Layered nonwoven fabric

Abstract

a first layer (T) of filaments comprising endless filaments containing a first carrier polymer (A1) and a first adhesive polymer (B1), said first adhesive polymer (B1) forming at least a part of the surface of said endless filaments and having a melting point at least 5°C lower than said first carrier polymer (A1); said first layer (T) of filaments comprising a plurality of spaced apart adhesive points interconnecting filaments and formed from said first adhesive polymer (B1); and a second layer (M) of filaments comprising filaments comprising a carrier material having a stiffness lower than that of said first carrier polymer (A1) and a second adhesive polymer (B2) having a melting point at least 5°C lower than that of said carrier material and first carrier polymer (A1), preferably at least 10°C lower, said second layer (M) of filaments comprising a plurality of spaced apart bond points which interconnect the filaments of the second layer (M) and which consist of said second adhesive polymer (B1).

Description

[Technical Field]

[0001] The present invention relates to a layered nonwoven fabric comprising at least two layers of filaments. The first layer of filaments comprises endless filaments containing a first carrier polymer and a first adhesive polymer, the first adhesive polymer forming at least a portion of the surface of the endless filaments and having a melting point at least 5°C lower than the first carrier polymer. The first layer of filaments comprises spaced bond points interconnecting the filaments and comprising the first adhesive polymer. The result is a soft, lofty spunmelt nonwoven fabric with good recovery and abrasion resistance, which is suitable for a variety of hygiene products as well as filtration and the like. The invention also encompasses a process for making the nonwoven fabric. [Background technology]

[0002] It is possible to bulk nonwoven fabrics using several known methods - namely, the selection of suitable polymers, modification of the filament shape (variously and using various methods of crimping or curving filaments) and bonding methods - thermally (e.g., calendering with a suitable embossed pattern, air-laying, ultrasonic bonding, etc.), mechanically (e.g., water-laying, needle-punching, etc.) or by a combination of several bonding methods.

[0003] Generally, the bulkier the material, the "looser" its structure, and the more advantageous it is for the bonding method not to compress the material. For example, bonding with a calendar roller generally results in the bonding embossment points being significantly thinner than the surrounding areas (see, for example, patent application WO2017190717, or its predecessor application WO2017190717). In this respect, it is more advantageous, for example, to use hot air for bonding while no compression occurs.

[0004] The coarseness of a structure is understood primarily as the presence of free space between the filaments, and is indicated by the terms "void ratio" or "void volume". The greater the proportion of free space between the filaments, the more important the stiffness of the individual filaments becomes. If the filaments are too flexible, they will not hold their structure, they will bend, and the whole structure will collapse - resulting in a fabric with a lower thickness than expected. This is particularly true with polyolefin-based filaments. This problem can be solved by using a stiffer polymer (e.g. polyester). This polymer is sufficiently stiff to maintain even very open fabric structures and has the advantage (i.e., resilience) of being able to return to its original bulk after compression (especially in airlaid materials) - see, for example, patent application WO2018059610, which describes the use of crimped filaments with a so-called crimp-compatible cross-section (e.g., eccentric core / sheath), and our own Czech patent application PV2018-647 (unpublished), which describes, for example, the use of filaments with a non-crimp-compatible cross-section (e.g., concentric core / sheath).

[0005] Although stiffer, less flexible filaments allow for the formation of a bulkier structure that can regain its initial loft after compression, stiffer, less flexible filaments can adversely affect the overall softness, flexibility, and drapeability of the nonwoven fabric, properties that are important especially in applications where the fabric is close to or in direct contact with the user's body (e.g., absorbent hygiene products).

[0006] To solve this problem, there are well-known attempts to layer filaments with different properties. Unlike worsted nonwovens, standard production lines for spunmelt nonwovens do not allow for direct blending of filaments from a single spin beam. The individual layers of stacked filaments must then be glued together, resulting in a combination of filaments based on the same polymer - see for example European Patent Application No. 2015153790, a joint patent application by Reifenhauser and Fibertex Personal Care, which describes the combination of layers based on polyolefins with different degrees of crimp.

[0007] Another attempt known in the art to achieve bulk exploits the different behavior of drawn filaments when activated with hot air, for example, by producing a layer of known shrinkage (e.g., bicomponent filaments of the PET / PE type), which is then bonded via adhesive points with a layer of low or no shrinkage (e.g., PP / PE) using a calender roller. This structure is then activated by a heat flow (e.g., hot air), causing the shrinkable layer to shrink and the non-shrinkable layer to be forced to curve into a "cushion" between the bonding impressions - see, for example, the patent application by Reifenhauser GmbH and KG Maschinenfabrik GmbH, European Patent Application No. 3192910. Summary of the Invention

[0008] The drawbacks and deficiencies of the prior art are overcome to a large extent by a layered nonwoven fabric comprising: a first layer of filaments, the layer comprising endless filaments comprising a first carrier polymer and a first adhesive polymer, the first adhesive polymer forming at least a part of the surface of the endless filaments and having a melting point at least 5°C lower than that of the first carrier polymer, while the first layer of filaments comprises a plurality of spaced apart adhesive points, the adhesive points interconnecting the filaments and consisting of the first adhesive polymer; a second layer of filaments comprising filaments containing a carrier material having a lower stiffness (typically tensile stiffness and / or bending stiffness) than said first carrier polymer and a second adhesive polymer having a melting point at least 5°C lower, more preferably at least 10°C lower, than said carrier material and said first carrier polymer, while said second layer of filaments comprises spaced apart adhesive points which interconnect the filaments and which consist of said second adhesive polymer.

[0009] The nonwoven fabric of the present invention does not have binding emboss points.

[0010] Preferably, the median spacing between adjacent bonded points in the first layer of filaments is 8 mm or less and / or the median spacing between adjacent bonded points in the second layer of filaments is 8 mm or less.

[0011] Similarly, advantageously, the carrier material of the filaments in the second layer of filaments is a second carrier polymer having a tensile or bending strength at least 100 MPa lower than the first carrier polymer, the second adhesive polymer forming at least a part of the surface of these filaments, and these filaments of the second layer being endless filaments.

[0012] Advantageously, the melting points of the first adhesive polymer and the second adhesive polymer differ by 0-5°C or are the same.

[0013] Preferably, the first carrier polymer and / or the second carrier polymer are selected from the group consisting of polyolefins, polyesters, polyamides and copolymers thereof, and / or the first adhesive polymer and / or the second adhesive polymer are selected from the group consisting of polyolefins, polyesters, polyamides and copolymers thereof.

[0014] Advantageously, the first carrier polymer forms at least 55% by weight of the filaments in the first layer and / or the second carrier polymer forms less than 55% by weight of the filaments in the second layer (M).

[0015] In a particularly advantageous configuration, the ratio of the weighted average density of the polymer in the endless filaments of the first layer to the weighted average density of the polymer in the endless filaments of the second layer is 1.0 to 1.5, preferably 1.1 to 1.3, and / or the ratio of the basis weight of the first layer to the basis weight of the second layer is 1.0 to 1.5, preferably 1.1 to 1.3.

[0016] The deficiencies of the prior art are likewise overcome to a large extent by a method for producing a layered nonwoven fabric, which comprises the following steps: a) A first carrier polymer and a first adhesive polymer having a melting point at least 5°C lower than that of the first carrier polymer are melted and then fed into a spinneret of a first spinning beam, thereby forming endless filaments having at least a portion of their surface made of the first adhesive polymer, and the filaments thus formed are drawn while being cooled and then deposited on a moving belt to form a first layer of filaments. b) depositing a second layer of filaments on the first layer of filaments, the second layer comprising a carrier material having a lower stiffness than the first layer of filaments; and a melting point of the second adhesive polymer is at least 5°C, more preferably at least 10°C, lower than the carrier material and the first carrier polymer. c) Then, by the effect of air heated to 100°C to 250°C, preferably 120°C to 220°C, more preferably 90°C to 140°C, and most preferably 110°C to 130°C, the first layer of filaments is consolidated by forming adhesion points from the first adhesive polymer between the filaments, and the second layer of filaments is consolidated by forming adhesion points from the second adhesive polymer. In step b), advantageously, a carrier material is melted as a second carrier polymer, said second carrier polymer having a bending stiffness and a tensile stiffness at least 100 MPa, preferably at least 200 MPa, more preferably at least 300 MPa, even more preferably at least 400 MPa, advantageously at least 500 MPa lower than the first carrier polymer and the second adhesive polymer, and is fed to the spinneret of the second spinning beam, thereby forming endless filaments at least part of whose surface consists of the second adhesive polymer, whereupon the thus formed filaments are cooled, drawn off and then deposited on a moving belt together with the first layer of filaments. Similarly, in step c), the heated air acts on the bed (T, M) for a time period of 200 to 20,000 ms, preferably 200 to 15,000 ms, most preferably 200 to 10,000 ms, and / or in step c), the heated air is advantageously fed through the bed (T, M) at a velocity in the range of 0.2 to 4.0 m / s, preferably 0.4 to 1.8 m / s.

[0017] Advantageously, the method further comprises a step of pre-consolidation of the layers after step b) and before step c), wherein pre-consolidation of the layers is carried out by heating the layers to a temperature in the range of 80 to 180°C, preferably 90 to 150°C, most preferably 110 to 140°C to partially soften the adhesive polymer.

[0018] definition The term "layer of filaments" refers to material in the form of filaments before they are glued together for the purpose of consolidation, a procedure that can be carried out in various ways, for example by forming connections through the ventilation effect or the calendaring effect. A "layer of filaments" usually consists of individual filaments that are not yet attached to each other, and while these filaments may be pre-interconnected / pre-integrated in a specific way, this pre-integration may be carried out during the deposition of the filaments or immediately after the deposition of the filaments, respectively, as part of the expansion of the layer of filaments. However, this pre-integration still leaves a significant number of filaments free to move and thus capable of rearrangement. The aforementioned "layer of filaments" may consist of one or more layers gradually deposited from several spinning beams.

[0019] The term "filament" is defined herein as essentially an endless filament, while the term "staple fiber" refers to a fiber that has been cut to a defined length. The terms "fiber" and "filament" are used interchangeably herein. In the case of cut fibers, only the term "staple fiber" is used.

[0020] The term "interfilament bond" or "bond point" refers to a bond that connects two filaments, usually where those filaments cross each other or where they touch or are adjacent to each other. A bond point / integral bond can connect more than two filaments or connect two portions of the same filament.

[0021] Therefore, the term "bonding point" in this specification refers to the connection of two fibers / filaments at the point of contact due to the interconnection of the component exhibiting a lower melting point. At the bonding point, the component of the filament formed with a higher melting point is not deformed or damaged. Conversely, the term "bonding impression" refers to the surface affected by the bumps of the calendar roller. The bonding impression has an area determined by the size of the bumps of the bonding roller and is generally thinner compared to the adjacent areas. During the bonding process, the area of ​​the bonding impression is generally subjected to high mechanical pressure, which, together with the temperature, may affect the shape of all filament components within the area of ​​the bonding impression.

[0022] The term "monocomponent filament" or "monocomponent fiber" refers to a filament formed from a single polymer or a single polymer blend, and is therefore distinct from a bicomponent or multicomponent filament.

[0023] The term "multicomponent fiber or filament" refers to a fiber or filament incorporating two or more individual subcomponents in its cross section, each of which is composed of a different polymer compound or a different blend of polymer compounds. Therefore, the term "multicomponent fiber / filament" is a broader term that includes, but is not limited to, "bicomponent fiber / filament." The various components of a multicomponent filament are typically arranged in distinct regions along the cross section of the filament and extend continuously along the length of the filament. The cross section of a multicomponent filament may be divided into several subsections, each of which may be of any shape or arrangement, including, for example, a coaxial arrangement of the subcomponents, a core / sheath arrangement, a radial arrangement, or a so-called "lands-in-the-sea" arrangement.

[0024] The terms "bicomponent" and "bicomponent" used to describe filaments are used interchangeably herein.

[0025] The measurement "filament diameter" is expressed in μm. The terms "grams of filament per 9000 m" (also called denier or den) or "grams of filament per 10000 m" (also called dTex) are used to express the degree of fineness or coarseness of the filament, as they correlate to the filament diameter (assuming a circular filament cross section) multiplied by the density of the material or materials used.

[0026] "Machine direction" (MD) - In relation to the manufacture of nonwoven fibrous materials and the actual nonwoven fibrous materials themselves, the term "machine direction" (MD) refers to the direction that corresponds essentially to the direction of forward movement of the nonwoven fibrous material on the manufacturing line that produces that material.

[0027] "Cross Direction" (CD) - In relation to the manufacture of nonwoven fibrous materials and the actual nonwoven fibrous material itself, the term "cross direction" (CD) refers to a direction that lies essentially in the plane of the nonwoven fibrous material, but is transverse to the direction of forward movement of the nonwoven fibrous material on the manufacturing line on which it is produced.

[0028] "Nonwoven material" or "nonwoven fabric" means a belt-like or fibrous formation made from directionally or randomly oriented filaments which are first formed during the formation of a filament layer, then consolidated together by friction or the induced cohesive or adhesive forces, and finally by the formation of interbonds. This consolidation may be achieved thermally (e.g., by airing, calendaring, ultrasonic effects, etc.), chemically (e.g., by the use of adhesives), mechanically (e.g., by hydroentangling, etc.), or by a combination of these methods. The term does not refer to fabrics formed by weaving or knitting, or to fabrics which use yarns or fibers to form bonded seams. The fibers may be of natural or synthetic origin and may be staple yarns, continuous fibers, or fibers produced directly at the processing site. Commercially available fibers range in diameter from less than about 0.001 mm to more than about 0.2 mm and come in a variety of forms: short fibers (known as staple or cut fibers), continuous individual fibers (filament or monofilament fibers), untwisted bundles of filaments (combed fibers), and twisted bundles of filaments (yarns). Nonwoven fabrics can be produced using many processes, including techniques such as meltblowing with staple fibers, spunbonding, spunmelt, solvent-based spinning, electrospinning, carding, film fibrillation, fibrillation, air-laying, dry-laying, wet-laying, and various combinations of these processes known in the art. The basis weight of a nonwoven fabric is typically measured in grams per square meter (g / m 2 )

[0029] As used herein, the term "layer" refers to a partial component or element of a fabric. A "layer" may be in the form of multiple filaments produced on a single spin beam or on two or more successively arranged spin beams that form essentially the same filaments. For example, two successively arranged spin beams intended for spunbonding processes can be combined to produce a single layer by being set up essentially the same and processing polymers of essentially the same composition. Conversely, if two spunbond-type spin beams, one producing, for example, monocomponent filaments and the other producing, for example, bicomponent filaments, two distinct layers are formed. The composition of a layer can be determined based on knowledge of the individual settings and components that determine the resin (polymer) composition used to form the layer, or by analysis of the nonwoven itself, for example, using an electron microscope, or by analysis of the composition used to produce the filaments contained in the layer by DSC or NMR techniques. Adjacent layers of filaments do not necessarily need to be strictly separated; intermingling of layers at their boundaries may occur as a result of filaments from a later layer falling into gaps between the filaments of a previously deposited layer.

[0030] The "spunbond" process is a nonwoven fabric manufacturing process in which a layer of nonwoven filaments having randomly oriented filaments is formed by converting a polymer directly into filaments and then depositing the filaments thus formed. This nonwoven layer of filaments is then consolidated into a nonwoven fabric by forming bonds between the filaments. The consolidation process can be carried out using various methods, such as air circulation or calendaring.

[0031] "Activation" is understood to be the process by which a fiber, filament or fibrous structure in a semi-stable state (i.e., the lowest possible energy state in which no crystallization has occurred) is heated and then slowly cooled, resulting in the transformation of said semi-stable state into a different, more stable state (i.e., a state corresponding to a different crystallization phase). If we assume that the new state has a different volume from the original state, i.e., a smaller volume, then this is defined as "shrinkage" or "contraction."

