BR112020026461B1 - BIODEGRADABLE TEXTILES, MATRIX BATCHES AND METHOD OF MAKING BIODEGRADABLE FIBERS - Google Patents

Abstract

This is a master batch, together with associated methods, and biodegradable filaments, fibers, textile yarns, and cloths. The master batch includes 0.2 to 5 wt.% CaCO3, an aliphatic polyester having a repeating unit with two to six carbons in the chain between the ester groups, with the proviso that the chain does not include side chain carbons, and a carrier polymer selected from the group consisting of PET, nylon, other thermoplastic polymers, and combinations thereof.

Description

[0001] The present invention relates to polymeric compositions suitable for textiles and which are also biodegradable in a reasonably short time frame, compared to most common polymers.

BACKGROUND

[0002] Textiles are fundamental to human culture and have been made and used by humans for thousands of years. The earliest textiles were - and continue to be - woven from natural fibers such as linen, wool, silk, and cotton. More recently, textile fibers, yarns, and fabrics have also been produced industrially from polymers such as polyester, nylon olefins, other thermoplastic polymers, and combinations thereof. Many modern polymers can be made into an almost infinite variety of shapes and products that are attractive, durable, and water-resistant. In many cases, these synthetic textile fibers or yarns (depending on the technique and desired end product) can be blended with natural fibers to obtain end products with desired characteristics of both natural and synthetic materials.

[0003] While durability and water resistance are desirable, these same properties can lead to secondary environmental problems. Textiles made from polymeric fibers do not naturally biodegrade in the same manner as natural fibers such as cotton and wool, and can remain in landfills and water (e.g., lakes, oceans) for hundreds of years or more. According to the U.S. Environmental Protection Agency, nearly 44 million pounds of synthetic (polymeric) textiles end up in landfills every day. In addition, a large portion of the microfibers that are released from clothing during the laundry cycle become trapped in wastewater treatment plant sludge. The sludge is eventually converted to biosolids that are sent to landfills or used as fertilizer. These polymeric microfibers then accumulate in soil or other terrestrial environments, and can even become mobile, eventually making their way from terrestrial to aquatic environments. According to some estimates, it is estimated that around half a million tons of plastic microfibers from textile laundering are released into the ocean each year. Certain high-surface-area microfibers can absorb large amounts of toxins and resemble microscopic plankton, thus bioaccumulating up the food chain by orders of magnitude. In turn, because humans typically consume top predator species, this microfiber pollution can negatively affect human health.

[0004] As additional issues, items such as carpets and upholstery (both residential and commercial) are bulky relative to clothing and typically incorporate larger, bulkier textile yarns and therefore can take up significant landfill space.

[0005] In the nonwoven context, the now ubiquitous “wipes” of all types (typically a sheet of nonwoven or multiple sheets of ply) also take up significant space and can also have a tendency, even when considered “flushable,” to clog municipal sewer systems, particularly due to the increasing use of low-volume, low-flow products.

[0006] In view of these environmental problems, the creation of biodegradable polymers has been the subject of intense academic and industrial interest. This includes the following examples, which are representative and not comprehensive.

[0007] Shah et al. in "Microbial degradation of aliphatic and aliphatic-aromatic copolyesters", Appl. Microbiol. Biotechnol (2014) 98:3437-3447 reviewed the literature on the degradation of polyesters and noted that "most biodegradable plastics are polyesters with potentially hydrolyzable ester linkages, and these are susceptible to hydrolysis by depolymerases"; and that aliphatic polyesters degrade readily compared to aromatic esters due to their flexible polymer chain. Some polyesters, such as PET, are not biodegradable as that term is used in the invention described herein.

[0008] Numerous patents have described biodegradable polymer compositions. For example, in WO 2016/079724 by Rhodia, polyamide compositions are modified to produce biodegradable polyamide fibers. In this patent, the rate of biodegradation is measured according to ASTM D5511 test standard. On pages 8 to 9, prior art approaches to biodegradation are discussed, including: photodegradation, pro-degradant additives such as transition metal salts, and biodegradable polymers that degrade rapidly leaving behind a porous structure with a high interfacial area and low structural strength; these biodegradable polymers 10 listed include polymers based on starch, polylactic acid, polycaprolactone, polybutylene succinate, polybutylene terephthalate-coadipate, and several others; However, the patent application states that "unfortunately, larger amounts are required to make the polymer biodegradable, compatibilizing and plasticizing additives are also necessary." As exemplary biodegrading agents, this patent refers to U.S. Patent Application Published No. 2008/0103232 15 by Lake et al. The biodegrading agent is advantageously a matrix batch that includes at least six additives: (1) chemoattractant or chemotactic compound; (2) glutaric acid; (3) carboxylic acid with a chain length of 5 to 18 carbons; (4) biodegradable polymer; (5) carrier resin; and (6) swelling agent. The inventive example produced polyamide fiber by melt spinning using 2% matrix batch of the commercially available biodegrading agent Eco-One®. The resulting fibers were tested using ASTM D5511 standard and found to degrade 13.9% or 15.5% after 300 days. Fibers without biodegradation agent degraded 2.2 and 2.3% under the same ASTM D5511 testing.

