibility and settling of the coating. In particular, maleated soybean oil may improve the compatibility of the polyester (or the two or more polyesters) and the cellulose ester, and / or may improve the mechanical properties of the composition. I.e., the maleated soybean oil may be used as a compatibilizer and plasticizer for the composition.

[0076] According to one embodiment, the plasticizer is vegetable oil, in particular functionalized vegetable oil, preferably maleated soybean oil. Maleated soybean oil is a modified soybean oil in which some of the unsaturation has been converted to a cyclic dicarboxylic acid.

[0077] Thus, according to a preferred embodiment, the coating composition further comprises a plasticizer, preferably maleated soybean oil, in an amount of 1 to 20 wt.%, more preferably 2 to 10 wt.%, for example 3 to 7 wt.%, calculated from the total weight of the composition.

[0078] According to one embodiment, the composition of the present invention further comprises an additive, especially a lubricant, such as stearic acid, stearate, for example calcium stearate, magnesium stearate and / or natural wax, such as carnauba wax, soybean wax, beeswax, sugarcane wax, cassava wax, candelilla wax, rice bran wax, berry wax, myrica fruit wax or laurel wax, and / or synthetic wax such as polyamide wax, stearamide such as ethylene-bis-stearamide (EBS) wax (biobased or synthetic), ethylene-bis-oleamide wax, polyethylene wax, Fischer-Tropsch wax, fatty acids and modified fatty acids, hybrid waxes, or any mixture thereof.

[0079] Thus, according to a preferred embodiment, the composition further comprises a lubricant, such as stearamide or stearate, preferably calcium stearate, zinc stearate, or ethylene-bis- stearamide, or a mixture thereof. In one embodiment, the amount of the lubricant, preferably stearate or stearamide, is 0.05 to 10 wt.%, preferably 0.1 to 8 wt.%, for example about 0.1 to 3 or 0.1 to 1 wt.%, calculated from the total weight of the composition. Lubricant affects especially to processability of the composition. Stearates and stearamides, such as EBS, are especially suitable for enhancing the processability as they prevent unnecessary adhering of the coating composition to the processing equipment without coloring the coating composition.

[0080] In a preferred embodiment, the coating composition comprises the combination of maleated soybean oil and a lubricant, such as stearamide or stearate, preferably calcium stearate, zinc stearate, or ethyl ene-b is- stearamide, or a mixture thereof, as additives.

[0081] In one embodiment, the coating composition further comprises a polysiloxane. According to a preferred embodiment, the polysiloxane is provided in a liquid form. The term “liquid form” in the present invention also comprises a solution. Thus, according to the present invention, material is in a liquid state if it is a liquid as such or dissolved, or at least dispersed, in a medium, preferably in a solvent. Polysiloxane is advantageous since it may bring hydrophobicity to the composition, which may improve waterproofing and water repellency of the composition, and an improved dirt repellency, chemical resistance, and abrasion resistance of the composition may be obtained.

[0082] In one embodiment, the composition comprises polysiloxanes in the amount of 0.05 to 10 wt.%, preferably 0.1 to 3 wt.%, for example about 2 wt.%, calculated from the total weight of the composition.

[0083] In one embodiment, the composition does not contain any polysiloxanes.

[0084] According to one embodiment the polysiloxane mixture is formed by mixing one or several different silane monomers. The silanes are preferably hydrolyzed with an aqueous acid solution, wherein the acid is preferably an organic acid. The content of the acid in the aqueous acid solution is typically in the range of 0.5 to 5 mol-%, for example 1 mol-%, of the aqueous acid solution.

[0085] According to one embodiment, the polysiloxane mixture is made of silane monomers having at least one functional group. Preferably, the monomers are selected from the group of methyltriethoxysilane (MTEOS), dimethyldiethoxysilane (DMDEOS), 3- glycidoxypropyl-trimethoxysilane (GPTMS), bis(triethoxysilyl)ethane (BTESE), methyltrimethoxy silane (MTMS), phenyltrimethoxy silane (PTMS) and (3- aminopropyl)triethoxysilane (APTES), ethoxytrimethylsilane (ETMS) and combinations thereof.