[0032] As used herein, the term "crimp-formable cross-section" refers to a multicomponent filament in which components with different properties are arranged across its cross-section. These filaments are arranged so that they follow the force vector that causes contraction when the filament is manufactured or subsequently heated to or above an activation temperature and then slowly cooled to crimp the filament. Although the interfacial adhesion between these filaments prevents the filaments contained within the fiber layer from forming an ideal helical shape, the so-called helical crimp forms when the filament unwinds. In a multicomponent filament, the center of gravity of each individual component in the cross-section of the filament can be determined (based on measurements of the surface / position of these components in a given cross-section—see Figure 5). Without being bound by theory, we assume that if the center of gravity of the entire surface of each component is essentially at the same point, heating to an activation temperature will not result in crimping on the filament. For example, in a bicomponent filament with a circular cross-section in which one polymer component forms the core and the other the sheath, and both are relatively concentric, the centers of gravity of both components are at the center of the cross-section.

[0033] The term "compressibility" as used herein refers to the distance in millimeters that a nonwoven fabric will compress under the influence of the load defined in the measurement of "resilience."

[0034] The term "recovery" as used herein refers to the ability of a fabric to recover its original shape after compression, which is primarily related to the ability to recover bulkiness based on the ratio of the fabric thickness after the release of the applied load to the initial thickness of the fabric.

[0035] Preferred embodiments of the present invention will now be described in more detail with reference to the accompanying schematic drawings. [Brief explanation of the drawings]

[0036] [Figure 1] 1A and 1B are diagrams showing examples of the external shape of a filament cross section. [Figure 2] FIG. 10 is a diagram showing an example of a cross section that does not correspond to the crimp of the fiber. [Figure 3] 1 is a graph illustrating the orientation of the directional placement of filaments in the plane of a layer of the present invention. [Figure 4] Photographs of filament severing before and after activation. [Figure 5] 1A and 1B are diagrams showing examples of cross sections corresponding to crimps of filaments. [Figure 6] FIG. 1 shows a comparison of micrographs of filaments with various levels of crimp. [Figure 7A] This is a diagram comparing the cross sections of fabrics bonded using embossing and fabrics bonded using adhesive points. [Figure 7B] This is a diagram comparing the cross sections of fabrics bonded using embossing and fabrics bonded using adhesive points. [Figure 8] 10 is a diagram showing an example of a cross section of a second layer M. FIG. [Figure 9] 10 is a diagram showing an example of a cross section of another second layer M. FIG. [Figure 10] 10 is a diagram showing an example of a cross section of another second layer M. FIG. [Figure 11] A top-down view of the second layer M. [Figure 12] FIG. 1 is a schematic explanatory diagram of a production line. [Figure 13] FIG. 1 is a perspective view of a Martindale average abrasion rating test apparatus. [Figure 14] FIG. 1 shows the rating index for evaluation of the Martindale Average Abrasion Resistance Rating Test. DETAILED DESCRIPTION OF THE INVENTION

[0037] The subject of the present invention is a thermally bondable nonwoven fabric formed from endless filaments of the spunmelt type, comprising at least a first layer of filaments (T) and a second layer of filaments (M).

[0038] The first layer of filaments (T) is based on bicomponent or multicomponent endless filaments containing a high-rigidity polymer, at least one of the components of the filaments being based on a first high-rigidity carrier polymer A1, and at least one of the other components present on at least a portion of the surface of the filaments being based on a first adhesive polymer B1 having a melting point lower than that of the first carrier polymer A1. Without being bound by theory, the inventors believe that the filaments containing a relatively high-rigidity polymer provide the nonwoven fabric of the present invention with bulk and resilience. It may be advantageous for the first layer of filaments (T) to contain endless spunbond filaments as a solution of the present invention.

[0039] The second layer of filaments (M) is based on bicomponent or multicomponent endless filaments containing a low-rigidity polymer, at least one of the components of the filaments being based on a second carrier polymer A2 having a lower rigidity than the first carrier polymer A1, and at least one other component present on a portion of the surface of the filaments being based on a second adhesive polymer B2 having a lower melting point than the second carrier polymer A2 and compatible with the first adhesive polymer B1 of the first layer of filaments T. Without being bound by theory, the inventors believe that the filaments containing a relatively low-rigidity polymer provide the nonwoven fabric of the present invention with greater softness and extensibility, thereby improving the fabric's hand and feel properties. For the solution of the present invention, it may be advantageous for the second layer of filaments M to contain endless filaments of the spunbond type.

[0040] Alternatively, the second layer of filaments (M) may consist of natural fibers with a relatively low stiffness, for example, combined with adhesive elements (adhesive filaments, powder, etc.) made of polymer B2. In such a case, the force required to bend a single natural fiber is compared with the force required to bend a single fiber of the same fineness (denier) and circular cross section made from polymer A1. Advantageously, for the solution of the invention, this ratio is greater than 1:1.1, more preferably greater than 1:1.2, and advantageously greater than 1:1.5.

[0041] Compatibility between polymers B1 and B2 is defined as their similar melting points and their ability to bond very well to form a strong and stable blend (mixture). Those skilled in the art will understand that polymers exhibit specific behavior. When heated, the temperature first exceeds the softening point, at which point the polymer begins to soften and is capable of bonding filaments together under hot air bonding conditions, and then the temperature reaches the melting point, at which the polymer transitions to a completely liquid phase. This transition to a liquid phase is undesirable from the standpoint of thermal bonding, as a completely liquid polymer would move freely in the structure, drip, form undesirable clusters, etc. From the standpoint of the present invention, it is desirable for polymers B1 and B2 to exhibit a common range in their intervals (softening point, melting point). In general, well-blendable polymers with a melting point difference of no more than 10°C, preferably no more than 5°C, can be assumed to be suitable for use in accordance with the present invention. It is advantageous to use the same polymer as polymer B2 as polymer B1.

[0042] The adhesive polymers B1 and B2 may form part of a blend with another polymer and / or may have various additives blended therein (e.g., color pigments, additives that promote the mutual compatibility of the polymers, functional additives, additives that modify the surface properties of the polymer, etc.) The blend polymers B1 and B2 may consist of virgin new polymers; may consist of blends of virgin polymers with recycled polymeric materials; or may consist purely of recycled materials.

[0043] The first carrier polymer A1, which has a higher stiffness (than A2), is a thermoplastic polymer suitable for processing in a spunmelt production line, said thermoplastic polymer preferably belonging to the polymer group of polyolefins, polyesters, polyamides or copolymers of these groups, such as polypropylene (PP), polyethylene terephthalate (PET), polylactic acid (PLA), etc.

[0044] The second carrier polymer A2, which has a lower stiffness (than A1), is a thermoplastic polymer suitable for processing in a spunmelt production line, said thermoplastic polymer preferably belonging to the polymer group of polyolefins, polyesters, polyamides or copolymers of these groups, such as polypropylene (PP), polyethylene terephthalate (PET), polylactic acid (PLA), etc.

[0045] The carrier polymers A1 and A2 may consist of virgin virgin polymers; may consist of blends of virgin polymers and recycled polymeric materials; or may consist of purely recycled materials.

[0046] The stiffness of a polymer can be expressed, for example, using the flexural modulus (flexural modulus) or tensile modulus (Young's modulus), which are significantly correlated with each other. Both the flexural and tensile moduli can be defined for both specific polymers and blends of polymers, and can therefore express the stiffness of the polymer, the stiffness of the elements of the filament, or the stiffness of the combination of polymers that represent the entire filament.

[0047] For example, the average flexural moduli for selected polymers are shown in the table below. TIFF0007729829000001.tif32127

[0048] As a solution of the present invention, it is advantageous if the difference between the stiffness of the first carrier polymer A1 and the stiffness of the second carrier polymer A2, expressed in tensile modulus (Young's modulus), is at least 100 MPa, more preferably at least 200 MPa, even more preferably at least 300 MPa, even more preferably at least 400 MPa, advantageously at least 500 MPa.

[0049] As a solution of the present invention, it is advantageous if the difference between the stiffness of the first carrier polymer A1 and the stiffness of the second carrier polymer A2, expressed in flexural modulus (flexural modulus), is at least 100 MPa, more preferably at least 200 MPa, even more preferably at least 300 MPa, even more preferably at least 400 MPa, advantageously at least 500 MPa.

[0050] The tensile and flexural moduli must be specified individually for each specific polymer. For flexural moduli, standard ISO 178:2010 is used, and for tensile moduli, standard CSN EN ISO 527-1 (640604) is used.

[0051] The adhesive polymers B1 and B2 with a lower melting point (than A1 and A2) are thermoplastic polymers suitable for processing in spunmelt production lines, said thermoplastic polymers advantageously belonging to the polymer group of polyolefins, polyesters, polyamides or copolymers of these groups. Suitable solutions include, for example, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polylactic acid (PLA), nylon and so-called low-melting copolymers, mainly of the above-defined groups (e.g. PP / PE copolymers, PET copolymers, PLA copolymers, etc.).

[0052] For example, a bicomponent filament comprises two elements arranged within the cross section of the filament. For example, a core-sheath (C / S) bicomponent filament comprises two elements, one representing the core of the filament and the other surrounding it to form the surface of the filament. A carrier polymer A with defined stiffness is advantageously used in this specification for the core, and the carrier polymer A either directly forms the core or is one of the input materials of a blend that forms the core of the filament. A low-melting adhesive polymer B forms the sheath or is one of the input materials of a blend that forms the sheath of the filament. Similarly, side-by-side (S / S) and eccentric core-sheath (eC / S) bicomponent filaments can be mentioned.

[0053] Advantageously, the solution of the invention is that the first component of the bicomponent filaments (e.g. the core, one side of the parallel filaments) has a higher stiffness in the first layer T than in the second layer M. Advantageously, the solution of the invention is that the difference, expressed in tensile modulus (Young's modulus), between the stiffness of the first component of the bicomponent filaments in the first layer T and the stiffness of the first component of the bicomponent filaments in the second layer M is at least 100 MPa, more preferably at least 200 MPa, even more preferably at least 300 MPa, even more preferably at least 400 MPa, advantageously at least 500 MPa.

[0054] As a solution of the invention, it is advantageous if the difference between the stiffness of the first bicomponent component of the filaments in the first layer T and the stiffness of the first bicomponent component of the filaments in the second layer M, expressed as the flexural modulus (flexural modulus), is at least 100 MPa, more preferably at least 200 MPa, even more preferably at least 300 MPa, even more preferably at least 400 MPa, advantageously at least 500 MPa.

[0055] Without intending to be limiting, some examples of material compositions of the present invention include: The solution of the invention may comprise, for example, a first layer T consisting of endless filaments of core / sheath (C / S) type, the core of which is made of PET (=A1) and the sheath of PE (=B1), and a second layer M consisting of endless filaments of core / sheath (C / S) type, the core of which is made of PP (=A2) and the sheath of PE (=B2). The difference in stiffness, expressed in flexural modulus, between polymers A1 and A2 is greater than 500 MPa, and polymers B1 and B2 are identical (PE) and have a melting point lower than that of polymers A1 and A2.

[0056] The solution of the invention may comprise, for example, a first layer T consisting of endless filaments of core / sheath (C / S) type, the core of which is made of PLA (=A1) and the sheath of PE (=B1), and a second layer M consisting of endless filaments of eccentric core / sheath (eC / S) type, the core of which is made of PP (=A2) and the sheath of PE (=B2). The difference in stiffness between polymers A1 and A2, expressed in flexural modulus, exceeds 200 MPa, and polymers B1 and B2 are identical (PE) and have a melting point lower than that of polymers A1 and A2. The filaments of layer M most likely exhibit a tendency to crimp or to crimp spontaneously (latent crimp or self-crimp).

[0057] The solution of the invention may comprise, for example, a first layer T consisting of endless filaments of core / sheath (C / S) type, in which the core is made of PET (=A1) and the sheath of CoPLA (=B1), and a second layer M consisting of endless filaments of side-by-side (S / S) type, in which one side is made of PLA (=A2) and the other side is made of CoPLA (=B2). The difference in stiffness, expressed in flexural modulus, between polymers A1 and A2 is greater than 100 MPa, and polymers B1 and B2 are identical (coPLA) and have a melting point lower than that of polymers A1 and A2. The filaments of layer M may exhibit a tendency to crimp or to crimp spontaneously (latent crimp or self-crimp).

[0058] The solution of the invention may comprise a first layer T consisting of endless filaments of eccentric core / sheath (eC / S) type, for example with a core made of PET (=A1) and a sheath made of PP1 (=B1), and a second layer M consisting of endless filaments of core / sheath (C / S) type, with a core made of PP2 (=A2) and a sheath made of PP3 (=B2). The difference in stiffness between polymers A1 and A2, expressed in flexural modulus, is greater than 200 MPa, and polymers B1 and B2 are compatible (PP1 and PP3) and have a melting point lower than that of polymers A1 and A2. The filaments of layer T most likely exhibit a tendency to crimp or to crimp spontaneously (latent crimp or self-crimp).

[0059] The solution of the invention may comprise a first layer T consisting of endless filaments of eccentric core / sheath (eC / S) type, for example with a core made of PET (=A1) and a sheath made of coPET (=B1), and a second layer M consisting of endless filaments of eccentric core / sheath (eC / S) type, with a core made of PLA (=A2) and a sheath made of coPET (=B2). The difference in stiffness between polymers A1 and A2, expressed in flexural modulus, is greater than 100 MPa, and polymers B1 and B2 are identical (coPET) and have a melting point lower than that of polymers A1 and A2. Both filaments of layers T and M most likely exhibit a tendency to crimp or to crimp spontaneously (latent crimp or self-crimp).

[0060] The solution of the invention may comprise, for example, a first layer T consisting of endless filaments in side-by-side (S / S) configuration, made, for example, from PET (=A1) on one side and coPET (=B1) on the other, and a second layer M consisting of endless filaments in side-by-side (S / S) configuration, made, for example, from PLA (=A2) on one side and coPET (=B2) on the other. The difference in stiffness, expressed in flexural modulus, between polymers A1 and A2 exceeds 100 MPa, and polymers B1 and B2 are identical (coPET) and have a melting point lower than that of polymers A1 and A2. Both filaments of layers T and M most likely exhibit a tendency to crimp or to crimp spontaneously (latent crimp or self-crimp).

[0061] The solution of the present invention may comprise, for example, a first layer T consisting of endless filaments of eccentric core / sheath (eC / S) type, where the core is made of PET (=A1) and the sheath is made of PE (=B1), and a second layer M consisting of short crimped cellulose fibers in a blend with powdered PE for air-laying applications. The ratio of the forces required to bend a single filament is greater than 1.5.

[0062] The solution of the invention may comprise, for example, a first layer T consisting of endless filaments of eccentric core / sheath (eC / S) type, the core of which is made of PP1 (=A1) and the sheath of PE (=B1), and a second layer M consisting of endless filaments of eccentric core / sheath (eC / S) type, the core of which is made of PP2 (=A2) and the sheath of PE (B2). The difference in stiffness, expressed in flexural modulus, between polymers A1 and A2 is greater than 100 MPa, and polymers B1 and B2 are identical (PE) and have a melting point lower than that of polymers A1 and A2. Both filaments of layers (T and M) very likely exhibit a tendency to crimp or to crimp spontaneously (latent crimp or self-crimp).

[0063] The solution of the present invention can comprise, for example, a first layer (T) and a second layer as follows: The first layer (T) consists of endless filaments of eccentric core / sheath (eC / S) type, the core of which is made of PP (=A1) and the sheath of PE (=B1). The second layer (M) consists of endless filaments of eccentric core / sheath (eC / S) type, the core of which is made of a blend (=A2) of several polypropylene-based polymers with different properties (the polymer blend can be formed, without being limited thereto, from homopolymers and copolymers, such as polypropylene, polypropylene with a high melt flow rate, and polypropylene with a low melt flow rate), and the sheath of which is made of PE (B2). The difference in stiffness between polymers A1 and A2, expressed in flexural modulus, exceeds 100 MPa, and polymers B1 and B2 are the same (PE) and have a melting point lower than that of the polymers (A1 and A2). Both filaments of the layers (T and M) are very likely to exhibit a tendency to crimp or a tendency to naturally crimp (latent crimp or self-crimp).