[0009] LaPray et al., in document No. US 2018/0100060, produce biodegradable articles, such as a film, bag, bottle, lid, sheet, box or other container, plate or the like that are made from a blend of a polymer with a carbohydrate-based polymer. Biodegradability is tested according to established standards, such as ASTM D-5511 and ASTM D-6691 (simulated marine conditions).

[0010] Tokiwa et al. describe biodegradable resin compositions comprising a biodegradable resin and a mannan digestion product (polysaccharide). Tokiwa et al. list that biodegradable mannan digestion products include various manno-oligosaccharides.

[0011] Bastioli et al., in U.S. Patent No. 308,466,237, describe a biodegradable aliphatic aromatic copolyester made from 51 to 37% of an aliphatic acid comprising at least 50% brassylic acid (1,11-undecanedicarboxylic acid) and 49 to 63% of an aromatic carboxylic acid. The biodegradable polymer can be further modified by the addition of starch or polybutylene succinate and by copolymerization with lactic acid or polycaprolactone.

[0012] Lake et al., in U.S. Patent No. 9,382,416, describe a biodegradable additive for polymeric material comprising a chemoattractant compound, a glutaric acid, a carboxylic acid 5 and a swelling agent. Furanone compounds are discussed as attractants for bacteria.

[0013] Wnuk et al., in US Patent No. 5,939,467, describe a biodegradable polyhydroxyalkanoate polymer that contains a second biodegradable polymer, such as polycaprolactone, with examples of films produced by blowing and casting.

[0014] A variety of biodegradable formulations are known, typically outside the field of textiles that do not address the issue of washability, some of which may utilize calcium carbonate. For example, Yoshikawa et al. in published U.S. patent application No. 2013/0288322, Jeong et al. in document No. WO/2005/017015, Tashiro et al. in U.S. patent 9,617,462, and Whitehouse in U.S. patent application 2007/0259584.

[0015] Despite these intensive efforts, there remains a need for innovative methods and materials that provide synthetic textiles that are durable and water resistant, but that degrade in anaerobic wastewater treatment digesters, under landfill conditions, and in marine environments. Thus, it would be beneficial to create synthetic textiles that maintain their desirable properties, but also degrade more rapidly than conventional synthetic textile materials during wastewater treatment, in anaerobic digesters, under landfill conditions, and in marine environments.

SUMMARY OF THE INVENTION

[0016] In one aspect, the invention provides a matrix batch comprising: 0.2 to 5 mass % CaCO3, an aliphatic polyester comprising a repeating unit with two to six carbons in the chain between ester groups, wherein the 2 to 6 carbon chain repeating unit does not include side chain carbons; and a carrier polymer comprising PET, nylon, olefins, other thermoplastic polymers, and combinations thereof. The 2 to 6 carbons in the chain repeating unit do not include carbons in the ester moiety (COOR) and if side chain carbons are present, there may be more than 6 carbons (plus ester carbon) in a repeating group.

[0017] In some preferred embodiments, according to any of the aspects of the invention, the aliphatic polyester comprises a repeating unit with three to six carbon atoms or with 2 to 4 carbon atoms, in the chain between the ester groups. In particularly preferred embodiments, the aliphatic polyester comprises polycaprolactone. In some preferred embodiments, the matrix batch further comprises polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polylactic acid (PLA), polyethersulfone (PES), polyhydroxybutyrate (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), polybutylene adipate terephthalate (PBAT), polybutylene succinate adipate (PBSA), poly(butylene succinate-co-terephthalate) (PBST), poly(butylene succinate/terephthalate/isophthalate)-co-(lactate) PBSTIL, and combinations thereof.

[0018] Preferably, the matrix batch (and the textile) comprises essentially no saccharides.

[0019] In another aspect, the invention provides a melt intermediate comprising: an aliphatic polyester, other than PET, comprising a repeating unit having two to six carbon atoms in the chain between the ester groups, wherein the repeating unit of the 2 to 6 carbon chain does not include side chain carbons; 0.01 to 0.2 mass % CaCO3; and at least 90 mass % PET, nylon, olefins, other thermoplastic polymers, and combinations thereof. As used herein, the phrase "other than PET" may be expressed as "other than polyethylene terephthalate" or "provided that the aliphatic polyester is not polyethylene terephthalate."

[0020] In a further aspect, the invention provides a fibre comprising: an aliphatic polyester, other than PET, comprising a repeating unit having two to six carbon atoms in the chain between the ester groups, wherein the repeating unit of the 2 to 6 carbon chain does not include side chain carbons; 0.01 to 0.2 mass % CaCO3 and at least 90 mass % PET, nylon, olefins, other thermoplastic polymers and combinations thereof.

