Method of producing a nonwoven fabric

Abstract

Method of producing a nonwoven fabric, comprising the steps of A) melting separately i. a first component comprising a carrier polyester composition, and ii. a second component comprising - a bonding polyester composition having its melting point lower than the carrier polyester composition and - a supplementary polyester composition, B) feeding the molten materials to capillaries of a spinning beam and extruding them, C) forming endless filaments from the molten polymeric materials, i. wherein the second component forms at least a part of the filament surface, D) cooling filaments by fluid medium having a temperature within the range of 10 to 90 °C and drawing the filaments with a draw down ratio within the range of 200 – 1300, E) laying the filaments randomly on a formation belt to form a nonwoven filamentary batt, F) thermally bonding the filamentary batt.

Description

[0001] Method of producing a nonwoven fabric

[0002] I. Field of invention

[0003] [1] The present disclosure generally relates to nonwovens made with the addition of a

[0004] 5 supplementary composition, which may comprise recycled polymeric material, and more particularly to spunbond nonwovens made with addition of a supplementary composition, which may comprise recycled polyester and methods of making the same.

[0005] II. Background of the invention 0

[0006] [2] Aromatic polyesters are well known in the field to be used in filament formation, typically polyethylene terephthalate (PET) is often used to create filaments, or at least one component of the filaments. Often the PET component is combined with a so called bonding component with lower bonding temperature, typically a type of copolymer of PET (coPET). In5 the industry, there are known combinations of PET and coPET for filament production. The difference between Polyethylene Terephthalate (PET) and Co-Polyethylene Terephthalate (coPET) lies in their chemical structures and properties. PET is a semi-crystalline polymer with high melting point, good mechanical strength, and excellent chemical resistance. On the other hand, coPET is an mostly amorphous or low-crystallinity polymer with lower melting0 temperature, slightly lower mechanical strength. Both polymers can be obtained from petrochemical industry. Bio-based PET and coPET, derived from renewable resources like corn starch or sugarcane, have been developed to reduce the environmental impact associated with petroleum-based PET and coPET (for example EP2016186906 filed by Nestle).

[0007] [3] Typically, coPET is used as bonding component, either as a filament component, or in5 a blend, or in other form(e.g. in case of mixed filaments it can form certain percentage of a mixture of filaments).

[0008] [4] Properties of PET / coPET based nonwoven or nonwoven layer can be affected by using additives. For example, crystal nucleating agents, mating agents, pigments, antifungal agents, antibacterial agents, flame retardant, hydrophilic agents, metal oxides, aliphatic bisamides0 and / or alternatively, an aliphatic monoamide or the like can be added. Among them, metal oxides such as titanium dioxide improve the spinnability by reducing the surface friction of the fibers and preventing the fusion of the fibers, and also increase the thermal conductivity during fusion molding of the nonwoven fabric with hot rolls. This has the effect of improving the fusion bondability of the nonwoven fabric. In addition, aliphatic bisamides such as ethylenebisstearic acid amide and / or alkyl-substituted aliphatic monoamides have the effect of increasing the releasability between the hot roll and the nonwoven web and improving the transportability (see for example WO2021132411A1 filed in 2019 by Toray industries).

[0009] [5] In the production of nonwoven products, there are global market demands related to the preservation of the environment, including demands for sustainable practices, recycling, and regulatory restrictions (e.g. on "single-use plastics"). To meet these demands, there is a need to produce nonwoven products with higher percentages of recycled materials.

[0010] [6] PET recycling is known and used in the industry, especially in carded nonwoven technology area. In general, polyesters such as PET are known as being recyclable polymers. The reuse of typically "PET flakes" is described for both mono and / or bico fibers. However, a person skilled in the art is aware that any reprocessing or regranulation of polymers can lead to degradation or unwanted impurities, which in the most cases will negatively impact the properties of the material and the product (e.g. fabric) made from the reprocessed or regranulated polymer resin.

[0011] III. Summary of the invention

[0012] [7] Drawbacks of prior art are eliminated to a great extent by a method of producing a nonwoven fabric, comprising the steps of

[0013] A) melting separately i. a first component comprising a carrier polyester composition, and ii. a second component comprising

[0014] - a bonding polyester composition and having its melting point lower than the carrier polyester composition and

[0015] - at least one supplementary polyester composition, wherein the bonding polyester composition comprises at least one bonding polyester, and

[0016] B) feeding the molten polymeric materials to capillaries of a spinning beam and extruding the molten polymeric materials through the capillaries, C) forming multicomponent endless filaments from the molten polymeric materials exiting the capillaries, i. wherein the second component extends in the longitudinal direction of the filaments and forms at least a part of the surface of the filaments, and

[0017] D) cooling of the formed filaments by fluid medium having a temperature within the range of 10 to 90 °C and drawing the filaments with a draw down ratio within the range of 200 - 1300 to achieve a semi-stable crystalline state of at least the second component, and

[0018] E) laying the filaments randomly on a formation belt to form a nonwoven filamentary batt, and

[0019] F) thermally bonding the filamentary batt.

[0020] [8] Preferably, the second component comprises at least 1 mass % of supplementary polyester composition, preferably at least 2.5 mass % of supplementary polyester composition, with an advantage at least 4 mass % of supplementary polyester composition, more preferably at least 5 mass % of supplementary polyester composition.

[0021] [9] Also preferably, the second component comprises up to 90 mass % of supplementary polyester composition, preferably up to 85 mass %, more preferably up to 75 mass %, most preferably up to 50 mass %.

[0022]

[0010] Advantageously, the carrier polyester composition comprises one or more carrier polyesters.

[0023]

[0011] Advantageously, the carrier polyester is a semi-crystalline polymer.

[0024]

[0012] According to a preferred embodiment, the carrier polyester is polyethylene terephthalate.

[0025]

[0013] Preferably, the carrier polyester is a polyester having crystallization enthalpy at first cooling of at least 2 J / g, preferably at least 4 J / g, with an advantage at least 6 J / g, most preferably at least 10 J / g.

[0026]

[0014] Also preferably, the carrier polyester has full width at half maximum of crystallization peak at first cooling of at least 12°C.

[0027]

[0015] Advantageously, the carrier polyester has full width at half maximum of crystallization peak at first cooling of at most 50°C.

[0028]

[0016] Preferably, the carrier polyester or the carrier polyester composition has heat of fusion of at least 35 J / g.

[0017] Advantageously, the carrier polyester composition in the filament component provides complex shear viscosity in the range of 250-500 Pa.s under amplitude of shear strain deformation of 5% at angular frequency of 1 rad.s-1 at temperature of 270°C defined within 5 minutes of experiment run under nitrogen atmosphere.

[0029]

[0018] Preferably, the bonding polyester composition comprises one or more bonding polyesters.

[0030]

[0019] Even more preferably, the bonding polyester is a copolymer of polyethylene terephthalate.

[0031]

[0020] Advantageously, the bonding polyester is a polyester having crystallization enthalpy at first cooling of at most 10 J / g, preferably at most 8 J / g, with an advantage at most 5 J / g, most preferably at most 2 J / g.

[0032]

[0021] Preferably, the bonding the polyester or bonding polyester composition has heat of fusion of at most 35 J / g.

[0033]

[0022] Preferably, the bonding polyester composition of a filament component provides complex shear viscosity in the range of 40-150 Pa.s at temperature of 270°C under amplitude of shear strain deformation of 5% at angular frequency of 1 rad.s-1 at temperature of 270°C defined within 5 minutes of experiment run under nitrogen atmosphere.

[0034]

[0023] Preferably, the supplementary polyester composition comprises one or more of the carrier polyesters.

[0035]

[0024] Advantageously, the supplementary polyester com position has crystallization enthalpy at first cooling of at least 2 J / g, preferably at least 4 J / g, with an advantage at least 6 J / g, most preferably at least 10 J / g.

[0036]

[0025] Also advantageously, the supplementary polyester composition has full width at half maximum of crystallization peak at first cooling of at most 12°C.

[0037]

[0026] Also advantageously, the supplementary polyester composition has heat of fusion of at least 35 J / g.

[0038]

[0027] Preferably, the supplementary polyester composition of a filament component provides complex shear viscosity in the range of 150-250 Pa.s under amplitude of shear strain deformation of 5% at angular frequency of 1 rad.s1at temperature of 270°C defined within 5 minutes of experiment run under nitrogen atmosphere.

[0039]

[0028] Preferably, the supplementary polyester composition is provided for step A) in the form of fibers and / or nonwoven substantially formed of PET / coPET composition.

[0029] With an advantage, the supplementary polyester composition comprises recycled carrier polyester composition and recycled bonding polyester composition.

[0040]

[0030] Advantageously, the supplementary polyester composition comprises at least 20 mass % of recycled carrier polyester composition, preferably at least 30% of recycled carrier polyester composition, with an advantage at least 40% of recycled carrier polyester composition, most preferably at least 50% of recycled carrier polyester composition.

[0041]

[0031] Preferably, the supplementary polyester composition comprises at least 5 mass % of recycled bonding polyester composition, preferably at least 10 mass % of recycled bonding polyester composition, with an advantage at least 15% of recycled bonding polyester composition, most preferably at least 20% of recycled bonding polyester composition.

[0042]

[0032] Advantageously, the supplementary polyester composition comprises recycled carrier polyester composition, recycled bonding polyester composition and recycled supplementary polyester composition.

[0043]

[0033] With an advantage, the supplementary polyester composition comprises at least 20 mass % of recycled PET, preferably at least 30 mass % of recycled PET, with an advantage at least 40 mass % of recycled PET, most preferably at least 50 mass % of recycled PET.

[0044]

[0034] Preferably, the supplementary polyester composition comprises at least 5 mass % of recycled coPET, preferably at least 10 mass % of recycled coPET, with an advantage at least 15 mass % of recycled coPET, most preferably at least 20 mass % of recycled coPET.

[0045]

[0035] The bonding polyester composition has preferably a lower melting temperature than the carrier polyester composition by at least 5°C, preferably at least 10°C, with an advantage at least 15°C, more preferably at least 20°C.

[0046]

[0036] Preferably, the melting temperature of the supplementary polyester composition is lower than melting temperature of the bonding polyester composition by at most 10°C.

[0047]

[0037] The melting temperature of the supplementary polyester composition is preferably higher than the melting temperature of the bonding polyester composition, wherein the difference is at most 50°C, preferably at most 30°C, with an advantage at most 20°C, most preferably at most 10°C.

[0048]

[0038] Preferably, the difference of supplementary polyester composition crystallization enthalpy at first cooling and at least one bonding polyester present in the bonding polyester composition crystallization enthalpy at first cooling is at least 10 J / g, preferably at least 20 J / g, with an advantage at least 30 J / g.