[0086] According to one embodiment, the polysiloxane mixture is formed in the presence of an acid selected from the group of inorganic acids, comprising nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid and boric acid, or from the group of organic acids, comprising lactic acid, acetic acid, formic acid, citric acid, oxalic acid, uric acid, itaconic acid, fumaric acid, succinic acid, biosuccinic acid, gluconic acid, glutamic acid, malic acid, maleic acid, 2,5-furan dicarboxylic acid, 3 -Hydroxypropionic acid, glucaric acid, aspartic acid, levulinic acid and combinations thereof.

[0087] One or more organic acids can be used at the same time. The acid acts as catalyst during the hydrolyzation reaction. In addition, it improves compatibility of the polysiloxane with the polymer matrix, i.e. the other polymers, such as polyester, cellulose ester and / or TPU, because the acid can also react with the polyester and / or the cellulose ester.

[0088] According to a preferred embodiment, the silane mixture is pre-treated, i.e. the polysiloxane mixture is formed, prior to mixing with the polymer matrix.

[0089] According to one embodiment, the coating composition of the present invention further comprises an inorganic colorant and / or a filler, especially inorganic filler, such as ashes, minerals, mineral sludges, clays, ceramics and other inorganics comprising for example calcium carbonate, kaolin, talc, gypsum, chalk, mica, wollastonite, glass, silica, alumina, titania and other inorganic oxides, crushed masonry, concrete and other stone and sand like materials, diatomite, metal hydrates, such aluminum hydrates, calcium hydrate, geopolymers and alike.

[0090] According to one embodiment, the composition comprises an organic agent, especially organic filler and colorant, such as wood, and plant-based materials and parts and side streams thereof, including beans, for example soybean, bean hull, wheat hull, and rice husk, seaweed, algae, natural resins and gums, carbon, carbon black, biocarbon, woad, willow and other tree bark, onion skin and other vegetable skins, lemon, turmeric root, all natural fibres such as cotton, hemp, flax, pulp, wood fibres; as well as components thereof such as lignocellulose, lignin, suberin, polysaccharides, including natural polysaccharides, such as cellulose, starch and hemicellulose, nanocellulose, and derivatives thereof; and any combinations thereof.

[0091] According to one embodiment, the composition of the present invention further comprises a chain extender and / or a cross-linking agent, such as epoxy, peroxide, epoxy, amine or acrylic functionalized chain extenders. In a preferred embodiment the amount of chain extender / cross-linking agent, especially epoxy-functionalized chain extender or peroxide, preferably epoxy-functionalized chain extender, is less than 1.0 wt.% or 0.5 wt.%, preferably 0.01-0.7 wt.%, 0.05-0.7 wt.%, or 0.01-0.2 wt.%, calculated from the total weight of the composition. Additionally, or alternatively, the amount of chain extender / cross-linking agent, especially epoxy-functionalized chain extender, is 0.01-0.7 wt.%, calculated from the total weight of the composition. Chain extenders / cross-linking agents can be used to increase the viscosity of the composition. Higher viscosity, i.e. less flowable composition, may be preferred in some applications, such as for example in film applications. Further, chain extenders / cross-linking agents increase durability of the composition by the bonds formed between the polymer chains. According to a preferred embodiment such components are added to the composition of the present invention after the silane modified polyester is formed in a separate process step. According to another embodiment, such components can be added to the composition at the end phase of the reactive extrusion process, wherein the siloxane and polyester are already mainly reacted.