[0064] The stiffness of the filament can be affected not only by the polymer used, but also, for example, by the thickness of the filament. The terms "filament thickness" and "filament diameter" are used interchangeably in this application.

[0065] From the perspective of the present invention, it can be advantageous if the thickness d1 of the filaments in the first layer (T) is greater than the thickness d2 of the filaments in the second layer (M), for example in applications where the most important factor is to achieve both high bulkiness of the nonwoven fabric and the requirement for a soft surface on the nonwoven fabric.

[0066] From the standpoint of the present invention, it can be advantageous if the thickness d1 of the filaments in the first layer (T) and the thickness d2 of the filaments in the second layer (M) are identical or very similar, i.e., d1 / d2 is between 0.8 and 1.3, for example in applications where material homogeneity on the surface and in the cross section is important.

[0067] In view of the present invention, it may be advantageous for the thickness d1 of the filaments in the first layer to be smaller than the thickness d2 of the filaments in the second layer. For example, this may be advantageous in applications where the overall softness and flexibility of the material is important. Those skilled in the art will readily recognize which combinations of filament thicknesses of the present invention are advantageous for their applications.

[0068] The stiffness of a filament can also be affected by the ratio of polymer components in the filament. For example, in the case of two filaments with the same core / sheath diameter d, where the core is made of polymer A and the sheath is made of polymer B, the filament with a lower ratio of core component, i.e., polymer A (e.g., 30%), will have a lower overall stiffness than the filament with a higher ratio of core component, i.e., polymer A (e.g., 50%). Each of the filaments of the first layer (T) and second layer (M) may be contained in the nonwoven fiber in a single or multiple layers.

[0069] For example, the first layer T may form the substrate layer and the second layer M may form the surface of the product (eg TM, TTM, MTM, MTTM, TMM, TTMM, etc.).

[0070] For example, the first layer T may have a coarse structure that allows it to form a narrowed inlet region within the second layer M (e.g., TM, TTM, TMT, TMM, TTTM, etc.).

[0071] For example, layers T and M may be arranged alternately, and the softness of the intermediate layer M may be made denser by the material, and hidden by the rigidity of layer T (for example, MTM, MTMT, MTMTM, TMTMT, etc.).

[0072] The nonwoven fabric of the present invention may also include another layer X, apart from the first layer T and the second layer M, provided that the layer X is thermally bondable to the first and second layers. For example, possible compositions include TXM, MXT, XMT, XTM, MTXTM, XMTMX, MTXM types, and many other types.

[0073] According to the present invention, the nonwoven fabric may also comprise a set of several T-M layers. For example, a nonwoven fabric produced with three spinning beams S1-S2-S3 may form the following layers: layer T1 of S1, layer M1 of S2 (adjacent to layer T1), which is simultaneously layer T2 (adjacent to layer M2) and layer M2 of S3.

[0074] According to the present invention, nonwoven fabrics are thermally bonded. It is generally energetically advantageous to completely thermally bond the volume of the fiber layers that make up the nonwoven fabric, and bonding points may be formed at any intersection of filaments within the structure. During this type of thermal bonding of the present invention, heat is passed through the filament layers, softening and even melting the B polymers of both layers at both the surface and the interface between the layers. At the filament contact points, the molten polymer bonds, and then hardens upon cooling, connecting the contacting filaments. The filament structure thus formed generally exhibits soft-loft type softness and flexibility, and often exhibits resilience. Suitable bonding methods of the present invention include, for example, bonding using a hot air stream or, particularly for low basis weights, bonding using infrared radiation.

[0075] For example, a bicomponent filament comprises two elements arranged within the cross-section of the filament. For example, a core-sheath (C / S) bicomponent filament comprises two elements: the first element represents the core of the filament, and the second element wraps around it, forming the surface of the filament. Polymer B, with its low melting point, is advantageously used here for the sheath, either forming the sheath directly or being one of the input materials in the blend that forms the sheath of the filament. Polymer A, with its defined stiffness, forms the core or is one of the input materials in the blend that forms the sheath of the core. Side-by-side (S / S), eccentric core-sheath (eC / S) bicomponent filaments, etc., can be described similarly. The arrangement of the components of the filament may be a known arrangement based on the setup used for its production, or may be specified using the method known as "estimation of filament cross-section type."

[0076] Advantageously, the solution of the invention is that the second component (e.g., sheath, one of the parallel components) of the bicomponent filament has a lower melting point than the first component. Advantageously, the solution of the invention is that the difference in melting point between the first and second components of the bicomponent filament is at least 5°C, more preferably at least 10°C, advantageously at least 15°C.

[0077] The melting point of polymer B, which has a relatively low melting point, is preferably determined relative to the respective polymer A for which stiffness is defined. For example, in the first layer, the melting point of polymer B1 is determined relative to the melting point of polymer A1. Since first layer T and second layer M are interconnected by polymers B1 and B2, polymer A2 must also be taken into account, and therefore the melting points of both polymers B1 and B2 must be determined relative to polymer A2. The difference in melting point between polymer A2 and B1, B2, respectively, is at least 5°C, more preferably at least 10°C, and advantageously at least 15°C.

[0078] Thermal bonding fundamentally affects the properties of the resulting nonwoven fabric, which is caused by the strength of the interconnections of the filaments, which in turn depends on several variables, including, among others, the amount of adhesive polymer in the structure, the amount of heat supplied during the bonding process, the bonding temperature, and the density of the filaments in the structure.

[0079] For example, a layer of filaments composed of 80:20 core-sheath bicomponent filaments will contain a relatively small amount of adhesive polymer, and the individual bond points between the filaments will be composed of a small amount of material, allowing the filaments to be separated with a relatively small force. The resulting structure will most likely be relatively soft (e.g., as expressed by the flexibility and compressibility of the nonwoven) due to the effects of filament bending and loosening of bonds, and will also have reduced resistance to abrasion. In contrast, a layer of filaments composed of, for example, 50:50 core-sheath bicomponent filaments will contain a relatively large amount of adhesive polymer, and the individual bond points between the filaments will be composed of a large amount of material. The resulting structure will be relatively stiff, have a high degree of resilience, and be more resistant to abrasion. For example, a layer of filaments composed of 20:80 core-sheath bicomponent filaments will contain a relatively large amount of adhesive polymer, and the individual bond points between the filaments will be composed of a large amount of material, interconnected only by very thin filaments comprising the original core of the filaments. The resulting structure will most likely be relatively soft but lack bulk.

[0080] For example, layers of filaments bonded at low temperatures corresponding to softening of the adhesive polymer or by very short exposure to high temperatures will have relatively very weak inter-filament connections and will break easily. A soft structure can be expected to have very poor resistance to abrasion. On the other hand, layers of filaments bonded, for example, at temperatures above the temperature of the adhesive polymer and / or by long exposure times at moderate temperatures, will have relatively strong inter-filament connections due to melting and re-adhesion of all the adhesive polymer. A hard structure with good resilience and abrasion resistance can be expected.

[0081] For example, a layer of very thin filaments will have a high number of bond points per unit volume; in contrast, a layer of thick filaments will have significantly fewer bond points for the same basis weight, but these filaments will generally be stiffer.

[0082] By appropriately setting the above parameters, it is possible to manufacture nonwoven fabrics with intentionally improved softness, flexibility, rigidity, abrasion resistance, etc.

[0083] In the material of the present invention, when two layers of filaments with different parameters are combined, conditions can be set such that, for example, one layer has low interconnectivity and the other has high interconnectivity. For example, if the degree of interconnectivity in the first layer T is low, the stiffness of the layer decreases, correlating with a decrease in abrasion resistance, while the layer's resilience is maintained. If, under the same adhesion conditions, a high degree of adhesion is provided for the second layer M, which includes a material with low stiffness that achieves relatively good abrasion resistance, while maintaining the softness obtained by the polymer composition and promoted, for example, by the fineness of the filaments, the material of the present invention may be very soft and resistant to abrasion from the application side (second filament layer M), while also having resilience.

[0084] Without being bound by theory, we believe that the resilience of the layer is primarily due to the combination of thermal bonding (e.g., hot air bonding) throughout the nonwoven fabric volume and filaments containing polymer A1, which have a relatively high stiffness. The filaments are interconnected through small bond points throughout the nonwoven fabric volume, and between each bond point—depending on the bulkiness of the layer—there are relatively small sections of filaments, which are located in all directions in three-dimensional space. The entire structure forms at a relatively high temperature (bonding temperature) that maintains the solid state of polymer A, but this temperature also alters the crystallization state, allowing it to be maintained at a relatively slow cooling rate. That is, when compressed in the z-direction (thickness direction of the nonwoven fabric), the resulting structure has a high tendency to return to its original state (recovery). In general, it is believed that the higher the stiffness of polymer A, the greater the tendency of the nonwoven fabric to return to its original state (recovery). Polymer B, with its relatively low melting point, exhibits significantly lower resilience. This is because, unlike polymer A, polymer B may partially or completely melt (to enable interconnection of the filaments) during the thermal bonding process, and its position, shape, etc. may change (for example, during the thermal bonding process, polymer B may be relatively concentrated at the contact positions of the filaments = bonding points, and conversely, its proportion may decrease in the filaments between the bonding points).

[0085] A second layer (M) containing a lower stiffness polymer A2, if present in the composite, will bond under the same conditions as the first layer (T). Again, the aforementioned bond point structure and the relatively short filament segments between the bond points will form. A lower stiffness polymer A2 tends to soften the layer and increase its drapeability. That is, human perception of layer stiffness may differ from standard layer stiffness evaluation methods (Handle-O-Meter, compressibility, softness), and a layer containing filaments containing a lower stiffness polymer A2 will generally be subjectively rated as softer than a layer containing filaments of a higher stiffness polymer A1, even if, in certain cases, for example, the Handle-O-Meter measurement of A1 is equal to or greater than that of A2.

[0086] Surprisingly, it has been found that nonwoven fabrics made in accordance with the present invention exhibit unique properties. When filaments comprising a relatively high stiffness polymer are combined with filaments comprising a relatively low stiffness polymer, a composite is formed that generally: - the degree of extensibility is generally comparable to that of material made only from filaments of the second layer M (higher than that of material made only from filaments of the first layer T); - the degree of resilience is generally comparable to or only relatively low compared to materials made from filaments of the first layer T; - the degree of softness, as revealed by measuring the compressibility of the nonwoven fabric, is generally comparable or only relatively low compared to materials made from filaments of the second layer M;

[0087] It may be advantageous for the nonwoven fabric of the present invention if the first layer (T) consists of relatively thick filaments (thickness greater than 25 microns, more preferably greater than 30 microns, advantageously greater than 35 microns, but desirably less than 100 microns, more preferably less than 70 microns, advantageously less than 50 microns) comprising a relatively high proportion of polymer A1 (for example, at least 55% by weight, more preferably at least 60% by weight, even more preferably at least 65% by weight, advantageously at least 70% by weight, relative to the total weight of the filaments) and a relatively low proportion of polymer B1 (for example, less than 45% by weight, more preferably less than 40% by weight, even more preferably less than 35% by weight, advantageously less than 30% by weight, relative to the total weight of the filaments). At the same time, the second layer (M) consists of relatively thin filaments (thickness less than 30 microns, more preferably less than 25 microns, advantageously less than 20 microns) comprising a relatively low proportion of polymer A2 (for example not more than 60% by weight, more preferably not more than 55% by weight, even more preferably not more than 50% by weight, advantageously not more than 45% by weight, relative to the total weight of the filaments) and a relatively high proportion of polymer B2 (for example more than 40% by weight, more preferably more than 45% by weight, advantageously more than 50% by weight, relative to the total weight of the filaments). Surprisingly, it was found that the nonwoven fabric thus produced has a high bulk and recovery of the first layer (T), and the high proportion of free space (void volume) in the structure, together with the low adhesion strength of the filaments (due to the low number of adhesion points at the filament contact positions and simultaneously the low volume of adhesive component B1), promotes a "soft-loft" type softness, but suffers from the drawback of a subjective "coarse" feel and touch. At the same time, the second layer (M), with its thinner filaments and higher proportion of adhesive component B2, has a lower bulkiness, but the use of soft polymers results in excellent touch and feel properties, which can be further enhanced, for example, by additives that improve touch and feel (e.g., erucamide for a silky touch and feel, special additives for a so-called cotton-like touch, etc.) This combination results in a bulky material that is perceived as being quite soft.

[0088] When touching from the side of the second layer (M), the skin experiences a pleasant sensation at first contact when the fabric softly flexes even under light pressure. At this time, the specific "roughness" of the first layer (T) is masked by the softness and silky texture of the second layer (M). As the pressure increases, the bulky first layer (T) also gradually begins to compress, and its resistance to pressure (e.g., expressed in elasticity measurements) increases. Because the increase in the required pressure is gradual and the resistance to compression also increases gradually, the material is subjectively perceived as pleasantly soft and comfortable.

[0089] In the case of the nonwoven fabric of the invention, it may be advantageous if the basis weight of the first layer (T) is greater than the basis weight of the second layer (M), for example the ratio of the basis weight of layer T to the basis weight of layer M is at least 55:45, more preferably at least 60:40, even more preferably at least 65:35, advantageously at least 70:30, but less than 95:5, more preferably less than 90:10, advantageously less than 85:15.

[0090] In the case of the nonwoven fabric of the invention, it can be advantageous if the ratio of the basis weight of the first layer T produced from one spinneret to the basis weight of the second layer M produced from one spinneret corresponds approximately to the average density of the polymer composition of the filaments in these layers. This solution is advantageous, particularly from the point of view of production costs, and allows the operational capabilities of both spinnerets to be fully utilized when produced with a standard spunbond spinneret. If calculations are carried out to determine the recommended basis weights of the individual layers T, M based on the ratio of the polymer-weighted density averages and the required total basis weight of the layered nonwoven fabric, then, for example, the basis weights of the first layer T and the second layer M may be calculated to be 5 g / m². 2 If it does not differ by more than 4g / m, it is more preferable 2 If it does not differ by more than 3 g / m, more preferably 2 If the difference is not more than 2 g / m 2 It is advantageous if the difference is not more than

[0091] Some examples are shown in the table (density: kg / m 3 ,Basic weight:g / m 2 ): TIFF0007729829000002.tif40142

[0092] TIFF0007729829000003.tif41151

[0093] TIFF0007729829000004.tif49147

[0094] The calculation is similarly carried out when the nonwoven fabric contains more than two layers.

[0095] In one advantageous solution of the invention, the polymer weighted density average is different for the filaments of the first layer (T) and the second layer (M). This density indicates the weight of polymer per unit volume. If the difference in values ​​is too large, undesirable effects will occur, as a result of which the filaments from the composition with a significantly higher weighted density average will act on the filaments of the layer with a lower weighted average, compressing them unevenly, especially when the filaments of layer (M) have a higher polymer weighted density average in the filaments. In one solution of the invention, the ratio of the weighted average density of the polymer in the endless filaments of the first layer (T) to the weighted average density of the polymer in the endless filaments of the second layer (M) is between 1.0 and 1.5, preferably between 1.1 and 1.3, and / or the ratio of the basis weight of the first layer (T) to the basis weight of the second layer (M) is between 1.0 and 1.5, preferably between 1.1 and 1.3.

[0096] The above polymer groups (polyolefins, polyesters) differ not only in their stiffness but also in other properties that can be exploited to enhance the desired final properties of nonwoven fabrics. Polyesters (e.g., PET, PLA, or their copolymers) exhibit what is known as shrinkage. Proper crystallization of these polymers generally requires a longer time than the time required to cool the filaments during the spunmelt manufacturing process. Reheating filaments containing these polymers (e.g., with a narrow hot air knife, hot air bonding, or infrared irradiation) generally results in recrystallization, and the new, more stable crystalline state generally has a smaller volume than the initial, semi-stable crystalline state (i.e., shrinkage).