[0039] Advantageously, the difference in full width at half maximum of crystallization peak at first cooling between the carrier polyester composition and the supplementary polyester composition is at least 2°C, preferably at least 3°C, with an advantage at least 5°C.

[0049]

[0040] Also advantageously, the difference of the carrier polyester composition heat of fusion and the bonding polyester composition heat of fusion is at least 5 J / g, preferably 7 J / g, with an advantage 10 J / g.

[0050]

[0041] Advantageously, the second component forms at least 10% of filament mass, with an advantage at least 15% of filament mass, preferably at least 20% of filament mass and / orthe second component forms at most 60% of filament mass.

[0051]

[0042] Preferably, the first component forms at most 90% of filament mass, preferably at most 80% of filament mass, with an advantage at most 70% of filament mass.

[0052]

[0043] With an advantage, in steps B) to D) filaments with concentric core-sheath or eccentric core-sheath or side-by-side cross-section are produced.

[0053]

[0044] Preferably, the first component comprises the supplementary polyester composition in an amount of at least 2.5% of mass of the first component, preferably at least 5% of mass, with an advantage at least 7.5% of mass, more preferably at least 10% of mass of the first component; and / orthe first component comprises the supplementary polyester composition in an amount of up to 90% of mass of the first component, preferably up to 85% of mass, with an advantage up to 75% of mass, more preferably up to 50% of mass of the first component.

[0054]

[0045] With a great advantage, the supplementary polyester composition mass percentage concentration is same or lower in the first component than in the second component.

[0055]

[0046] In some cases, it is preferred, when in the step F) thermally bonding the filamentary batt is performed by air-through-bonding.

[0056]

[0047] In other cases, it is preferred, when in the step F) thermally bonding is performed by a pair of heated rollers, more preferably, by a pair of smooth and embossed heated rollers.

[0057]

[0048] The drawbacks of the prior art are eliminated to a great extent also with a nonwoven fabric produced according to the above described method.

[0058] IV. Definitions

[0049] The terms "fibers" and "filaments" are used interchangeably in this application unless otherwise specified (for example, "endless filaments" (meaning continuous filaments) as opposed to "staple fibers" (meaning short fibers)).

[0059]

[0050] The "Fiber diameter" is expressed in microns (micrometers). It is possible to use, for example, an optical or electronic microscope (depending on the diameter of the measured fibres). At least 50 individual fibers were measured to calculate the average value. The terms "number of grams of filament per 9000 m" (also denier or den) or "number of grams of filament per 10000 m" (dTex) are used to express the degree of fineness or coarseness of a filament as they relate to the filament diameter (a circular filament cross-section is assumed) multiplied by the density of the material or materials used. The term "mono-component"" relates to a filament formed from a single polymer or from a single polymer blend, whereby it is differentiated from a bi-component filament or multi-component filament.

[0060]

[0051] For the purposes of the present disclosure, the term "recycled" or "r" in connection with polymer name - for example "recycled PET" or "rPET" is intended to mean resin that has been previously used in the manufacture of other products such as, but not limited to, fibers, nonwovens, filaments, films, solid plastic articles, and injection-molded components, and is ready to be used in further production, either in straight dosing into melting unit (e.g. extruder) or converted back into pellets or other suitable form for the subsequent production of a filament or spunmelt nonwoven. Recycled polyester suitable for use, as described here, is in general intended to fulfil the standard requirements for filament or spunmelt nonwoven virgin polymer (e.g., color stability, pellet size (if applied), melt flow rate, thermostability or other requirements) set by filament or spunmelt nonwoven production companies for their production lines. Recycled materials are typically generated from two different waste streams. Post-industrial recycled (PIR) materials otherwise considered as pre-consumer waste stream is essentially the waste generated from the original manufacturing process that is in-turn used for producing new products. Post-consumer recycled (PCR) materials refers to everything that gets tossed into the recycling bin by a consumer. PCR is generally known to have higher levels of contamination and variability, due to additional life cycle of the product by the consumer and exposure of materials to uncontrolled conditions post manufacturing process.

[0061]

[0052] The term "crystalline" or "semi-crystalline" can be used interchangeably. Both relates to polymer crystallinity and are used to express the fact, that polymers thermoplastic polymers forming crystals are never fully crystallized. For purpose of calculations values for 100% crystalline can be estimated, but in reality, thermoplastic polymers always comprise some amorphous content.

[0062]

[0053] The term "melting temperature" here is used for all types of polymers and their blends and it shall be understood in the following way: a. For semicrystalline polymer melting temperature TM represents the maximum of fusion peak in DSC measurement. b. For amorphous polymers, it is known that melting temperature does not exist. Rigid solid polymer when heated passes a glass transition temperature and moves to soft solid state, where the material gradually softens and with lowering viscosity will start to slowly flow without any clearly visible transition. For the purpose of this application melting temperature shall be understood as technological processing temperature. In case of doubts Glass transition temperature + 50°C shall be used. c. For polyester compositions the melting temperature shall be understood as melting temperature of polyester part having lowest melting temperature. To avoid confusion of small amount additives, evaluating the DSC spectrum, all heat of fusion peaks (HM) shall be calculated together. Any peak with heat of fusion lower than 10% of calculated overall heat of fusion is not to be taken into account in melting temperature evaluation. In case amorphous polyester is present in the composition in an amount lower than 30%, its melting temperature (see previous paragraph) is not to be taken into account.

[0063]

[0054] The term "multi-component " designates a fiber or filament of which the cross-section incorporates more than one individual partial component, whilst each of these independent components in the cross-section consists of a different polymeric compound or a different blend of polymeric compounds. The term "multi-component " is thus a superior term, that includes, but is not limited to "bi-component ". The different components of multi-component filaments are arranged essentially in clearly defined areas arranged along the cross-section of the filament and extend out continuously along the length of the filament. A multi-component filament may have a cross-section divided into several partial areas consisting of various components of selectable shapes or arrangements. For example, the partial components of the cross-section can be arranged in a coaxial arrangement in the form of core and sheath, radial or so-called islands-in-the-sea arrangement, etc. The terms "two-component" and "bicomponent" used to describe filaments are herein used interchangeably. The design used to produce multi-component filaments has a determining impact on the resulting longitudinal shape of the filament, for example its propensity to crimp. A good way to recognise the design of a multi-component filament is to see and evaluate its cross-section which makes visible the position of different components of a filament. In the majority of cases, the different components are made out of different polymer formulations which are selected and characterized by e.g. different melting temperatures and / or different shrinkage properties after spinning, quenching, drawing and final fiber solidification. Typically, rotationally symmetric position of filament components in its cross section (e.g. concentric core / sheath) will result in non-crimped filaments, while asymmetric position of filament components (e.g. side by side, or eccentric Core / Sheath) will result in differential, potential crimp force to achieve either self-crimping and / or heat activated crimped filaments. To simplify the language in this application we use the terms „crimpable cross-section" and „non-crimpable crosssection" in place of „filaments having a cross-section which is supporting the crimp " and "filaments having a cross-section which doesn't support a crimp". The term "crimpable crosssection" herein refers to multicomponent fibers, wherein components with different shrinkage properties are arranged across the cross-section so, that either these filaments will self-crimp during the filament drawing and solidification or, when heated to or above an activation temperature and then slowly cooled down, the fibers crimp, which causes these fibers to follow the vectors of the shrink forces. Thereby, when the fiber is released, it creates a so-called helical crimp, although when contained within a fiber layer the mutual adhesion of the fibers does not permit the creation of ideal helixes. For a multicomponent fiber, we can determine the center of mass for each individual component in the fiber cross-section (considering their areas / positions in the cross-section). Not to be bound by a theory, it is believed that when the centers of gravity of the areas of each component are substantially at the same point, as described as rotationally symmetric concentric core / sheath, the fiber is "non-crimpable". For example, for a round bicomponent fiber with symmetric or centric core / sheath cross section structure the center of mass is in the center of the cross-section (see the Fig. 1).

[0064]

[0055] The terms "bonds between filaments" or "bonding points" relate to the bonds that usually connect two filaments in a location where these filaments intersect each other or in a location where they come into contact or alternatively where they adjoin each other. By means of bonding points it is possible to connect more than two filaments or to connect two parts of the same filament. Thus, the term "bonding point" here represents the connection of two or more fibers or filaments at the point of contact by the interconnection of their components having the lower melting characteristic (melt temperature). In the bonding point, the formed component of the filament with the higher melt temperature is in general less impacted than the formed component of the filament with the lower melt temperature. For example, the sheath polymer may soften and start to flow while the core remains essentially unchanged. Conversely, the term "bonding impression" represents a surface upon which the boss of a calender roller has acted. A bonding impression has a defined area given by the size of the emboss on the bonding roller and compared to the adjacent area typically has a smaller thickness. During the bonding process the area of the bonding impression is typically subjected to significant mechanical pressure, which together with temperature may affect the shape of all filament components within the area of the bonding impression. Bonding impressions can be formed by protrusions of embossed roller, impressing engraved pattern into nonwoven batt. Combination of embossed roller and smooth roller can be used as well as combination of two embossed rollers or combination of two smooth rollers. In case of combination of two smooth rollers, bonding impression represents typically whole nonwoven surface.

[0065] "Nonwoven material" or "nonwoven fabric" is a batt or fibrous formation produced from directionally or randomly oriented filaments that are first formed during the creation of a layer of filaments and then consolidated together by means of friction, or cohesive forces or adhesive forces, and finally consolidated by the creation of bonds points, whilst this consolidation is accomplished thermally (e.g. by the effect of flowing air, calendering, effect of ultrasound, etc.), chemically (e.g. using an adhesive), mechanically (e.g. hydroentanglement, etc.), or alternatively by a combination of these methods. The term does not refer to fabrics formed by weaving or kniting or fabrics using yarns or fibers to form bonding stitches. The fibers may be of natural or synthetic origin and may be staple yarns, continuous fibers or fibers produced directly at the processing location. Commercially available fibers have a diameter ranging from approximately 0.001 mm or even less to approximately 0.2 mm or even more and are supplied in various forms: short fibers (known as staple or cut fibers), continuous individual fibers (filaments or mono-filament fibers), nontwisted bundles of filaments (combed fibers) and twisted bundles of filaments (yarns). A nonwoven fabric can be produced using many methods, including technologies such as meltblown, spunbond, spunmelt, spinning using solvents, electrostatic spinning, carding, film fibrillation, fibrillation, air-laying, dry-laying, wet-laying with staple fibers and various combinations of these processes as known in the art. The basis weight of nonwoven fabrics is usually expressed in grams per square metre (g / m2 or gsm).

[0066]

[0056] The "spunbond" or "spunlaid" or "spunmelt" process is a nonwoven fabric production process, which includes a direct conversion of polymers to filaments, which is directly followed by the deposition of such created filaments, thereby creating a layer of nonwoven filaments containing randomly arranged filaments. This nonwoven layer of filaments is subsequently consolidated in such a way as to enclose the nonwoven fabric by the creation of bonds between the filaments. The consolidation process can be performed using various methods, for example by the effect of passing air, calendering, etc.

