CZ2021234A3 - Non-woven fabric with increased strength - Google Patents

Abstract

A non-woven fabric (21) containing continuous fibers and bonding impressions or bonding points, wherein the continuous fibers comprise at least 80 wt.%. of aliphatic polyesters, the continuous fibers contain a first component forming at least 55% of the fiber surface, the first component contains at least one aliphatic polyester and at least 0.1 wt.% additives, where the additive contains an amide group, and corresponds to the general formula (i) R1-(CO)-NH2, (ii) R1-(CO)-NH-R2 or (iii) R1-(CO)-NH-R3- NH-(CO)-R2.

Description

Non-woven fabric with increased strength

Field of technology

The invention relates to thermally bonded non-woven fabrics of the spunmelt type containing aliphatic polyesters with increased efficiency of thermal bonding leading to increased strength of the fabric.

Current state of the art

The strength or mechanical resistance of a non-woven fabric is mainly determined by two main factors. The first is given by the fiber itself (the polymer composition and the characteristics of its crystallization, the way it is distributed, the thickness of the fiber). In the case of biopolymers, in particular aliphatic polyesters, such as polylactic acid (PLA), for example, a patent filed by the company Kimberly Clark in the USA and granted under the number US7994078 is known, which describes suitable mixtures of aliphatic polyesters (a combination of more crystalline and more amorphous polymers) for achieving better fiber quality and subsequently nonwoven fabric. Said mixtures can be used in monocomponent fibers or in various combinations in bicomponent fibers, when it is desirable to use a more amorphous component with a lower melting temperature on the surface of the fiber.

The second factor fundamentally influencing the resulting mechanical properties of the non-woven fabric is the connection of the fibers to each other. For the purposes of this document, we will limit ourselves to thermal bonding, when part of the fiber is melted, the softened or melted parts of the fibers come together and form a joint. For example, joining using a pair of calendering rolls is very common, where in addition to the effect of temperature, pressure is also used, when the protrusions on one or both rolls form so-called joining impressions. Another well-known method is, for example, bonding using hot air, which passes through the entire fabric and forms bonding points where the fibers touch. Connection methods and various advantages are described, for example, in WO2012130414 or WO2017190717, where the advantages of different shapes and distributions of the bonding impressions created by a double smooth bonding roller with a roller with protrusions are highlighted. Hot air bonding and its advantages are described, for example, in file WO2020103964 or in Czech application PV 2020-591.

The essence of the invention

The task of the invention is in particular to increase the strength of non-woven fabrics containing fibers with aliphatic polyesters, and this task is solved by a non-woven fabric containing continuous fibers and bonding impressions or bonding points, the continuous fibers contain at least 80% by weight of aliphatic polyesters, the continuous fibers contain the first component forming at least 55% of the surface fibers, the first component contains at least one aliphatic polyester and at least 0.1% by weight of an additive, the additive contains an amide group, the additive corresponds to the general formula (i) or (ii) or (iii) (i) Rl-(C0)-NH2 ( ii) R1-(CO)-NH-R2 (iii) R1-(CO)-NH-R3-NH-(CO)-R2

With benefit

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a. RI is an aliphatic hydrocarbon chain with a length of at least 10 carbons, preferably at least 12 carbons, preferably at least 15 carbons; or

b. R2 is an aliphatic hydrocarbon chain with a length of at least 10 carbons, preferably at least 12 carbons, preferably at least 15 carbons; or

c. R 3 is an aliphatic hydrocarbon chain of 1 to 3 carbons in length

It is also advantageous when

a. R1 is an aliphatic hydrocarbon chain with a maximum length of 30 carbons, preferably a maximum of 25 carbons, preferably a maximum of 20 carbons, and/or

b. R2 is an aliphatic hydrocarbon chain with a maximum length of 30 carbons, preferably a maximum of 25 carbons, preferably a maximum of 20 carbons.

It is also advantageous when

a. R 1 is an unbranched aliphatic chain; or

b. R 2 is an unbranched aliphatic chain; or

c. R 3 is an unbranched aliphatic chain.

According to the advantageous embodiment:

a. R 1 is a saturated aliphatic chain; or

b. R 2 is a saturated aliphatic chain; or

c. R 3 is a saturated aliphatic chain.

It is also preferred if the first component contains at least 0.15 wt% additive, better at least 0.20 wt% additive, preferably at least 0.25 wt% additive.

In a preferred embodiment, the first component contains no more than 10% additive, better no more than 5% additive, preferably no more than 1% additive.

Advantageously, the additive is N,N'-ethylenebis(stearamide).

Preferably, the first component forms at least 70% of the fiber surface, better at least 85% of the fiber surface, better at least 90% of the fiber surface, preferably at least 95% of the fiber surface.

The first component preferably forms a sheath in a core-sheath bicomponent fiber type.

In another embodiment, the first component forms one of the sides in a side/side bicomponent fiber type.

The endless fibers preferably contain at least 90% by weight of polymer components, better at least 95% by weight of polymer components, preferably at least 99% of polymer components.

It is also advantageous if the first component contains a mixture of aliphatic polyesters with different heats of cold crystallization.

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And it is also advantageous if the first component contains PLA or a combination of at least two types of PLA with different values of heat of cold crystallization, or if the first component consists of a mixture of PLA and another aliphatic polyester.

In a particularly advantageous embodiment, the fibers of the nonwoven fabric contain a second component, wherein the first component has a lower melting point than the second component.

At the same time, the second component preferably contains at least one aliphatic polyester, preferably PLA or a mixture of different types of PLA with different values of heat of cold crystallization.

The above task is also solved by the non-woven fabric production method, which includes the following steps:

a) a material for the production of continuous fibers is prepared, which contains at least 80% by weight of polymeric components, while this material contains the components of the first component of continuous fibers, which contains at least one aliphatic polyester and an additive in an amount of at least 0.1% by weight of the total amount of the first component , while the additive contains an amide group and corresponds to the general formula (i) or (ii) or (iii) (i) R1-(CO)-NH2 (ii) R1-(CO)-NH-R2 (iii) R1-( CO)-NH-R3-NH-(CO)-R2

b) melt and mix at least the components of the first component,

c) at least the first component is fed to the nozzles of the spinning head, with the help of which continuous fibers are formed, of which at least 55% of the surface is made up of the first component, after which the fibers formed in this way are cooled and elongated and then deposited on the running belt,

d) after which the layer of fibers created in this way is thermally bonded.

Advantageously, in step d), the layer of fibers is joined by calendering and/or the action of hot air.