[0021] In various embodiments, the textile can have one or any combination of the following properties: biodegradability such that when subjected to the conditions of ASTM D5511 for 266 days, the textile decomposes at least 40%, or at least 50%, or in the range of 40% to about 80%, or in the range of 40% to about 75%; wherein the decomposition products from the ASTM test are primarily methane and carbon dioxide; dimensional stability such that the textile maintains its shape and shrinks by less than 10%, or less than 5%, or less than 3% when subjected to the conditions of the AATCC 135-2015 1llAii Home Laundering Test (machine wash at 80°F (26.67°C), tumble dry, five wash cycles); wherein the textile is colored and has a colorfastness of at least Grade 3, or at least Grade 4, or Grade 5 when subjected to the conditions of AATCC 61-2013 2A (mod 40.56 °C (105 °F)) or AATCC 8-2016, or AATCC 16.3-2014 (Option 3, 20 AFU); a burst strength of at least 137,895.14 Pa (20 psi), preferably at least 344,737.85 Pa (50 psi), or at least 689,475.70 Pa (100 psi), or in the range of 344,737.85 Pa to about 1,378,951.40 Pa (50 to about 200 psi), or 344,737.85 Pa to about 1,034,213.55 Pa (50 to about 150 psi), when subjected to the conditions of ASTM D3786/D3886M-13; and an absorbent capacity such that when subjected to the conditions of AATCC 197-2013; Option B, the textile absorbs water over a distance of at least 10 mm or at least 20 mm, or in the range of about 10 or about 20 mm to about 150 mm in 2 minutes.

[0022] In yet another aspect, the invention provides a method of manufacturing textile fibers, yarns or fabrics comprising: blending the matrix batch described herein with a polymer comprising: PET, nylon, olefins, other thermoplastic polymers and combinations thereof to form a molten blend; extruding the blend to form filaments; and cooling the filaments. These filaments may be textured and knitted ("filament textile yarn"), formed into nonwoven webs or cut into staples for woven, nonwoven and knitted fabric applications. Alternatively, the molten blend may be extruded to form pellets and the pellets may subsequently be remelted prior to the step of extruding the blend to form fibers. In another aspect, the invention provides a textile comprising: a fiber comprising CaCO3 and at least 90% by weight of PET, nylon, olefins, other thermoplastic polymers, and combinations thereof and having biodegradability such that, when subjected to the conditions of ASTM D5511 for 266 days, the textile decomposes by at least 40%, or at least 50%, or in the range of 40% to about 80%, or in a range of 40% to about 75%; and wherein the textile comprises one or more of the following properties: a dimensional stability such that the textile holds its shape and shrinks by less than 10%, or less than 5%, or less than 3%, when subjected to the conditions of AATCC 1352015 1llAii Home Laundering Test 5 (machine wash at 26.67°C (80°F)), tumble dry, five wash cycles); wherein the textile is colored and has a colorfastness of at least Grade 3, or at least Grade 4, or Grade 5 when subjected to the conditions of AATCC 61-2013 2A (mod 40.56°C (105°F)) or AATCC 8-2016, or AATCC 16.3-2014 (Option 3, 20 AFU); a tensile strength of at least 137,895.14 Pa (20 psi), preferably at least 344,737.85 Pa (50 psi), or at least 689,475.70 Pa (100 psi), or in the range of 344,737.85 Pa to about 1,378,951.40 Pa (50 to about 200 psi), or of 344,737.85 Pa to about 1,034,213.55 Pa (50 to about 150 psi), when subjected to the conditions of ASTM D3786/D3886M-13; and absorbent capacity such that when subjected to the conditions of AATCC 197-2013, Option B, the textile absorbs water over a distance of at least 10 mm or at least 20 mm, or in the range of about 10 or about 20 mm to about 150 mm in 2 minutes.

[0023] Advantages of the invention may include, in some preferred embodiments, improved biodegradability per mass % of a matrix batch; increased durability of the fiber or textile compared to other biodegradability treatments; improved maintenance of fiber or textile properties.

[0024] The foregoing and other objects and advantages of the invention and the manner in which the same are carried out will become clearer from the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figures 1 through 5 are plots of percent (%) biodegradation versus elapsed time (expressed in days) for various embodiments of the present invention, along with control examples of conventional cellulosic and polymer materials.

[0026] Figure 6 is an SEM micrograph of partially digested fibers in accordance with the invention.

[0027] Figure 7 is a series of photographs illustrating plant testing of the invention.

DETAILED DESCRIPTION OF THE INVENTION GLOSSARY

[0028] An "aliphatic polyester" contains repeating ester units with hydrocarbon chains comprising open (non-aromatic) chains. These may be homopolymers, copolymers containing only aliphatic groups, or copolymers containing both aliphatic groups and aryl groups.

[0029] A "carrier polymer" is a polymer in the matrix batch that is the same as, or is compatible and miscible with, the polymer into which the matrix batch is blended.

[0030] Denier (Dpf) is the weight in grams of 9,000 meters of the individual filament. It can be calculated by taking the denier of the textile yarn and dividing it by the number of filaments in the textile yarn bundle.