[0067]

[0057] The term "batt" refers to layer(s) of filaments that are found in the state prior to bonding, a process that can be performed in various ways, for example, air-through-bonding, calendaring etc. The "batt" consists of individual filaments between which a fixed mutual bond is usually not yet formed even though the filaments may be pre-bonded / pre-consolidated in certain ways, where this pre-consolidation may occur during or shortly after the laying of the filaments in the spunlaying process. This pre-consolidation, however, still permits a substantial number of the filaments to be freely moveable such that they can be repositioned. The above mentioned "batt" may consist of several layers created by the deposition of filaments from several spinning beams in the spunlaying process.

[0068]

[0058] In the sense used herein, the term "layer" relates to the partial component or element of a fabric. A "layer" may be in the form of multiple filaments produced on a single spinning beam or on two or more consecutively arranged spinning beams, which create essentially the same filaments. For example, two consecutively arranged spinning beams intended for performing the spunbond procedure, have essentially the same setings and process polymers of essentially the same composition, can combine to produce a single layer. Conversely, two spunbond-type spinning beams of which one produces, for example, single-component filaments and the other produces, for example, bi-component filaments, will form two different layers. The composition of a layer can be ascertained on the basis of knowledge of the individual setings and components determining the resin (polymer) composition used for the creation of the layer or by means of analysis of the nonwoven fabric itself, for example, by using electron microscopy, or alternatively by analysis of the composition used in the production of the filaments contained in the layer using the DSC method. Adjacent layers of filaments do not necessarily have to be strictly separated, the layers in their border region may blend in together as a result of the filaments of a later deposited layer falling into the gaps between the filaments of an earlier deposited layer.

[0069]

[0059] "Machine direction" (MD) - in relation to the production of nonwoven fibrous material and the actual nonwoven fibrous material itself, the term "machine direction" (MD) represents the direction that essentially corresponds to the forward motion direction of the nonwoven fibrous material on the production line on which this material is produced.

[0070]

[0060] "Cross direction" (CD) - in relation to the production of nonwoven fibrous material and the actual nonwoven fibrous material itself, the term "cross direction" (CD) represents the direction that is essentially transversal to the forward motion direction of the nonwoven fibrous material on the production line on which this material is produced, whilst located on the plane of the nonwoven fibrous material.

[0071]

[0061] "z-direction" - in relation to the production of nonwoven fibrous material is the vertical direction to the plane MD x CD. The extension in z-direction describes the thickness of the nonwoven material.

[0072] V. Brief Description of the Drawings

[0073]

[0062] A detailed description of preferred embodiments follows referring to the accompanying drawings, which show:

[0074] Fig. 1A: Examples of crimpable cross-sections

[0075] Fig. IB: Examples of non-crimpable cross-section

[0076] Fig. 2: Examples of filament cross-section shapes used in industry (source: Lecture: Textile and clothing basics production 2, MUNI, CZ;

[0077] Fig 3: DSC measurement result - interpretation of spectra,

[0078] Fig. 4 definition of full width at half maximum (source: https: / / upload.wikimedia.Org / wikipedia / commons / c / cb / FWHM.svg)

[0079] Fig 5 A-G: Exemplary DSC measurement results of carrier polyester composition, bonding polyester composition and supplementary polyester composition. Fig. 6: examples of bonding impressions in nonwoven fabric with and without supplementary polyester composition in first and second component of the filament.

[0080] 6A - supplementary polyester composition dosed to core and sheath

[0081] 6B - supplementary polyester composition dosed only to the core

[0082] 6C - supplementary polyester composition dosed only to the sheath

[0083] Fig. 7: simplified sketch of spunmelt production line

[0084] VI. Detailed description

[0085]

[0063] The subject-matter of the invention is a thermally bonded nonwoven textile made of fibers created substantially of polyester polymers, specifically of a blend of properly chosen aromatic polyesters or copolyesters in at least one of its components, wherein specific parameters of the nonwoven are enhanced. Desired properties of such product include well balanced mechanical properties and softness characteristics. With reasonable degree of simplification, it can be stated that properties of nonwoven fabrics stem primarily from two elements: a. The filaments, having specific mechanical characteristics such as strength and flexibility. b. The bonds formed in the nonwoven influencing the overall on nonwoven structure stability.

[0086]

[0064] Both factors must be properly balanced and can be affected by polymer composition, choice of filament and bonding technology used and by specific process conditions.

[0087]

[0065] Nonwoven fabric production can be in general described as a sequence of major steps: melting polymer composition, fiber creation including cooling and drawing, batt formation, bonding step. There are two general possibilities - either all steps are performed at once (spunmelt technology) or some steps are performed separately and for example formed fibers are cut to defined length, treated, mixed and after the batt is formed and bonded together (carded technology). Both principles can be used to produce nonwoven according to invention.

[0088]

[0066] The nonwoven produced according to the invention is formed of filaments suitable for thermal bonding. Typically, each filament comprises at least two components, where one of the components (second) has lower melting temperature and acts as a bonding component and another component (first) acts as a carrier component. Bonding component (second) is typically at least on a part of the surface of the filament. Alternatively, especially in carded nonwovens, bonding component (second) can be added in the form of filaments or other suitable form mixed with other filaments in a batt. A bonded nonwoven according to the invention comprises filaments containing first component comprising carrier polyester composition, wherein the filaments are connected with other filaments containing first component comprising carrier polyester composition by means of bonding polyester composition.

[0089]

[0067] The subject matter of the invention is a thermally bonded nonwoven textile made from endless spunmelt-type filaments and / or carded staple fibers containing at least one first component comprising carrier polyester composition and at least one second component comprising bonding polyester composition, wherein the bonding polyester composition comprises at least one bonding polyester and supplementary polyester composition.

[0090]

[0068] According to a preferred embodiment the subject matter of the invention is thermally bonded nonwoven textile made from endless spunmelt-type filaments comprising at least one first component and at least one second component, wherein the second component comprises at least one bonding polyester and supplementary polyester composition.

[0091]

[0069] According to an alternative embodiment the subject matter of the invention is thermally bonded nonwoven textile made from staple fibers comprising at least one first component and at least one second component, wherein the second component comprises at least one bonding polyester and supplementary polyester composition.

[0092]

[0070] According to a different alternative embodiment the subject matter of the invention is thermally bonded nonwoven textile made from staple fibers, wherein at least some staple fibers comprise at least one first component comprising carrier composition and at least some staple fibers comprise at least one second component comprising bonding polyester composition, wherein the second component comprises at least one bonding polyester and supplementary polyester composition.

[0093]

[0071] According to a different alternative embodiment the subject matter of the invention is thermally bonded nonwoven textile made from staple fibers, wherein at least some staple fibers comprise at least one first component comprising carrier composition and at least one second component comprising bonding polyester composition is added to the fiber batt in different than fiber form, wherein the second component comprises at least one bonding polyester and supplementary polyester composition.

[0094]

[0072] Further description of the invention will use endless spunmelt filaments as example, but the principle is the same for all above-mentioned alternatives.

[0095]

[0073] The nonwovens comprise primarily bi-component or multi-component filaments containing at least first component comprising predominately a carrier composition and at least one second component comprising predominantly a bonding polyester composition that is present at least on a part of the surface of the filament, wherein the bonding composition comprises at least one bonding polyester and supplementary polyester composition.

[0096]

[0074] In an exemplary embodiment of the invention, the second component forms at least 20% of filament surface, with an advantage at least 40% of filament surface, preferably at least 60% of filament surface, even more preferably at least 80% of filament surface.

[0097]

[0075] For example, a bi-component filament contains 2 components arranged within the cross-section of the filament. For example, a core-sheath (C / S) type of bi-component filament contains two components, where one represents the core of the filament and the other wraps around it and forms the surface of the filament. The carrier composition is used here with an advantage for the core, wherein it can consist of a polyester composition or a blend comprising a more than 50 mass % of polyester. Bonding component contains a bonding polyester composition with a lower melting point as a predominant input material, wherein the bonding component forms the sheath of the filament. Likewise, it is possible to describe side-by-side (S / S) type, eccentric core-sheath (eC / S) type bi-component filaments, etc.

[0098]

[0076] In an exemplary embodiment of the invention, the first component comprises at least 60 mass % of carrier polyester composition, preferably at least 70 mass % of carrier polyester composition, with an advantage at least of 80 mass % of carrier polyester composition.

[0099]

[0077] In exemplary embodiment of the invention, the second component comprises at least 60 mass % of bonding polyester composition, preferably at least 70 mass % of bonding polyester composition, with an advantage at least of 80 mass % of bonding polyester composition.

[0100] Filaments can have various cross-sectional shapes. Very common are round shape fibers, but in industry are known and used many different alternatives. For example, oval, polygonal, star, triangular, trilobal, X-shape, multi-lobal, flat, etc. Some examples can be seen at Figs. 1A, IB and 2. There can be various components distribution in filament cross-section, providing at least one bonding polymer is present at least on a part of the surface of the filament, wherein the bonding component comprises additive polymer.

[0101]

[0078] Carrier polyester composition is formed of at least one carrier polyester.

[0102]

[0079] Bonding polymer composition is formed of at least one bonding polyester.

[0103]

[0080] Polymer characteristics and properties, which we consider beneficial forthe invention, are disclosed below.

[0104]

[0081] A carrier polyester is a thermoplastic polymer suitable for processing on a spunmelt production line or staple fiber production line belonging to the polymer groups of polyesters or copolyesters, preferably polyethylene terephthalate (PET) or copolymer of polyethylene terephthalate (coPET). An advantageous solution represents, for example polyethylene terephthalate (PET).

[0105]

[0082] A bonding polyester is a thermoplastic polymer suitable for processing on a spunmelt production line or staple fiber production line belonging to the polymer groups of polyesters or copolyesters, preferably polyethylene terephthalate (PET) or copolymer of polyethylene terephthalate (coPET). An advantageous solution represents, for example copolymer of polyethylene terephthalate (coPET).

[0106]

[0083] A supplementary polyester composition comprises a thermoplastic polymer or polymer blend suitable for processing on a spunmelt production line or staple fiber production line belonging, with an advantage, to the polymer groups of polyesters or copolyesters.

[0107]

[0084] In exemplary embodiment of the invention, the bonding polyester composition has a lower melting temperature than the carrier polymer polyester composition by at least 5°C, preferably by at least 10°C, more preferably by at least 15°C, and most preferably by at least 20°C.

[0108]

[0085] The difference between the melting temperatures of carrier polyester composition and the bonding polyester composition also influences the manufacturing process. Lower melting polymers exposed to a temperature required to melt the higher melting polymer can, for example, undergo thermo-degradation or other unwelcome changes.