Definition

The term "layer of fibers" here refers to materials in the form of fibers that are in a state prior to mutual bonding. A "layer of fibers" includes individual fibers which are usually not yet bonded together, although they may be pre-bonded in some manner, this pre-bonding may occur during or shortly after deposition of the fibers in, for example, a spunmelt process. However, this preliminary connection still allows the free movement of a substantial number of fibers, which can therefore be moved. Said "fiber layer" may include several layers formed by laying fibers from several spinning heads in the spunmelt process, provided that the distribution of fiber diameter thickness and porosity in the sublayers deposited from individual heads does not differ significantly. Adjacent layers of fibers do not have to be separated from each other by a sharp transition, individual layers can partially intertwine in the area around the border.

The term "filament" herein refers to an essentially continuous fiber, 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 here.

SI units of length - micrometers (pm) or nanometers (nm) - are used to express the "diameter of the fiber". The term fiber diameter or fiber thickness are interchangeable for the purposes of this document. In case the fibers do not have a circular cross-section, the diameter of the fiber is considered, which corresponds to an equivalent fiber with a circular cross-section. Terms "number of grams of fiber per 9000 m"

-3 CZ 2021 - 234 A3 (also titre denier or Tden or den) or "number of grams of fiber per 10000 m" (dTex) are used to express the degree of fineness or coarseness of the fiber.

The term "monocomponent fiber" refers to a fiber consisting of a single polymer component or a single mixed polymer component, as distinguished from a bicomponent or multicomponent fiber.

The term "mixture" or "blend" here typically refers to the polymer materials that are contained in the fiber. Such as when multiple polymers are mixed together. This does not exclude the addition of other substances, typically in smaller quantities (e.g. dyes, process additives, additives modifying surface properties, etc.). Blend can be used both in monocomponent fibers and as a component of bicomponent or multicomponent fibers.

The terms "bicomponent fiber" and "bicomponent fiber" refer to a fiber whose cross-section includes two separate polymer components, two separate mixed polymer components, or one single polymer component and one separate mixed polymer component. The term "bicomponent fiber" falls under the collective term "multicomponent fiber". A bicomponent fiber can have a cross section divided into two or more parts made up of different components of any type or arrangement, including, for example, co-axial arrangement, core-sheath arrangement, side-to-side arrangement, "segmented pie", etc. The term "major component" describes a component that has a greater thread share.

The term "first component" refers to a polymer or mixture of polymers which is the only component in the case of a monocomponent fiber and which is one of the components in the case of a multicomponent fiber.

A bicomponent filament having a "core-sheath structure" is a filament whose cross-section comprises two separate sub-sections, each consisting of a different polymer component or mixture of polymer components, wherein the polymer component or mixture of polymer components forming a closed shell is surrounded by the polymer component or a mixture of polymeric components forming the core. For example, the term "C/S 70/30" describes a bicomponent fiber in a core-sheath configuration, where the core is 70% by weight of the fiber and the sheath is 30% by weight of the fiber.

"Nonwoven fabric" is a structure in the form of a web or fiber layer, which is made of controlled laid or randomly oriented fibers, from which a layer of fibers is first formed, which is then interconnected (bonded). The fibers can be connected to each other by friction, by the action of cohesive forces, by gluing with a binder or other adhesives, or thermoplastically to form one or more binding binding patterns consisting of binding impressions created by bounded compression and/or the action of pressure, heating, ultrasound or thermal energy, or a combination of these effects. The term does not include fabrics which are made by weaving and knitting or using yarns or threads forming connecting stitches. Fibers can be of natural or synthetic origin, and can be staple fibers, continuous fibers or fibers created directly at the processing site. Commonly available fibers have diameters ranging from about 0.0005 mm to about 0.25 mm and come in several different forms: short fibers (also known as staple or staple). Endless individual fibers (so-called filaments or monofilaments), or bundles of endless fibers (so-called multifilaments or so-called skeins) and bundles of endless fibers with a common twist (yarn). Nonwovens can be made by many processes, including meltblown, spunbond, spunmelt, solvent spinning, electrospinning, carding, film fibrillation, melt film fibrillation, air jet lamination, dry lamination, wet staple lamination fibers and various combinations of these and other techniques known in the art. The basis weight of nonwoven fabrics is usually expressed in grams per square meter (gsm).

The "spunbond" process is a nonwoven fabric manufacturing process that involves the direct conversion of polymer into filaments, which is immediately followed by the spreading of the thus formed filaments behind

-4CZ 2021 - 234 A3 formation of a non-woven layer of fibers containing randomly arranged filaments. This non-woven layer of fibers is subsequently reinforced so that the bonds between the fibers form a non-woven fabric. At the same time, the strengthening process can be carried out in different ways, for example by the action of passing air, by passing between the bonding rollers, etc.

The terms "bonds between filaments" or "connecting points" refer to bonds that usually connect two filaments in an area where these filaments cross each other or locally meet or adjoin each other. It is possible to connect more than two filaments or to connect two parts of the same filament through connecting points/reinforcing ties. The term "joining point" here therefore represents the connection of two fibers / filaments at the point of contact by connecting their components with a lower melting point (see Fig. 1 B). The fiber component with a higher melting point is not damaged or shaped in any way at the joining point. In contrast, the term "bonding impression" represents the surface on which the protrusion of the calendering cylinder acted (see Fig. 1 V). The bonding impression has a defined area determined by the size of the protrusion of the bonding roller and typically has a smaller thickness compared to the surrounding area. Typically, a significant mechanical pressure also occurs in the surface of the bonding impression during connection, which, together with the temperature, can affect the shape of all components of the fiber in the surface of the bonding impression.

The terms "bonding roll", "calendering roll" and "roller" are used interchangeably here.

The term "sanitary absorbent article" here refers to articles or aids that absorb and retain body excreta, more specifically, articles or aids that are attached to the body or placed near the user's body to absorb and retain various body excreta. Articles with absorbent properties may include disposable diapers, diaper panties, adult incontinent underwear and pads, feminine hygiene pads, breast pads, changing mats, bibs, bandages, and similar products. The term "excreta" as used herein includes, in particular, urine, blood, vaginal secretions, breast milk, sweat and feces.

In connection with the production of nonwoven textile material and the nonwoven textile material itself, the term "transverse direction" (CD) refers to a direction that is essentially perpendicular to the direction of forward movement of the textile material through the production line in which it is produced. In relation to the layer of fibers passing through the pressing gap of a pair of calendering rollers to form a non-woven fabric with strong bonds between the fibers, the transverse direction is then perpendicular to the direction of passage of the fibers through the pressing gap and at the same time parallel to this pressing gap.

In connection with the production of nonwoven textile material and the nonwoven textile material itself, the term "machine direction of movement" (MD) refers to a direction that is essentially parallel to the direction of forward movement of the textile material through the production line in which it is produced. In relation to the layer of fibers passing through the pressing gap of a pair of calendering rollers to form a non-woven fabric with strong bonds between the fibers, the direction of movement of the machine is then parallel to the direction of passage of the fibers through the pressing gap and at the same time perpendicular to this pressing gap.