[0031] For purposes of the present invention, a non-biodegradable polymer is one that degrades by 10% or less after 266 days of testing according to ASTM D-5511.

[0032] PET, nylon and elastane have the conventional meaning. Nylon is a polyamide; a preferred nylon is nylon 6,6. Elastane is a polyether-polyurea copolymer.

[0033] Polymers are large molecules (molecular weight above 100 Daltons, typically thousands of Daltons) comprising many repeating units.

[0034] A textile is a type of material composed of natural and/or synthetic textile fibers, filaments or threads 5 and can be in the form of knitted, woven or non-woven fabric.

[0035] The term "nonwoven fabric" is well understood by one of ordinary skill in the art and is used herein in a manner consistent with such understanding, including definitions such as those in Tortora, Phyllis G. and Robert S. Merkel. Fairchild's Dictionary of Textiles. 7th ed. New York, NY: Fairchild Publications, 2009, page 387.

[0036] Thus, a nonwoven fabric is “a textile structure produced by bonding or interlacing fibers, or both; accomplished by mechanical, chemical, thermal or solvent means and combinations thereof.” Exemplary methods of forming the basic web include carding fibers, air laying, and wet forming. These webs may be attached or bonded by the use of adhesives, including low melting point fibers interspersed within the web, thermal bonding to appropriate thermoplastic polymers, needle punching, cross-linking (hydroentanglement), and spinning bonding processes.

[0037] One skilled in the art understands that in the textile arts, the word “spinning” has two different definitions, both of which are clear in context. In synthetic filament formation, the term “spinning” refers to the step of extruding the molten polymer into filament.

[0038] In the context of natural fibers, or staple fibers chopped from textured synthetic filament, the term "spinning" is used in its most historical sense (dating back to antiquity) of twisting filaments into a cohesive textile yarn structure from which cloths can be woven.

[0039] As a general reference, Phyllis G. Tortora and Robert S. Merkel, Fairchild's Dictionary of Textiles 7th Edition, New York, Fairchild Publications 2009, provide many other definitions recognized by people of ordinary skill in the art (persons of skill).

[0040] ASTM and AATCC testing protocols are considered industry standards. These protocols typically do not change significantly over time; however, if there is any doubt regarding the dates of these standards, which are not specified in this document, the standard in effect in January 2018 should be selected.

[0041] Unless otherwise defined, the term "percent" or the symbol "%" refers to the percentage of mass ("% by mass"), which carries the same meaning in this specification as "percent by weight" or "percent by weight". These uses are well understood in context by the person skilled in the art.

[0042] The matrix batch formulation that enables biodegradation typically comprises a carrier polymer. The carrier polymer is preferably formulated to be compatible with the matrix (i.e., the non-biodegradable polymer). Thus, in exemplary embodiments, the carrier polymer is selected from the group consisting of PET, nylon, olefins, other thermoplastic polymers, and combinations thereof. As demonstrated by the examples, PET and nylon, in combination with other components of the invention, have been shown to result in superior biodegradability in a washable textile.

[0043] Surprisingly, the inventors found that the addition of calcium carbonate to the matrix batch substantially increases the biodegradability of the resulting textiles while avoiding negative effects on the way they are washed.

[0044] While the invention is not limited by the mechanism by which calcium carbonate operates, and while the inventors do not wish to be limited by any particular theory, the following hypothesis seems reasonable. The presence of microscopic inorganic particles of calcium carbonate mixed into a homogeneous organic polymer matrix introduces a large number of nucleation sites for biodegradation. This calcium carbonate is dosed simultaneously with other biodegradable ingredients, causing the nucleation sites to be in close proximity to those ingredients. Calcium ions may play an important role in bacterial cultivation. Calcium-binding proteins present in bacteria aid in signal transduction and may assist in the important process of positive chemotaxis, in which bacteria move toward higher concentrations of a chemical.

[0045] According to this hypothesis, the breakdown of the polymer into monomers and oligomers, by hydrolysis of the ester connections and by the action of anaerobic bacteria, is accelerated by the presence of dispersed calcium carbonate. The presence of carbon dioxide, a metabolic byproduct, can also increase the dissolution of calcium carbonate present in the polymer matrix.

[0046] Another mechanism in which calcium and calcium-binding proteins in bacteria may play an important role is in quorum sensing; that is, a means of communicating with bacteria optimized for population cultivation. Individual bacteria work to create a hydrogel, composed of bacteria and extracellular polymeric materials that creates a coordinated functional community. This macroscopic structure amplifies bacterial action and helps to lead to the biodegradation of polymers according to the invention, especially high surface area microfibers that may be incorporated into such a hydrogel.