[0109]

[0086] In an exemplary embodiment of the invention, the bonding polyester composition has a lower melting temperature than the carrier polyester composition by at most 200°C, preferably at most 180°C, with an advantage at most 160°C, most preferably at most 150°C.

[0087] According to an exemplary embodiment of the invention, the melting temperature of the supplementary polyester composition is lower than the melting temperature of the bonding polyester composition by at most 10°C.

[0110]

[0088] According to an exemplary embodiment of the invention, the melting temperature of the supplementary polyester composition is higher than the melting temperature of the bonding polyester composition, wherein the difference is at most 50°C, preferably at most 30°C, with an advantage at most 20°C, most preferably at most 10°C.

[0111]

[0089] A difference between the carrier and the bonding polyesters can be assessed by the crystallinity level of the polymers. The carrier polyester is preferably a semi-crystalline polymer. The bonding polyester is preferably semi-crystalline or an amorphous polymer. The carrier polyester composition is preferably more crystalline than bonding polyester composition.

[0112]

[0090] To distinguish among suitable carrier polyester, bonding polyester and supplementary polyester composition, for example differential scanning calorimetry (DSC) can be used. During first cooling carrier polyester performs a typical curve for slow crystallization (rather wide, not too high peak). Bonding polyester performs a typical curve for no or very limited crystallization (no or small indistinctive peak). On the contrary, supplementary polyester composition performs curve typical for fast crystallization (rather narrow peak typically higher than carrier polyester). Forthe purpose of this application, crystallization enthalpy (He) can be used to describe the difference.

[0113]

[0091] In an exemplary embodiment of the invention, the crystallization enthalpy of the bonding polyester composition at first cooling is at most 10 J / g, preferably at most 8 J / g, with an advantage at most 5 J / g, most preferably at most 2 J / g.

[0114]

[0092] In an exemplary embodiment of the invention, the crystallization enthalpy of the carrier polyester at first cooling is at least 2 J / g, preferably at least 4 J / g, with an advantage at least 6 J / g, most preferably at least 10 J / g.

[0115]

[0093] In an exemplary embodiment of the invention, the crystallization enthalpy of the supplementary polyester composition at first cooling is at least 2 J / g, preferably at least 4 J / g, with an advantage at least 6 J / g, most preferably at least 10 J / g.

[0116]

[0094] In an exemplary embodiment of the invention, the difference between the crystallization enthalpy at first cooling of the carrier polyester and the crystallization enthalpy at first cooling of the bonding polyester is at least 5 J / g, preferably at least 10 J / g, with an advantage at least 15 J / g.

[0117]

[0095] In exemplary embodiment of the invention, the difference between the crystallization enthalpy at first cooling of the supplementary polyester composition and the crystallization enthalpy at first cooling of at least one bonding polyester present in bonding polyester composition crystallization enthalpy at first cooling is at least 10 J / g, preferably at least 20 J / g, with an advantage at least 30 J / g.

[0118]

[0096] For the purpose of this invention and with the necessary level of simplification we can estimate it provides certain information about amount of crystallization energy, but without any information about crystallization process. As indicated above, speed of crystallization distinguishes polymers for inventions. For the purpose of this patent application, full width at half maximum of crystallization peak at first cooling was chosen to define the difference between wide and narrow peak. In a distribution, full width at half maximum (FWHM) is the difference between the two values of the independent variable at which the dependent variable is equal to half of its maximum value. In other words, it is the width of a spectrum curve measured between those points on the y-axis which are half the maximum amplitude (fig. 4). Full width at half maximum of crystallization peak at first cooling is set from DSC measurement and expressed in °C.

[0119]

[0097] In an exemplary embodiment of the invention, the carrier polyester composition has full width at half maximum of crystallization peak at first cooling of at least 12°C.

[0120]

[0098] In an exemplary embodiment of the invention, the carrier polyester has full width at half maximum of crystallization peak at first cooling of at most 50°C.

[0121]

[0099] In an exemplary embodiment of the invention, the supplementary polyester composition has full width at half maximum of crystallization peak at first cooling of at most 12°C.

[0122]

[0100] In an exemplary embodiment of the invention, the difference in full width at half maximum of crystallization peak at first cooling between carrier polyester composition and supplementary polyester composition is at least 2°C, preferably at least 3°C, with an advantage at least 5°C.

[0123]

[0101] Apart of crystallization characteristics it should be noted, that for thermal bonding process, also heat of fusion (HM) measured by DSC can show difference in carrier and bonding polyesters. In general, it can be stated, that bonding polyester or bonding polyester composition is preferable to perform lower heat of fusion values than carrier polyester composition. Lower heat of fusion togetherwith lower melting point leads to softening and / or melting of bonding polyester or polyester composition while carrier polyester or polyester composition stays in more solid state, providing the overall bonded structure stability.

[0124]

[0102] In an exemplary embodiment of the invention, the bonding polyester or bonding polyester composition has heat of fusion of at most 35 J / g.

[0125]

[0103] In an exemplary embodiment of the invention, the carrier polyester or carrier polyester composition has heat of fusion of at least 35 J / g.

[0126]

[0104] In an exemplary embodiment of the invention, the supplementary polyester composition has heat of fusion of at least 35 J / g.

[0127] In an exemplary embodiment of the invention, the difference of carrier polyester composition heat of fusion and bonding polyester composition heat of fusion is at least 5 J / g, preferably 7 J / g, with an advantage 10 J / g.

[0128]

[0105] Another important aspect to filament formation are the rheological characteristics of the polymers. Using a parallel-plate oscillatory rheometer, the dependencies of visco-elastic properties are determined from shear stress evaluation in the controlled strain mode in the wide range of angular frequencies, typically in the range of 0.01 rad.s1to 100 rad.s-1, with constant strain deformation within linear-viscoelastic region, making it possible to define the dependence of complex shear viscosity on the change of angular frequencies. For the purpose of this invention complex shear viscosity defined at constant angular frequency was chosen. Shear stress acts parallel to the material's surface - a force trying to shift one part of the material relative to another part. These values are believed to estimate polymer composition processability in filament formation.

[0129]

[0106] In an exemplary embodiment of the invention, the carrier polyester composition of a filament component provides complex shear viscosity in the range of 250-500 Pa.s under amplitude of shear strain deformation of 5% at angular frequency of 1 rad.s1at temperature of 270°C defined within 5 minutes of experiment run under nitrogen atmosphere.

[0130]

[0107] In an exemplary embodiment of the invention, the bonding polyester composition of a filament component provides complex shear viscosity in the range of 40-150 Pa.s at temperature of 270°C under amplitude of shear strain deformation of 5% at angularfrequency of 1 rad.s1at temperature of 270°C defined within 5 minutes of experiment run under nitrogen atmosphere.

[0108] In an exemplary embodiment of the invention, the supplementary polyester composition of a filament component provides complex shear viscosity in the range of 150- 250 Pa.s under amplitude of shear strain deformation of 5% at angular frequency of 1 rad.s1at temperature of 270°C defined within 5 minutes of experiment run under nitrogen atmosphere.

[0131]

[0109] With surprise, we found that the required parameters of the supplementary polyester composition can be achieved by using material from recycled nonwoven products formed substantially of carrier and bonding polyester composition. There are various methods how to recycle nonwoven textile scrap back to production - from straight joining e.g. cut edges to the extrusion system through many technical solutions, to stand alone regranulation of the scrap into resin pellets (possibly including certain blending or additivities). In case the supplementary polyester composition is some form of reused polymer, its properties shall be evaluated at the point when it is dosed to virgin polymer (in form of granules, nonwoven or even in a melt form).

[0132]

[0110] It should be noted that in general, the use of recycled or reused polymer in production of nonwovens is considered as lowering the quality of the final product. On the contrary this particular part of described invention presents use of reused thermoplastic polymer resin to improve final fabric properties.

[0133]

[0111] It is believed that final properties of nonwoven fabric are dependent on the combination of filaments properties and bonding properties. Especially, but not limited to, tensile strength of produced nonwoven is a good example. The fabric produced according to the invention can be formed of multicomponent filaments comprising first component and second component. Strength of the fabric is given by many factors, for the purpose of this invention we focus on combination of strength of single filaments and strength of formed bonds.

[0134]

[0112] Not to be bound by a theory, we believe that three main influences are: tensile strength of polymer composition in filament component, filament components cohesivity and ability of bonding polymer to spread during bonding process.

[0135]

[0113] The properties of the polymer composition, including the inherent tensile strength of polymer composition, has general influence on tensile strength of the filaments. A person skilled in the art appreciates, that process conditions (e.g. cooling, drawing etc.) can have a big impact. For the described invention, it is important to consider the effect of impurities. In the scope of this invention, any additional element will be considered an impurity when it causes a lower filament tensile strength due to an influence on the filament formation, including crystallization rate, total degree of crystallinity, or polymer chain orientation. If the additional element does not impact the tensile strength, it is not considered an impurity. For example, TiOz, a commonly used white pigment, can be in one composition considered as supportive nucleating agent improving filament tensile strength and in a different composition an impurity, that decreases filament tensile strength.

[0136]

[0114] In an exemplary embodiment of the invention, the supplementary polyester composition can be considered an impurity when added to carrier polyester composition, due to its negative effect on tensile strength of the filament, while still providing positive effects in other aspects.

[0137]

[0115] In an exemplary embodiment of the invention, the supplementary polyester composition can be considered an impurity when added to bonding polyester composition due to its neutral to negative effect on tensile strength of filament, while still providing positive effects in other aspects.

[0138]

[0116] The filament components cohesivity describes the strength of the interface after the components are process into a filament. Without being bound by theory, itis believed to have minor effect on the filament tensile strength but a major effect on the tensile strength of the nonwoven. For example, if the bonding polyester composition and the carrier polyester composition have a high level of cohesivity, a higher level of energy is needed to separate them as a result, with a reasonable level of simplification, both components will break simultaneously when subject to a tensile deformation and therefore, both component contribute to the overall tensile strength. If the level of cohesivity is low, the interface between the two components will be weak, and require low energy to separate them. As a result, with reasonable level of simplification, it can be assumed that each component will break independently when subject to a tensile deformation separately. Typically, the stiffer carrier polyester composition breaks first and immediately after (typically with no or very low extra force) bonding polyester composition also breaks, therefore the overall tensile strength is directly dependent on the strength of the carrier polyester composition and not on the strength of the bonding polyester composition

[0139]

[0117] For the purpose of this application, the cohesivity of the components is dependent on the chemical affinity between the components but also on the physical interaction, or a mechanical connection. Not to be bound by a theory we believe that adjacent components with smooth mutual interface provide different tensile strength results than adjacent components with shaped mutual interface, especially when shaping is in a direction of applied force. Component shaping can be provided in various ways, for example supplementary polyester composition added to bonding polymers can contain substance with great compatibility to carrier polyester composition and for example due to fast cooling and drawing, some of domains close to components interface can partially connect with carrier polyester composition or its part and form something like "puzzle structure" increasing component to component cohesivity.

