Recyclable and biodegradable composite yarn

Abstract

The present invention relates to a recyclable and biodegradable composite yarn, a method for obtaining said yarn and articles comprising said yarn.

Description

[0001] The present invention relates to a recyclable and biodegradable composite yarn, a method for obtaining said yarn and articles comprising said yarn.STATE OF THE ART

[0002] In the textile industry, there is a strong need for having materials characterized by a high sustainability and a low environmental impact. In this perspective, there is a strong need for creating high-quality sustainable products that can be both recyclable and biodegradable.

[0003] In particular, the term recyclable refers to a material that can be used again in production processes, whereas the term biodegradable refers to a material that can decompose into simpler chemical compounds through the action of microorganisms, sunlight or other natural atmospheric agents.

[0004] Biodegradable polymers include all polymers of a natural origin such as cellulose or fibroin, which are in fact widely used in the textile industry (these can be, for example, fibers of a natural origin such as cotton, wool, linen and silk). These natural polymers, however, are not capable of providing the desired properties offered by polymers of a synthetic origin such as polyethylene and polypropylene, such as, for example, durability and resistance to abrasion.

[0005] Synthetic fibers, on the other hand, have significant disadvantages in terms of environmental impact as they degrade in the environment only after decades.

[0006] In this context, biodegradable polymers have recently been developed, such as starch-based polymers and aromatic / aliphatic polyesters such as polyhydroxyalkanoates (PHAs) and polylactic acid (PLA). Even these polymers, however, due to their chemical properties, are not able to provide relevant mechanical properties on their own.

[0007] There is therefore a need for increasing the biodegradability of synthetic fibers.

[0008] In this context, various biodegradation additives have been developed which, if incorporated into the polymerization or extrusion phase of the synthetic polymer, can improve the degradability of the latter. These additives, however, still tend to reduce the mechanical and chemical properties of the materials obtained, in addition to accelerating their deterioration during the period of use of the product.

[0009] In view of what has been specified in the previous paragraphs, there is a need for biodegradable fibers for textile applications that can overcome the limitations and disadvantages that characterize the prior art.OBJECT OF THE INVENTION

[0010] The present invention relates to a composite yarn (F) comprising: a core yarn (FC) and a coating layer (FR) which covers said core yarn (FC) and which comprises a non-biodegradable polymer (FSR) and a biodegradation agent, wherein said biodegradation agent comprises one or more of the following components: a biodegradable polymer selected from the group consisting of aromatic polyesters, aliphatic polyesters, polysaccharides and mixtures thereof; a monosaccharide.

[0011] The present invention also relates to a process for producing the yarn (F) described above comprising the following steps: a) Adding the biodegradation agent to a non-biodegradable polymeric material to obtain a mixture; b) Coating the core yarn (FC) with the mixture obtained in step a), more preferably by extrusion or dip coating.

[0012] The present invention also relates to an article comprising the yarn described above.DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 shows the results of the test for determining the final aerobic biodegradability of the yarn carried out in Example 1 according to the method ISO 17556:2019 (Determination of the final aerobic biodegradability of plastic materials in soil by measuring the oxygen demand in a respirometer or the quantity of carbon dioxide developed). Figure 2 shows the results of the test for determining the final aerobic biodegradability of the yarn carried out in Example 1 according to the method ISO 22404:2019 (Determination of the aerobic biodegradation of non-floating materials exposed to marine sediments - method by analysis of the carbon dioxide emitted). DETAILED DESCRIPTION OF THE INVENTION

[0014] As previously stated, the present invention relates to a composite yarn (F) comprising: a core yarn (FC) and a coating layer (FR) which covers said core yarn (FC) and which comprises a non-biodegradable polymer (FSR) and a biodegradation agent, wherein said biodegradation agent comprises one or more of the following components: a biodegradable polymer selected from the group consisting of aromatic polyesters, aliphatic polyesters, polysaccharides and mixtures thereof; a monosaccharide.

[0015] In particular, it has been surprisingly found that the yarn (F) according to the present invention is capable of synergistically combining the properties of the components present in the core yarn (FC) and in the coating layer (FR) (in terms of mechanical and chemical properties of the materials obtained), at the same time allowing excellent properties in terms of recyclability and biodegradability to be obtained.