[0047] The matrix batch formulation is incorporated into the polymer matrix. As another aspect of the hypothesis, the chemical part of the hydrolytic attack on the polymer chains begins from the inside. The matrix batch dispersed within the matrix creates nucleation points for attack and exponentially multiplies the fiber surface area. The bacterial enzymes attack from the outside in. The bacteria, being in the 1 micron range, will initially work on the textile fibers from the outside, but as the polymer matrix solvates and breaks down, new surface area is exposed. With the formation of a coordinated bacterial community in the hydrogel, large polymer chains are broken down into oligomeric chains and subsequently broken down into monomers and digested into CO2 and CH4.

[0048] As a result, the matrix batch of the invention can be considered to act in two phases: physiochemical in the beginning to break down into smaller pieces and biochemical in the latter half to digest the material 25.

[0049] In some embodiments, the fibers in the textile or textile yarns have a denier per filament (dpf) in the range of 1 to 50 or 2 to 30, or as high as 1,000. The denier of the fibers is not believed to be critical in biodegradability, since fibrous textiles will generally have sufficient surface area to support bacterial cultivation.

[0050] In exemplary embodiments, the matrix batch comprises at least 0.5% by weight calcium carbonate, in some embodiments up to 10% calcium carbonate, in some cases between about 0.5 and 5% calcium carbonate, and typically at least about 1.0% calcium carbonate. Compositions of the invention preferably use fine powders of calcium carbonate, preferably having a mass average particle size of 15 microns (μm) or less, 10 μm or less, in some embodiments 7 μm or less, and may be in the range of a mass average particle size between 0.1 and 10 μm, or between 1 and 8 μm, or between 5 and 8 μm. As is conventional, particle size may be measured by commercial photoanalysis equipment or other conventional means. The calcium carbonate powder has a surface area of at least 0.5 square meters per gram (m2/g); in some cases, at least 1.0 m2/g, and in some embodiments, between 0.5 and 10 m2/g. As is conventional, the surface area may be determined by a method such as the ISO 9277 standard for calculating the specific surface area of solids, which in turn is based on the Brunauer-Emmett-Teller (BET) theory.

[0051] In some preferred embodiments, the matrix batch formulation contains one or any combination of the following: polycaprolactone (PCL), polyhydroxybutyrate (PHB), polybutylene succinate (PBS), polylactic acid (PLA), and poly(tetramethylene adipate-coterephthlate). Polycaprolactone, or blends comprising PCL as the major aliphatic polyester component appear favorable because, surprisingly, PCL has been found to outperform polylactic acid (PLA), PHB, and PBS.

[0052] Since textiles need to be durable, the matrix batch and textile compositions should avoid components that adversely affect durability. Preferably, the compositions have less than 5% by weight; more preferably, less than 2% or less than 1% saccharides; or less than these amounts of furanones; or less than these amounts of organic (carbon-based) components that leach out during laundering. In some embodiments, the inventive compositions lack any components that substantially decrease laundering durability.

[0053] The textiles preferably have dimensional stability such that the textile maintains its shape and shrinks by less than 10%, or less than 5%, or less than 3%, as measured by AATCC Home Laundering Testing 135-2015 1llAii (machine wash at 80 F (26.67 C), tumble dry, five wash cycles).

[0054] The textiles or fibers may be colored (such as red, blue, green, etc.), and preferably have a colorfastness of at least Grade 3, or at least Grade 4 or Grade 5, as measured by AATCC 61-2013 2A (mod 40.56 °C (105 °F)) or AATCC 8-2016 or AATCC 16.3-2014 (Option 3, 20 AFU). A sheet of the textile (e.g., a cloth sample cut from a shirt or pants) preferably has a breaking strength of at least 137,895.14 Pa (20 psi), preferably at least 344,737.85 Pa (50 psi), or at least 689,475.70 Pa (100 psi), or in the range of 344,737.85 Pa to about 1,378,951.40 Pa (50 to about 200 psi), or 344,737.85 Pa to about 1,034,213.55 Pa (50 to about 150 psi), wherein the breaking strength is measured in accordance with ASTM D3786/D3886M-13.

[0055] In some preferred embodiments, the cloths are free from pilling or defects (Grade 5 according to ASTM D 3512M 16).

[0056] In some embodiments, the textile absorbs water; this is especially desirable in garments in which sweat is wicked away from the wearer; in some preferred embodiments, the cloth absorbs water from a distance of at least 10 mm, or at least 20 mm, or in the range of about 10 or about 20 mm to about 150 mm in 2 minutes; as measured by AATCC 197-2013. Measurements of textiles made in accordance with some embodiments of the invention are shown in the performance testing comparison tables (i.e., Tables 1-7).

[0057] In some cases, the precise chemical structure within the fibers may not be known and one, or a combination, of the properties discussed above is the most accurate and/or precise way to characterize the textile. The matrix batch is blended with a non-biodegradable polymer, such as polyethylene terephthalate, nylon, olefins, other thermoplastic polymers, and combinations thereof. For purposes of the present invention, a non-biodegradable polymer is one that degrades by 10% or less (preferably, 5% or less, in some embodiments, 3% or less, and in some embodiments, between 2 and 10% or 2 and 5%) after 266 days of testing in accordance with ASTM D-5511 when the polymer does not contain the additives (in other words, prior to blending with the matrix batch). The fiber comprises at least 50% by mass; more preferably, at least 70%; even more preferably, at least 90%, or at least 95%, and, in some embodiments, at least 99% of a polymer selected from the group consisting of polyethylene terephthalate (PET), nylon, olefins, other thermoplastic polymers, and combinations thereof.