[0092] According to one embodiment, the composition of the present invention further comprises a stabilizing agent, such as light stabilizer, UV stabilizer, antioxidant, heat stabilizer or flame retardant or a mixture thereof. Additionally, or alternatively, the antioxidant is selected from tris(2,4-di-tert-butylphenyl) phosphite (e.g., Irgafos 168), pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (e.g., Irganox 1010), and octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (Irganox 1076). Additionally, or alternatively, the flame retardant is selected from organophophates, and aluminium compounds. These compositions are advantageous since they may enhance the processability of the composition. Thus, in an embodiment, the composition may further comprise at least one of the following auxiliary agents: an inorganic colorant and / or a filler, especially inorganic filler, such as ashes, minerals, mineral sludges, clays, ceramics and other inorganics comprising for example calcium carbonate, kaolin, talc, gypsum, chalk, mica, wollastonite, glass, silica, alumina, titania and other inorganic oxides, crushed masonry, concrete and other stone and sand like materials, diatomite, metal hydrates, such as aluminium hydrates, calcium hydrate, geopolymers and alike, or any combination thereof, an additive, especially a plasticizer, such as glycerol, polyethylene glycol, triethyl citrate, tributyl citrate, acetyl tributyl citrate, vegetable oil, such as soybean oil, linseed oil, tall oil, castor oil, canola, or their modification, such as maleated, acrylated, vinylated, succinated, epoxidized, hydroxylated vegetable oil or other vegetable ester oil or resin including epoxidized soybean oil, maleated soybean oil, epoxidized linseed oil, or any combination thereof, an organic filler or colorant, such as wood or plant-based material or parts or side streams thereof, including beans, for example soybean, bean hull, wheat hull, and rice husk, seaweed, algae, natural resins and gums, carbon, carbon black, biocarbon, woad, willow and other tree bark, onion skin and other vegetable skins, lemon, turmeric root, all natural fibres such as cotton, hemp, flax, pulp, woodfibres; as well as components thereof such as lignocellulose, lignin, suberin, polysaccharides, including natural polysaccharides, such as cellulose, starch and hemicellulose, nanocellulose, and derivatives thereof; and any combinations thereof, a chain extender and / or a cross-linking agent, such as epoxy, peroxide, amine or acrylic functionalized chain extender, a lubricant, including stearamides and stearates such as calcium stearate and magnesium stearates and natural waxes, such as carnauba wax, soybean wax, beeswax, sugarcane wax, cassava wax, candelilla wax, rice bran wax, berry wax, myrica fruit wax and laurel wax, or any mixture thereof, and a stabilizing agent, such as light stabilizer, UV stabilizer, antioxidant, heat stabilizer or flame retardant or any mixture thereof. According to one embodiment, the composition comprises in total up to 10, 8, 5, 3 or 1 wt.% of the auxiliary agents described above, such as 0.1 to 10 or 1 to 10 wt.%, preferably 0.5 to 5 wt.%, calculated from the total weight of the composition.

[0093] According to one embodiment, at least some of the components of the coating composition are recycled components. Preferably at least 50 wt.% of the total weight of the polymers are recycled. The plasticizer additive optionally used can be made completely or partly using of waste or sidestream ingredients.

[0094] According to a preferred embodiment, the composition does not contain water or any other solvents.

[0095] In one embodiment, the coating composition comprises the combination of polyester, cellulose ester and plasticizer, such as maleated soybean oil.

[0096] Thus, according to one embodiment, the composition comprises, preferably consist of,

[0097] - 40-75 wt.%, preferably 50-70 wt.%, of polyester,

[0098] - 20-50 wt.%, preferably 25-45 wt.% of cellulose ester, and

[0099] - 2-10 wt.% of plasticizer, preferably maleated soybean oil, the amounts being calculated from the total weight of the composition.

[0100] According to another embodiment, the composition comprises, preferably consist of,

[0101] - 40-75 wt.%, preferably 50-70 wt.%, of polyester,

[0102] - 20-50 wt.%, preferably 25-45 wt.% of cellulose ester, and

[0103] - 2-10 wt.% of plasticizer, preferably maleated soybean oil,

[0104] - 0.05-10 wt.%, preferably about 0.1-1 wt.%, of stearate, especially zinc and / or calcium stearate, and

[0105] - optionally 0.1-10 wt.%, preferably 0.5-5 wt.%, of any auxiliary agent(s) of described above, the amounts being calculated from the total weight of the composition.

[0106] In one embodiment, the composition comprises, preferably consist of,

[0107] - 50-70 wt.%, of polybutylene succinate,

[0108] - 25-45 wt.% of CAB or CAP, - 2-10 wt.% of maleated soybean oil, and

[0109] - 0.1-3 wt.% of zinc and / or calcium stearate, the amounts being calculated from the total weight of the composition.