[0140]

[0118] In a nonwoven fabric comprising numerous randomly orientated filaments, the components cohesivity is relatively much more impactful than in a single filament. It should be noted that the strength of the filament is measured in axis of the filament while for the nonwoven, the direction of the tensile load will not be in the axis of all the filaments. Not to be bound by theory, we believe that bonding polyester composition with typically lower strength is torn in the bonded areas when subject to a unidirectional tensile load such as in a tensile test. Thermally induced bonding ("thermo-bonding") of batts can result for example in the formation of individual bonding points (typically so-called air-through-bonding as described for example in W02020103964) or for example in the formation of bonding impressions (typically so-called calender-bonding as described for example in W02017190717). The combination of the bonding polyester composition, the carrier polyester composition, and their level of cohesivity is beneficial to the nonwoven textile, no matter which form of thermo-bonding is used. The better the cohesivity is, the higher the nonwoven tensile strength is.

[0141]

[0119] In an exemplary embodiment of the invention, a supplementary polyester composition added to bonding polymer composition has neutral to positive effect on tensile strength of filament, by enhancing the cohesivity between the bonding component and the carrier component.

[0142]

[0120] In an exemplary embodiment of the invention, a supplementary polyester composition added to carrier polymer composition has neutral to positive effect on tensile strength of stretched filament.

[0121] In an exemplary embodiment of the invention, a supplementary polyester composition added to bonding polyester composition has neutral to positive effect on tensile strength of the nonwoven fabric.

[0143]

[0122] The thermo-bonding process of multicomponent filaments is in general built on the principle of softening and / or melting the bonding part of filaments and puting them in contact leading to the merge or fusion bonding part of the same or other filaments at the contact points, and then leting them cool and solidify, which forms a bond, resulting in the bonded filaments being connected together. Not to be bound by a theory, we believe, that the bonding polymer has to be able to spread or flow when heated during thermo-bonding process to form effective bonds of required properties.

[0144]

[0123] For example, a calendering process with an embossing roll provides a typical patern formed of multiple bonding impressions in the bonded fabric. Even though some characteristics are given by design of bonding patern, the effectivity of the filament-to- filament connection is key factor. During the calendering process, the filaments in contact with the calender are heated to a temperature at which at least the bonding polyester has a specific level of softening and surface adhesive characteristics, while, at the same time the filaments are compressed together, resulting in a bonding impression.

[0145]

[0124] Providing that when the bonding polyester of a filament has the specific level of softening and surface adhesive characteristics it is able to spread more, it can cover higher area and possibly touch and bond together more neighboring filaments. Providing that when the bonding polyester of a filament is less able to spread, it remains closer to the filament itself and does not bond to as many neighboring filaments and / or forms weaker bonds.

[0146] For example, so called fluid-through-bonding (typically air-through-bonding) performs bonding throughout the entire fabric, where each individual fiber-to-fiber contact may form a bond. Bonds are small, formed at the contact points where two or more filaments touch.

[0147]

[0125] Hot fluid flows around the filaments of the bat and a part of the heat carried by the hot fluid is transferred into the colder filaments. For bonding to be performed, bonding polyester needs to accept so much energy (heat), that it comes to its specific level of softening and surface adhesive characteristics where when bonding components of two filaments touch each other they sticks together, and bond is formed. When bonding polyester is able to spread more, stronger filament to filament bond can be formed and overall nonwoven tensile strength can be expected to grow.

[0126] Person skilled in the art appreciates that a specific level of softening and surface adhesive characteristics state differs based on chosen thermal bonding method. Surprisingly, combination of supplementary composition according to the invention with bonding composition according to the invention improves its ability to spread and results in better and more solid formed bonds and to improvement in overall nonwoven fabric tensile strength properties.

[0148]

[0127] In an exemplary embodiment of the invention, additive polymer according to the invention added to bonding polymer has positive effect on tensile strength of thermal bonded nonwoven fabric.

[0149]

[0128] As described below, thermal bonding is affected by multiple, often contradictory effects that need to be balanced together. Still in general, one would say, that bonding polyester composition shall preferably be kept at lower level of crystallinity to reach desired effective bonding. With surprise, we found that adding a supplementary polyester composition to the bonding polyester compositions of the second component has an unexpected positive impact on the overall nonwoven fabric tensile strength. In different words, contradictory to general rule, we add to bonding polymer composition a supplementary composition with not only higher crystallinity (e.g. higher crystallization enthalpy at cooling) but also with faster crystallization (e.g. full width at half maximum of crystallization peak).

[0150]

[0129] In an exemplary embodiment of the invention, the supplementary polyester composition added to second component in filament improves nonwoven fabric tensile strength for at least 5%, preferably at least 7%, with an advantage at least 10%.

[0151]

[0130] In an exemplary embodiment of the invention the second component comprises at least 1 mass % of supplementary polyester composition, preferably at least 2.5 mass % of supplementary polyester composition, with an advantage at least 4 mass % of supplementary polyester composition, more preferably at least 5 mass % of supplementary polyester composition.

[0152]

[0131] Supplementary polyester composition can be designed as virgin polymer or blend of virgin polymers, or recycled material can be used. For example, during nonwoven production edges can be cut and fed to the production line extrusion system. For example, filament or nonwoven scrap can be shredded and fed to the production line extrusion system.

[0132] In an exemplary embodiment of the invention, supplementary polyester composition is in the form of fibers substantially formed of carrier / bonding polyester composition.

[0153]

[0133] In an exemplary embodiment of the invention, supplementary polyester composition is in the form of nonwoven substantially formed of carrier / bonding polyester composition.

[0154]

[0134] In an exemplary embodiment of the invention, supplementary polyester composition is in the form of fibers and / or nonwoven substantially formed of PET / coPET composition.

[0155]

[0135] In an exemplary embodiment of the invention, supplementary polyester composition comprises recycled carrier polyester and recycled bonding polyester.

[0156]

[0136] In an exemplary embodiment of the invention, supplementary polyester composition comprises at least 20 mass % of recycled carrier polyester, preferably at least 30 mass % of recycled carrier polyester, with an advantage at least 40 mass % of recycled carrier polyester, most preferably at least 50 mass % of recycled carrier polyester.

[0157]

[0137] In exemplary embodiment of the invention, supplementary polyester composition comprises at least 5 mass % of recycled bonding polyester, preferably at least 10 mass % of recycled bonding polyester, with an advantage at least 15 mass % of recycled bonding polyester, most preferably at least 20 mass % of recycled bonding polyester.

[0158]

[0138] In an exemplary embodiment of the invention, supplementary polyester composition comprises recycled carrier polyester, recycled bonding polyester and recycled supplementary polyester composition.

[0159]

[0139] In an exemplary embodiment of the invention, supplementary polyester composition comprises at least 20 mass % of recycled PET, preferably at least 30 mass % of recycled PET, with an advantage at least 40 mass % of recycled PET, most preferably at least 50 mass % of recycled PET.

[0160]

[0140] In an exemplary embodiment of the invention, supplementary polyester composition comprises at least 5 mass % of recycled coPET, preferably at least 10 mass % of recycled coPET, with an advantage at least 15 mass % of recycled coPET, most preferably at least 20 mass % of recycled coPET.

[0161]

[0141] Recycling can be performed also separately, for example using so called regranulation line. Suitable scrap from production for example in the form of fibers or nonwoven, but also post-consumer scrap can be used in any form. Important is to collect scrap of the same or compatible polymer compositions. For example, PET / coPET bicomponent filaments might form one suitable group. Based on dosing unit, scrap can be dosed straight to the dosing unit or can be shredded in advance. Polyester is in general hygroscopic polymer, so based on conditions, pre-drying might be recommended. Dosing unit leads scrap to extrusion system, where material is heated over its melting temperature. Based on extrusion design, material can be only moved forward (e.g. single screw), semi-mixed (e.g. single screw with passive mixing parts) or mixed (e.g. double screw). With an advantage additive can be also added into melted composition. In general, regranulation extrusion is designed in a cost-effective way - amount of needed process time and heat is limited to necessary level. Melted composition is then filtered and cooled in shape suitable for further production. Typically, some form of pellets.

[0162]

[0142] In an advantageous example, PET / coPET bi- and / or multi-component fiber and / or nonwoven scrap is collected, dosed through the dosing unit into extrusion system comprising zone of pre-heating with temperature set to 100 - 150°C, several heated extrusion zones with temperature set to 200 - 300°C, preferably graduating from 200 - 250°C at the beginning to 250°C - 300°C at the end. Melted polymer blend is filtered, cooled and formed to pellets cooled further to ambient temperature.

[0163]

[0143] Adding supplementary polymer composition into first component brings combination of positive and negative effects as described above. Polymer tensile strength effect is neutral to negative, component cohesivity effect positive and bonding polymer ability to spread effect is also positive. All of the above can be highly influenced by component ratio in filaments and their shape in filament cross-section.

[0164]

[0144] For example, the amount of bonding composition can influence bonding quality and so also tensile properties of nonwoven fabric. If, for example, there is just a small quantity of bonding polyester composition, bonds can be formed, but their strength will be limited, especially at lower cohesivity level. On contrary, high amount of bonding polyester composition assure strong bonds, but providing same fiberdiameter as previous case, amount of carrier polyester would be limited, and so fabric stability and also tensile strength.

[0165]

[0145] In an exemplary embodiment of the invention, bonding polyester composition forms at least 10% of filament mass, with an advantage at least 15% of filament mass, preferably at least 20% of filament mass.

[0166]

[0146] In an exemplary embodiment of the invention, bonding polyester composition forms at most 60% of filament mass.

[0147] In an exemplary embodiment of the invention, carrier polyester composition forms at least 40% of filament mass, with an advantage at least 50% of filament mass, preferably at least 60% of filament mass.

[0167]

[0148] In an exemplary embodiment of the invention, carrier polyester composition forms at maximum 90% of filament mass, preferably at maximum 80% of filament mass, with an advantage at maximum 70% of filament mass.

[0168]

[0149] For example, different components distribution in fabric cross-section are known in industry. Not to be bound by a theory, we believe that contact area between components can affect all 3 above-described influences. The most obvious effect seems to be seen in component cohesivity. The larger the contact area between components is, the stronger is the effect of even a small improvement of components cohesivity on overall filament or nonwoven tensile. For example, at same first component to second component mass ratio, side-by-side composition of filament would have smaller contact area than core-sheath composition of filament that would be still small compared to islands in the sea composition. Or, component shape can ease or complicate the bonding polymer function. Islands in the sea composition does not require bonding polyester composition to spread as much as in case of side-by-side composition to form strong bonds among bonding components of filaments. Also providing supplementary polymer composition acts as impurity as described above in view of polymer tensile strength, its effect on overall strength would be different for coresheath structure with carrier part present in the form of one backbone and different for example in segmented pie shape, where carrier part is divided into several parts divided by bonding polyester composition.