The term "aliphatic polyester" represents any biodegradable polymer (homo and copolymer) based on aliphatic polyester. Examples of biodegradable aliphatic polyesters useful for this invention include, but are not limited to, polyhydroxy butyrate (PHB), polyhydroxy butyrate-co-valerate (PHBV), polycaprolactone (PCL), polybutylene succinate (PBS), polybutylene succinate -co-adipate (PBSA), polyglycolic acid (PGA), polylactide or polylactic acid (PLA), polybutylene oxalate, polyethylene adipate, polydioxanone (PDO). Due to availability and price, the polylactide group, especially PLA and its derivatives, is currently the most preferred group.

A "bonding boss" or "protrusion" is a feature on the surface of a bonding cylinder that is radially farthest from the axis of the cylinder and is surrounded by recessed areas. Thus, the bonding projection has a bonding surface that has the largest radial distance relative to the axis of rotation of the bonding cylinder and has a certain shape, the area of this bonding surface having a defined shape and generally being part of the outer

-5CZ 2021 - 234 A3 cylindrical surfaces and thus has an essentially constant radius and therefore a constant distance from the axis of rotation of the connecting cylinder; however, the discontinuous projections having separate bonding surface shapes are often so small relative to the radius of the bonding cylinder that the bonding surfaces appear to be a flat or planar overall surface. The surface area of the connecting protrusion of the given shape on the cylinder can thus be approximated with sufficient accuracy by a plane surface of the same shape. Individual bonding lugs may have flanks that are perpendicular to the bonding surface, although typically they are arranged at an angle to the bonding surface of the lug, such that the cross-section of the base of the bonding lug is greater than the area of the bonding surface of the same lug. Bonding protrusions can be formed on the calender roll in large numbers, and can be arranged in a certain pattern. This large number of connecting protrusions then has a connecting surface per unit area of the outer cylindrical surface, which can be expressed as a percentage ratio, specifically as a ratio of the sum of the areas of the shaped connecting surfaces of all the protrusions formed on the cylinder to the total surface of this cylinder, or the surface of its peripheral shell.

Clarification of drawings

Giant. 1: Comparison of cross-section of fabric connected by means of connecting impressions (V) and fabric connected by means of connecting points (B)

Giant. 2 A: SEM image of the bonding impression of the comparative non-woven fabric according to example 1

Giant. 2 B: SEM image of the bonding imprint of the nonwoven fabric according to the invention according to example 2

Giant. 3: Scheme of the production line for spunmelt non-woven fabric.

Giant. 4: Schematic of thermal bonding using a pair of heated rollers (calender)

Examples of implementation of the invention

The subject of the invention is a thermally bonded non-woven fabric made of continuous fibers of the spunmelt type, which contains an aliphatic polyester or a mixture of aliphatic polyesters in combination with a non-polymeric additive that changes the crystallization dynamics of the material in the fibers and increases the efficiency of thermal bonding.

Aliphatic polyesters have a characteristic behavior during thermal bonding. When exposed to heat flow, after absorbing a certain amount of heat, the volume of the polymer will change (for example, in the region of so-called cold crystallization), a phenomenon known as precipitation. Precipitation is generally considered an undesirable phenomenon and there is a clear tendency in the field to place at least part of the surface of the thermally bonded fibers with aliphatic polyester with a high proportion of amorphous components (they are characterized by a low value of the heat of cold crystallization and are typically lower in melting point than crystalline components. Without wanting to bound by theory, we believe that some degree of exothermic cold crystallization is desirable. In the case of a very amorphous polymer, rapid surface melting can occur without overheating and softening the entire fiber, or at least its entire bonding component. The molten portion of the polymer on the surface of the fiber is sticky and easily adheres to the surface of one of the line elements. Releasing such a fiber requires a higher force than releasing a fiber loosely laid on the belt. When many fibers are caught, the overall adhesion of the fiber belt to the substrate increases and the fiber belt may break and become unwieldy per element in the production line.

At the same time, even a relatively small amount of coagulation can also cause problems during production. It should be noted that during production, the web of the fiber layer is on a moving belt, drum or cylinder, which are not always perfectly smooth. The fiber layer of the non-woven fabric presents a relatively open structure with partially mobile parts of the fibers before consolidation. It then easily happens that the fiber or part of it gets in close proximity to the protrusion or depression and already at the first

-6CZ 2021 - 234 A3 a small collapse of the material will shrink around it and catch it. Release, as in the case described above, requires a higher force and there is a risk of breaking the fiber band. Typically, for example, on a hot roller with protrusions, a belt during the transition from one element to another, a drum in a drum dryer or a hot air bonding unit, etc.

Aliphatic polyesters are available in different degrees of crystallinity, i.e. with different values of the group heat of cold crystallization, both described effects can intermingle and support and narrow the process window for thermal bonding of nonwoven fabric. The described behavior has been observed, for example, for PLA fibers with significantly amorphous polymer on the fiber surface at temperatures above 140 °C at a speed of 150 m/min, or for example at temperatures above 110 °C at a speed of 7 m/min).

Without wishing to be bound by theory, we believe that the crystallization dynamic additive aids in more homogenous softening and subsequently melting of the polymer, such that fiber sintering or fiber binder components sintering occurs, and at the same time shifts the softening onset temperature of the aliphatic polyester to allow for proper thermal bonding of the surfaces fibers.

The additive according to the invention is a non-polymeric organic compound consisting of a polar central part and non-polar ends. The polar central part is generally compatible with the structure of aliphatic polyesters, while the relatively short and in terms of 3D structure flexible non-polar ends locally affect the dynamics of polymer crystallization. Too short ends will not provide the necessary effect, and too long non-polar ends in the polar environment of the aliphatic polyester will tend to clump and reduce the homogeneity of the mixture.

In an advantageous embodiment according to the invention, the central polar part is formed by a combination of positive and negative partial charges on the elements of the central part. It preferably contains amides (i) or N-substituted amides (ii), where the nitrogen is bound by a single bond to the carbon of the keto group C=O and another single bond to the next carbon of the continuing aliphatic chain R1-(CO)-(NH)-R2.

(i) amides

(ii) N-substituted amides

With an acceptable degree of simplification, this arrangement of atoms in the molecule results in a partial negative charge on the oxygen and a partial positive charge on the nitrogen, and as such is well compatible with polar aliphatic ester chains. The effect is further enhanced if the group - (CO)-(NH) - in the core of the additive is repeated in the combination R1-(CO)-(NH)-R3-(NH)-R1 (iii). The aliphatic chains R1, R2 and R3 can be of different lengths.

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O o (iii) R1-(CO)-(NH)-R3-(NH)-R

In a preferred embodiment according to the invention, part R1 represents an aliphatic hydrocarbon residue with a length of at least 10 carbons, preferably at least 12 carbons, preferably at least 15 carbons.