[0110] Additionally, or alternatively, the composition comprises, preferably consists of,

[0111] - 30-50 wt.% polyester, preferably polybutylene succinate;

[0112] - 30-50 wt.% cellulose ester, preferably CAB or CAP;

[0113] - 5-25 wt.% thermoplastic polyurethane;

[0114] - 2-10 wt.% maleated soybean oil;

[0115] - 0.2-1.0 wt.% stearate lubricant, preferably zinc and / or calcium stearate;

[0116] - 0.2-1 wt.% chain extender, preferably chain extender BASF Joncryl ADR 4468; and

[0117] - 0.2-1 wt.% antioxidant, the amounts being calculated from the total weight of the composition.

[0118] Additionally, or alternatively, the composition comprises, preferably consists of,

[0119] - 20-50 wt.% polyester, preferably polybutylene succinate;

[0120] - 20-50 wt.% cellulose ester, preferably CAB or CAP;

[0121] - 5-50 wt.% thermoplastic polyurethane;

[0122] - 2-10 wt.% maleated soybean oil;

[0123] - 0.2-1.0 wt.% stearate lubricant, preferably zinc and / or calcium stearate;

[0124] - 0.2-1 wt.% chain extender, preferably chain extender BASF Joncryl ADR 4468; and

[0125] - 0.2-1 wt.% antioxidant, the amounts being calculated from the total weight of the composition.

[0126] Additionally, or alternatively, the composition comprises, preferably consists of,

[0127] - 20-50 wt.% polyester;

[0128] - 20-50 wt.% cellulose ester;

[0129] - 5-50 wt.% thermoplastic polyurethane;

[0130] - 2-10 wt.% maleated soybean oil;

[0131] - 0.2-1.0 wt.%; additive, especially a lubricant, such as stearic acid, stearate, for example calcium stearate, magnesium stearate and / or natural wax, such as carnauba wax, soybean wax, beeswax, sugarcane wax, cassava wax, candelilla wax, rice bran wax, berry wax, myrica fruit wax or laurel wax, and / or synthetic wax such as polyamide wax, stearamide such as ethylene-bis-stearamide (EBS) wax (biobased or synthetic), ethylene-bis- oleamide wax, polyethylene wax, Fischer-Tropsch wax, fatty acids and modified fatty acids, hybrid waxes, or any mixture thereof;

[0132] - 0.2-1 wt.% chain extender, preferably chain extender BASF Joncryl ADR 4468; and

[0133] - 0.2-1 wt.% antioxidant, the amounts being calculated from the total weight of the composition.

[0134] According to one embodiment, the coating composition is produced in a melt compounding process, and a porous substrate is coated or laminated with such coating composition. In a melt compounding process the coating composition is mixed through melt extrusion, during which the components are compounded into a biopolymer composition. Melt compounding process provides effective mixing and even heat distribution, which enables efficient mixing between the components of the coating composition. Further, melt compounding is environmentally friendly, since it enables formation of the composition without solvents due to the use of the melt compounding through melt extrusion, since the melt extrusion enables processing of different viscosities, wherein dissolution of the polymers in solvent is not needed. Overall, melt extrusion offers high flexibility enabling a continuous process with efficient mixing and short residence time but also an economic production of small amounts of special material.

[0135] One or both of surfaces of the porous substrate can be coated or laminated. Also, part of the surface(s) or the whole surface(s) can be coated or laminated.

[0136] Thus, according to one embodiment, the present invention relates to a method for recycling a porous substrate coated with a thermoplastic coating composition, comprising the steps of

[0137] - shredding the coated porous substrate,

[0138] - dissolving the coating composition, and

[0139] - separating the dissolved coating composition and the undissolved porous substrate, wherein the thermoplastic coating composition is at least 50 wt.%, preferably at least 60 or 80 wt.%, such as 60 to 90 wt.%, biobased, and / or, wherein the thermoplastic coating composition comprises one or more thermoplastic polymers(s) selected from the group of polyester, such as polybutylene succinate (PBS) or polybutylene succinate adipate (PBSA), cellulose ester and thermoplastic polyurethane (TPU), and / or, wherein the total amount of polyester, cellulose ester and / or thermoplastic TPU is at least 50 wt.%, preferably at least 70 wt.%, more preferably at least 80 wt.%, such as 60 to 99 wt.% or 70 to 95 wt.%, calculated from the total weight of the coating composition.