[0016] As previously indicated, biodegradation is the decomposition or transformation of a material into products such as water, carbon dioxide, methane and biomass through the action of microorganisms (e.g. bacteria and fungi), sunlight or other natural atmospheric agents. Biodegradation can take place aerobically (in the presence of oxygen) or anaerobically (in the absence of oxygen).

[0017] In particular, the presence of the biodegradation agent facilitates the biodegradation of the polymer present in the coating layer (FR) and, possibly, of the synthetic fiber present in the core yarn (FC), under both aerobic and anaerobic conditions.

[0018] The biodegradation agent is preferably selected for promoting only anaerobic degradation. In this way, the degradation of the yarn does not take place (or is however significantly slowed down) during the normal period of use of the yarn (for example the normal period of use of a garment).

[0019] Specifically, the biodegradation agent can help microorganisms to break down the polymer at a significantly faster rate. The biodegradation agent, for example, can enable microorganisms to break the first C-C bonds within the polymeric material (with the formation of smaller constituents such as oligomers and monomers). In this way, it is possible to increase the surface area of the polymer exposed to attack by microorganisms (which can in fact also become inserted inside the openings of the polymer and not act exclusively on the external surface of the yarn). Furthermore, the biodegradation agent can reduce the lipophilicity of the coating layer (thanks, for example, to the presence of suitable functional groups such as hydroxyl groups) and promote the hydrolysis process, thus allowing the biodegradation process to be accelerated.

[0020] Possible aromatic polyesters compatible with the present invention can, for example, be polyethylene terephthalate and polybutylene terephthalate.

[0021] Possible aliphatic polyesters compatible with the present invention can, for example, be polylactic acid, poly(lactic-co-glycolic acid), polyglycolic acid, polycaprolactone, polyhydroxyalkanoate and mixtures thereof. Said aliphatic polyester is more preferably polylactic acid.

[0022] Possible monosaccharides compatible with the present invention can for example be glucose, galactose, mannose, allose, altrose, gulose, idose, talose and mixtures thereof.

[0023] Possible polysaccharides compatible with the present invention can for example be starch and / or chitosan.

[0024] In a preferred embodiment, said biodegradation agent comprises at least one aliphatic polyester (preferably selected from polylactic acid, poly(lactic-co-glycolic acid), polyglycolic acid, polycaprolactone, polyhydroxyalkanoate and mixtures thereof, more preferably polylactic acid) and a monosaccharide (preferably selected from the group consisting of glucose, galactose, mannose, allose, altrose, gulose, idose, talose and mixtures thereof).

[0025] In a further preferred embodiment, said biodegradation agent comprises at least: polylactic acid and a monosaccharide selected from the group consisting of glucose, galactose, mannose, allose, altrose, gulose, idose, talose and mixtures thereof, more preferably selected from glucose, galactose, mannose and mixtures thereof.

[0026] In one embodiment, said biodegradation agent comprises at least: an aliphatic polyester and glucose and / or galactose and / or mannose.

[0027] In one embodiment, said biodegradation agent comprises at least polylactic acid and glucose.

[0028] The core yarn (FC) can comprise: a fiber of a natural origin or deriving from material of a natural origin, preferably said fiber of a natural origin or deriving from material of a natural origin is selected from viscose, cotton, wool, linen, silk and hemp, or a synthetic fiber, said synthetic fiber preferably selected from polyamide (also known as Nylon), polyester, polyurethane (e.g. thermoplastic polyurethane), polypropylene and polyethylene (e.g. high-molecular-weight polyethylene and ultra-high-molecular-weight polyethylene).

[0029] In particular, it should be pointed out that, when the core yarn (FC) comprises a fiber of a natural origin or deriving from a biodegradable material of a natural origin, it is possible to further reduce the environmental impact typical of garments produced entirely with non-biodegradable synthetic materials (especially in terms of water pollution due to the release of microplastics during the washing operations of the article comprising the composite yarn), as the quantity of these materials is reduced. This natural fiber can be obtained from plants (such as flax, hemp, cotton and viscose) or derive from materials of an animal origin (such as, for example, wool and silk).

[0030] The core yarn (FC) can also alternatively comprise a bio-based polymer of a biodegradable type (such as, for example, polylactic acid - PLA, polybutylene succinate - PBS and polyhydroxyalkanoates - PHAs, including for example polyhydroxybutyrate - PHB).

[0031] In one embodiment, when the core yarn (FC) comprises a synthetic fiber, it can also comprise a biodegradation agent to further enhance the biodegradability of the composite yarn (F). Said biodegradation agent can comprise for example one or more of the following components: a biodegradable polymer selected from the group consisting of aromatic polyesters, aliphatic polyesters, polysaccharides and mixtures thereof; a monosaccharide.