[0169]

[0150] In an exemplary embodiment of this invention, it might be advantageous to use coresheath, eccentric core-sheath or side-by-side composition of filament.

[0170]

[0151] Recycling is in general desired in industry. Providing supplementary polyester composition which comprises recycled polymers (for example recycled carrier polyester, recycled bonding polyester, and possibly also recycled supplementary polyester composition) it might be advantageous to dose higher amount into filament composition.

[0171]

[0152] In an exemplary embodiment of the invention, supplementary polyester composition can be present in the second component of filament in an amount of up to 90% of its mass, preferably up to 85% of its mass, with an advantage up to 75% of its mass, more preferably up to 50% of its mass.

[0172]

[0153] In some exemplary embodiments of the invention, supplementary polyester composition is present in the second component ofthe filament in an amount lowerthan 50% of its mass, preferably lower than 40% of its mass, with an advantage lower than 30% of its mass, more preferably lower than 20% of its mass.

[0173]

[0154] In the same logic, it might be advantageous to add supplementary polyester composition to first filament component, i.e. to carrier composition, to increase the level of recycled material in the filament or nonwoven. As described above, any additive in carrier polymer might bring neutral to negative effect concerning carrier polyester composition tensile strength. At the same time adding of supplementary polyester composition to the carrier composition might bring positive effect on filament component cohesivity. Not to be bound by a theory, we do not expect straight effect on bonding polymer to spread, for example by slight increase of carrier polymer flexibility, it might bring effect on bonding. For example, in core-sheath filament composition, even a slight increase of core, formed of carrier polyester, flexibility allows it to become more elliptic oval under pressure, decrease its diameter and just by its shape help bonding polymer to spread more.

[0174]

[0155] In an exemplary embodiment of the invention, supplementary polyester composition can be added to first component of filament to form at least 2.5% of its mass, preferably at least 5% of its mass, with an advantage at least 7.5% of its mass, more preferably at least 10% of its mass.

[0175]

[0156] In an exemplary embodiment of the invention, supplementary polyester composition can be added to first component of filament to form up to 90% of its mass, preferably up to 85% of its mass, with an advantage up to 75% of its mass, more preferably up to 50% of its mass. In an exemplary embodiment of the invention, supplementary polyester composition can be added to both first and second component of the filament provided the supplementary polyester composition mass concentration would be the same or lower in the first component than in the second component.

[0176]

[0157] A method for producing a nonwoven fabric from continuous filaments, in particular from continuous filaments of thermoplastic material is used to describe the invention. Person skilled in the art would appreciate that described principles would work also for carded technology where nonwoven fabric is created substantially from staple fibers, which have much shorter lengths, for example 10 mm to 60 mm.

[0177]

[0158] A recommended embodiment of the invention is characterized by at least one nonwoven layer being formed as a spunbonded nonwoven fabric by means of a spunbond process (Fig. 7).

[0178]

[0159] Nonwoven fabric according to the invention can be used as one-layer nonwoven, as composite of several substantially same layers produced from several beams with substantially same polymer composition and setings or as composite of layer according to the invention in combination with any other layer suitable of thermal bonding together. Suitable nonwoven textile materials useful in the present invention include, but are not limited to spun-bond, melt-blown or spun-melt, solvent-spun, electro-spun, carded, film fibrillated, melt-film fibrillated, air-laid, dry-laid, wet-laid staple fibres, and many other nonwoven web materials formed in part or in whole of polymer fibres, as known in the art. A suitable nonwoven web material may also be an SMS material, comprising a spun-bonded, a melt- blown and a further spun-bonded layer, or any other combination of spun-bonded and melt- blown layers, such as a SMMS or SSMMS etc. Examples include one or more layers of fibres with diameters bellow 1 micrometer (nanofibres and nanofibre layers); example of these rise in combinations of SMS, SMNS, SSMNS or SMNMS nonwoven webs (where "N" designates a nanofibre layer). In some examples, permanently hydrophilic nonwovens, and in particular, nonwovens with durably hydrophilic coatings may be desirable. Typically, the suitable nonwoven is air permeable. Typically, the suitable nonwoven is water or liquid permeable, but may also be water impermeable by reason of fibre size and density, and hydrophobicity of the fibres.

[0179]

[0160] The multicomponent or bicomponent filaments of the nonwoven fabric layer are spun by a spinning device or spinneret and then passed preferably for cooling through a cooling device. In the cooling device, the filaments are conveniently cooled using a fluid medium, in particular by means of cooling air. It is within the scope of the invention that the spun filaments are then passed through a drawing device, and the filaments are drawn. The drawn filaments are then deposited on a tray - preferably laid on a formation moving belt to form a nonwoven bat. According to a preferred embodiment of this invention, a diffuser interposed as a storage device managing the laying down of the filaments is installed between the drawing device and the deposition location. A particularly recommended embodiment of the invention is characterized in the drive unit of the cooling device and the drawing device being designed as a closed system. In this closed system, in addition to the supply of the cooling medium or cooling air into the cooling device, no further air supply from outside is utilized. Such a closed system has proven itself superior in the production of nonwovens.

[0180]

[0161] A particularly recommended embodiment of the method according to the invention is characterized by a nonwoven fabric that is produced from multicomponent filaments, in particular bicomponent filaments, having core-sheath, eccentric core-sheath or side-by-side composition of filament.

[0181]

[0162] It should be noted that filaments having so called crimpable cross-section can (self)crimp during cooling, drawing or laying down on the belt, possibly later on due to activation by additional thermal energy. It should be also noted that filaments with so called non-crimpable cross-section can form irregular crimp based for example on controlled shrinkage effect, as disclosed e.g. in W02020103964. Person skilled in the art would understand what process conditions would support crimping and what would keep fibers uncrimped.

[0182]

[0163] The first component of the filament, forming, for example, the core, is comprised of carrier polyester composition. The second component of the filament, forming, for example, the sheath, is comprised of bonding polyester composition, which differs from carrier polyester composition. For example, it comprises a different type of polyester or blend comprising different type of polyester. In an exemplary embodiment of the invention, the bonding polyester composition has a lower melting temperature than carrier polymer polyester com position by at least 5°C, preferably at least 10°C, with an advantage at least 15°C, more preferably at least 20°C.

[0183]

[0164] In an exemplary embodiment of the invention, the bonding polyester composition has a lower melting temperature than carrier polyester composition by at most 200°C, preferably at most 180°C, with an advantage at most 160°C, most preferably at most 150°C.

[0184]

[0165] Carrier polyester composition is formed of at least one carrier polyester.

[0185]

[0166] Bonding polymer composition is formed of at least one bonding polyester.

[0186]

[0167] Polymer characteristics and properties, which we consider beneficial forthe invention, are disclosed below.

[0187]

[0168] The carrier polyester is a thermoplastic polymer suitable for processing on a spunmelt production line or staple fiber production line belonging to the polymer groups of polyesters or copolyesters, preferably polyethylene terephthalate (PET) or copolymer of polyethylene terephthalate (coPET). An advantageous solution represents, for example polyethylene terephthalate (PET).

[0188]

[0169] The bonding polyester is a thermoplastic polymer suitable for processing on a spunmelt production line or staple fiber production line belonging to the polymer groups of polyesters or copolyesters, preferably polyethylene terephthalate (PET) or copolymer of polyethylene terephthalate (coPET). An advantageous solution represents, for example copolymer of polyethylene terephthalate (coPET).

[0189]

[0170] The supplementary polyester composition is a thermoplastic polymer or polymer blend suitable for processing on a spunmelt production line or staple fiber production line belonging, with an advantage, to the polymer groups of polyesters or copolyesters.

[0190]

[0171] The preferred bicomponent filaments have the ratio of the mass of the first component to the mass of the second component from 40:60 to 90:10. It is in the context of the process according to the invention that the mass ratios of the core-sheath configuration can be freely varied during production without stopping the machine.

[0191]

[0172] In an exemplary embodiment of the invention, bonding polyester composition forms at least 10% of filament mass, with an advantage at least 15% of filament mass, preferably at least 20% of filament mass.

[0192]

[0173] In an exemplary embodiment of the invention, bonding polyester composition forms at most of 60% of filament mass.

[0193]

[0174] In an exemplary embodiment of the invention, carrier polyester composition forms at least 40% of filament mass, with an advantage at least 50% of filament mass, preferably at least 60% of filament mass.

[0194]

[0175] In an exemplary embodiment of the invention, carrier polyester composition forms at most 70% of filament mass, preferably at most 80% of filament mass, with an advantage at most 90% of filament mass.

[0195]

[0176] It is within the scope of the invention that the resulting nonwoven layer is thermally pre-bonded, i.e. pre-consolidated, possibly thermally activated and then thermally bonded.

[0196]

[0177] Person skilled in the art would understand that drying or crystallization of polyester- based materials might be needed prior to feeding to extrusion system. Recommendation from polymer producer is a good lead.

[0178] It is within the invention that the formed nonwoven fabric consists of one or several layers, each formed on a spunbond beam (1). It is understood that multiple layers are laid on top of each other and transported together on at least one forming belt (2) to a final bonding device (3). It is within the invention that other layers can be part of nonwoven composite, including meltblown layer.

[0197]

[0179] The filaments 4 are spun using a spinneret 5. The arrangement of the filaments is optimized by a staggered arrangement so that each filament gets a very similar mass and a very similar temperature of cooling air. The spinnerets can vary in number of capillaries as well in the diameter (d) and the length (I) of the capillaries. The length (I) is typically calculated as multiple of the capillary diameter and for this application is in the range from 2 to 10 l / d. The number of capillaries must be chosen based on the required final filament diameter and the required or planned total polymer throughput together with the required filament spinning speed. The number of capillaries can be varied from 800- 7000 capillaries per meter, providing a filament diameter range from 8 to 45 pm. Filament speed should be defined between 3000 and 5500 m / min, the capillary diameter should be in between 200 and 1000 pm for round capillaries. Non-round capillaries show typically higher draw down ratios, greatly dependent on the capillary shape and its surface-to-volume ratio. The volume and temperature of the cooling air is set to achieve the correct draw down ratio and cooling conditions. The volume and temperature of the cooling air is controlled in the cooling device (6).

[0198]

[0180] Thereafter, the filaments are guided through the draw down zone (7). The filaments are drawn down by pulling forces created by the air speed of the cooling air. The volume of cooling air and the adjustable geometry of the draw down zone results in an air speed, which is also converted into filament speed. The filament speed together with the polymer throughput also defines the filament diameter.