[0140] In general, the present invention can be used to recycle porous substrates having a thermoplastic coating, especially bio-based thermoplastic coating, and generally for replacement of conventional thermoplastic functional coatings and their recycling methods, especially in the context of porous substrates.

[0141] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0142] Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed.

[0143] As used herein, a plurality of items, structural elements, compositional elements, and / or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and examples of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention. Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In this description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc.

[0144] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[0145] The following non-limiting examples are intended merely to illustrate the advantages obtained with the embodiments of the present invention.

[0146] EXAMPLES

[0147] Example 1

[0148] Several thermoplastic coating compositions were produced (see Table 1). The compositions were produced by melt compounding through extrusion.

[0149] As an example, Composition 1 of Table 1 was produced as follow:

[0150] 117 kg of commercial grade polybutylene succinate (BioPBS FD92B), 117 kg of cellulose acetate propionate (CAP 482.05) and 45 kg partly (46 wt.%, rest being non bio-based) biobased thermoplastic polyurethane (TPU) were dried overnight in a circulated air oven at 60-80 °C. The dried polybutylene succinate, cellulose acetate propionate and thermoplastic polyurethane were mixed with 3.0 kg of ethylene-bis-stearamide wax, 1.5 kg of tris(2,4-di-tert-butylphenyl) phosphite antioxidant, 1.5 kg epoxy -functionalized chain extender (Joncryl ADR 4468) prior to melt compounding. The obtained mixture was melt compounded using a twin-screw extrusion with extrusion temperature of 200 °C and screw speed of 200 rpm. In addition, 15 kg of the maleated soybean oil was pumped into the extruder during compounding. The compounded material was extruded into strands, cooled in a water bath and pelletized into granules.

[0151] Table 1. Thermoplastic coating compositions

[0152] Coating the substrate Cotton and polyester substrates were coated with the coating compositions of Table 1 using hot-melt coating. The coating composition granulate was first melted in an extruder, after which the molten coating composition was placed into the gap of two heated calendaring rolls with temperatures between 145-165 °C. The molted composition was transferred from the calendaring rolls into the substrate after which the subsequent calender rolls further smoothed and applied pressure to the coating of the substrate to obtain substrate with coating thickness of 75-120 g / m2.

[0153] Example 2

[0154] Recycling

[0155] A piece of fabric substrate (according to table 2) coated with the thermoplastic coating composition (Composition 1 of Table 1 of Example 1) was shredded to smaller particle size (particle size above 1cm x 1cm). The shredded coated fabric was then added to a reactor containing a solvent (according to table 2). The weight ratio of the coating composition to the solvent was 1 :5. The mixture was then heated to a temperature of 70 °C and mixed for 120 minutes. During this time the thermoplastic coating composition was dissolved to the solvent, whereas the fabric remained solid. After the dissolution was completed, the solid fabric and the solvent containing the dissolved thermoplastic coating composition were separated by filtration, while the mixture was still warm.

[0156] The recovered fabric from the filtration was transferred to its own recycling process. The solvent was removed from the thermoplastic coating composition by evaporation, and the evaporated solvent was collected, wherein it can be re-used in the dissolution step. After the evaporation, the recovered solid thermoplastic coating composition can be melt- processed and re-used as a coating material.

[0157] Table 2. Used substrate and solvent Mechanical properties

[0158] Next, mechanical properties of the recycled coating compositions were researched.

[0159] Film samples having thickness of approximately 0.15 mm were prepared by compression molding at 190 °C of the recycled coating compositions of Samples A and B of Table 2, i.e. samples obtained using the coating composition 1 after the recycling process (named Example 1 A and Example 1 B). Coating composition 1 of Table 1 of Example 1 before the recycling process was used as a reference. Samples were cut from the films and their tensile properties were measured according to ISO 527-3, which describes a test method for the determination of the tensile properties of plastic films and sheets. Specimen type 5 and 5 mm / min test speed were used. The results are shown in Table 3.