In a preferred embodiment according to the invention, part R1 represents an aliphatic hydrocarbon residue with a maximum length of 30 carbons, preferably a maximum of 25 carbons, preferably a maximum of 20 carbons.

In a preferred embodiment according to the invention, part R2 represents an aliphatic hydrocarbon residue with a length of at least 10 carbons, preferably at least 12 carbons, preferably at least 15 carbons.

In a preferred embodiment according to the invention, part R2 represents an aliphatic hydrocarbon residue with a length of a maximum of 30 carbons, preferably a maximum of 25 carbons, preferably a maximum of 20 carbons.

In a preferred embodiment according to the invention, part R3 represents an aliphatic hydrocarbon residue with a length of 1 to 3 carbons, preferably 2 carbons.

In a preferred embodiment according to the invention, part R1 and/or R2 and/or R3 is formed by an unbranched aliphatic chain.

In a preferred embodiment according to the invention, part R1 and/or R2 and/or R3 is formed by a saturated aliphatic chain.

In a preferred embodiment according to the invention, part R1 and/or R2 and/or R3 is formed by an unbranched saturated aliphatic chain.

In a preferred embodiment according to the invention, the parts R1 and R2 are formed by equally long aliphatic saturated unbranched hydrocarbon residues.

An example of a suitable non-polymeric additive from the group of amides is, for example, erucamide, behenamide or oleamide (structural formulas shown below and description in Table 1).

Erucamide

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Oleamide

Compound Erucamide Behenamide Oleamide IUPAC name (Z)-doco s-13-enamide docosanamide (9Z)-Octadec-9-enamide Formula C22H43NO C22H45NO C18H35NO R1 length 21 C 21 C 17 C R1 type unbranched unbranched unbranched R1 bonds 1 unsaturated (dual from C12) saturated 1 unsaturated (double from C8)

Table 1: description of compounds erucamide, behenamide and oleamide

An example of a suitable non-polymeric additive from the group of N-substituted amides is, for example, N,N'-Ethylenebis(stearamide) known by the abbreviation EBS with the formula C38H76N2O2. The structural formula is shown below.

1^'-EOi'^enebis(stearamide) = EBS

EBS additive for non-woven fabric according to the invention, where the hydrocarbon residues R1 and R2 are equally long aliphatic saturated unbranched chains of 17 carbons and R3 is aliphatic saturated unbranched chains of 3 carbons.

In a preferred embodiment according to the invention, the fiber of the non-woven fabric contains at least 0.10% by weight of non-polymeric additive, preferably at least 0.20% by weight of non-polymeric additive, preferably at least 0.25% by weight of non-polymeric additive.

In an advantageous embodiment according to the invention, the amount of the non-polymeric additive according to the invention does not exceed the amount of 10%, better 5%, preferably 1%.

When thermally bonding a layer of fibers into a non-woven fabric, it can be advantageous to use bi- or multi-component (= multi-component) fibers, where the first component contained at least on part of the surface of the fiber (for example, a sheath in a core/sheath combination, or one of the sides in a combination

-9CZ 2021 - 234 A3 page/page) is made of a material with a lower melting point than the other component. In the course of joining, the first component will primarily soften and in the places of contact of the surface of the fibers with the content of the first component, a joint will be formed. When using aliphatic polyesters, it is advantageous if the first component contains a larger proportion of amorphous polymer than the second component.

In a preferred embodiment according to the invention, the first component covers at least 55% of the fiber surface, better at least 70% of the fiber surface, better at least 85% of the fiber surface, better at least 90% of the fiber surface, preferably at least 95% of the fiber surface.

In a preferred embodiment according to the invention, the first component contains at least 0.10 wt% of the non-polymeric additive according to the invention, better at least 0.20 wt% of the non-polymeric additive according to the invention, preferably at least 0.25 wt% of the non-polymeric additive according to the invention.

In an advantageous embodiment according to the invention, the amount of non-polymeric additive according to the invention in the first component does not exceed the amount of 10%, better 5%, preferably 1%.

The behavior of pure PLA compared to the PLA - EBS mixture was tested using Differential Scanning Calorimetry (DSC), the results are shown in Tables 2 and 3.

Second heat 100% PLA 1 (crystalline type) 90% PLA1 + 10% EBS Glass transition temperature (ISO midpoint) 58°C 58°C Cold crystallization Start peak End Heat 101°C 134°C 157°C 34 J/g 105°C 119 °C 137°C 21 J/g Thaw Start peak End Heat 163°C 170°C 177°C -34 J/g 141°C 145°C 148°C -36 J/g

Table 2: DSC PLA 1 without and with EBS admixture

From the given data for the crystalline type PLA1, it is clear that the presence of the additive did not significantly affect the glass transition temperature, however, in the area of cold crystallization dynamics (in terms of the beginning, end and amount of heat received) together with the melting area (reduction of the onset of softening by 20 °C and halving the temperature interval) significant changes are observable.

With the addition of EBS, the region of cold crystallization was significantly shortened (from the interval of 56 °C to the interval of 31 °C) and the amount of exothermic heat was also drastically reduced (from 34 J/g to 21 J/g). Without wanting to be bound by theory, we believe that the change in the dynamics of cold crystallization due to the described non-polymeric additive leads to a reduction in the rate of precipitation, and thus to a reduction in the unwanted capture of fibers behind the elements of the production line. Although in the case of such a high amount of EBS addition, the reduction in the amount of released heat is borderline. Further reduction will probably lead to undesirable effects on the production line (increased risk of textile trapping and fiber web breakage).

Lowering the temperature of the beginning of melting is another benefit that helps to better connect the fibers of the non-woven fabric to each other, both in the form of pressure-formed bonding impressions in the case of calender bonding, and for example bonding points formed at the points of fiber contact in the case of hot air bonding.

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Second heat 100%PLA2 (amorphous type) 96% PLA2 + 3.6% PBAT + 0.4% EBS 96% PLA2 + 3.6% PLA1 + 0.4% EBS Glass transition temperature (ISO midpoint) 57 °C 59 °C 60 °C Cold crystallization Start peak End Heat She is not observed 107°C 118°C 131°C 30 J/g 106°C 117°C 130°C 31 J/g Thaw Start peak End Heat 139°C 147°C 157°C -i J/g 145°C 150 °C 157°C -31 J/g 144°C 150 °C 159 °C -34 J/g

Table 3: DSC PLA 2 without and with addition of EBS and other substances

From the given data for the amorphous PLA2 type, it is clear that the presence of the additive did not significantly affect the glass transition temperature here either, but it has a major influence in the area of cold crystallization and melting temperature. The data presented in Table 3 also show that admixtures of other polyesters (aromatic PBAT, crystalline PLA1) do not cancel the desired described effect of the additive according to the invention. The area of cold crystallization here was significantly supported by the addition of EBS. While it is not observed at all for amorphous PLA2, for both polymer mixtures we observe cold crystallization in a similar region (from approx. 106 °C to approx. 130 °C) and a comparable amount of exothermic heat (approx. 30 J/g). The amount of EBS is optimized here to achieve the maximum effect in thermal bonding for a specific type of polymer - without wanting to be bound by theory, we observe that in the optimum region the heats of cold crystallization and heats of fusion are very close to each other.