[0097] Although shrinkage is generally considered an undesirable phenomenon, it can also be beneficial if properly controlled. For example, our previous Czech patent application PV2018-647 (unpublished) describes the use of controlled polymer shrinkage to produce bulky materials with resilience and so-called structural softness.

[0098] In the material of the present invention, it may be advantageous for the first layer T, or both layers M and T, to comprise endless filaments having a cross-section that does not support crimping. These filaments may be multicomponent, preferably bicomponent. Without being bound by theory, it is believed that the center of gravity of a cross-section of a component distributed across the cross-section of the filament is essentially co-located with the centers of gravity of the cross-sections of all other components, and that the cross-section cannot be crimped by heating to an activation temperature.

[0099] The layers of the present invention may comprise primarily endless filaments having, for example, circular cross sections, triangular cross sections, star cross sections, etc. (Figure 1).

[0100] The endless filament may be, for example, a multicomponent filament, while the arrangement of the individual components in the cross-section of the filament may be represented by a core and sheath (concentric arrangement), a compartment, or other arrangement in which the center of gravity of the surface of the components is at a single location within the cross-section of the endless filament (Figure 2).

[0101] Regardless of the theoretical basis, we believe that the decisive factor for forming filaments with the desired properties is the specific combination of two components. First, it is preferable that the filament components for forming the nonwoven structure, and for example the core of this structure, contain a polymer A1 capable of shrinking under certain conditions. This polymer A1 can then be changed during the filament formation process—particularly during the cooling and drawing stages—to the state desired in the subsequent activation stage. For example, polymer A1 can initially be brought to a semistable state (e.g., a state with the lowest possible energy at the time, without ongoing crystallization), where it is heated during the activation stage, and then slowly cooled to change from the aforementioned semistable state to another, different, more stable state (e.g., a state corresponding to another low-volume crystallization stage). This change generates internal forces that cause shrinkage. Here, we assume that the vector of these internal forces is oriented in the direction of the median curve of the filament.

[0102] The filament diameters of spunmelt nonwovens are in the millimeter and / or submillimeter range. However, these filaments are generally non-directionally oriented (see Figure 3), and they are in contact with each other so that the free spaces between the filaments also have dimensions in the millimeter and / or submillimeter range. The mutual binding between the filaments acts against the internal force vector, thereby forming their respective first resistance points. This resistance point may also be referred to as the threshold point of resistance to structural contraction. For example, if a filament is activated in the right way, it may form, for example, irregular arcs or three-dimensionally extending waves. In contrast, filaments constrained by the surrounding structure formed by neighboring filaments do not have such degrees of freedom.

[0103] According to the present invention, the layer is formed using bicomponent filaments, the second component comprising polymer B, which has a lower melting point and preferably also provides other desired properties such as softness leading to more pleasant touch and feel characteristics, etc. Polymer material A1 and polymer material B1 should have different shrinkage properties, which means that in a preferred configuration polymer material B (preferably the material forming the sheath of the filaments) is less shrinkable (contractible) than polymer material A (preferably the material forming the core of the filaments).

[0104] As a result, different forces that cause contraction are generated, and these forces act inside the two polymer materials that are in contact with each other. Regardless of the theoretical basis, the inventors believe that polymer material A and polymer material B always have different properties, which means that the vectors of the internal forces that cause contraction are never equal at the same time. This force inequality allows the formation of a second threshold point of resistance to contraction. This resistance point may also be referred to as the threshold point of resistance to contraction of the filament.

[0105] Regardless of theoretical justification, we believe that this particular regularity of displacement is the primary reason for the regular crimping of the free portions of the individual filaments. In contrast, according to the present invention, also regardless of theoretical justification, in the case of filaments with cross sections that do not correspond to crimp, the internal vectors of the crimp-causing forces in the first and second components cannot regularly deviate from one another, and as a result, such filaments form irregular arcs or wavy portions in any direction. In fairly brief summary, we can state that the filaments have no regular tendency to bend toward any particular portion of their cross section or circumference, resulting in an irregular final shape. After activation, the cross sections of such filaments remain essentially in a state that does not correspond to crimp. See Figure 4.

[0106] Regardless of the theoretical basis, we believe that if the internal force causing shrinkage is small and therefore cannot counteract the opposing force corresponding to the threshold point of filament resistance, the fabric will remain unchanged. However, if the internal force causing shrinkage is large enough and therefore can counteract forces in all directions corresponding to the threshold point of resistance in the MD / CD directions, the fabric will shrink according to the MD / CD ratio and form a flat structure. If the internal force causing shrinkage is large enough to specifically counteract the threshold point of filament resistance to shrinkage, but is not large enough to counteract the threshold point of resistance to shrinkage of the structure in the MD / CD directions, and the lowest structural resistance is primarily oriented in the Z direction, the fabric will form the desired bulky structure. It will be obvious to a qualified expert in the art that the internal force required to cause shrinkage is greater than the internal point of resistance of the filaments, but less than the threshold point of resistance to shrinkage of the structure in the MD / CD directions.

[0107] The first layer (T) of the present invention is composed of a large number of filaments, with numerous contact points between the filaments. Observation of this layer on the millimeter and / or submillimeter scale reveals that the filaments, or more precisely, millimeter and / or submillimeter portions of the filaments, exhibit unique states as a result of the interaction between adjacent filaments. In these unique states, the filaments are subject to unique combinations of forces generated upon activation, which can produce a wide variety of filament shapes in the final structure. Contrary to this, the fact that the filaments remain almost perfectly planar in the MD / CD planes may seem contradictory. However, in contrast, the filaments can shift "up" and "down" to form a wide variety of three-dimensional structures encompassing all MD, CD, and Z directions. Regardless of theoretical justification, we believe that the wide variety of orientations of the endless filaments within the layer is advantageous in terms of final properties. According to the present invention, the layer is homogeneous on a macroscopic scale. The wide variety of filament shapes within the layer, combined with the interaction of these filaments with each other, makes it possible to obtain advantages from the present invention, primarily in that the layer can respond in a desired way to the action of external effects (for example, to pressure and its release, or to the effect of a liquid passing through the layer).

[0108] To summarize quite simply, the orientation of the filaments can also be expressed as the ratio of the filament length to the fabric length.

[0109] The layer M or T thus produced, having a cross section that does not correspond to the crimp, comprises: At least 20% of the filaments have a "filament length to fabric length" ratio greater than 1.2, preferably at least 30% of the filaments have a "filament length to fabric length" ratio greater than 1.2, preferably at least 40% of the filaments have a "filament length to fabric length" ratio greater than 1.2, preferably at least 50% of the filaments have a "filament length to fabric length" ratio greater than 1.2; At least 10% of the filaments have a "filament length to fabric length" ratio greater than 1.5, preferably at least 15% of the filaments have a "filament length to fabric length" ratio greater than 1.5, preferably at least 20% of the filaments have a "filament length to fabric length" ratio greater than 1.5, preferably at least 25% of the filaments have a "filament length to fabric length" ratio greater than 1.5, preferably at least 30% of the filaments have a "filament length to fabric length" ratio greater than 1.5; At least 5% of the filaments have a ratio of "filament length to fabric length" greater than 2, preferably at least 10% of the filaments have a ratio of "filament length to fabric length" greater than 2, preferably at least 15% of the filaments have a ratio of "filament length to fabric length" greater than 2, preferably at least 20% of the filaments have a ratio of "filament length to fabric length" greater than 2.

[0110] The layer M or T thus produced, having a cross section that does not correspond to the crimp, simultaneously comprises: At least 10% of the filaments have a "filament length to fabric length" ratio of less than 2.5, preferably at least 20% of the filaments have a "filament length to fabric length" ratio of less than 2.5, preferably at least 30% of the filaments have a "filament length to fabric length" ratio of less than 2.5, preferably at least 40% of the filaments have a "filament length to fabric length" ratio of less than 2.5, preferably at least 50% of the filaments have a "filament length to fabric length" ratio of less than 2.5; At least 5% of the filaments have a ratio of "filament length to fabric length" of less than 2, preferably at least 10% of the filaments have a ratio of "filament length to fabric length" of less than 2, preferably at least 15% of the filaments have a ratio of "filament length to fabric length" of less than 2, preferably at least 20% of the filaments have a ratio of "filament length to fabric length" of less than 2.

[0111] In the material of the present invention, it may be advantageous if the first layer T, or both layers M and T, contain endless filaments having a cross-section that corresponds to crimp (Figure 5). These filaments may be multicomponent, preferably bicomponent. Without being bound by theory, it is believed that crimping is promoted by a cross-section in which the center of gravity of the surface formed by one component of the filament is located away from the center of gravity of the surface of the other component.

[0112] It is well known in the field of technical knowledge that the so-called crimp can be achieved by a specific combination of polymers with different crimp levels in a so-called cross-sectional configuration that allows for crimping. At the same time, this crimp can be an immediate, natural crimp or a latent crimp that is a prerequisite for a prior activation (for example, thermal activation). When the cross-section of a filament is crimped, it creates regular curls that form the so-called helical crimp. In very brief terms, it can be stated that a filament with a crimpable cross-section tends to bend towards the component with the greater degree of contraction, thus forming a non-uniform helical crimp. In other words, this means that the crimpable cross-section causes the vectors of the internal forces acting on each other in the first and second components to regularly deviate from each other.

[0113] The layer of filaments may primarily comprise endless filaments having, for example, circular cross-sections, triangular cross-sections, star cross-sections, etc. (Figure 1).

[0114] For example, crimping can be expected in cross-sectional component arrangements such as parallel and eccentric core / sheath types.

[0115] As in the previous case, here too, during the filament formation process—particularly during the cooling and drawing stages—it is possible to change the state of polymer A in a way that is desirable for the subsequent activation stage. Polymer A can, for example, initially be in a semistable state (i.e., a state with the lowest possible energy, without ongoing crystallization), where it is heated during the activation stage and then slowly cooled in order to change from the aforementioned semistable state to another, different, stable state (e.g., to a state corresponding to another, lower-volume crystallization stage). This change generates internal forces, which cause contraction. We assume here that the vectors of the internal forces are directed in the direction of the central curves of the filament's components. In the case of a filament with a cross-section corresponding to a crimp, a change in the volume of polymer A will increase the internal forces within the filament (increasing the forces of mutually offset vectors), which will most likely reduce the radius of the formed arcs and, in the case of layers of filaments, will cause a certain "shrinkage" (=contraction) of the entire structure.

[0116] Filaments with a cross-section corresponding to the crimp tend to form a regular shape, specifically a helix; that is, the tendency of the filaments to bend regularly toward the side of the filament containing the material with higher shrinkage. Nevertheless, at the same time, these filaments within the layer are constrained by their neighbors, which prevents them from maintaining a regular helix. Regardless of the theoretical basis, we believe that the greater the force with which the filaments are contracted before being deposited on the belt, the greater the "crimp per unit length" of the filaments, which explains the greater the number of helical portions within the fiber structure. Conversely, if the degree of crimp is low, e.g., less than 25 turns per inch (when individual "loops" are located every slightly more than 1 mm of the length of the formed helix), the free space between the contact points of the filaments becomes insufficient to maintain even a partial helix, while the reorientation forces resulting from the filaments' contact with each other increase in proportion to the magnitude of the crimp. At twists per inch below 15 (i.e., when individual "loops" are located every slightly more than 2 mm along the length of the resulting helix), it becomes difficult to distinguish the sections of the helix. At twists per inch below 10 (i.e., when individual loops are located every slightly more than 2.5 mm along the length of the resulting helix), the specific forces acting on the filaments are completely overcome by the opposing forces acting against the regular mutual offset of the vectors of the internal contraction forces, allowing the formation of regular crimps, resulting in a structure that acquires a completely irregular appearance. However, a qualified expert in the art will recognize that there are also various other factors that promote the formation of a bulky structure resulting from the regular mutual offset of the vectors of the internal contraction forces (in the case of filaments with a cross-section that corresponds to crimps) and from the irregular crimps of the filaments (in the case of filaments with a cross-section that does not correspond to crimps).An example of the structural differences due to crimping of synthetic silk filaments is shown in Figure 6 (the differences are described in the article "Fiber Crimp Distribution in Nonwoven Structure" by Kunal Singh and Mrinal Singh, 2013, available at the address http: / / article.sapub.org / 10.5923.j.fs.20130301.03.html).

[0117] During the thermal activation of the structure, the volume of polymer A decreases, resulting in a so-called shrinkage of the entire structure. In the material of the invention, it may be advantageous if the first layer T subjected to activation, or both layers M and T, have a crimp in the CD or MD direction of less than 20%, preferably less than 15%, preferably less than 13%, preferably less than 11%, most preferably less than 9%. The shrinkage of both layers may be different.

[0118] In one solution of the invention, it is advantageous to combine a first layer T that exhibits shrinkage with a second layer M that does not exhibit shrinkage. In this material of the invention, it may be advantageous if in the first layer T that is subjected to activation, the degree of shrinkage achieved is not more than 20%, preferably not more than 15%, preferably not more than 13%, preferably not more than 11%, most preferably not more than 9% in either the CD or MD direction.

[0119] In one advantageous solution of the present invention, when the first layer (T) utilizes polymer shrinkage (when using crimped and non-crimped types), it is preferable that the first layer (T) is formed from core / sheath type bicomponent filaments having a circular or three-point cross-sectional shape.

[0120] The endless filaments contained in this first layer T are formed from two or more components. The first component may, for example, be selected from the group consisting of polyesters (e.g., aromatic polyesters such as polyethylene terephthalate (PET) or aliphatic polyesters such as polylactic acid (PLA)), polyamides, polyurethanes, or copolymers or suitable blends thereof. It is within the scope of the present invention that the first component consists of or essentially consists of a plastic selected from the group of polyesters, such as copolymers of polyesters (coPET) or copolymers of polylactic acid (COPLA). The polyester preferably used is polyethylene terephthalate (PET) or polylactic acid (PLA).

[0121] The second component B1 may be selected, for example, from the group consisting of polyolefins (i.e., polypropylene or polyethylene), polymers with low melting points, or copolymers or blends of suitable polymers. It is within the scope of the present invention that the second component consists or essentially consists of a plastic selected from the group of polyesters, such as copolymers of polyesters (coPET) or copolymers of polylactic acid (COPLA). The polyolefin preferably used is polyethylene (PE).

[0122] Preferred component A / B combinations selected for the bicomponent filaments in the nonwoven layers of the present invention are PET / PE, PET / PP, PET / CoPET, PLA / COPLA, PLA / PE, and PLA / PP combinations.

[0123] In the case of bicomponent filaments with a cross section that corresponds to the crimp, it is necessary to use a combination of polymers that crimp in a given combination, or in some cases to utilize, for example, nucleating agents or other additives that correspond to the crimp.

[0124] In a preferred configuration, the bicomponent filament has a weight ratio of the first component A1 to the second component B1 in the range of 50:50 to 90:10.

[0125] In a further embodiment, the composition of the components may also contain additives intended to modify the properties of the endless filaments. For example, the core may contain color pigments or crimping agents. The published literature in the art allows identifying various specific combinations of crimping agents, which are capable of modifying to some extent the behavior of the polymer during crystallization and shrinkage (as described, for example, in U.S. Pat. No. 5,753,736, filed by the author Gajanan in 1995). Conversely, for example, ordinary titanium dioxide, which is frequently used as an additive to achieve higher whiteness, only slightly alters the behavior of the polymer, which can be modified, if necessary, by slightly adapting the process conditions.

[0126] The sheath may, for example, contain color pigments or surfactants (e.g., to achieve silky hand and feel properties). A qualified expert in the art will recognize that many other possibilities exist, guided by the requirements of the particular application.