[0199]

[0181] In the next step, the filaments are guided to the diffuser 8 which has divergent side walls in relation to the flow direction of the filaments. These walls can be adjusted and are adjusted in a way to achieve a uniform nonwoven fabric in which single filaments create a filament laydown arrangement exhibiting omnidirectional orientation in the MD / CD plane.

[0200]

[0182] It is understood that a filament laydown is influenced by the air guiding the filaments in the diffuser. The air can be adjusted to create arrangements from distinct zigzag lay down arrangements to real round loops, and furthermore CD-orientated elliptical structures. The filaments are laid down on the formation belt and transported into at least one preconsolidation device (9). Cooling air is moved through the filament lay down layer and the formation belt out of the process. The volume of suction air can be adjusted to help the filament lay down and also to ensure that the filament batt is fixed on the formation belt. The pre-consolidation device is located close to the diffuser. The filament batt is controlled on the way from the diffuser to the pre-consolidation device by suction air.

[0201]

[0183] The desired level of pre-consolidation of the web / batt is highly dependent on the production process conditions. The key is to correctly set the level of fiber-to-fiber cohesion within the batt and, thereby, control the level of batt coherence based on the requirements of the subsequent production step. In the case of an online production process with activation on the belt itself, the desired level of cohesion is rather low, and required only for preventing tears or thinning caused by significant undesirable fiber movements during the activation process. In other cases, for example when the fibers themselves provide very good cohesion in contact with each other or their underlay, caused, for example, by their cross-section shape, entanglement rate or material composition, the cohesion of the batt may be good enough even without thermal pre-consolidation. In other cases, for example when the production process is divided into two steps and when prior to full activation the pre-consolidated batt is transported for example in the form of rolls, the required level of cohesion is much higher and so the pre-consolidation level also needs to be far higher. Persons skilled in the art having knowledge of their process conditions will easily recognize the level of pre-consolidation required for their specific case.

[0202]

[0184] Pre-consolidation can be performed by various methods including compact rolls, flow of fluid (e.g. air) or any other suitable forms. Pre-consolidation can be performed at cold, ambient, increased or high temperature.

[0203]

[0185] Final bonding can be performed by multiple methods in bonding device (3).

[0204]

[0186] In one embodiment of the invention, procedure of treating the filament batt with hot air in a bonding device is applied. In the bonding device the filament batt of a single layer and / or more layers is bonded together, preferably without reducing the diameter of the filament batt significantly and having almost no bonding gradient throughout the thickness of the nonwoven. In the bonding device, the bonding temperature and forces applied to the filament batt need to be adapted to the required process effect of low softening and low forces but sufficient to affect the integrity of the nonwoven filament batt. This can be achieved in multiple different devices like an Omega drum bonding device, a flat belt bonding device as well as a multiple drum bonder. The bonding time for the batt is recommended between 200 and 20000 ms, preferably between 200 and 15000 ms and most preferably between 200 and 10000 ms. The bonding air speed used in this bonding unit device is adjustable between 0.2 and 4.0 m / s, preferably between 0.4 and 1.8 m / s. It is recommended that the bonding temperature for thermal bonding is between 100°C and 250°C, preferably between 120°C and 220°C. In one embodiment, the bonding temperature is 90°C to 140°C, in particular 110°C to 130°C. According to a preferred embodiment, the nonwoven layer of bicomponent filaments has a core component comprising carrier polyester composition, preferably polyethylene terephthalate (PET) and a sheath component comprising bonding polyester composition, preferably a polyethylene terephthalate copolymer (CoPET), and supplementary polyester composition, the bonding temperature is preferably 140°C to 230°C.

[0205]

[0187] In other embodiment of the invention, pair of heated rolls can be applied to the batt. For example nonwoven batt can be consolidated by means of heated calender rollers with one smooth roll and opposed embossed roll forming by its protrusions bonding impressions creating a pattern repeated in direction of the nonwoven web movement (MD). Various pattern designs are known in industry (for example, W02017190717). For example, a pairs of smooth rolls, a pair of embossed rolls or any combination thereof can be used. According to a preferred embodiment, the nonwoven layer of bicomponent filaments has a core component comprising carrier polyester composition, preferably polyethylene terephthalate (PET) and a sheath component comprising bonding polyester composition, preferably a polyethylene terephthalate copolymer (CoPET), and supplementary polyester composition, the bonding temperature is preferably 140°C to 240°C.

[0206]

[0188] It should be noted that also combination of various bonding steps can be applied to nonwoven batt. For example, nonwoven can be thermobonded first, and hydroentagled or hydroenhanced in following step (for example WO2022235648; WO2022235652; WO2018112259 or W02006031656). Or air-through-bonding can be combined with calander bonding or 3D shaping or any combination of above. Person skilled in the art would be able to choose suitable combination to reach desired fabric properties.

[0207]

[0189] The bonded nonwoven is finally wound up on a winder 11. In case surface properties of the nonwoven need to be modified for example to achieve improved fluid transportation or wicking performance a spraying device or kiss roll is placed either in between the forming belt and the final bonding device or in between the final bonding device and the winder.

[0208]

[0190] Nonwoven web according to the invention can be manufactured with any basis weight.

[0209]

[0191] For some applications it can be advantageous having the basis weight at most 70 g / m2, better at most 60 g / m2, still better at most 50 g / m2, advantageously at most 40 g / m2. Person skilled in the art realizes, that it is necessary for the nonwoven web to contain at least minimum material quantity in order that the required properties may be reached. In accordance with this assumption, it is possible to use the nonwoven web having the basis weight at least 6 g / m2, better at least 8 g / m2, advantageously at least 10 g / m2. It is obvious, that in described medium to low basis weight range nonwoven, due to limited amount of material, any benefit to nonwoven tensile strength is not only beneficial, but can be considered crucial.

[0210]

[0192] In other cases, for example, when using the nonwoven webs for production of articles, such as disposable garments, wipes or dusters, higher basis weights amounting up to 100 g / m2 or even 150g / m2 may be required. In this context it is believed, that described invention has beneficial effects on bonding in full width of the nonwoven.

[0211] VII. Examples

[0212]

[0193] Further details and specific features of the invention will be explained based on examples. The examples illustrate the practice of the present invention but are not intended to be considered as limitations thereof. Additional embodiments and modifications within the scope of the claimed invention will be apparent to one of ordinary skill in the art. Accordingly, the scope of the present invention shall be defined by the appended claims.

[0213]

[0194] Polymers used in following examples provide properties as shown in Table 1:

[0214] * PET4 - melting temperature estimated from glass transition temperature (69°C)

[0215] Table 1: properties of polymers used in examples.

[0216]

[0195] Examples 1-11:

[0217]

[0196] In the following examples 1-11 of the production of nonwoven fabric, one layer of bicomponent fibers was prepared using a spunbond-type spinneret with round capillaries using a REICOFIL 4 technology on a pilot line at STFI (Sachsisches Textilforschunginstitut e.V.). The core (carrier polyester composition) was produced from Type 5520 resin (PET2) in examples 1-8 and XPURE Polyester V062 (PET1) resin in examples 9-11 from Indorama and the sheath (bonding polyester composition) was produced using coPET XPURE Polyester 701K (PET3) resin from Indorama. Core / Sheath ratio was set to 70 / 30 (mass). Cabin pressure was set to 8 000 Pa. The batt was consolidated by compaction roll at temperature of 80°C. No activation was performed. Pre-consolidated batt was thermally bonded using a pair of hot calander rollers (smooth roller temperature 180°C, embossed roller temperature 190°C), of which the embossed roller is provided with an elevated pattern known as gravure U 2888 (by Ungricht) with a total bonding area of 18.1 %. Supplementary polyester composition 1 (SI) for examples 1-8 is represented by r(PET / coPET) produced at single screw regranulation line from scrap of bicomponent filaments, where the core was produced from PET2 resin and the sheath from PET3 resin. Supplementary polyester composition 2 (S2) for example 11 is represented by r(PET / coPET) produced at single screw, supplementary polyester composition 3 (S3) for example 10 is represented by r(PET / coPET) produced at twin screw regranulation line, both of them from scrap of bicomponent filaments, where the core was produced from PET1 resin and the sheath from PET3 resin. Supplementary composition was dosed to filament - concentrations shown in Table 2. Properties of polyester components are shown in Table 1.

[0218] Table 2: examples 1-11

[0219]

[0197] Examples 1 - 8 represent one polymer composition with varying concentration of supplementary polyester composition. Example 1 represents a comparative sample of fabric without any supplementary polyester composition. From the shown data it is clear that when supplementary polyester composition is added to the sheath (second component comprising boding polyester composition), overall tensile of fabric increases (+13 to + 20% in MD at examples 4 to 7). Filament diameter and basis weight of the nonwoven remains withing normal technological variation and does not place any ground for such a big increase in tensile strength. Examples 9-11 show the same principle on nonwoven fabric of with slightly different polymers composition and different supplementary polyester composition resin (+8% and +29% in MD).

[0220]

[0198] Comparative examples 2 and 3 show that adding supplementary polyester composition to the core (carrier polyester composition) does have negative effect on fabric tensile strength - here with growing concentration of supplementary polyester composition grows also drop in tensile (-16% and -20% in MD).

[0221]

[0199] Example 8, according to the invention shows how negative effect of dosing supplementary polyester composition into core (first component) can be balanced by dosing it to the sheath (second component).

[0222]

[0200] Examples 12-17:

[0223]

[0201] In the following examples 12-17 of the production of nonwoven fabric, two REICOFIL 5 bicomponent spunbond beams core / sheath type have been used. The core / sheath mass ratio was 70 / 30. The core (carrier polyester composition) was produced from XPURE Polyester V062 resin from Indorama (PET1) and the sheath was produced using XPURE Polyester 701K resin from Indorama (PET3). Cabin pressure was set to 10 500 Pa. The batt was consolidated by compaction roll at temperature of 65°C. No activation was performed. Pre-consolidated batt was thermally bonded using a pair of hot calender rollers (smooth roller temperature 203°C, embossed roller temperature 213°C), of which the embossed roller is provided with an elevated pattern known as gravure with a total bonding area of 24.0 %. Supplementary polyester composition is represented by S2 resin. Supplementary composition was dosed to filament - concentrations shown in Table 3. Properties of polyester components are shown in Table 1.

[0224] Table 3: Examples 12 to 17

[0225]

[0202] Examples 13-17 show results from fast high throughput commercial line. Example 12 represents a comparative sample of fabric without any supplementary polyester composition. Similarly to examples 4-7, examples 13 and 14 show mild increase (+5%) of fabric tensile strength when supplementary polyester composition is added to the sheath (second component, bonding polyester composition). In the following examples 15-17, concentration of 5 mass % of supplementary polyester composition in the sheath is kept and concentration of supplementary polyester composition in the core is increased gradually. Apart of previous examples, here the "impurity" effect is lower, and without being bound by a theory, we believe, positive effect of cohesivity and possibly also carrier polyester composition flexibility in synergy with an advantages of supplementary polyester composition presence in bonding polymer composition brings further increase in fabric tensile strength (+16% at example 15). With increasing concentration of supplementary polyester composition in the core, "impurity" effect gets stronger and overall tensile strength is geting worse - still with dosing 5% / 5% comparable to comparative example 12.