[0058] The invention includes textiles comprising these fibers, either as single component textiles or in blends with other fibers. Many textiles comprise mixtures (blends) of fibers, for example, elastane-containing textiles often include cotton fibers. In some embodiments, the textiles include at least 10%, or at least 20%, or at least 50%, or at least 80%, or at least 90%, or 100% of the fibers made from polyethylene terephthalate (PET), nylon, olefins, other thermoplastic polymers, and combinations thereof.

[0059] The fibers produced from the matrix batch typically include at least 90% by mass of a non-biodegradable polymer. Because the matrix batch is preferably added in an amount between 0.5 to 5%, preferably at least 1%, in some embodiments between 1 and 5%, in some embodiments between 2 and 5%, and because the entire matrix batch is present in the composition, the resulting fibers will contain the corresponding amounts of materials.

[0060] The invention also includes intermediates, fibers, textile yarns and blended textiles. Examples of finished products according to the present invention include: knitted fabrics, nonwoven fabrics, nonwoven fabrics, clothing, upholstery, carpets, bedding such as sheets or pillowcases, industrial cloths for agriculture or construction. Examples of clothing include: shirts, pants, bras, panties, hats, underwear, coats, skirts, dresses, socks, stretch pants and scarves.

[0061] The calcium carbonate particles are, of course, ground to a size useful for the invention. Functionally expressed, the ground particles may be as small as possible, and very small particles present no disadvantage.

[0062] An upper particle size limit is, however, set in part by denier, which the layman would describe in terms of diameter. In these terms, the average particle size of calcium carbonate should not be greater than 10% of the diameter of the extruded filament, and the maximum particle size should not be greater than 20% of the diameter of the extruded filament, because particle sizes greater than about 10% of the diameter of the filament are much more likely to lead to breakage at all stages of production and use.

[0063] As noted above, the lower limit is less critical, the primary consideration being the increasing difficulty and cost of producing smaller and smaller particles.

[0064] Thus, as a practical example, a one denier (1 D) polyester fiber has a diameter of 10 microns (p), which means that the particle size of calcium carbonate should not exceed about 1 p. Persons skilled in the art will be able to select relevant particle sizes based on this general 10% ratio.

[0065] In a similar ratio, the matrix batch composition may be produced in solid fragment form for storage and transportation. The end user may then mill the fragment into the desired sizes for their specific end-use applications.

[0066] In some embodiments, the milled matrix batch particles are then mixed with a liquid that will in turn be miscible with the desired final polymer. As an example (but not a limitation), polyethylene glycol or ethyl alcohol are suitable for polyester processes.

[0067] As other considerations, the prepared master batch may be added to the target polymer at alternative stages of production. As an option, the master batch may be added to a polymer production line after the polymer has been made, but while the polymer remains in the molten state.

[0068] Alternatively, the matrix batch may be added to a continuous polymer line during polymerization of the target polymer. In such arrangements, the matrix batch works well if miscible with the last polymerization stage, for example, in the high polymerizer of a continuous line.

[0069] Elastane. In the context of the invention, elastane may be the target polymer for the matrix batch process, provided that the elastane is melt-spun. One skilled in the art recognizes that variations of elastane are solvent-spun rather than melt-spun, and the invention is used with the melt-spun versions.

[0070] The examples throughout this description are not intended to be limiting, but in various embodiments, the invention may be characterized by any selected combination of features. In some embodiments, the compositions may be defined, in part, by the absence of certain components. In some embodiments, the compositions avoid including starch or saccharides; such components may be excessively soluble and lead to textiles that do not have sufficient durability. Additives, such as polybutylene succinate, preferably do not copolymerize with the non-biodegradable polymer, but rather form degradable phases within the compositions.

[0071] In some embodiments, compositions of the invention avoid aliphatic aromatic polyesters.

[0072] The inventive fibers, yarns, and fabrics can be characterized by their physical properties, such as by the ASTM and/or AATCC tests described in the Examples. For example, the fibers, yarns, and fabrics can be defined by the extent of degradation according to an ASTM test based on the mass % of the biodegrading agent in the fiber. The molecular composition of the precursors, intermediates, and end products can be determined by conventional methods, such as gel permeation chromatography, more preferably gradient analysis of polymer blends.

[0073] One skilled in the art will naturally understand that since the matrix batch is used in conjunction with the main polymer, the composition numbers will change proportionally to the relative amount of matrix batch added to the main polymer.

[0074] The skilled artisan will also appreciate that when the invention is considered in its embodiments as a melt intermediate, the melt can be extruded into any of the pellet or filament forms in most common textile applications. Extruding and quenching the melt into pellets provides the opportunity to store, ship, and remelt the pellets at a different location; for example, at a customer's location.