[0127] In other forms of construction, the components may also contain specific amounts of different polymers. Thus, for example, a first component (e.g., core) can contain a certain proportion of the polymer(s) forming the second component (e.g., sheath), or, conversely, a second component (e.g., sheath) can contain a certain proportion of the polymer(s) forming the first component (e.g., core). Published literature makes it possible to determine specific levels of content to allow for the correct combination of polymers. For example, author Moore (in U.S. Patent Application No. 2012088424, filed by 3M Innovative Properties) states that blending polyester with up to 10% polypropylene results in filaments with stable properties.

[0128] When combined with this first layer (T) exhibiting a certain level of shrinkage, the second layer (M) advantageously contains filaments with a low level of shrinkage or no shrinkage at all. In such cases, the forces induced by the activation of the filament layer in the second layer (M) itself are significantly smaller or even non-existent. At the same time, due to the adhesive effect of the layers or possibly the formation of adhesive points between the layers, this second layer (M) is forced to change its spatial orientation (forced shrinkage) due to the shrinkage of the first layer (T). This exerts an external force that forces a change in the position of the filaments within the structure. Without intending to be theoretically bound, it is believed that the thickness of the nonwoven increases due to the filaments or parts of themselves being further oriented in the z-direction. In advantageous cases, the increase in fabric thickness is greater than the forced shrinkage in the MD and CD, thereby increasing the total bulk of the layers and, therefore, the bulk of the fabric.

[0129] The combination of shrinkable and non-shrinkable layers that are bonded at the bond points by calender rollers, or more preferably by flat bond embossing, where the filaments are compressed together in a bond embossment and locally bonded by the effect of heat, is well known in the art. This structure is then activated by a heat flow (e.g., hot air), causing the shrinkable layer to shrink and forcing the non-shrinkable layer to curve into a "cushion" between the bond points - see, for example, patent application by Reifenhauser & KG Maschinenfabrik, European Patent Application No. 3192910.

[0130] The nonwoven fabric of the present invention has a unique structure. In contrast, in the aforementioned patent application, the strength of the fabric is essentially imparted by the regular arrangement of adhesive embossments, and activation is controlled to prevent further filament adhesion (which would increase the fabric's stiffness and reduce its drapeability). The nonwoven fabric of the present invention activates shrinkable component A1 at a temperature corresponding to the adhesion temperature of component B. The fabric of the present invention is not interconnected at regularly arranged local adhesive embossments across the surface plane of the fabric (imparted by the arrangement of ridges on the calendar roller), but rather is interconnected within the entire volume of the nonwoven fabric, with essentially every filament intersection forming an adhesive point that holds the fabric together. The fabric of the present invention does not contain adhesive embossments and the curved "cushions" of free filament segments between them. Instead, the thickness of the fabric is essentially uniform, and the free filament segments (from one filament intersection to the next) are much shorter. At the same time, the absence of fixed adhesive embossments allows some freedom of movement for the individual filaments of both layers during the activation period. At the same time, a calendar adhesive is typically applied, whereby the formation of adhesive embossments changes the shape of the filament plane in the embossment, completely flattening the filament plane shape. In the case of bicomponent filaments, not only is the component with the lower melting point melted, but the component with the higher melting point is also subjected to mechanical and thermal stress (e.g., by being flattened in the plane of the embossment), forming weak points (e.g., the transition between the embossment and the free part of the filament). Without being bound by theory, it is assumed that the precise combination of limiting the stress on the component with the higher melting point (A), together with the freedom of movement during the forced activation process, and the immediate fixation of the structure by the curing of the adhesive component, which allows the formation of a very bulky fiber structure, promotes recovery and gives rise to the softness and compressibility characteristic of the second layer M.

[0131] Figures 7A and 7B show the difference between a nonwoven fabric structure bonded using a bonding embossment V (Figure 7A) and a structure bonded using a heat flow to form bonding points B throughout the entire volume (Figure 7B).

[0132] As generally applied, nonwoven fabrics bonded using a calendar contain adhesive embossments spaced apart by millimeters (usually 3 to 20 mm), this distance also defining the free filament section (usually 3 to 30 mm). The fabric of the invention is thermally bonded over its entire volume using a heat flow and contains adhesive points spaced apart by approximately 0.3 to 8 mm of free filament section, depending on the bulkiness of the structure. In both cases, the lower limit applies more generally to denser filaments and the upper limit to coarser filaments. The typical limits given refer to the average length of the free filament section in the structure.

[0133] The second layer M that has been forced to shrink may form a homogeneous layer with a regular arrangement of filaments, as shown in Figure 8. It is also possible to form a structure in which the local circularity of the filaments in layer M varies, as shown in Figure 9, or to form locally irregular bulges in the filament bundle, as shown in Figure 10.

[0134] By appropriately configuring the process conditions, particularly the process temperature and drawing force during the heating process after exposing the dough to the heat flow, it is possible to promote and / or limit the formation of non-uniform morphology and swelling. For example, it is possible to form an irregular swelling structure as shown in Figure 11.

[0135] Example A preferred embodiment of the inventive construction is therefore characterized by at least two nonwoven layers. One advantageous construction is a nonwoven fabric of the invention formed by interconnecting at least two layers M and T of filaments produced using a spunbonding process. The nonwoven fabric may also be composed of several layers, where one layer represents the first layer T and another layer represents the second layer M, and the fabric also comprises another layer X. Layer X may, for example, be composed of a layer of meltblown filaments or a layer of staple fibers, etc.

[0136] In a preferred embodiment of the present invention, the layers T or M of the nonwoven fabric are made of multicomponent or bicomponent filaments, which are spun using a spinning machine or spinneret and then preferably passed through a cooler. Inside the cooler, the filaments are typically cooled by a fluid medium, primarily by cooling air. The scope of the present invention includes the spun filaments subsequently passing through a drawing mechanism where they are processed by drawing. The drawn (stretched) filaments are then deposited on a moving belt, where they form a layer of filaments. In one advantageous configuration, by adjusting certain parameters that determine the draw ratio, it is then possible to form filaments within the layer with a controlled degree of potential shrinkage.

[0137] According to a preferred embodiment of the invention, an inserted diffuser is used as the magazine mechanism. This device controls the deposition of the filaments and is installed between the drawing mechanism and the filament deposition position. The scope of the invention also includes the use of at least one diffuser, the opposing side walls of which diverge from each other in the direction of filament passage. A particularly preferred embodiment of the invention is characterized in that the drive unit of the cooling mechanism and the drawing mechanism are designed as a closed system. No additional air supply is used within this closed system to supplement the supply of an external cooling medium or cooling air to the cooling mechanism. Such a closed system has proven to be particularly suitable for the production of nonwoven fabrics.

[0138] The technical solution of the present invention, which overcomes the problems associated with filament shrinkage when shrinkage is utilized to produce the nonwoven fabric of the present invention, has been found to be functionally reliable and effectively feasible when using the closed unit described above, especially when, apart from the preferred configuration, a diffuser is also used, which is placed between the drawing mechanism and the filament deposition location. It has already been mentioned that the shrinkage of nonwoven belts produced by the spunbond method can be very specifically adapted or adjusted by the parameters of the draw ratio, the cooling air / polymer ratio and the filament speed.

[0139] From the above definition, it is clear that spunbond manufacturing involves the direct conversion of polymers into filaments, followed by random spreading of the filaments at a deposition site to form a nonwoven layer containing these filaments. The spunbond process determines not only the properties of the individual filaments but also the properties of the final nonwoven fabric. The final nonwoven fabric cannot necessarily be used to determine the various properties and conditions of the individual filaments that occur during the individual manufacturing steps of the nonwoven fabric, such as rheological properties, polymer structural properties, and shrinkage. The potential shrinkage of a nonwoven fabric generally determines its ability to form a bulky nonwoven fabric. This determination is made possible by the shrinkage of the individual filaments, resulting in a relative increase in the thickness of the filament layer, without disrupting the fabric structure and / or significantly changing the length and width of the filament layer. The scope of the present invention encompasses defining the shrinkage of filaments by using different raw materials in the filament composition and / or by setting different material processing conditions during the production of the nonwoven filaments and / or by using different filament cross-sectional shapes and / or by adjusting the mass ratio between the various input materials and / or by setting different filament orientations.

[0140] The preferred embodiment of the present invention does not distinguish between filaments with a cross-section compatible with crimping and filaments with a cross-section not compatible with crimping. Both types can be advantageously used in certain applications. Similarly, a suitable combination can be formed by using layers of crimped and non-crimped filaments. It will be obvious to a skilled artisan that filaments with a cross-section not compatible with crimping, as opposed to crimped filaments, are technically advantageous in obtaining bulky and soft materials. Unlike filaments with a cross-section not compatible with crimping, it is not easy to control the manufacturing process when processing filaments that crimp (naturally) during manufacturing. In many types of filaments with a cross-section compatible with crimping, crimps are formed during the deposition stage and / or activation. During this crimping process, filaments move relative to each other, so they easily come into contact with or become entangled with each other; in other words, the filaments can be said to be capable of interfering with each other. Nonwoven layers made of filaments that have the ability to naturally crimp often experience limitations in their shape and alignment due to filament misalignment caused by relative movement. These limitations necessitate subsequent basic measures, including reducing throughput, slowing down the manufacturing process, and adding special steps in the manufacturing process to ensure the relative alignment of the filaments.

[0141] Filaments that do not naturally crimp during the spinning, cooling, and drawing processes allow for a more uniform deposition of the filaments within the layer, allowing the lowest possible basis weight to be used while still maintaining the desired fabric properties and / or allowing for high production line speeds, thus increasing the amount of processed material. This makes it much easier to control the manufacturing process, and for non-crimp cross sections, it is also possible to use less expensively manufactured spinnerets and spin beams.

[0142] An advantageous embodiment of the present invention also includes thermally pre-consolidating the resulting filament layers, i.e., the layers are pre-consolidated and contain thermally formed bonds. An advantageous embodiment of the present invention also includes thermally activating the resulting nonwoven fabric in order to control the shrinkage of at least one of the layers. Consolidation and, optionally, thermal activation are preferably carried out by the effect of at least one hot medium flow (e.g., by hot air or infrared radiation) and / or contact with a hot surface. Examples of such hot surfaces include, primarily, parts of rollers. Thermal activation is preferably carried out under conditions in which shrinkage occurs uniformly over the entire surface of the fiber layer. Thermal activation can be carried out in a chamber supplied with hot air or by passing the filament layer through an oven. Thermal activation and consolidation can also be carried out by infrared or ultraviolet light, transmitted microwaves, and / or laser irradiation. Within the scope of this "on-line" procedure, the thermal consolidation may be performed immediately after the completion of the preceding steps in the manufacturing procedure, or both steps of the thermal activation and consolidation procedures may be performed "off-line" separately from the preceding steps in the manufacturing procedure. Thus, thermal activation can essentially be performed "off-line" at a different time and place.

[0143] Advantageously, the solution of the invention involves a flow of hot medium through the fabric, so that heat is transferred throughout the entire volume of the nonwoven.

[0144] The required level of pre-consolidation of the fiber fabric / filament layer depends heavily on the conditions of the manufacturing process. A crucial prerequisite is to correctly set the level of mutual cohesion of the filaments within the filament layer, and therefore also to be able to control the level of mutual cohesion based on the requirements of the subsequent steps of the manufacturing process. If the manufacturing process is carried out on a production line and activation is carried out on the belt, the required level of cohesion is relatively low, since it is only necessary to prevent unraveling or thinning caused by significant undesirable movements during the activation process. In special cases, for example, if the filaments bond very well while in contact with each other by themselves or through the substrate, and this bonding is possible, for example, due to their cross-sectional shape, the rate of entanglement, or their material composition, the bonding properties of the filament layer may be sufficiently good even without thermal pre-consolidation. In other cases, for example, if the manufacturing process is divided into two steps, or if the filament layer is pre-consolidated before complete activation and transported, for example, in the form of a roll, the desired level of cohesion may be very high, resulting in a very high level of pre-consolidation.

[0145] The activation temperature must be between the glass transition temperature and the softening temperature (Vicat softening temperature according to ISO DIN 306) of component(s) A.

[0146] In one advantageous configuration, the present invention provides a high-loft nonwoven fabric made using filaments in which the shrinkage of these filaments is matched or controlled, such that shrinkage occurs evenly throughout the layer of filaments, thereby ensuring that this procedure results in uniform nonwoven properties and uniform control of shrinkage.

[0147] Within a convection cooler, the filaments are typically cooled by a flowing medium, primarily cooling air. As noted above, the potential shrinkage of the filaments must be evenly distributed over the entire length, width, and thickness of the layer exhibiting the shrinkage. While shrinkage properties can be altered by adjusting the filament draw ratio, cooling air / polymer ratio, and speed, according to the present invention, these parameters are in fact uniform for each individual filament.

[0148] Within the scope of the present invention, the nonwoven fabric produced consists of several layers, of which at least one first layer T, at least one first layer T and one second layer M, or each layer forming the nonwoven fabric, is preferably formed by a spinning beam. 1 The present invention includes forming a spunbonded fabric by superposing multiple layers at the same time and then joining the layers together on at least one forming belt. 2 It is clear that the material is transferred upwards and then to mechanism 3 for final integration.

[0149] filament 4 is a spinneret 5The filaments are formed by spinning at a constant speed. The filament arrangement may be optimized by alternating the filaments, thereby achieving conditions in which each individual filament has a very similar weight and is supplied with cooling air at very similar temperatures. The spinneret has a variable number of capillaries, which in turn vary in diameter (d) and length (l). The length (l) is generally calculated as a multiple of the capillary diameter, and in this application area, the length (l) is selected in the range of 2 to 10 l / d. The number of capillaries must be selected based on the desired final diameter of the filament and the required or planned total throughput of polymer, as well as the required filament spinning speed. The number of capillaries may vary from 800 to 7,000 per meter, which allows for filament diameters in the range of 8 to 45 μm. The capillary diameter and filament speed are selected to appropriately control the level of potential shrinkage of the final filament. The filament speed should be specified in the range of 1000 to 10,000 m / min, while the speed of filaments with a cross section that does not correspond to crimp and exhibits shrinkage should be in the range of 3000 to 5,500 m / min. The capillary diameter should be selected in the range of 200 to 1000 μm. For circular capillaries, a suitable process draw ratio in the range of 200 to 1,300 can be achieved. To achieve the required level of production line productivity, however, it is most advantageous for these circular capillaries to have a draw ratio in the range of 300 to 800. Noncircular capillaries generally exhibit high draw ratio values, which are highly dependent on the shape of the capillary and its relative surface-to-volume ratio. The amount and temperature of the cooling air should be set to achieve the correct draw ratio and the correct cooling conditions. In the present invention, such settings have been found to be useful when the ratio of cooling air volume to spun polymer is in the range of 20:1 to 45:1. The amount and temperature of the cooling air are controlled in the cooler (6). This temperature can be set in the range of 10°C to 90°C, preferably 15°C to 80°C, so that cooling conditions can be used to control the shrinkage process in certain cases. The cooling conditions determine how quickly the filaments are cooled from the melt temperature to the glass transition temperature during the spinning process.For example, setting the cooling air temperature high will slow down the cooling of the filaments. In practice, for the purposes of this invention, the required and usable cooling air temperature range can be easily achieved by dividing the cooler into two zones whose temperature ranges can be controlled separately: the first zone, located near the spinneret; 6a In the first zone, the temperature can be set in the range of 10°C to 90°C, preferably in the range of 15°C to 80°C, and most preferably in the range of 15°C to 70°C. In the second zone (6b), located immediately adjacent to the first zone, the temperature can be set in the range of 10°C to 80°C, preferably in the range of 15°C to 70°C, and most preferably in the range of 15°C to 45°C.

[0150] The filament is then drawn into the drawing zone. 7 Here, the filaments are drawn by a drawing force generated by the effect of the cooling air velocity. The adjustable cooling air volume and the drawing zone geometry make it possible to achieve a specific air velocity, which is then transmitted to the filament velocity. This filament velocity then determines the diameter of the filament together with the amount of polymer processed. The potential shrinkage (reduction rate) is adjusted by the filament velocity, the draw ratio and the cooling air / polymer ratio.