[0226] VIII. Testing methodology

[0227]

[0203] The "basis weight" of a nonwoven fabric is measured using testing methodology according to norm EN ISO 9073-1:1989 (corresponding to methodology WSP 130.1). For measurement, 10 layers of nonwoven fabric are used, whilst the sample size is 10x10 cm2.

[0228]

[0204] The "tensile strength" and "elongation" of a nonwoven fabric is measured using testing methodology according to WSP 110.4. R4 (12) standard.

[0229]

[0205] The "DSC" or "Differential scanning calorimetry" measurement is measured using testing methodology according to CSN EN ISO 11357-3 Plastics - Differential scanning calorimetry (DSC) - Part 3: Determination of temperature and enthalpy of melting and crystallization; where: first heating: 20-310°C; speed 10 K / min first cooling: 310-20°C; speed -lOK / min - second heating: 20-310°C, 10 K / min second cooling: 310-20°C; speed -lOK / min

[0230]

[0206] The "complex shear viscosity" defined at constant angular frequency of a polymer or polymer composition is measured according to ISO 6721-10: Plastics — Determination of dynamic mechanical properties — Part 10: Complex shear viscosity using a parallel-plate oscillatory rheometer; where amplitude of shear strain deformation of 5% at angular frequency of 1 rad.s1at temperature of 270°C was applied within 5 minutes of experiment run under nitrogen atmosphere.

[0231] IX. Industrial applicability

[0232]

[0207] The invention is applicable wherever a polyester nonwoven fabric is required — for example in the hygiene industry as various components of absorbent hygiene products (e.g. baby diapers, incontinence products, female hygiene products, changing pads, etc.) or in healthcare, for example, as a part of wound sponges and / or protective garments, surgical cover sheets, underlays and other barrier material products. Further uses are also possible in industrial applications, for example, as a part of protective garments, in filtration, insulation, packaging, sound adsorption, footwear industry, automotive, furniture, etc. The invention is usable with an advantage particularly in applications, where there is a requirement for polyester fabric and also stress on sustainability.

Claims

Claims1. A method of producing a nonwoven fabric, comprising the steps ofA) melting separately i. a first component comprising a carrier polyester composition, and ii. a second component comprising- a bonding polyester composition and having its melting point lower than the carrier polyester composition and- at least one supplementary polyester composition, wherein the bonding polyester composition comprises at least one bonding polyester, andB) feeding the molten polymeric materials to capillaries of a spinning beam and extruding the molten polymeric materials through the capillaries,C) forming endless filaments from the molten polymeric materials exiting the capillaries,1. wherein the second component extends in the longitudinal direction of the filaments and forms at least a part of the surface of the filaments, andD) cooling of the formed filaments by fluid medium having a temperature within the range of 10 to 90 °C and drawing the filaments with a draw down ratio within the range of 200 - 1300, andE) laying the filaments randomly on a formation belt to form a nonwoven filamentary batt, andF) thermally bonding the filamentary batt.

2. The method of producing a nonwoven fabric according to claim 1, wherein the second component comprises at least 1 mass % of supplementary polyester composition, preferably at least 2.5 mass % of supplementary polyester composition, with an advantage at least 4 mass % of supplementary polyester composition, more preferably at least 5 mass % of supplementary polyester composition.

3. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the second component comprises up to 90 mass % of supplementary polyester composition, preferably up to 85 mass %, more preferably up to 75 mass %, most preferably up to 50 mass %.

4. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the carrier polyester composition comprises one or more carrier polyesters.

5. The method of producing a nonwoven fabric according to claim 4, wherein the carrier polyester is a semi-crystalline polymer.

6. The method of producing a nonwoven fabric according to claim 4 or 5, wherein the carrier polyester is polyethylene terephthalate.

7. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the carrier polyester is a polyester having crystallization enthalpy at first cooling of at least 2 J / g, preferably at least 4 J / g, with an advantage at least 6 J / g, most preferably at least 10 J / g.

8. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the carrier polyester has full width at half maximum of crystallization peak at first cooling of at least 12°C.

9. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the carrier polyester has full width at half maximum of crystallization peak at first cooling of at most 50°C.

10. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the carrier polyester or the carrier polyester composition has heat of fusion of at least 35 J / g.

11. The method of producing a nonwoven fabric according to any of the preceding claims, wherein carrier polyester composition in the filament component provides complex shear viscosity in the range of 250-500 Pa.s under amplitude of shear strain deformation of 5% at angular frequency of 1 rad.s-1 at temperature of 270°C defined within 5 minutes of experiment run under nitrogen atmosphere.

12. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the bonding polyester composition comprises one or more bonding polyesters.

13. The method of producing a nonwoven fabric according to claim 12, wherein the bonding polyester is a copolymer of polyethylene terephthalate.

14. The method of producing a nonwoven fabric according to any of the preceding claims 12 to 13, wherein the bonding polyester is a polyester having crystallization enthalpy at first cooling of at most 10 J / g, preferably at most 8 J / g, with an advantage at most 5 J / g, most preferably at most 2 J / g.

15. The method of producing a nonwoven fabric according to any preceding of the preceding claims 12 to 14, wherein bonding polyester or bonding polyester composition has heat of fusion of at most 35 J / g.

16. The method of producing a nonwoven fabric according to any of the preceding claims, wherein bonding polyester composition of a filament component provides complex shear viscosity in the range of 40-150 Pa.s at temperature of 270°C under amplitude of shear strain deformation of 5% at angular frequency of 1 rad.s-1 at temperature of 270°C defined within 5 minutes of experiment run under nitrogen atmosphere.

17. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the supplementary polyester composition comprises one or more of the carrier polyesters.

18. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the supplementary polyester composition has crystallization enthalpy at first cooling of at least 2 J / g, preferably at least 4 J / g, with an advantage at least 6 J / g, most preferably at least 10 J / g.

19. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the supplementary polyester composition has full width at half maximum of crystallization peak at first cooling of at most 12°C.

20. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the supplementary polyester composition has heat of fusion of at least 35 J / g.

21. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the supplementary polyester composition of a filament component provides complex shear viscosity in the range of 150-250 Pa.s under amplitude of shear strain deformation of 5% at angular frequency of 1 rad.s1at temperature of 270°C defined within 5 minutes of experiment run under nitrogen atmosphere.

22. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the supplementary polyester composition is provided for step A) in the form of fibers and / or nonwoven substantially formed of PET / coPET composition.

23. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the supplementary polyester composition comprises recycled carrier polyester composition and recycled bonding polyester composition.

24. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the supplementary polyester composition comprises at least 20 mass % of recycled carrier polyester composition, preferably at least 30 mass % of recycled carrier polyester composition, with an advantage at least 40 mass % of recycled carrier polyester composition, most preferably at least 50 mass % of recycled carrier polyester composition.

25. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the supplementary polyester composition comprises at least 5 mass % of recycled bonding polyester composition, preferably at least 10 mass % of recycled bonding polyester composition, with an advantage at least 15 mass % of recycled bonding polyester composition, most preferably at least 20 mass % of recycled bonding polyester composition.

26. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the supplementary polyester composition comprises recycled carrier polyester composition, recycled bonding polyester composition and recycled supplementary polyester composition.

27. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the supplementary polyester composition comprises at least 20 mass % of recycled PET, preferably at least 30 mass % of recycled PET, with an advantage at least 40 mass % of recycled PET, most preferably at least 50 mass % of recycled PET.

28. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the supplementary polyester composition comprises at least 5 mass % of recycled coPET, preferably at least 10 mass % of recycled coPET, with an advantage at least 15 mass % of recycled coPET, most preferably at least 20 mass % of recycled coPET.

29. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the bonding polyester composition has a lower melting temperature than the carrier polyester composition by at least 5°C, preferably at least 10°C, with an advantage at least 15°C, more preferably at least 20°C.

30. The method of producing a nonwoven fabric according to any of the preceding claims, wherein melting temperature of the supplementary polyester composition is lower than melting temperature of the bonding polyester composition by at most 10°C.

31. The method of producing a nonwoven fabric according to any of the preceding claims, wherein melting temperature of the supplementary polyester composition is higher than the melting temperature of the bonding polyester composition, wherein the difference is at most 50°C, preferably at most 30°C, with an advantage at most 20°C, most preferably at most 10°C.

32. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the difference of supplementary polyester composition crystallization enthalpy atfirst cooling and at least one bonding polyester present in the bonding polyester composition crystallization enthalpy at first cooling is at least 10 J / g, preferably at least 20 J / g, with an advantage at least 30 J / g.

33. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the difference in full width at half maximum of crystallization peak at first cooling between the carrier polyester composition and the supplementary polyester composition is at least 2°C, preferably at least 3°C, with an advantage at least 5°C.

34. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the difference of the carrier polyester composition heat of fusion and the bonding polyester composition heat of fusion is at least 5 J / g, preferably 7 J / g, with an advantage 10 J / g-35. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the second component forms at least 10% of filament mass, with an advantage at least 15% of filament mass, preferably at least 20% of filament mass.

36. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the second component forms at most 60% of filament mass.

37. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the first component forms at most 90% of filament mass, preferably at most 80% of filament mass, with an advantage at most 70% of filament mass.

38. The method of producing a nonwoven fabric according to any of the preceding claims, wherein in steps B) to D) filaments with concentric core-sheath or eccentric core-sheath or side-by-side cross-section are produced.

39. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the first component comprises the supplementary polyester composition in an amount of at least 2.5% of mass of the first component, preferably at least 5% of mass of thefirst component, with an advantage at least 7.5% of mass of the first component, more preferably at least 10% of mass of the first component.

40. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the first component comprises the supplementary polyester composition in an amount of up to 90% of mass of the first component, preferably up to 85% of mass of the first component, with an advantage up to 75% of mass of the first component, more preferably up to 50% of mass of the first component.

41. The method of producing a nonwoven fabric according to any of the preceding claims, wherein the supplementary polyester composition mass percentage concentration is same or lower in the first component than in the second component.

42. The method of producing a nonwoven fabric according to any of the preceding claims, wherein in the step F) thermally bonding the filamentary batt is performed by air-through- bonding.

43. The method of producing a no nwoven fabric according to any of the claims I to 41, wherein in the step F) thermally bonding is performed by a pair of heated rollers.

44. The method of producing a nonwoven fabric according to claim 43, wherein in the step F) thermally bonding is performed by a pair of smooth and embossed heated rollers.

45. A nonwoven fabric produced according to any of the preceding claims.

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