[0075] When quenched, the filaments of the composition may be textured using techniques well understood by the person skilled in the art, after which cloth may be formed directly from the textured filament ("filament textile yarn"), or the textured filament may be cut into staple fiber. This staple fiber may in turn be spun into a textile yarn, most commonly in an open-end system, but of course in ring spinning as well. The textile yarn may in turn be formed into fabrics (woven, knitted, nonwoven) or may be blended with another polymer (e.g., rayon), or with natural fiber (cotton or wool) to form a blended textile yarn, which in turn may be spun into cloths having the character of blended fibers.

[0076] Any recipe in Table 1 may be used in any of the filaments, pellets, staple fibers, textured staple fibers, textured filaments or fabrics referred to herein.

[0077] As used herein, the term "carding" as well as "carding" or "carded" refers to the well-understood finishing step for manufactured textiles, e.g., Tortora, supra at pages 378-379. In this context, the invention is also useful in polar fleece; that is, the soft carded insulating fabric typically made of polyester.

[0078] When formed into suitable filament, the compositions according to the invention are expected to work very well as filler for insulated garments.

[0079] The nature, structure, and many variations of insulated garments are well understood by the person skilled in the art. Basically, an insulating material is enclosed in a lightweight shell, for which low denier nylon is typical, which often includes a water repellent treatment that can withstand at least some precipitation.

[0080] Down is obviously the best insulating material based on weight-for-weight compressibility, range, and heat:weight ratio, but synthetic fillers, as in the present invention, offer lower cost and better insulating properties when wet, although slightly heavier and somewhat less compressible.

[0081] As another example, textile filaments, fibers or yarns according to the invention are expected to function very well as a biodegradable carpet or portions of such carpets. As well understood by the person skilled in the art, a carpet is a textile floor covering typically formed of pile textile yarns or tufted textile yarns attached to a backing. Before the advent of synthetic materials, and which are still used today, the typical pile was made of wool and the backing was made of a woven cloth, to which the textile yarn could be woven, tufted or otherwise attached.

[0082] One of ordinary skill in the art typically uses the terms "carpet" and "rug" interchangeably, although in some contexts a "carpet" covers an entire room ("wall-to-wall carpet") and a "rug" covers an area smaller than an entire room.

[0083] Because synthetic materials such as nylon, polypropylene, polyester, and blends thereof with wool are useful carpet materials, the textile fibers or yarns formed from the invention are entirely suitable and useful for carpeting. A person skilled in the art will recognize a wide variety of backing materials, backing structures, and means of attaching a pile or tuft to the backing. To repeat all of these possibilities would be redundant rather than clarifying, and the person skilled in the art can adopt the necessary steps and materials in any given context and without undue experimentation.

EXAMPLES

[0084] A variety of master batch compositions were prepared with the compositions shown in Table 1.

[0085] These master batches were blended in polyethylene terephthalate (1% of the master batch is typical) and fed via a gravimetric feeder in a closed loop to the twin-screw melt extruder. The additive batch is mixed at 250°C and extruded via a cable die into a water bath or equivalent quenching equipment. After a classifier removes particles at the extremes of the pellet size distribution, the pellets are dried and bagged.

[0086] The calcium carbonate used in the testing had a mass average particle size of 6.5 microns and a surface area of approximately 1.5 square meters per gram.

[0087] The formulations were extruded into PET at a 1% loading rate and the recipes that were most compatible with the extrusion process were tested for degradation in accordance with ASTM D5511. The results are shown in Figure 1 and Table 2 for 266 days and in Figure 2 and Table 3 for 353 days.

[0088] Initial readings were taken at 59 days; in this first reading, recipe 13 (Table 1) appears to have shown 3.9% degradation, while recipe 14 appears to have not begun to degrade. Based on a barometric event and confusion in the data, however, it appears that the data for recipes 13 and 14 are unreliable and cannot be reproduced. Furthermore, this low degradation reading is too close to the baseline to be reliable (3% degradation for PET without additive), and testing of these recipes has been discontinued.

[0089] The results shown above demonstrate superiority over the prior art. Under these landfill conditions, PET fibers degrade to methane and carbon dioxide. After 266 days, PET samples made with 1% by mass of master batch recipes #2, 3, 6, 7, and 11 in the Table degraded 43.6, 66.1, 56.5, 21.3, and 38.3%, respectively. Unmodified PET degraded 3.2% under the same conditions. The greatest degradation occurred in a master batch containing 49% polycaprolactone and 10% polyhydroxybutyrate, while the lowest degradation occurred in a master batch containing 39% polycaprolactone and 20% polybutylene succinate. The material made from 49% polycaprolactone and 10% polyhydroxybutyrate also degraded substantially better than PET modified with 1% of a matrix batch containing 39% polycaprolactone, 10% polyhydroxybutyrate and 10% polybutylene succinate.