[0151] In the next step, the filament is 8 and the diffusion device 8 The opposing walls of the spunbond filament diverge from each other in the direction of filament flow. The positions of these walls can be adjusted to obtain a nonwoven fabric with uniform composition, where the individually deposited filaments form a non-directionally oriented array in the MD / CD plane.

[0152] At the same time, the filament deposition is clearly influenced by the air flow as these filaments are fed into the diffuser. The air flow can be modified to produce a variety of configurations, from apparently zigzag filament deposition to circular loops and even elliptical structures oriented in the CD direction. The filaments are deposited on the forming belt and at least one mechanism for pre-consolidation is provided. 9The cooling air flows through the deposited filament layer, flows through the forming belt, and is then conveyed away from the processing area. The volume of the aspirated air can be adjusted in a manner that facilitates the deposition of the filaments and also ensures effective contact between the filament layer and the forming belt. The pre-integration mechanism is located near the diffuser. The formation of the filament layer is controlled by the aspirated air throughout the entire path between the diffuser and the pre-integration mechanism. The pre-integration of the filament layer is achieved by hot air.

[0153] The amount of energy transferred to the filament layer is controlled in such a way that it only softens or premelts the filaments to a certain extent and ensures good bonding between the individual filaments. After the necessary bonding between the filaments is achieved, the fiber layer can be transferred to a forming belt without the additional support of auxiliary mechanisms and without the risk or disruption / damage caused by the forces generated during this transfer. This pre-consolidation procedure is also useful for transferring a filament layer to another deposition area on a production line consisting of several spinning beams. The energy transferred to the filaments is not sufficient to activate the contraction of these filaments. The method of the present invention involves determining a balance between the pre-consolidation parameters: pre-consolidation temperature, pre-consolidation air speed, and pre-consolidation time. Pre-consolidation time is understood to mean the time during which the layer of filaments is modified by the pre-consolidation air.

[0154] The recommended pre-integration time of the filament layer is in the range of 1-10000 ms, preferably in the range of 2-1000 ms, and most preferably in the range of 4-200 ms.

[0155] The pre-integration air velocity used in this pre-integration unit is set in the range of 0.1 to 10 m / s, preferably in the range of 0.8 to 4 m / s. The recommended pre-integration temperature is in the range of 80°C to 200°C, preferably in the range of 100°C to 180°C. In one embodiment of the configuration, the pre-integration temperature is in the range of 90°C to 150°C, mainly in the range of 110°C to 140°C.

[0156] According to various advantageous forms of construction, the nonwoven fabric comprises layers of bicomponent filaments such as: - one component (A) made from polyethylene terephthalate (PET) and a second component (B) made from a polyolefin, in particular polyethylene or polypropylene, the pre-combination temperature preferably being in the range from 110°C to 160°C, in particular in the range from 120°C to 150°C; - one component (A) made from polyethylene terephthalate (PET) and a second component (B) made from a copolymer of polyethylene terephthalate (CoPET), the pre-combination temperature preferably being in the range of 110°C to 180°C; - one component (A) made from polylactic acid (PLA) and a second component (B) made from a polyolefin, in particular polyethylene or polypropylene, the pre-combination temperature preferably being in the range of 80°C to 130°C; - one component (A) made from polypropylene (PP) and a second component (B) made from a polyolefin, in particular polyethylene or a copolymer of polyethylene and polypropylene, the pre-combination temperature preferably being in the range of 80°C to 130°C.

[0157] In one advantageous configuration in the region of the production line following the diffusion device, the layer of filaments is transferred to at least one activation unit. 10 The filaments are activated by hot air. At the same time, it is understood that the actual shrinkage of the shrinkable component of the filaments is a function of the temperature of the shrinkable component of the filaments, as well as a function of the time during which it is subject to the influence of temperature. Furthermore, it is clear that the speed of the shrinkage process also depends on the temperature of the shrinkable component of the filaments. According to the invention, the course of the process is controlled by a method consisting in delaying the onset of shrinkage, so that the forces generated in the layer as a result of this shrinkage are less than the bonding forces between the filaments. The result that can be achieved by this control of the process is a cohesive and uniform structure of the nonwoven fabric with a reduced density of the filament structure, which in turn leads to an increase in the thickness of the nonwoven fabric.

[0158] According to one aspect of the configuration of the present invention, in carrying out the steps of the pre-integration and / or activation method, the pre-integration and / or activation time, the wind speed required for the pre-integration and / or activation, and the pre-integration and activation temperature are controlled by a combined method in a combined pre-integration and activation mechanism.

[0159] An advantageous method of the present invention involves determining the balance between the activation parameters: activation temperature, activation air speed, and activation time. Activation time is understood to mean the time during which the layer of filaments is modified by activation air. It is clear that these parameters may be varied within defined ranges in response to the potential shrinkage level of the filaments, as well as with the aim of setting an ideal combination between activation time, activation temperature, and activation air speed.

[0160] The recommended activation time of the filament layer is in the range of 20-5000 ms, preferably in the range of 30-3000 ms, and most preferably in the range of 50-1000 ms.

[0161] The activation air velocity used in this activation unit is set in the range of 0.1 to 2.5 m / s, preferably in the range of 0.3 to 1.5 m / s. The recommended activation temperature for thermal activation is in the range of 80°C to 200°C, preferably in the range of 100°C to 160°C. In one configuration, the activation temperature is in the range of 90°C to 140°C, mainly in the range of 110°C to 130°C.

[0162] According to various advantageous forms of construction, the nonwoven fabric comprises layers of bicomponent filaments such as: - one component (A) made from polyethylene terephthalate (PET) and a second component (B) made from a polyolefin, in particular polyethylene or polypropylene, the activation temperature of which is preferably in the range from 90°C to 140°C, in particular from 100°C to 140°C; - one component (A) made from polyethylene terephthalate (PET) and a second component (B) made from a copolymer of polyethylene terephthalate (CoPET), the activation temperature of which is preferably in the range of 120°C to 160°C; - one component (A) made from polylactic acid (PLA) and a second component (B) made from a polyolefin, in particular polyethylene or polypropylene, the activation temperature of which is preferably in the range of 80°C to 140°C.

[0163] An advantageous embodiment of the present invention includes a final consolidation step, which consists of modifying the filament layer with hot air in a consolidation device (3). Within this consolidation device, the filament layer is consolidated, which may consist of a single layer or multiple layers with bonded filaments within the layer. At the same time, these layers do not significantly reduce the thickness of the filament layer, and there is no significant consolidation gradient present throughout the thickness range of the nonwoven fabric. The consolidation temperature must be high enough to achieve the necessary adhesion between the filaments of the nonwoven fabric without softening or disintegrating the processed filament layer, so the residual thickness and residual elasticity of the nonwoven fabric are obviously affected by the consolidation temperature. Within the consolidation device, the consolidation temperature and the consolidation force acting on the filament layer must be compatible with the desired effects of the process, such as a low level of softening force and low internal force. At the same time, the temperature and force must nevertheless be high enough to achieve the desired effect on the integrity of the filament layer for the production of the nonwoven fabric. This can be achieved by a number of different devices, such as a bell-type drum integration mechanism, a flat belt integration mechanism, or a multiple drum integration mechanism.

[0164] The consolidated nonwoven fabric is wound onto a spool (11) in the final stage. If the surface properties of the nonwoven fabric need to be modified, for example to improve fluid transmission or fluid drainage, a spray mechanism or dip roll is placed between the moving belt and the final consolidation mechanism or between the final consolidation mechanism and the spool.

[0165] One form of the configuration of the present invention consists of combining the activation and integration steps, and within the integration mechanism, controlling the activation time and / or integration time, the wind speed required for activation and / or integration, and the activation temperature and / or integration temperature.

[0166] The basic element is to determine the balance between the consolidation parameters: consolidation temperature, consolidation air speed and consolidation time. Consolidation time is understood to mean the time during which the layer of filaments is modified by the consolidation air. It is clear that these parameters may be varied within the specified ranges depending on the potential consolidation level of the filament layer, as well as with the aim of achieving an ideal combination between consolidation time, consolidation temperature and consolidation air speed.

[0167] The recommended integration time of the filament layer is in the range of 200-20000 ms, preferably in the range of 200-15000 ms, and most preferably in the range of 200-10000 ms.

[0168] The integrated air velocity used in this integrated unit is set in the range of 0.2 to 4.0 m / s, preferably in the range of 0.4 to 1.8 m / s. The recommended integration temperature during thermal integration is in the range of 100°C to 250°C, preferably in the range of 120°C to 220°C. In one form of configuration, the integration temperature is in the range of 90°C to 140°C, mainly in the range of 110°C to 130°C.

[0169] According to various advantageous forms of construction, the nonwoven fabric comprises layers of bicomponent filaments such as: - one component (A) made from polyethylene terephthalate (PET) and a second component (B) made from a polyolefin, in particular polyethylene, the consolidation temperature preferably being in the range of 90°C to 140°C, in particular 100°C to 140°C; - one component (A) made from polyethylene terephthalate (PET) and a second component (B) made from a polyolefin, in particular polypropylene, the consolidation temperature preferably being in the range of 90°C to 160°C, in particular 110°C to 160°C; - one component (A) made from polyethylene terephthalate (PET) and a second component (B) made from a copolymer of polyethylene terephthalate (CoPET), the combination temperature preferably being in the range of 140°C to 230°C; - one component (A) made from polylactic acid (PLA) and a second component (B) made from a polyolefin, in particular polyethylene or polypropylene, the consolidation temperature preferably being in the range of 80°C to 140°C; one component (A) made from polypropylene (PP) and a second component (B) made from a polyolefin, in particular polyethylene, or a copolymer of polypropylene and polyethylene, the consolidation temperature preferably being in the range of 90°C to 140°C, in particular 100°C to 140°C.

[0170] The nonwoven fabric of the present invention combines layers of various compositions and achieves the appropriate pre-consolidation, activation and bonding temperatures by infiltration of the individual layers at the recommended temperature intervals. The above specified temperature ranges can be used in various independent processes so that the consolidation air temperature and likewise the consolidation air speed remain within the specified range, even though the consolidation mechanism will be at different levels in various areas.

[0171] The present invention is based on the finding that nonwoven fabrics according to the invention can be designed to be relatively bulky and thus relatively thick, while maintaining satisfactory stability. The layers of the present invention exhibit excellent resilience even after being subjected to loads, i.e., pressure loads. These advantageous properties can be achieved with a relatively low nonwoven basis weight.

[0172] The method of the present invention further has the particular advantage that the continuous production of nonwoven fabrics can be carried out in a simple manner, at relatively high production rates, and without interrupting the production process. The production parameters of nonwoven fabrics are highly variable during the production process, making them flexible and adaptable, allowing the production of a variety of end products without interrupting the production process. Furthermore, the steps of the procedure consisting of pre-consolidation, activation, and consolidation can be easily modified insofar as their parameters are concerned.

[0173] The method of the present invention can be carried out in a simple manner "on-line," but the option remains to carry out various manufacturing steps "off-line" if necessary. Thus, the pre-consolidation, shrinkage activation, and final consolidation steps can be easily separated from the actual production of the layered material. It can therefore be concluded that it is possible to produce entirely new fabrics with highly advantageous three-dimensional structured surfaces, high bulk and thickness, and satisfactory compressive strength by a simple, inexpensive, and effective method. The various parameters of the nonwoven fabric or the resulting nonwoven layers can be varied and flexibly adapted throughout the manufacturing procedure.

[0174] The nonwoven fabric of the present invention can be, for example, a two-layer fabric produced on a laboratory production line at the Polymer Systems Center of the University of Zlín in Zlin. This laboratory production line, model LBS-300, is capable of producing monocomponent or bicomponent filaments for spunbond or meltblown nonwovens. The extrusion system, consisting of two extruders, can heat the polymer up to 450°C. Spunbond nonwoven filaments can be produced using a spunbond extruder with 72 holes (0.35 mm diameter, 1.4 mm length) in a square area measuring 6 x 6 cm. The extruder for processing bicomponent filaments can be configured in several configurations, including core / sheath, side-by-side, compartmental, or island configurations. The system is open, and suction air pressure up to 150 kPa is available on the input system. The filaments can be withdrawn intact or deposited on a belt running at speeds ranging from 0.7 to 12 m / min. The final product width is less than 10 cm. The total extrusion rate can be set in the range of 0.02 to 2.70 kg / h. The final basis weight is 30 to 150 g / m 2 Furthermore, there is the option to consolidate layers of filaments by using calender rolls at temperatures up to 250°C.

[0175] To model airflow consolidation under laboratory conditions (Examples 1-4), a standard stationary oven was used. As a result of the wide variety of heat transfer conditions present in a still atmosphere oven and in the mechanism of forced airflow through the fabric, as well as the heat losses that occur when the oven is opened and closed, it was necessary to set the activation + bonding time at 130°C for 3 minutes.

[0176] The layers described in the examples were produced using the laboratory production line described above. In examples 1-6, a compression roller was used behind the spinning beam with minimal down pressure and at room temperature. In other examples, a hot air stream (130°C) created using a hot air gun attachment was used instead of the compression roller.

[0177] The nonwoven fabric consists of two layers of bicomponent core / sheath filaments with a circular cross section. The mass ratio of core to sheath and the production line settings are shown in the table. For the production of the individual layers, the following temperature profiles were set for the defined polymer combinations: PET / PE: Component A = PET (Polyethylene terephthalate, Polymer Type 5520, Invista) Component B = PE (Polyethylene, ASPUN® 6834, manufactured by Dow) The extruder for component A was heated to 340°C (with three zones heated to 340°C, 335°C, and 325°C, respectively), and the extruder for component B was heated to 235°C (with three zones heated to 200°C, 215°C, and 235°C, respectively). The spin beam temperature was set at 305°C. The polymer throughput was set at 0.25 g / min / 1 capillary. The filaments were cooled with air at a temperature of 20°C. PP / PE: Component A = PP (polypropylene, Tatren HT2511, manufactured by Slovnaft) Component B = PE (Polyethylene, ASPUN6834, manufactured by Dow) The extruder for component A was heated (three zones heated to 195°C, 220°C, and 240°C, respectively), and the extruder for component B was heated to 235°C (three zones heated to 200°C, 215°C, and 235°C, respectively). The spin beam temperature was set to 240°C. The polymer throughput was set to 0.25 g / min / 1 capillary. The filaments were cooled with air at a temperature of 20°C. PLA / PE: Component A = PLA (Polylactic Acid, Ingeo, Nature Works) Component B = PE (Polyethylene, ASPUN 6834, manufactured by Dow) The extruder for component A was heated to 240°C (with three zones heated to 195°C, 220°C, and 240°C, respectively), and the extruder for component B was heated to 235°C (with three zones heated to 200°C, 215°C, and 235°C, respectively). The spin beam temperature was set to 240°C. The polymer throughput was set to 0.25 g / min / 1 capillary. The filaments were cooled with air at a temperature of 20°C. PLA / coPLA: Component A = PLA (Polylactic Acid, Ingeo, Nature Works) Component B = coPLA (polylactic acid copolymer, Ingeo, Nature Works) The extruder for component A was heated to 240°C (with three zones heated to 195°C, 220°C, and 240°C, respectively), and the extruder for component B was heated to 235°C (with three zones heated to 200°C, 215°C, and 235°C, respectively). The spin beam temperature was set to 240°C. The polymer throughput was set to 0.25 g / min / 1 capillary. The filaments were cooled with air at a temperature of 20°C.