Compared to the case of the PLA1 crystalline type, we observe a slight increase in the melting temperature, when we reach temperatures of 144-145 °C, very similar to the above-mentioned level of 141 °C, but the fundamental change here is the change in the melting heat, when we observe an increase from 1 J/g to 31 - 34 J/g. Without wanting to be bound by theory, we believe that the above-mentioned increase in the melting temperature slows down the melting of the polymer surface, in simple terms, it contributes to the homogenization of the melting of the entire component, which makes it possible to achieve the desired sintering of the fibers or their parts during thermal bonding and limits the danger of the textile being caught by the element on the production line and rupture of the fiber belt.

Without wishing to be bound by theory, we believe that the addition of aromatic polyester may be of further benefit. Benzene cores with their specific distribution of free electrons and relatively rigid spatial structure can support the crystallization of amorphous parts of the polymer in particular, and at the same time, the non-polymeric additive maintains the degree of crystallization at the desired level.

For the solution according to the invention, the addition of aromatic polyester, better biodegradable aromatic polyester, can be advantageous. In an advantageous embodiment, the addition of aromatic polyester does not exceed 10 wt% of the first component, better does not exceed 7 wt% of the first component, preferably does not exceed 5 wt% of the first component. In an advantageous solution according to the invention, the biodegradable aromatic polyester is, for example, PBAT (Polybutylene adipate terephthalate).

The above-described changes described using the DSC method can also be observed directly on the non-woven fabric, for example in the form of bonding impressions. For example, an SEM photograph of a bonding imprint of pure PLA (made as described in Example 1) shows bonding imprints with insufficiently interconnected fibers. The wrappings of the bicomponent fibers used did not connect properly, it seems as if they stuck to each other only by the surface or by the mere application of pressure (Fig. 2 A). The joints created in this way do not have the necessary strength and the fibers can be separated from each other relatively easily. The second photo shows a bonding imprint of PLA containing 0.3% EBS (made as described in Example 2), where

-11 CZ 2021 - 234 A3 obvious full interconnection of fibers (Fig. 2 B). The nonwoven fabric shown in this image also has significantly higher strength and surface abrasion resistance. The same temperature and pressure of the same calendering rolls were used in the production of both samples. When trying to increase the bonding temperature in the case of pure PLA, the fabric caught on the rollers and there was a risk of wrapping the fabric strip and interrupting the production process.

The process of spunbond technology consists in spinning the polymer melt under a nozzle. The production line (Fig. 3) may include one or more spinning heads 1 adapted for the production of spunbond fibers. Each of the spinning heads is connected to at least one extruder, into which the required polymer mixture is dosed. Each of the heads can process a different polymer mixture. In the extruder, the mixture is melted and delivered to the spinneret 5. It is well known in the art that different spinneret configurations can be used to obtain fibers of different cross-sectional shapes and diameters, which can produce monocomponent or multicomponent fibers in different configurations (for example, core/sheath , side/side, islands in the sea, etc.) The initial spunbond fibers 4 produced by the spinning nozzle 5 are cooled and stretched in the cooling and stretching chamber 7 by an air stream (supplied by the cooling and stretching air inlet 6), then vibrated in the diffuser 8 and placed on moving surface 2, which can be a breathable belt. If necessary, the layer of fibers can be pre-strengthened by one or more preconsolidation units 9, 10. In the case of using several consecutive spinning heads, the fibers from the second and each subsequent head 1 fall on the layer of fibers formed by the previous spinning heads L Different polymer composition and/or different the process setting of the spinning heads 1 (e.g. power, cooling rate and elongation) leads to different characteristics of the layer of fibers laid by a given production head on the substrate - different multilayer composites with specific properties can be created.

It is also well-known in the field to insert one or several other spinning heads between the spunbond heads, e.g. of the meltblown, advanced meltblown or melt fibrillation type, thus inserting a typically barrier layer with a significantly lower fiber diameter between the spunbond layers. In the field, these composites are known as SMS materials.

The layer of fibers formed by all the spinning heads used includes individual fibers between which usually no solid bond has yet been formed, although they may be bonded in some way, this preliminary bonding may take place during or shortly after the deposition of the loose fiber layer in the preconsolidation units 9, 10, for example by using cylinders, hot air currents, heat radiation, etc. However, this preliminary connection still allows the free movement of a substantial number of fibers, which can therefore be moved. This layer of fibers can be bonded thermally (for example, by means of calendering rolls, by means of a stream of hot media, etc.) to form a non-woven fabric.

The polymer mixture contained in the fibers of the nonwoven fabric according to the invention can be formed from one or more granulates based on polymer materials such as aliphatic polyesters, more specifically, for example, polylactic acid polymer (PLA). In a preferred embodiment according to the invention, aliphatic polyesters represent at least 80% by weight of fiber, preferably at least 90% by weight of fiber, better at least 95% by weight of fiber, preferably at least 99% by weight of fiber. It is desirable to emphasize here that the share of polymer components, or the proportion of aliphatic polyesters is calculated from the entire fiber, regardless of whether it is a mono or multi-component fiber.

In a preferred embodiment according to the invention, one aliphatic polyester represents a basic component constituting at least 60% by weight of the content of aliphatic polyesters.

In a preferred embodiment according to the invention, the aliphatic polyester based on polylactide is the basic component constituting at least 60% by weight of the content of aliphatic polyesters.

The fibers of the non-woven fabric according to the invention may contain other additives, such as color pigments, substances that increase the pleasantness of the taste (soft-touch, cotton-touch and others), process additives, etc.

-12 CZ 2021 - 234 A3

The fibers of the nonwoven fabric according to the invention may contain other additives such as aromatic polyesters, thermoplastic polysaccharides and other substances. Advantageously, these other additives are biodegradable. The advantages of aliphatic polyester blends are known in the art. For example, the advantages of combining PLA and PBS in different ratios and crystalline states are explained in a number of older works.

The fibers of the nonwoven fabric according to the invention may contain a mixture of at least two aliphatic polyesters, at least one of which is characterized by a lower value of the heat of cold crystallization than the others. A preferred solution according to the invention is a mixture of at least two aliphatic polyesters, of which at least one has a lower heat of cold crystallization by at least 1 J/g, better by at least 2 J/g, preferably by at least 3 J/g than at least one other aliphatic polyester in composition, while another aliphatic polyester also means another type (grade) of chemically the same aliphatic polyester.

The fibers of the nonwoven fabric according to the invention may contain other additives, such as, for example, aliphatic polyolefins, such as polypropylene or polyethylene, or their copolymers.