[0160] Table 3. Mechanical properties of the recycled coating compositions with reference to coating composition before recycling.

[0161] The results in Table 3 show that the recycled coating compositions have similar mechanical properties than the reference coating composition, thus the recycling process does not affect the mechanical properties of the coating composition.

[0162] Melt flow index

[0163] Next, melt flow index (MFI) of one of the recycled coating compositions was researched, namely the recycled coating composition of Sample B of Table 2, i.e. coating composition 1 after the recycling process (named Example 2) was used for MFI measurement. Coating composition 1 of Table 1 of Example 1 before the recycling process was used as a reference. MFI of the sample was measured according to ISO 1133-1, using temperature of 190 °C and 2.16 kg weight. The results are shown in Table 4. Table 4. Melt flow index of the recycled coating composition with reference to coating composition before recycling.

[0164] The results in Table 4 show that the recycled coating composition has only slightly higher MFI value than the reference. Thus, the recycling process does not have significant effect to the thermal behaviour of the coating composition.

[0165] Example 3

[0166] Recycling

[0167] Recycling method similar to Example 2 was tested for all the coating compositions of Table 1 of Example 1. Each composition was coated on an own piece of a cotton substrate.

[0168] The coated substrate was shredded to smaller particle size (particle size above 1cm x 1cm) and the shredded coated fabric was then added to a reactor containing a solvent (both ethyl acetate and acetone were tested in different experiments). The weight ratio of the coating composition to the solvent was 1 :5. The mixture was then heated to a temperature of 70 °C and mixed for 240 minutes. During this time the thermoplastic coating composition was dissolved to the solvent, whereas the fabric remained solid. After the dissolution was completed, the solid fabric and the used solvent containing the dissolved thermoplastic coating composition were separated by filtration, while the mixture was still warm.

[0169] The recovered fabric from the filtration was transferred to its own recycling process. The solvent was removed from the thermoplastic coating composition by evaporation, and the evaporated solvent was collected, wherein it can be re-used in the dissolution step. After the evaporation, the recovered solid thermoplastic coating composition can be melt- processed and re-used as a coating material. Example 4

[0170] Samples similar to the samples A to D of Table 2 of Example 2 were produced and subjected to recycling as follow.

[0171] A piece of fabric substrate (according to Table 2 of Example 2) coated with the thermoplastic coating composition (composition 1 on Table 1) was shredded to smaller particle size (particle size above 1cm x 1cm). The shredded coated fabric was then added to a reactor containing a solvent (according to table 2 of Example 2). The weight ratio of the coating composition to the solvent was 1 :5. The mixture was then heated to a temperature of 60 °C and mixed for 180 minutes. During this time the thermoplastic coating composition was dissolved to the solvent, whereas the fabric remained solid. After the dissolution was completed, the solid fabric and the solvent containing the dissolved thermoplastic coating composition were separated by filtration, while the mixture was still warm.

[0172] The recovered fabric from the filtration was transferred to its own recycling process. Thermoplastic coating composition was further separated from the solvent by precipitation. Water was used as a non-solvent by adding the solvent containing the dissolved thermoplastic coating composition to cold water, i.e. 4 °C or less, (weight ratio 1 : 1) and stirrder for 30 minutes. Precipitated solid thermoplastic coating composition was then collected by filtration and dried at 50 °C overnight. After drying the recovered solid thermoplastic material can be melt-processed and re-used as a coating material.

[0173] Example 5

[0174] Samples similar to the samples A to D of Table 2 of Example 2 were produced and subjected to recycling as follow.

[0175] A piece of fabric substrate (according to Table 2 of Example 2) coated with the thermoplastic coating composition (Composition 1 of Table 1) was shredded to smaller particle size (particle size above 1cm x 1cm). The shredded coated fabric was then added to a reactor containing a solvent (according to table 2 of Example 2). The weight ratio of the coating composition to the solvent was 1 :5. The mixture was then heated to a temperature of 70 °C and mixed for 120 minutes. During this time the thermoplastic coating composition was dissolved to the solvent, whereas the fabric remained solid. After the dissolution was completed, the solid fabric and the solvent containing the dissolved thermoplastic coating composition were separated by filtration, while the mixture was still warm.