[0178] TIFF0007729829000005.tif175154

[0179] In Examples 1-6, the initial pre-consolidation of the filaments involved the use of a room-temperature compression roller directly behind the spinning beam, which significantly affected the structural changes caused by the activation of Layer T—thickness increase (z-direction) was significantly limited. Example 6 shows that Layer M does not shrink by itself. Example 1 shows that the thickness of the fabric consisting of Layer T increased by approximately 13%. Calculation of the change in fabric bulk reveals that the increase in thickness roughly corresponds to a decrease in both the machine and cross sections, and that the total volume of the fabric remains unchanged. Examples 2-5 show a further significant increase in nonwoven thickness with approximately the same shrinkage in both the MD and CD directions, which also corresponds to an increase in total volume (approximately +15% to +20%). Without being bound by theory, we speculate that this increase occurs due to the forced shrinkage of Layer M.

[0180] TIFF0007729829000006.tif146150

[0181] In Examples 7-11, a hot air stream with a temperature of 130°C was used directly behind the spinning beam for the initial pre-consolidation of the filaments. The filaments were not compressed, and significant structural changes occurred in the z-direction during activation, and the total bulk of the material also increased significantly.

[0182] In Examples 2 to 8 and 8 to 11 of the present invention, the core in the first layer T consists of polymer A1 (polyethylene terephthalate, polymer type 5520, manufactured by Invista), and the core in the second layer M consists of polymer A2 (polyethylene, ASPUN6834, manufactured by Dow). The difference between the tensile modulus and the flexural modulus is greater than 500 MPa.

[0183] Inventive Examples 4+5 and 10+11 have lower bulk compared to Inventive Examples 2+3 and 8+9, which is mainly due to the large difference in nonwoven basis weight. The higher total basis weight also represents a greater load on the bottom layer, which is slightly loose due to its elasticity, thus reducing the total bulk of the layers.

[0184] TIFF0007729829000007.tif161146

[0185] In Examples 13 to 17, a hot air stream with a temperature of 130°C was used directly behind the spinning beam for the initial pre-consolidation of the filaments. In Examples 14 and 15, filaments with a cross section corresponding to the crimp (eC / S, S / S) were used in one of the layers. In Example 13 of the present invention, the core in the first layer T consists of polymer A1 (polylactic acid, Ingeo, Nature Works), and the second load-bearing core in the second layer M consists of polymer A2 (polyethylene, ASPUN6834, Dow). The difference between the tensile and flexural moduli is greater than 200 MPa.

[0186] In Examples 14-15, according to the present invention, the core in the first layer T consists of polymer A1 (polyethylene terephthalate, polymer type 5520, manufactured by Invista) and the core in the second layer M consists of polymer A2 (polyethylene, ASPUN6834, manufactured by Dow). The difference between the tensile and flexural moduli is greater than 500 MPa.

[0187] Example 16 describes the combination of layer T formed from spunbond filaments with layer M formed from crimped cellulose staple fibers (airlaid). The ratio of the force required to bend the filaments 90° is greater than 2 (filaments formed from polymer A1):1 (cellulose fibers).

[0188] In Example 17, according to the invention, the core in the first layer T consists of a first load-bearing polymer A1 (polypropylene 1 = Mosten NB425, Unipetrol) and the second load-bearing core in the second layer M consists of polymer A2 (polypropylene 2 = MR2002, Total Petrochemicals). The difference in flexural modulus is 100 MPa.

[0189] Examples 1-5 and 7-16 utilize shrinkage. Examples 6 and 7 do not include a shrinking layer.

[0190] Examples 18-20 below describe nonwoven fabrics made on a spunmelt manufacturing line with REICOFIL 5 technology using two bicomponent spunbond spinnerets.

[0191] Example 18 The first layer (T) was produced using a sheath / core (C / S) bicomponent nozzle with a circular cross section. The weight ratio of components A:B in the filaments was 70:30. The core of the filaments was made of PET (polymer type 5520, manufactured by Invista) and the sheath was made of PE (ASPUN6834, manufactured by Dow). The production conditions were such that the filaments formed irregular arcs or waves with a random orientation. This layer was pre-consolidated using a hot air knife (HAK) and hot air flow (HAF). The second layer (M) was produced using a sheath / core (C / S) bicomponent nozzle with a circular cross section and deposited on the first pre-consolidated layer. The weight ratio of components A:B in the filaments was 70:30. The core of the filaments was made of PP (polymer type HG475FB, manufactured by Borealis) and the sheath was made of PE (ASPUN6834, manufactured by Dow). The filaments themselves did not exhibit crimp within the layer. Both layers were further pre-integrated together using HAK (hot air knife) and HAF (hot air flow), and then completely bonded by hot air in the gluing unit.

[0192] Example 19 The first layer (T) was produced using an eccentric core / sheath (eC / S) two-component nozzle with a circular cross section (the nozzle used was the nozzle disclosed in European Patent Application No. 3771761 by REIFENHAUSER and KG MASCHINENFABRIK). The weight ratio of components A:B in the filaments was 50:50. The core of the filaments was made of PP (Polymer Type 3155, Exxon) and the sheath was made of PE (ASPUN 6850, Dow). The production conditions were set to allow the filaments to form crimps. This layer was pre-consolidated using HAK (hot air knife) and HAF (hot air flow). The second layer (M) was produced using the same eccentric core / sheath (eC / S) two-component nozzle as the first layer and deposited on the first pre-consolidated layer. The weight ratio of components A:B in the filaments was 45:55. The core of the filament was made from a blend of PP (4.5% Borealis polymer type HL712FB and 0.6% Exxon polymer type 3155 mixed with white TiO2 pigment), and the sheath was made from PE (Dow ASPUN6834). The manufacturing conditions were set so that the filament was self-crimping. Both layers were further pre-consolidated together using HAK (hot air knife) and HAF (hot air flow) and then connected by hot air in a bonding unit.

[0193] Example 20 The first layer T was produced using a sheath / core (C / S) two-component nozzle with a circular cross section. The weight ratio of components A:B in the filament was 70:30. The core of the filament was made of PET (polymer type 5520, Invista), and the sheath was made of PE (ASPUN 6834, Dow). The production conditions were set so that the filaments formed irregular arcs or waves in any direction. This layer was pre-consolidated using a hot air knife (HAK) and hot air flow (HAF). The second layer M was produced using an eccentric core / sheath (eC / S) two-component nozzle with a circular cross section (the nozzle used was the nozzle disclosed in European Patent Application No. 3771761 by REIFENHAUSER and KG MASCHINENFABRIK) and deposited on the first pre-consolidated layer. The weight ratio of components A:B in the filament was 45:55. The core of the filament was made from a blend of PP (4.5% Borealis polymer type HL712FB and 0.6% Exxon polymer type 3155 mixed with white TiO2 pigment), and the sheath was made from PE (Dow ASPUN6834). The manufacturing conditions were set so that the filaments in the layer were self-crimping. Both layers were further pre-consolidated together using HAK (hot air knife) and HAF (hot air flow), and then completely interconnected by hot air in a bonding unit. The process parameters for Examples 18 to 20 were set according to the above description, and the exact values ​​are shown in the table below.

[0194] TIFF0007729829000008.tif168146

[0195] Examples 18-20, for example, demonstrate the various layer weight combination possibilities. In Example 18, the individual spinneret discharge rates were set to produce a symmetrical product (30 + 30 gsm). In contrast, in Example 20, both spinnerets were set to their optimum discharge rates, resulting in a higher average density of filaments produced by the spinnerets and an increased filament weight per unit area (35 + 25 gsm). In Example 19, the filament densities were identical and the filament weight per unit area was also symmetrical.

[0196] Examples 18-20 also demonstrate further potential advantages of the present invention. By using layers M and T as outer layers of a composite, as in these examples, the final product can take advantage of the different properties of the layers, e.g., in terms of its own "double-sidedness." For example, one outer layer in Examples 18 and 20 is formed from layer T, which has high abrasion resistance (grade 1), while the second layer is almost non-resistant (grade 4). In Example 19, there is no difference in abrasion resistance, but there is a difference, e.g., in subjectively perceived softness, with the product being rated as softer from the side of layer M.

[0197] Test Method The "basis weight" of nonwoven fabric is measured using a test method that complies with the EN ISO9073-1:1989 standard (corresponding to the WSP130.1 method). For the measurement, 10 layers of nonwoven fabric are used, and the sample size is 10 x 10 cm. 2 is. The "thickness" or "measurement height" of nonwoven materials is measured by the test measurement method according to EN ISO 9073-2:1995 (corresponding to WSP 120.6 method), modified as follows: 1. The material is measured using samples taken from the manufacturing process without being subjected to high deformation forces or pressure (e.g., pressure from rollers on manufacturing equipment) for more than one day. Otherwise, the material must be left lying freely on a surface for at least 24 hours. 2. The total weight of the top arm of the measuring instrument with ballast added is 130g. The term "regeneration" or "recovery" of bulkiness relates to the ratio of the thickness of the dough after the release of the applied load to the initial thickness of this dough. The thickness of the dough is measured according to the EN ISO 9073-2:1995 standard, applying a preload force equivalent to a pressure of 0.5 kPa. The procedure for measuring regeneration consists of the following steps: 1. Prepare a fabric sample measuring 10 x 10 cm. 2.Measure the thickness of one piece of fabric. 3. Apply a preload force equivalent to a pressure of 0.5 kPa and measure the thickness of the five layers of fabric in the stacked state (Ts). 4. A load (2.5 kPa pressure) is applied to five pieces of fabric stacked on the thickness measuring device for five minutes. 5. Open the device and wait for 5 minutes. 6. Apply a preload force equivalent to a pressure of 0.5 kPa and measure the thickness of the five layers of fabric in the stacked state (Tr). 7. Calculate the regeneration rate according to the formula below. Regeneration rate = Tr / Ts (unitless) Ts = thickness of new sample Tr = thickness of the regenerated sample

[0198] The term "compressibility" as used herein refers to the distance, in millimeters, that a nonwoven fabric is compressed under the influence of a load, as defined when measuring "resilience." It can also be calculated as the product of the modulus of elasticity (unitless) and the thickness (mm). The "resilience" of a nonwoven fabric is measured by a test method according to the EN ISO 964-1 standard, modified as follows: 1. Measure the thickness of one dough layer. 2. Prepare several dough samples so that after stacking they have a total thickness of at least 4 mm, most preferably 5 mm. A group of stacked dough pieces contains at least one sheet of dough. 3. Measure the thickness of these stacked fabric samples. 4. A force of 5N is applied to the piled fabric samples at a loading rate of 5mm / min. 5. Measure the distance equivalent to the movement of the clamping element. 6. Calculate the modulus of elasticity according to the formula below. R (unitless) = T1 (mm) / T0 (mm) or, R(%) = T1(mm) / T0(mm) x 100% T1 = distance [mm] corresponding to the movement of the clamping element under a load of 5 N = degree of compression of the stacked dough pieces T0 = ​​thickness (according to the EN ISO9073-2:1995 standard with a preload force of 1.06 N) [mm].

[0199] The "ratio of endless filament length to fabric length" can be measured in three different ways. a) The length of the filament is measured by pulling the filament so that it is stretched linearly without crimping it. b) For fabrics that are integrated to a certain level, the method a) cannot be used to measure the filament length, so it must be estimated as follows. a. Take an image of the layer to be evaluated at a magnification that allows the filament to be seen clearly. b. Select one filament with a path through all or at least a portion of the image. c. Estimate the actual length of this filament based on the measured length of the specified filament in the image. d. Measure the length of fabric containing the filament specified above. e. Calculate the ratio (percentage) of the estimated length of the filament to the measured length of the fabric. c) In the fabric, the "Method for determining the statistical shape values ​​of filaments in nonwoven materials" is used. In this method: a. The geometric description of the fabric selected for analysis is 8 mm in the MD and 8 mm in the CD, with the full thickness of the sample maintained in the Z direction. b. From a measurement point of view, only the filaments in the fabric that enter on one side of the cut specimen and exit on the other side are the filaments that are relevant to the measurement. c. At least 20 filaments must be measured. d. Calculate the ratio (percentage) of the filament length to the measured fabric length.

[0200] The "free filament length", which is the length of the free filament between bond points or bond embossments, can basically only be determined in two different ways. 1) Estimation using two-dimensional images of fabric a. Take an image of the evaluation layer at a magnification that allows the filament to be seen clearly. b. Mark the free filament area. c. Measure the length of the marked filament section. d. Measurements are made on at least 100 randomly selected filament segments according to the basic rule of random selection, and the median free filament segment length is determined by statistical calculation. 2) For fabrics, the "Method for Determining the Statistical Shape Value of Filaments in Nonwoven Materials" is used. This method: a. The geometric description of the fabric selected for analysis is at least 8 mm in the MD and 8 mm in the CD, with the full thickness of the sample maintained in the Z direction. b. From the viewpoint of measurement, only the filaments that pass from one side of one adhesive point to the other adhesive point, or from one adhesive embossment to the other adhesive embossment, or from one adhesive embossment to another adhesive point in the cut sample are relevant to the measurement. c. Measurements are made on at least 100 randomly selected filament segments according to the basic rules of random selection, and the median free filament segment length is determined by statistical calculation.

[0201] "Martindale Average Abrasion Resistance Grade Test" or "Martindale" Figure 13 is a perspective view of the Martindale Average Abrasion Rating Test Apparatus. Figure 14 is a rating scale for evaluating fuzz in the Martindale Average Abrasion Rating Test herein, as described in U.S. Patent Application Publication No. 20200170853 by Procter & Gamble. The Martindale average abrasion resistance rating of nonwoven fabrics is determined using a Martindale abrasion tester. The test is carried out in the dry state. ● Condition the nonwoven fabric sample by placing it under conditions of a temperature of 23±2°C and a relative humidity of 50±2% for 24 hours. ● Cut ten circular samples, each 162 mm (6.375 in) in diameter, from each nonwoven fabric sample. Cut one piece of standard felt to a circle 140 mm in diameter. Place the cut felt on each Martindale test abrasion table, then place the cut nonwoven fabric sample on it, and secure each sample in place. Then, secure the clamp ring to prevent wrinkles on the nonwoven fabric sample. Assemble the abrader holder. The abrader is a 38 mm diameter, 1 / 32 inch thick FDA-compliant silicone rubber (McMaster-Carr, part number 86045K21-50A). Place the required weight on the abrader holder to apply 9 kPa of pressure to the specimen. Place the abrader holder on the Model #864 so that the abrader is in contact with the nonwoven (NW) specimen as instructed in the Operator's Guide. ● Operate Martindale wear under the following conditions: Mode: Wear test Speed: 47.5 cycles / min; and Cycles: 16 cycles ● After the test is completed, the abraded nonwoven fabric is placed on a smooth, non-glossy black surface and the level of fuzzing is evaluated using the scale in Figure 14. Each sample is evaluated by observing and judging both the size and number of defects from the top and the loft height of the defects from the side. The sample is then rated on a scale of 1 to 5 based on the closest match to this scale. The Martindale average abrasion rating is then calculated as the average rating for all samples and reported to the nearest 10-point scale.

[0202] In terms of procedural conditions, it is known that the "filament cross-section type" is defined by the shape of the extrusion tool used to form these filaments. However, if the procedural conditions are unknown, they can be estimated as follows:

[0203] A nonwoven fabric sample is taken and images of the filament cross sections are taken for at least 20 filaments. These cross section images are taken of the free parts of the filaments, not of the bonded areas or areas in contact with other filaments, as deformation is expected at these locations. The surface of each component is marked for each cross section in the image, i.e., for each component independently. The position of the centroid of each component is determined based on determining the geometric center of a planar object, and the centroid position is recorded using a Cartesian coordinate system that assigns the coordinate [0;0] to this geometric center of the filament cross section. The strain (D) at the centroid position of each component and at each filament cross section is calculated according to the following formula: D = absolute value of the product (x × y), where x and y are the coordinates of the center of gravity. If one of the values ​​x and y is 0 and at the same time is not equal to the other value, the sample is excluded from the evaluation.

[0204] The mean and standard deviation are calculated for each component.

[0205] If the ratio of the sum ((average strain) + (standard deviation)) to the total cross-sectional area is less than 5%, the filament is considered to be unformable due to crimp.