[0090] The above results can be compared with the results reported in WO 2016/079724 (“Table 1 - Results after 300 days”), in which polyamide fibers were melt-spun using 2% matrix batch of the commercially available biodegradation agent Eco-One® (https:/ecologic-llc.com/about/eco-one- video-tour; accessed February 11, 2019). The resulting fibers were tested using ASTM D5511 and found to degrade 13.9% (“PA 6.6”) or 15.5% (“PA 5.6”) after 300 days. The fibers from WO 2016/079724 without biodegradation agent degraded 2.2 and 2.3% under the same ASTM D5511 testing.

[0091] Based on the unmodified fibers and ignoring the difference between 266 and 300 days, conventional PET (Table 2 in this document) appears to be 3.2/2.25=1.42x more degradable than the polyamide fibers of WO 2016/079724. In comparison, the modified PET according to the invention was between 21.3/15.5=1.37x and 66.1/15.5=4.26x more degradable than the modified polyamide fibers of WO 2016/079724. Correcting for the fact that the polyamide fibers of document No. WO 2016/079724 were modified in twice as many matrix batches (2% versus 1%), the PET according to the invention was between 2.74x and 8.52x more degradable. Correcting for the difference of 2.74/1.42 between the unmodified polyester and the polyimide, the present invention demonstrated a greater biodegradability between 1.92x and 3.00x.

[0092] Table 4 and Figure 3 show the improvement in biodegradation of cloths made from Recipe 2 (Table 1) and a control polyester.

[0093] ASTM D5210 - Anaerobic degradation in the presence of sewage sludge

[0094] Finished cloths of two formulations were stone ground to create microfibers, and then the microfibers were tested for degradation in accordance with ASTM D5210 for 55 days, which models the conditions typically experienced in a water treatment plant. The results are shown in Table 5 and Figure 4.

[0095] ASTM D6691 - Modeling of Aerobic Degradation 5 in a Marine Environment.

[0096] The finished cloth of a formulation was stone ground to create microfibers, and the microfibers were tested for degradation in accordance with ASTM D6691 for 112 days. The results are summarized in Table 6 and Figure 5.

[0097] Example - Non-toxicity

[0098] A composition was tested using ASTM Method E1963, a protocol for conducting plant toxicity tests using terrestrial plant species such as beans, corn, and peas to determine the effects of test substances on plant growth and development. Peas are a good indicator because they are very sensitive to soil conditions. Residual soil leachate containing byproducts, according to ASTM D5511 test Recipe 2, was used in this ASTM E 1963 test. Figure 7 shows the results of the ASTM E 1963 test.

[0099] Inspection of the plant growth in the background (1st column) and in the sample (3rd column) demonstrates that there is no inhibitory effect of the leachate from the relevant by-product sample on the plant growth. TABLE 7 - EXAMPLES OF TEXTILE PROPERTIES WITH AND WITHOUT MATRIX BATCH

[0100] Microscopic analysis of fibers subject to bacterial decomposition

[0101] Electron microscopic imaging of fibers subject to bacterial fiber decay according to the invention in ASTM D5511 are shown in the SEM image of Figure 6 (SEM HV: 15 kV; 173 micron field of view; SEM magnification 1.5; Tescan™ Vega 3™ tungsten thermionic emission SEM system (https://www.tescan.com/en-us/technology/sem/vega3); accessed February 12, 2019), and show bacterial colonization on the surface of the raw polyester fibers according to the invention after >1 year of exposure to bacteria.

[0102] In the drawings and in the descriptive report, a preferred embodiment of the invention has been established and, although specific terms have been used, they are used in a generic and descriptive sense only and not for purposes of limitation, and the scope of the invention is defined in the claims.

Claims (8)

1. Biodegradable fiber characterized by the fact that it comprises: a matrix batch comprising polycaprolactone and calcium carbonate; and polyethylene terephthalate, in which the fiber comprises: 0.39 to 0.49% by weight of polycaprolactone; 0.01% by weight of calcium carbonate; and at least 90% by mass of polyethylene terephthalate. 2. Fiber, according to claim 1, characterized by the fact that the matrix batch further comprises polybutylene succinate in an amount of 10 percent by mass. 3. Fiber, according to claim 1, characterized by the fact that it further comprises a composition selected from the group consisting of 0.05 to 0.1% by weight of PLA, 0.05 to 0.1% by weight of PHB, 0.05 to 0.1% by weight of PBAT, 0.10 to 0.20% by weight of PBS, 0.01% by weight of silicon dioxide and combinations of these compositions. 4. Textured fiber characterized by the fact that it is formed as defined by claim 1. 5. Textile yarn characterized by the fact that it is formed by the textured fiber as defined by claim 4. 6. Cloth characterized by the fact that it is formed by the textile yarn as defined by claim 5. 7. Cloth according to claim 6, characterized in that it is selected from the group consisting of woven, nonwoven and knitted fabrics. 8. Dyed cloth characterized by the fact that it is formed as defined by claim 7.