[0176] The recovered fabric from the filtration was transferred to an additional washing step by adding it to a reactor filled with the same solvent that was used in the dissolution step, heated to a temperature of 70 °C and mixed for 60 minutes. After washing the fabric was recovered by filtration and can then be transferred to its own recycling process.

[0177] The solvent was removed from the thermoplastic coating composition by evaporation, and the evaporated solvent was collected, wherein it can be re-used in the dissolution step. After the evaporation, the recovered solid thermoplastic coating composition can be melt- processed and re-used as a coating material.

[0178] Example 6

[0179] Recycling method similar to Example 2 was tested for the following coated substrates:

[0180] - A piece of polyester substrate coated with the Composition 1 of Table 1 of Example 1 with a coating thickness of 300-400 g / cm2,

[0181] - A piece of cotton substrate coated with cellulose acetate propionate (CAP) with a coating thickness of 100-200 g / cm2, and

[0182] - A piece of cotton substrate coated with thermoplastic polyurethane (TPU) coating with a coating thickness of 100-200 g / cm2.

[0183] The coated substrate was shredded to smaller particle size (particle size above 1cm x 1cm) and the shredded coated fabric was then added to a reactor containing a solvent (all solvents according to Table 5 were tested). The weight ratio of the coating composition to the solvent was 1 :5. The mixture was kept at room temperature and mixed for 240 minutes. During this time the thermoplastic coating composition was dissolved to the solvent, whereas the fabric remained solid. After the dissolution was completed, the solid fabric and the used solvent containing the dissolved thermoplastic coating composition were separated by filtration.

[0184] Table 5, Solvents used in Examples 6 and 7,

[0185] The recovered fabric from the filtration was transferred to its own recycling process. The solvent was removed from the thermoplastic coating composition by evaporation, and the evaporated solvent was collected, wherein it can be re-used in the dissolution step. After the evaporation, the recovered solid thermoplastic coating composition can be melt- processed and re-used as a coating material.

[0186] Example 7

[0187] Recycling

[0188] Recycling method similar to Example 2 was tested for a piece of a cotton substrate coated with a thermoplastic polyurethane (TPU) coating with coating thickness of 100-200 g / cm2. The coated substrate was shredded to smaller particle size (particle size above 1cm x 1cm) and the shredded coated fabric was then added to a reactor containing a solvent (solvents 1, 4, 6, 8 and 10 according to Table 5 of Example 6 were tested). The weight ratio of the coating composition to the solvent was 1 :5. The mixture was then heated to a temperature of 70 °C and mixed for 120 minutes. During this time the thermoplastic coating composition was dissolved to the solvent, whereas the fabric remained solid. After the dissolution was completed, the solid fabric and the used solvent containing the dissolved thermoplastic coating composition were separated by filtration, while the mixture was still warm.

[0189] The recovered fabric from the filtration was transferred to its own recycling process. The solvent was removed from the thermoplastic coating composition by evaporation, and the evaporated solvent was collected, wherein it can be re-used in the dissolution step. After the evaporation, the recovered solid thermoplastic coating composition can be melt- processed and re-used as a coating material.

[0190] Mechanical properties

[0191] Next, mechanical properties of the recycled TPU coating were researched.

[0192] Film samples having thickness of approximately 0.10 mm were prepared by compression molding at 190 °C of the recycled TPU coating composition. Virgin TPU coating before the recycling process was used as a reference. Samples were cut from the films and their tensile properties were measured according to ISO 527-3, which describes a test method for the determination of the tensile properties of plastic films and sheets. Specimen type 2 and 100 mm / min test speed were used. The results are shown in Table 6.

[0193] Table 6. Mechanical properties of recycled TPU coating expressed as a percentage of virgin TPU coating. The results in Table 6 show that the recycled TPU coating has similar mechanical properties than the reference TPU coating, thus the recycling process does not have major effect to the mechanical properties of the TPU coating.

Claims

Claims1. A method for recycling a porous substrate coated with a thermoplastic coating composition, comprising the steps of- shredding the coated porous substrate,- dissolving the coating composition, and- separating the dissolved coating composition and the undissolved porous substrate.