[0032] As already indicated, the coating layer (FR) that covers said core yarn (FC) comprises a polymer that is non-biodegradable in itself (FSR). Said polymer can be any synthetic polymer or bio-based polymer (i.e. a polymer obtained from renewable natural sources such as algae, bacteria, microorganisms, plants, etc.) that is non-biodegradable in itself and compatible with the textile sector, for example polyurethane (PU), polyamide (PA), co-polyamide (Co-PA, for example low-melt co-polyamide), polyester, co-polyester, ethyl-vinyl acetate, polypropylene, polyethylene, bio-based polyethylene, bio-based polyethylene terephthalate, bio-based polyamide, bio-based polyurethane. A thermoplastic elastomer (for example polyester-based - TPE, polyester-polyether - TPC-ET or thermoplastic polyurethane - TPU) can also be used.

[0033] In a preferred embodiment, said biodegradation agent is present in a quantity ranging from 0.1 to 10%, more preferably from 0.25 to 3%, by weight with respect to the total weight of said coating layer (FR).

[0034] Said biodegradation agent can further comprise an enzyme capable of degrading the non-biodegradable polymer (FSR), preferably said enzyme being selected from the group consisting of lipases, nylonases, proteinase K and carboxylesterases. The presence of said enzymes can in fact allow for an easier decomposition of the polymer into smaller constituents such as oligomers and monomers, which can then be degraded more efficiently. In a further embodiment, said enzymes can be formulated in such a way as to regulate their activity (for example to prevent the activity of said enzymes from leading to premature degradation of the yarn).

[0035] In a preferred embodiment, said core yarn (FC) comprises a fiber selected from viscose, cotton, wool, linen, silk and hemp and said coating layer (FR) comprises polyurethane (more preferably thermoplastic polyurethane). Polyurethane in fact imparts excellent resistance to abrasion and UV rays. In any case, it should be noted that the selection between the fiber contained in the core yarn (FC) and the polymer contained in the coating layer (FR) derives mainly from the characteristics required for a given application and can be independently carried out by skilled persons in the field on the basis of common knowledge in the sector according to the specific needs to be satisfied. For a woven fabric used in furnishing (which must have a rather stiff yarn), for example, it is advisable to have a composite yarn comprising viscose in the core yarn and co-polyester.

[0036] The yarn (F) according to the present invention can be produced in different diameters (for example, the diameter ranges from 0.2 to 1.5 mm, more preferably from 0.4 to 1 mm). The yarn (F) according to the present invention can also be coloured according to processes known in the field.

[0037] The weight ratio between said core yarn (FC) and said coating layer (FR) can range from 10:1 to 1:200, more preferably from 1:1 to 1:100.

[0038] The yarn (F) according to the present invention can have different surface finishes, shiny or opaque, smooth or rough. Furthermore, the section of the yarn (F) according to the present invention can be circular, rectangular or with any kind of geometric sections (for example hexagonal, octagonal, oval, etc.).

[0039] The coating layer (FR) can be transparent, opaque or coloured with special pigments and / or powders.

[0040] The present invention also relates to a process for producing the yarn described above comprising the following steps: a) Adding the biodegradation agent to a non-biodegradable polymeric material, more preferably said polymeric material being of a synthetic origin, to obtain a mixture; b) Coating the core yarn (FC) with the mixture obtained in step a), more preferably by extrusion or dip coating.

[0041] In particular, the polymeric material can be present in liquid form, molten (for example at a temperature ranging from 150 to 200°C, more preferably from 170 to 190°C), in granular form or in powder form when the biodegradation agent is added to it.

[0042] The resulting mixture is used for coating the core yarn (FC) using processes known in the field, such as extrusion or dip coating (also known as immersion coating). The production of the core yarn (FC) to be coated can be effected using techniques known in the industry.

[0043] In particular, in the extrusion process, the resulting mixture is pushed in molten form at high pressure through the orifices of the die forming continuous filaments that can be used for coating the core yarn (FC), whereas in the dip coating process the core yarn (FC) is immersed in the resulting mixture.

[0044] The biodegradation agent can be added in solid form (granulate and / or powder) and / or in liquid form (e.g. in the form of a solution or suspension).