Individual fibers can be single-component or multi-component. Multicomponent fibers include, in particular, bicomponent fibers, such as core-sheath or side-to-side fibers. Individual components can often be divided into a first component - a binding component with a lower melting point and a second component. In the case of aliphatic polyesters, for example, a more amorphous form of polyester can be used as the first component with a lower melting point. For example, a first component with a lower melting point can be placed in the shell so that it will act as a binder during thermal bonding of the nonwoven fabric. Side-to-side or eccentric core/sheath fibers can be advantageously used, for example, in the production of high volume materials. The use of suitable polymers in the individual components of the bicomponent fiber can, for example, lead to so-called self-curved fibers, which significantly increase the volume of the nonwoven fabric. For the solution according to the invention, it is advantageous if the first component with a lower melting point is the above-mentioned mixture containing at least one aliphatic polyester and an additive. A person skilled in the art will readily appreciate the various other possibilities and advantages of using different types of fibers. For the solution according to the invention, it is advantageous if the difference between the melting temperatures of the first and second components in the bicomponent fiber is at least 5 °C, better at least 10 °C and the first component with a lower melting temperature occupies at least 55% of the fiber surface, better at least 70% of the fiber surface , preferably at least 85% of the fiber surface, better at least 90% of the fiber surface, preferably at least 99% of the fiber surface.

For the solution according to the invention, it is advantageous if the first component represents at least 5% by weight of fiber, better at least 10% by weight of fiber, preferably at least 15% by weight of fiber.

The solution according to the invention can be realized as a spunlaid nonwoven fabric containing mainly bicomponent spunbond fibers with a proportion of the first component of at least 5 wt% of the fiber occupying at least 55% of the fiber surface.

The non-woven fabric prepared in this way undergoes thermal bonding in the bonding unit 3, which can be realized in different ways - for example, by means of a pair of heated calendering rollers 50, 51, or by means of a stream of hot media (e.g. air).

The solution according to the invention can advantageously be realized by means of thermal bonding of the non-woven fabric by a pair of calendering rollers 50,51. The technological process of thermal bonding of this type includes the step of forming bonds between the fibers forming the layer of fibers, during which the fibers are to a certain extent consolidated and connected to each other to form a textile and at the same time increasing the values of mechanical properties, e.g. tensile strength, which may be necessary to , so that the material can maintain sufficient structural integrity and dimensional stability during subsequent production procedures and also during use of the finished product. As can be seen from Fig. 4, the calendering bond formation can be performed by passing the layer of fibers 21a through a gap between a pair of rotating calendering rollers 50, 51, thereby compressing and consolidating the fibers to form a nonwoven

-13 CZ 2021 - 234 A3 textiles 21. One or both of the calendering rolls 50, 51 may be heated to promote heating, plastic deformation, interweaving and/or heat melting/bonding of superimposed fibers as they are compressed in the gap between the rolls . The cylinders may form functional parts of a coupling mechanism in which they are pressed together with a force of a controllable magnitude so as to exert the desired compressive force / desired pressure in the slot. In some procedures, a source of ultrasonic energy may be incorporated into the bonding mechanism, which allows the ultrasonic vibrations to be transmitted to the fibers, which in turn generate thermal energy that improves bonding.

On the outer surface of one or both calendering rolls 50, 51, a bonding pattern consisting of connecting protrusions and recessed areas can be formed by machining, etching, engraving or other means, as a result of which the bonding pressure acting on the layer of fibers as it passes through the slot 52 is concentrated on the bonding surfaces connecting protrusions, while in recessed areas it is reduced or substantially reduced. Bonding surfaces have predetermined shapes. As a result, a non-woven fabric 21 is formed with a pattern consisting of connecting impressions V (see Fig. 1) between the fibers forming this non-woven fabric 21, the shape of which corresponds to the shape of the connecting protrusions arranged in the same pattern on the surface of the calendering roll 50, 51. One roll, for example, the cylinder 51 can have a smooth cylindrical surface without a pattern, so it represents a pressing or abutting cylinder, while the second cylinder 50 can be provided with the pattern described above and thus represent a cylinder creating a bonding pattern in the processed material; the pattern created on the non-woven fabric by this combination of rollers will then exactly match the pattern on said second roller 50. In some cases, patterns can be provided on both rollers 50, 51, and these patterns can also be different. In such a case, the effect of these patterns on the nonwoven fabric creates a combined pattern, such as is described, for example, in the U.S. patent file. 5,370,764.

For the solution according to the invention, it is advantageous if the total bond area represents at least 8% of the total area of the nonwoven fabric, preferably at least 11% of the total area of the nonwoven fabric.

For the solution according to the invention, it is advantageous if the total bond area does not exceed 30% of the total area of the nonwoven fabric, preferably does not exceed 25% of the total area of the nonwoven fabric, preferably does not exceed 20% of the total area of the nonwoven fabric.

Calendering rolls bond the fibers together using a combination of heat and pressure. Therefore, it is advantageous to set the temperature of the rolls to a temperature close to below the melting point of the bonding polymer. The temperature is preferably set to be 1-15°C lower than the melting temperature of the bonding polymer, more preferably the temperature is set to be 1-10°C lower than the melting temperature of the bonding polymer. The indicated joining temperatures are suitable for sufficiently fast production lines, especially for slow laboratory lines with belt speeds in the order of meters significantly lower temperatures are sufficient. The recommended limit of roller temperatures corresponds to a production speed of at least 50 m/min

The solution according to the invention can advantageously be implemented by means of thermal bonding of non-woven fabric using a hot medium. The textile according to the invention can be made from a layer of fibers containing multi-component filaments which, at least on part of their surface, include a bonding polymer with a lower melting point. The layer of fibers on the moving belt is subjected to heat treatment. Heat can be transferred to the fiber layer by means of a hot fluid, e.g. hot air. In general, the transfer of heat to the fiber layer can take place at different stages of the manufacturing process, e.g. immediately after the filaments are placed on the strip to preconsolidate the structure, during the heat activation process, during the bonding process (final consolidation), etc.

The hot fluid enters the surface of the filaments of the fiber layer, flows around the filaments, and part of the heat transferred by the hot fluid passes to the cooler filaments. It should be noted that the formation of mutual connections between filaments also depends on the local pressure intensity of the liquid resistance, i.e. the filaments can be in contact with each other or cross each other and not form a connection (bonding point) or only form a weak connection (bonding point), while the filaments in more intense contact, it forms stronger bonds (bonding points) through the molten polymer with a lower melting temperature. For

-14 CZ 2021 - 234 A3 solution in accordance with the invention is advantageous when the flow of hot medium passes through the fabric and thus results in heat transfer through the entire volume of the non-woven fabric.

A preferred embodiment in accordance with the invention includes a joining procedure (final consolidation) which is carried out using at least three different consolidation sections. The airflow is essentially perpendicular to the fabric and maintains a uniform temperature and volume flow with low fluctuations.