2. The method according to claim 1, wherein the coating composition is dissolved by a solvent selected from the group of ethyl acetate, acetone, methyl ethyl ketone, propylene glycol monoethyl ether acetate, n-butyl propionate, n-propyl acetate, butyl diglycol acetate, n-propyl propanoate, n-butyl acetate, dibasic esters, methyl acetate, tetrahydrofuran, iso-propyl acetate, n-amyl acetate, butyl glycol acetate and mixtures thereof.

3. The method according to claim 1, wherein the coating composition is dissolved by ethyl acetate.

4. The method according to any of the preceding claims, wherein the coating composition has a weight ratio to a solvent used in the dissolution in the range of 1 :3 to 1 :7, preferably in the range of 1 :4 to 1 :6, such as 1 :5.

5. The method according to any of the preceding claims, wherein the dissolution is performed at a temperature in the range of 50 to 120 °C, preferably in the range of 60 to 80 °C, more preferably at 70 °C, and preferably continued for at least 60 minutes, more preferably at least 100 minutes, such as for 120 minutes.

6. The method according to any of the preceding claims, wherein the dissolved coating composition and the undissolved porous substrate are separated by filtration, the filtration being performed while the mixture of the dissolved coating composition and the undissolved porous substrate being at a temperature of at least 40 °C, preferably at least 50 °C, more preferably at least 60 °C, such as at a temperature in the range of 40 to 90 °C or 50 to 80 °C.

7. The method according to any of the preceding claims, wherein the separated undissolved porous substrate is directed to a washing step, preferably comprising further dissolution of the porous substrate, and / or to a separate recycling process, such as mechanical recycling of textile fibers.

8. The method according to any of the preceding claims, wherein the separated dissolved coating composition is further separated from the solvent, preferably by evaporation, precipitation and / or filtration, to recover the solvent and the coating composition.

9. The method according to claim 8, wherein the recovered solvent is directed back to the dissolution of the coating composition and / or the recovered coating composition is reprocessed for further use, preferably by melt-processing.

10. The method according to any of the preceding claims, wherein the thermoplastic coating composition comprises one or more thermoplastic polymers(s) selected from the group of polyester, such as polybutylene succinate (PBS) or polybutylene succinate adipate (PBSA), cellulose ester and thermoplastic polyurethane (TPU).

11. The method according to claim 10, wherein the total amount of polyester, cellulose ester and / or thermoplastic TPU is at least 50 wt.%, preferably at least 70 wt.%, more preferably at least 80 wt.%, such as 60 to 99 wt.% or 70 to 95 wt.%, calculated from the total weight of the coating composition.

12. The method according to any of the preceding claims, wherein the thermoplastic coating composition is at least 50 wt.%, preferably at least 60 or 80 wt.%, such as 60 to 90 wt.%, biobased.

13. The method according to any of the preceding claims, wherein the thermoplastic coating composition comprises a plasticizer, wherein the plastizicer is maleated soybean oil, and a lubricant, such as stearamide or stearate, preferably calcium stearate, zinc stearate, or ethylene-bis-stearamide, or a mixture thereof.

14. The method according any of the preceding claims, wherein the thermoplastic coating composition consist of- 30-75 wt.%, preferably 30-65 wt.%, more preferably 30-50 wt.%, of polyester,- 20-50 wt.%, preferably 25-45 wt.% of cellulose ester,- 2-10 wt.% of plasticizer, preferably maleated soybean oil,- 0.05-10 wt.%, preferably 0.1-1 wt.%, of lubricant, preferably zinc and / or calcium stearate, and- optionally 0.1-10 wt.%, preferably 0.5-5 wt.%, of an auxiliary agent(s),- the amounts being calculated from the total weight of the composition.

15. The method according to any of the preceding claims, wherein the substrate is a fiberbased material, such as textile, for example tablecloth, clothe, protective textile, interior textile, consumer device, for example watch strap or heart rate belt.

16. The method according to any of the preceding claims, wherein the substrate is textile.

17. The method according to any of the preceding claims, wherein the coating composition is insoluble in water.

Images