[0045] The polymeric material, for example, can be melted (preferably directly inside the extruder) and with the addition of the biodegradation agent (which can be in liquid and / or solid form).

[0046] Alternatively, the biodegradation agent (which can be in liquid and / or solid form) is added for example to the polymeric material in powder form to obtain a mixture that is then melted (preferably inside the extruder). It is subsequently possible to carry out steps known in the field, such as cooling and drying.

[0047] The biodegradation agent can be present in a quantity ranging from 0.1 to 10%, more preferably from 0.25 to 3%, by weight with respect to the total weight of said coating layer (FR).

[0048] As previously indicated, said non-biodegradable polymeric material can be any polymer of a synthetic or bio-based origin that is in itself non-biodegradable and compatible with the textile sector, for example polyurethane (PU), polyamide (PA), co-polyamide (Co-PA, for example low-melt co-polyamide), polyester, co-polyester, ethyl-vinyl acetate, polypropylene, polyethylene, bio-based polyethylene, bio-based polyethylene terephthalate, bio-based polyamide, bio-based polyurethane. A thermoplastic elastomer (for example polyester-based - TPE, polyester-polyether - TPC-ET or thermoplastic polyurethane - TPU) can also be used.

[0049] The core yarn (FC) to be coated in step c) can comprise: a fiber of a natural origin or deriving from material of a natural origin, said fiber of a natural origin or deriving from material of a natural origin is preferably selected from viscose, cotton, wool, linen, silk and hemp, or a synthetic fiber, said synthetic fiber is preferably selected from polyamide, polyester, polyurethane, polypropylene and polyethylene.

[0050] As previously indicated, the weight ratio between said core yarn (FC) and said coating layer (FR) can range from 10:1 to 1:200, more preferably from 1:1 to 1:100.

[0051] It should be pointed out that the yarn (F) according to the present invention is compatible with all known textile machines (such as orthogonal looms, jacquard looms, multi-axial looms, unidirectional looms, flat knitting machines, small and large diameter circular knitting machines, sewing machines, embroidery machines, TFP machines, braiding machines, etc.).

[0052] The present invention also relates to an article comprising the yarn described above. Said article is preferably a textile garment or an ornamental fabric. The yarn (F) according to the present invention can in fact be used in various applications, such as for example, the production of: embroidery; fabrics for composite materials for industrial, aeronautical, nautical, automotive use; warp-knit fabrics; nets; fabrics and / or products destined for the world of fashion; technical and / or industrial textile material.

[0053] Furthermore, the yarn (F) according to the present invention can be easily recycled in order to produce further products intended for different uses (such as shoe soles, panels for building use, parts of car interiors, products deriving from injection such as vases and containers, etc.). Regardless of whether the core yarn (FC) comprises a fiber of a natural or synthetic origin, it can, in fact, be pulverized and melted to obtain new granules (which can then be used in any process of interest).

[0054] In order to satisfy specific requirements, skilled persons in the field can apply to the embodiments described above, modifications and / or replacements of elements described with equivalent elements, without thereby departing from the scope of the enclosed claims.EXAMPLESExample 1 - production of a yarn according to the present invention

[0055] The thermoplastic polyurethane was mixed with a commercial biodegradation agent in powder form (comprising polylactic acid and glucose) to obtain a mixture in which the quantity by weight of the thermoplastic polyurethane with respect to the total weight of the mixture is equal to 99.5% and the quantity by weight of the biodegradation agent with respect to the total weight of the mixture is equal to 0.5%. This mixture was then inserted into an extruder and brought to a temperature ranging from 170 to 190°C. The molten material was subsequently passed through the orifice of the die and then conveyed around a core yarn (FC) comprising viscose and moved at a speed of 500 m / min by means of a winding machine. In this way, it was possible to produce the composite yarn. This composite yarn was then subjected to a cooling and drying step.Example 2 - determination of the biodegradability using method ISO 17556:2019

[0056] The composite yarn produced according to Example 1 was subjected to experimental tests in order to determine its final aerobic biodegradability according to the method ISO 17556:2019 (determination of the final aerobic biodegradability of plastic materials in soil by measuring the oxygen demand in a respirometer or the quantity of carbon dioxide developed).