The first consolidation section preheats the fabric to a temperature close to below the melting point of the bonding polymer. The temperature is preferably set to be 5-20°C lower than the melting temperature of the bonding polymer, more preferably the temperature is set to be 5-15°C lower than the melting temperature of the bonding polymer, preferably the temperature is set to to be 5-10 °C lower than the melting point of the bonding polymer. The first consolidation section preferably includes alternating heat flow directions entering the first and second outer surfaces of the fabric.

The second consolidation section is set to achieve a narrow melting temperature range of the low melting polymer composition so as to allow the fusion bond to form. On the other hand, the set temperature in relation to the basis weight of the fabric, the size of the fibers and the cross-sectional ratio of the polymer components should be in the range of no more than 5.0 °C below to a maximum of 3.0 °C above the melting temperature of the bonding polymer. For example, if the melting temperature is 130 °C, the set temperature should be in the range of 5 °C below the melting temperature of the bonding polymer to a temperature equal to the melting temperature of the bonding polymer, more preferably the temperature is set in the range of 4 °C to 1 °C below the temperature melting of the bonding polymer. The second consolidation section preferably includes alternating directions of heat flow entering from the first and second outer surfaces of the fabric.

The third consolidation section is a cooling section, providing significantly cooler air, preferably at a temperature of 10-40°C, more preferably 20-30°C. Ambient air can be used. The cooling section helps solidify the filaments or at least the filaments on the surface of the fabric and stabilize the formed structure of the fabric strata. Advantageously, no additional voltage is applied directly before and during the cooling process. Advantageously, an additional cooling step can be applied after the consolidation unit. Additional cooling can be provided by an additional air stream, a cooling cylinder, etc. Preferably, the additional cooling is performed when the temperature of the fabric leaving the third consolidation section does not yet reach the ambient temperature. The fabric should preferably reach ambient temperature, preferably the fabric should reach a temperature of 40-10°C, even more preferably the fabric should reach a temperature of 20-30°C. The described process produces voluminous, soft, non-woven fabrics with a low tendency to felting at a high production capacity and at a high production speed for economically advantageous reasons.

For example, in one embodiment in accordance with the invention, a consolidation device using the effect of passing hot air, comprising 4 drums, may be used. This equipment enables a process with short dwell times even at high speeds, but also with sufficient exposure to the necessary hot air flow and hot air volume along the maximized filament path to achieve the necessary low viscosity melt flow to create fusion joints within a defined narrow parameter range. The drums in the direction of passage through the machine enable contact angles of at least 100°, preferably at least 130°, more preferably at least 150°, preferably at least 160°.

The exact range of parameter settings for device selection depends on the binder polymer selected as well as filament size, filament cross-section, and weight ratio between component polymer formulations.

The device, containing 4 drums, also enables intensive, alternating, essentially vertical air flow through the substrate in a short time. The first pair of drums is set to preheat the textile structure directly below the melting point of the polymer composition with a low melting point. The second pair of drums is set to reach the melting temperature range of the low melting point polymer composition to allow for the formation of fusible links. In order to maintain the structure of the fabric and to keep the fusible links intact, the last drum contains a hot section and a cooling section along its

-15 CZ 2021 - 234 A3 of the circuit in the direction of the machine. It is advantageous if the textile structure is stiffened or at least the surface of the textile structure is stiffened before the fabric is released from the consolidation device. A separate additional cooling cylinder with a high flow of cooling air through the fabric is located at the shortest possible distance from the last cylinder of the consolidating device, using the connection by the effect of passing air, which completes the solidification of the fabric with immediate cooling.

The interconnected non-woven fabric 21 is finally wound onto a roll on a reel 11. In the case where it is necessary to modify the surface characteristics of the non-woven fabric, e.g. in order to achieve an improved transfer of liquids or to increase the ability to remove them, a spraying device or a soaking roller is placed either between the moving belt and the final consolidation device or between the final consolidation device and the reel.

The nonwoven fabric according to the invention can be modified by other known methods as needed. For example, it is known to use a water jet for softening non-woven fabric hydroengorgement (described for example in patent US 8093163) or hydro-patterning (described in the as yet unpublished patent application US 63/183,148) aimed directly at the treatment of non-woven fabric containing bonding impressions. For example, it is possible to perforate the textile according to the invention by various methods (overbonding, hot needles, water jet, etc.)

Non-woven textiles according to the invention can be produced with any basis weight. It is known in the art that higher basis weight is generally associated with greater measurable thickness and improved texture of the resulting fabric, but also with commensurately higher cost. On the other hand, the lower surface weight is associated with proportionally lower costs, but at the same time it makes it difficult, for example, to create the covering outer layer of hygienic absorbent products, where a given level of coverage or barrier properties is required. In accordance with this assumption, in such cases it is possible to use a non-woven fabric according to the invention having an area weight of a maximum of 60 grams per square meter, better a maximum of 40 grams per square meter, better a maximum of 30 grams per square meter, preferably a maximum of 26 grams per square meter. A person skilled in the art will realize that in order to achieve the desired properties, it is necessary for the nonwoven fabric according to the invention to contain at least a minimum amount of material. In accordance with this assumption, in such cases it is possible to use a non-woven fabric according to the invention having an area weight of at least 6 grams per square meter, better at least 8 grams per square meter, preferably at least 10 grams per square meter.

In other cases, for example when using the nonwoven fabrics of the invention to produce such articles as disposable clothing components, parts of the absorbent core of diapers, wipes or dusters, higher basis weights of not more than 150 grams per square meter may be required with preferably no more than 100 grams per square meter. The optimal surface weight is determined on the one hand by different needs related to individual methods of use and on the other hand by the price of the material.

In the following nonwoven fabric production examples 1-11, one layer of core/sheath bicomponent fibers with an average thickness of 14-17 microns with a weight ratio of core:sheath components = 80:20 was prepared from a REICOFIL 4 technology spunbond spinning head at a nozzle power of 220- 225 kg/h/m on the pilot line at STFI (Sachsisches Textilforschungsinstitut e.V.). The type in the individual components of the aliphatic polyester used and the type and quantity of the additive for individual examples are shown in Table 4. The Ingeo type represents the products of the Nature Works company and the Luminy type the products of the Total Corbion company. Examples 1, 3 and 9 represent comparative compositions without the addition of the additive according to the invention. Examples 4-8 and 10-11 contain, in addition to the aliphatic polyester and the additive according to the invention, PBAT (Polybutylene adipate terephthalate) - aromatic polyester in an amount not exceeding 5% by weight of the component (coat). The fiber layer was thermally bonded using a pair of hot calendering rolls 50.51 (smooth roll, patterned roll), one of which features a raised pattern known as Ungricht engraving U 2888 with a total bonding area of 18.1%. The values of roller temperatures and pressure are also shown in Table 4 and the measured properties of the produced nonwoven fabric in the following Table 5.