[0206] If the ratio of the difference ((average strain) - (standard deviation)) to the total cross-sectional area is less than 5%, the filament is assumed to be unformable due to crimping.

[0207] The "median filament diameter" in a layer is expressed in SI base units, micrometers (μm) or nanometers (nm). To determine this median value, samples of the nonwoven fabric must be taken from at least three locations at least 5 cm apart. In each of these samples, the diameters of at least 50 individual filaments must be measured in each examined layer. For this purpose, for example, an optical microscope or an electron microscope (depending on the diameter of the measured filaments) can be used. If the filament diameter of one sample differs significantly from that of the other two samples, it is necessary to exclude this sample and prepare new ones.

[0208] For circular filaments, the diameter is measured as the diameter of the cross section. If the filament has another cross section (for example, a hollow or three-point cross section), the measured cross section of each filament must be calculated and recalculated to the area of ​​a circle of the same dimensions. The diameter of this theoretical circular area is then the diameter of the filament.

[0209] The measurements for each layer of all three samples are then combined into a set of values ​​from which the median is then determined. At least 50% of the filaments are required to have a diameter less than or equal to the median, and at least 50% of the filaments are required to have a diameter greater than or equal to the median. To determine the median for a given set of sample values, simply arrange the values ​​in dimensional order and select the value in the middle of this list. If the set has an even number of samples, the median is usually determined as the arithmetic mean of the values ​​at positions N / 2 and N / 2+1.

[0210] The term "porosity" as used herein refers to the volume of pores in a material as a percentage of the total volume of that material.

[0211] The total volume of the material is equal to the total volume of the nonwoven fabric in this case, 1 m 2 For a nonwoven fabric, the total volume can be calculated from the thickness (height) of the nonwoven fabric according to the following formula: Total volume (m 3 / m 2 ) = ((Fabric height (mm) / 1000) x 1 (m) x 1 (m)) / m of nonwoven fabric 2 Then, the volumetric value representing the porosity of the material can be calculated using the following formula: Porosity = total volume of fabric (m 3 / m 2 ) - Volumetric weight (m 3 / m 2 ) Next, 1 m of nonwoven fabric 2 The volumetric weight per unit can be calculated using the following formula: Volume weight (m 3 / m 2 )=(Basic weight (g / m 2 ) / 1000) / polymer weight density (kg / m 3 ) The weight density value of a polymer can be calculated from its known composition or by measurement according to standard ISO 1183-3:1999, and in the case of filaments it is equal to the weighted average density specified above.

[0212] Then, the porosity value of the material can be calculated using the following formula: TIFF0007729829000009.tif28125Alternatively, porosity is the free area (m 3 ) This value can be calculated using the following formula: TIFF0007729829000010.tif30121For layered materials with large differences in porosity between individual layers, it is possible to express the total porosity of the entire material or to calculate the porosity of a given layer after setting the thickness and basis weight of each layer.

[0213] The "bulk" of a nonwoven fabric is a simplified expression of porosity and is suitable only for comparing nonwoven fabrics of similar composition with each other or for simplified comparisons. Those skilled in the art will understand that the formula does not include polymer density and that the formula allows the appropriateness and limitations of this calculation to be evaluated. Bulky (kg / m 3 ) = basis weight (g / m 2 ) / Fabric height (mm) The stiffness of nonwoven fabrics, expressed in measurements "Handle-O-Meter" (HOM), is determined in accordance with International Standard WSP 90.3. The sample dimensions are 100 x 100 mm unless otherwise stated for the measurements. The HOM is measured separately in the MD and CD directions. The arithmetic mean of these two values ​​is taken unless the MD or CD direction is specified.

[0214] "Method for determining statistical shape values ​​of filaments in nonwoven materials" The following description relates to a software method used to analyze samples of nonwoven fibrous materials in order to characterize their geometric properties. The method utilizes a machine learning procedure to identify the individual filaments contained in the sample, followed by a geometric analysis of these filaments in order to obtain statistical data suitable for characterizing the material. Results include filament orientation and density separation. The workflow used to perform this analysis was developed by Math2Market and is part of GeoDict, a digital materials laboratory software.

[0215] Step 1: Acquiring a 3D μCT image of the sample First, a 3D image of the sample's nonwoven fabric is created by digitizing the sample using a μCT scanner. This 3D image consists of a uniform Cartesian grid, and for each cell (volume element or voxel) of the grid, the attenuation value of the X-ray radiation is determined at the corresponding location on the investigated sample. Porous areas generally exhibit low attenuation (low grayscale values), while material phases exhibit high attenuation values, the magnitude of which depends on the specific material and the geometry of the μCT device used.

[0216] Step 2: Segmentation of μCT images to separate material from pore-containing spaces For further analysis, the grayscale images are filtered to remove noise using a non-local instrumental method [1]. The images are then binarized using a global threshold derived by the Otsu algorithm [2]. This binarization classifies each voxel of the image as either pore space or filament material. Voxels with grayscale values ​​below the threshold are classified as pore space; all other voxels are classified as filament material. Both interference filtering and threshold comparison procedures use the ImportGeo module of GeoDict software.

[0217] Process 3: Material density separation analysis Additionally, material density separation is calculated in the Z direction. For each image section (made in the Z direction at a given depth), material density is calculated as the number of voxels of white material divided by the total number of voxels in the respective section. This analysis is performed using the MatDict function in the GeoDict program.

[0218] Step 4: Use of neural networks to identify the center curve of the filament The main challenge with identifying individual filaments in μCT-type images arises from the lack of spatial separation of filaments at their contact points during binarization, which results in insufficient segmentation and multiple objects (filaments) being erroneously classified as a single filament. To separate the filaments, Math2Market developed a procedure that allows the central curves of the filaments to be identified. These central curves are displayed in a binary voxel image with the same dimensions as the original image. In this image, voxels located approximately 1-2 voxels from the center of the filament are marked. For this purpose, we used a neural network-based semantic segmentation method [3]. The image is analyzed by sliding 3D input windows that are moved over the image. For each input window, a small output window is defined at the center of the input window. The neural network analyzes the binary voxel values ​​of the input window and predicts the voxels of each output window. The predicted values ​​determine whether a voxel in the output window is part of a central curve. Combining the results of all these output windows results in a binary image in which each voxel is classified as a material contained in the original image. This image transformation is performed using the FiberFind-AI module in the GeoDict program using the Tensorflow software library [4].

[0219] Step 5: Creating data for neural network training To train the so-called neural network used to carry out the aforementioned transformation, Math2Market took several artificial 3D images of the nonwoven material using the FiberGeo probabilistic structure-generating module, part of the GeoDict software program. This module generates an analytical geometric visual image of the filament as a sequence of segments. At the same time, it outputs the structure of the filament in the form of a binary image, which is then compared with the binarization result from step 2. By changing the dimensions of the filaments in the analysis image by about 2-3 voxels, an image of the central curved surface corresponding to the artificial fiber structure can be formed. This image pair (i.e., an image of the filament and an image of the center curve) can then be used to train a neural network to convert the image of the filament into an image of the center curve. Through this procedure, the fabric effectively "learns to shrink" the filament in the direction of the center curve.

[0220] Step 6: Tracking the center curve of the filament to represent the shape of the filament After shrinking these filaments so that they can be represented only by their center curves, we assume that the center curves of the filaments do not touch each other. Then, when separating individual center curves by analyzing the connected components of the center curve image, we assume that each component corresponds to the center curve of one filament. At the same time, we define a connected component as part of a voxel collection of material, where all voxels have the same color and cannot be expanded by adding other voxels of the same color that are in contact with each other. Then, for each central curve, we track this cluster within the voxel cluster and represent the shape of the corresponding filament in the form of an array of interconnected fragments (dashed lines). This process is also part of the FiberFind-AI function in the GeoDict program.

[0221] Step 7: Calculating histograms to separate filament orientations To identify the orientation configuration in any plane (e.g., plane XY), we first project each fragment of the filament onto this plane, then calculate the angles in this plane. Next, we calculate the histogram of angular orientations for all fragments. Finally, we visualize this histogram of angular orientations by plotting it using polar coordinates, where the radius at a given angle is proportional to the number of occurrences of the corresponding orientation. This analysis is repeated for the remaining two planes (XZ and YZ). [Industrial Applicability]

[0222] The present invention can be used whenever a high-bulk, soft nonwoven fabric with increased compressibility and improved ability to recover to its original state is needed, for example, in the industrial production of hygiene products. In this case, the material can be used in accordance with the present invention to manufacture various parts of hygiene products with absorbent properties (e.g., baby diapers, products for incontinent individuals, personal hygiene products, changing mats, etc.) or in medicine, for example, as part of protective clothing, surgical face masks, sheets, and other products containing impermeable materials. Further application possibilities include use in various industrial sectors, for example, as part of protective clothing, as part of filtration, thermal insulation, packaging, and soundproofing products, and in the footwear, automotive, or furniture industries. The present invention can be advantageously used in areas where there is an increased need for endless filaments, particularly in areas where there is an increased need for high bulk, compressibility, and fiber recovery.

[0223] For various nonwoven applications, it may be desirable to use filaments of various thicknesses. For example, when used as a topsheet or backsheet in absorbent sanitary products, finer filaments are more advantageous (e.g., diameters in the range of 10-40 microns). For example, when used as an inner layer in absorbent sanitary products, slightly thicker filaments are advantageous (e.g., diameters in the range of 15-50 microns). For example, when used in filtration products in the form of auxiliary or acquisition layers, thicker filaments are generally required for auxiliary layers (approximately 30-100 microns), while for acquisition regions, thinner filaments are generally appropriate (10-40 microns). A person skilled in the art will be able to readily determine the appropriate filament thickness for his or her application.

Claims

1. a first layer (T) of filaments comprising endless filaments comprising a first carrier polymer (A1) and a first adhesive polymer (B1), said first adhesive polymer (B1) forming at least a portion of the surface of said endless filaments and having a melting point at least 5°C lower than said first carrier polymer (A1), said first layer (T) of filaments comprising a plurality of spaced apart bond points, said bond points interconnecting filaments and formed from said first adhesive polymer (B1); a second layer (M) of filaments comprising filaments containing a carrier material having a stiffness lower than that of the first carrier polymer (A1) and a second adhesive polymer (B2) having a melting point at least 5°C lower than that of the carrier material and the first carrier polymer (A1), the second layer (M) of filaments comprising a plurality of spaced apart bond points which interconnect the filaments of the second layer (M) and which consist of the second adhesive polymer (B2); Including, The bonded points are formed by thermal bonding at the intersections of the filaments, and the layered nonwoven fabric does not have bonded embossed points formed by compression.

2. 2. The nonwoven fabric according to claim 1, wherein the filament carrier material in the second layer (M) of filaments is a second carrier polymer (A2), the tensile and / or flexural modulus of which is at least 100 MPa lower than the tensile and / or flexural modulus of the first carrier polymer (A1), the second adhesive polymer (B2) forms at least a part of the surface of the filaments, and the filaments of the second layer (M) are endless filaments.

3. 3. The nonwoven fabric according to claim 1, wherein the melting points of the first adhesive polymer (B1) and the second adhesive polymer (B2) are the same or have a difference of 0 to 5°C.

4. 3. The nonwoven fabric according to claim 2, wherein the first carrier polymer (A1) and / or the second carrier polymer (A2) is selected from the group consisting of polyolefins, polyesters, polyamides and copolymers thereof.

5. The nonwoven fabric according to any one of claims 1 to 4, characterized in that the first adhesive polymer (B1) and / or the second adhesive polymer (B2) is selected from the group consisting of polyolefins, polyesters, polyamides, and copolymers thereof.

6. 3. The nonwoven fabric of claim 2, wherein the first carrier polymer (A1) forms at least 55% by weight of the filaments in the first layer (T) and / or the second carrier polymer (A2) forms less than 55% by weight of the filaments in the second layer (M).

7. The nonwoven fabric according to any one of claims 2 to 6, characterized in that the ratio of the weighted average density of the polymer in the endless filaments of the first layer (T) to the weighted average density of the polymer in the endless filaments of the second layer (M) is 1.0 to 1.

5.

8. A nonwoven fabric described in any one of claims 2 to 7, characterized in that the ratio of the basis weight of the first layer (T) to the basis weight of the second layer (M) is 1.0 to 1.

5.

9. 9. The nonwoven fabric according to claim 1, wherein the filaments of the first layer of filaments (T) and / or the filaments of the second layer of filaments (M) are of sheath / core type.

10. The nonwoven fabric according to any one of claims 1 to 9, wherein the median thickness of the first layer (T) filaments is in the range of 0.8 to 1.5 times the median thickness of the second layer (M) filaments.

11. 11. The nonwoven fabric according to claim 1, wherein the thickness of the second layer (M) filaments is less than 30 microns.

12. 12. The nonwoven fabric according to claim 1, wherein the first adhesive polymer (B1) and / or the second adhesive polymer comprises at least 80% by weight of polyethylene.

13. 1. A method for producing a layered nonwoven fabric, comprising the steps of: a) melting a first carrier polymer (A1) and a first adhesive polymer (B1) having a melting point at least 5°C lower than that of said first carrier polymer (A1), and then feeding them into the spinneret of a first spinning beam, thereby forming endless filaments at least partly consisting of said first adhesive polymer (B1), after which the filaments thus formed are cooled and drawn out and then deposited on a moving belt to form a first layer of filaments (T); b) depositing a second layer of filaments (M) on the first layer of filaments, the filaments of the second layer (M) comprising a carrier material having a lower stiffness than the first carrier polymer (A1) and a second adhesive polymer (B2) having a melting point at least 5° C. lower than the carrier material and the first carrier polymer (A1); c) thereafter, by the effect of air heated to 100°C to 250°C, the first layer (T) of filaments is integrated by forming adhesive points from the first adhesive polymer (B1) between the filaments, and the second layer (M) of filaments is integrated by forming adhesive points from the second adhesive polymer (B2). A method comprising:

14. 14. The method according to claim 13, wherein in step b) the second adhesive polymer (B2) and the carrier material are melted, the carrier material being a second carrier polymer (A2), the bending stiffness and tensile stiffness of which are at least 100 MPa lower than those of the first carrier polymer (A1), and the second carrier polymer (A2) and the second adhesive polymer (B2) are fed to a spinneret of a second spinning beam, whereby endless filaments are formed, at least a part of whose surface consists of the second adhesive polymer (B2), whereupon the thus formed filaments are cooled, drawn out and then deposited on the first layer (T) of filaments on a moving belt.

15. 15. A method according to claim 13 or 14, characterized in that in step c) the heated air acts on the bed (T, M) for a period of 200 to 20,000 ms.

16. 16. Method according to any one of claims 13 to 15, characterized in that in step c) heated air is passed through the layers (T, M).

17. 17. A method according to claim 16, characterized in that in step c) the heated air is passed through the beds (T, M) at a velocity ranging from 0.2 to 4.0 m / s.

18. 18. The method according to claim 13, further comprising a pre-integration step of the layers (T, M) after step b) and before step c), wherein the pre-integration of the layers is carried out by heating the layers (T, M) to a temperature in the range of 80 to 180°C to partially soften the adhesive polymers (B1, B2).

19. 19. The method according to claim 18, wherein in a preliminary integration step performed after the step b), hot air is blown onto the layers (T, M) for a time period ranging from 1 to 10,000 ms, and the blowing time of the hot air in the preliminary integration step is less than 0.5 times the blowing time of the hot air in the step c).

20. 20. A method according to claim 18 or 19, characterized in that in the pre-integration step, heated air is blown onto the layers (T, M), the air flowing through the layers (T, M) at a speed ranging from 0.1 to 10 m / s.

21. 21. The method according to claim 13, further comprising a pre-integration step of the layer (T) performed after step a) and before step b), wherein the pre-integration is performed by heating the layer (T) to a temperature in the range of 80 to 180°C to partially soften the first adhesive polymer (B1).

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