[0057] As can be seen from Figure 1, for the sample analyzed, a biodegradability was observed after 240 days equal to approximately 45% of the value obtained with the reference material (the reference material being made of cellulose). This value appears to be acceptable for considering the product as being biodegradable: the biodegradability observed is in fact sufficient for significantly reducing the environmental impact of the product (at the same time without altering its original properties). In particular, on the basis of the experimental data obtained, it is possible to estimate that the composite yarn according to the present invention can be degraded in approximately 2-5 years.Example 3 - determination of the biodegradability using method ISO 22404:2019

[0058] The composite yarn produced according to Example 1 was subjected to experimental tests in order to determine its final aerobic biodegradability according to the method ISO 22404:2019 (Determination of aerobic biodegradation of non-floating materials exposed to marine sediments - method by analysis of the carbon dioxide emitted).

[0059] In particular, this standard specifies a laboratory test method for determining the degree and rate of aerobic biodegradation of plastic materials. The biodegradation is determined by measuring the CO 2 emitted by the plastic material when exposed to marine sediments sampled from a tidal sandy area and kept wet with salt water under laboratory conditions.

[0060] As can be seen from Figure 2, for the sample analyzed, a biodegradability after 270 days was observed equal to about 40% of the value obtained with the reference material. This value appears to be acceptable for considering the product as being biodegradable: the biodegradability observed is in fact sufficient for significantly reducing the environmental impact of the product (at the same time without altering its original properties). In particular, on the basis of the experimental data obtained, it is possible to estimate that the composite yarn according to the present invention can be degraded in about 2-5 years.

Claims

1. A composite yarn (F) comprising: • a core yarn (FC) and • a coating layer (FR) which covers said core yarn (FC) and which comprises a non-biodegradable polymer (FSR) and a biodegradation agent, wherein said biodegradation agent comprises one or more of the following components: • a biodegradable polymer selected from the group consisting of aromatic polyesters, aliphatic polyesters, polysaccharides and mixtures thereof; • a monosaccharide.

2. The yarn (F) according to claim 1, wherein the core yarn (FC) comprises: • a fiber of a natural origin or deriving from material of a natural origin, preferably said fiber of a natural origin or deriving from material of a natural origin is selected from viscose, cotton, wool, linen, silk and hemp, or • a synthetic fiber, said synthetic fiber is preferably selected from polyamide, polyester, polyurethane, polypropylene and polyethylene.

3. The yarn (F) according to any of the previous claims, wherein said non-biodegradable polymer (FSR) of said coating layer (FR) is selected from polyurethane, polyester, co-polyester, polyamide, co-polyamide, ethyl-vinyl acetate, polypropylene and polyethylene.

4. The yarn (F) according to any of the previous claims, wherein said biodegradation agent is present in a quantity ranging from 0.1 to 10%, preferably from 0.25 to 3%, by weight with respect to the total weight of said coating layer (FR).

5. The yarn (F) according to any of the previous claims, wherein said biodegradation agent comprises at least: • an aliphatic polyester, preferably selected from polylactic acid, poly(lactic-co-glycolic acid), polyglycolic acid, polycaprolactone, polyhydroxyalkanoate and mixtures thereof and • a monosaccharide selected from the group consisting of glucose, galactose, mannose, allose, altrose, gulose, idose, talose and mixtures thereof.

6. The yarn (F) according to any of the previous claims, wherein said biodegradation agent comprises at least • polylactic acid and • a monosaccharide selected from the group consisting of glucose, galactose, mannose, allose, altrose, gulose, idose, talose and mixtures thereof, preferably selected from glucose, galactose, mannose and mixtures thereof.

7. The yarn (F) according to any of the previous claims, wherein said core yarn (FC) comprises a fiber selected from viscose, cotton, wool, linen, silk and hemp and said coating layer (FR) comprises polyurethane, preferably thermoplastic polyurethane.

8. The yarn (F) according to any of the previous claims, wherein the weight ratio between said core yarn (FC) and said coating layer (FR) ranges from 10:1 to 1:200, preferably from 1:1 to 1:100.

9. A process for producing a yarn (F) according to claims 1-8 comprising the following steps: a) Adding a biodegradation agent to a non-biodegradable polymeric material to obtain a mixture, wherein said biodegradation agent comprises one or more of the following components: • a biodegradable polymer selected from the group consisting of aromatic polyesters, aliphatic polyesters, polysaccharides and mixtures thereof; • a monosaccharide, b) Coating the core yarn (FC) with the mixture obtained in step a), preferably by extrusion or dip coating.

10. An article comprising a yarn (F) according to claims 1-8, said article preferably being a textile garment or an ornamental fabric.

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