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example kernel main component of the first component (shell) Additive to the first component (shell) wt% Line speed [m/min] Basis weight of non-woven fabric [gsm] Pressure of calendering rolls [N/mm] Cylinder temperature 51 (oil inside the cylinder) [°C] Cylinder temperature 50 (oil inside the cylinder) [°C] 1 PLA-Lumins LI30 PLA-Lumins LI75 - 145 25 50 140 138 2 PLA-Lumins LI30 PLA-Lumins LI75 0.3% EBS 145 25 50 140 138 3 PLA-Ingeo 6100 D PLA-Ingeo 6752 D - 148 25 50 140 138 4 PLA-Ingeo 6100 D PLA-Ingeo 6752 D 0.2% EBS 148 25 50 140 138 5 PLA-Ingeo 6100 D PLA-Ingeo 6752 D 0.3% EBS 148 25 50 140 138 6 PLA-Ingeo 6100 D PLA-Ingeo 6752 D 0.3% EBS 175 20 50 140 138 7 PLA-Ingeo 6100 D PLA-Ingeo 6752 D 0.3% EBS 230 15 50 140 138 8 PLA-Ingeo 6100 D PLA-Ingeo 6752 D 0.5% EBS 148 25 50 140 138 9 PLA-Lumins LI30 PLA-Lumin LX930 - 147 25 50 138 135 10 PLA-Lumins LI30 PLA-Lumin LX930 0.2% EBS 148 25 50 140 138 11 PLA-Lumins LI30 PLA-Lumin LX930 0.3% EBS 148 25 50 140 138

Table 4: Polymer composition and process settings of Examples 1-11

example main component of the first component (shell) Additive to the first component (shell) wt% Strength MD [N] % increase in MD strength against reference sample CD strength [N] % increase in CD strength against the reference sample Elongation (elongation) MD [%] Elongation (elongation) CD [%] 1 PLA-Lumins L175 - 27 - 6 - 7 18 2 PLA-Lumins L175 0.3% EBS 38 41% 9 64% 12 15 3 PLA-Ingeo 6752 D - 14 - 3 - 3 13 4 PLA-Ingeo 6752 D 0.2% EBS 37 165% 10 269% 6 8 5 PLA-Ingeo 6752 D 0.3% EBS 38 177% 10 271% 6 9 6 PLA-Ingeo 6752 D 0.3% EBS 29 ON 7 ON 5 6 7 PLA-Ingeo 6752 D 0.3% EBS 17 ON 4 ON 3 6 8 PLA-Ingeo 6752 D 0.5% EBS 39 184% 10 266% 6 8 9 PLA-Lumin LX930 - 18 - 10 - 9 21 10 PLA-Lumin LX930 0.2% EBS 55 200% 25 138% 21 26 11 PLA-Lumin LX930 0.3% EBS 57 210% 27 156% 21 27

Table 5: Properties of the produced textile according to examples 1-11

All of the examples are rebuilding combinations of variants of different types of PLA from two different manufacturers, with the lower melting point type always in the shell. The strength of the nonwoven fabric according to the invention always increased significantly from an increase of about half (+41% in example 2) to a threefold increase (+200%)

- 17 CZ 2021 - 234 A3 for examples 10 and 11). The different rates of increase indicate that different commercial types of polymer are different far from the desired state that is achieved with the aid of the described additive.

Examples 1 and 2 represent the effect of an additive (in this case EBS) on the strength of a thermally bonded (in this case calendered) nonwoven fabric made of aliphatic polyester (in this case PLA). Comparative Example 1 presents a composition with 100% PLA distributed in a bicomponent fiber such that the lower melting point component forms the sheath. Example 2 represents the same polymer composition with the difference that an EBS additive is added to the shell. A significant increase in strength (+41% in the MD and +64% in the CD direction) is immediately observed here. Also in Fig. XX there is an obvious difference in the appearance of the binding impressions, where the fibers in the binding impression on the non-woven fabric according to example 1 only act as if glued together, while the fibers in the binding impression of the non-woven fabric according to example 2 are sintered in the binding impression and form a significantly stronger unit.

Examples 4-8 and 9-10 show the material with the addition of an aromatic polymer (PBAT) to the shell, in a concentration from about 2% to almost 5%. In no case did the allowance reach the full 5% value. It is clear from the results that the described addition of aromatic polyester does not limit the positive effect of the additive. On the contrary, a possible synergistic effect is shown.

Examples 6 and 7 show a nonwoven fabric according to the invention with a lower basis weight (20 and 15 gsm). Although there are no additive-free standards available to calculate strength gains, it is apparent from comparison with Example 3 (25 gsm) that significant strength gains must have occurred. The nonwoven fabric according to the invention with a basis weight of 15 gsm (Example 7) has higher strengths than a comparative nonwoven fabric without additives with a basis weight of 25 gsm (Example 3).

Testing methodology The "area weight" of the nonwoven fabric is measured using the testing methodology in accordance with the EN ISO 9073-1:1989 standard (corresponds to the methodology according to WSP 130.1). 10 layers of non-woven fabric are used for measurement, while the sample size is 10x10 cm2.

"Material strength and elongation" is measured using the EDANA standard method defined in WSP 110.4.R4 (12) with a specimen width of 50 mm, jaw spacing of 100 mm, speed of 100 mm/min and a preload of size 0.1N.

Crystallinity, (group) heat of crystallization, cold crystallization temperature, "heat of fusion" and melting point are measured using ASTM D3417 test method using DSC, with a temperature change rate of 10 °C/min in the measurement range of 25-230 °C and sample weight 7.0 - 7.5 mg.

Industrial applicability

The invention can be used anywhere where a non-woven fabric containing aliphatic polyesters is required - for example in the hygiene industry in the form of various components of hygiene products with absorption capabilities (e.g. baby diapers, incontinence products, hygiene products for women, disposable changing mats, etc.) or in healthcare, for example as part of wound care sponges and/or protective clothing, surgical drapes, underlays and other barrier material products. Further uses are also possible in industrial applications, for example in the form of parts of protective clothing, in filtration, insulation, packaging, sound absorption, shoe industry, automobile industry, furniture industry, etc. The invention is advantageously usable especially in applications where origin from renewable resources and partial or full biodegradability.

Claims (19)

PATENT CLAIMS 1. A nonwoven fabric (21) comprising continuous fibers and connecting impressions or connecting points, the continuous fibers contain at least 80% by mass of aliphatic polyesters, the continuous fibers contain a first component forming at least 55% of the surface of the fiber, the first component contains at least one aliphatic polyester and at least 0.1% mass, additives, the additive contains an amide group, the additive corresponds to the general formula (i) or (ii) or (iii) (i) R1-(CO)-NH2 (ii) R1-(CO)- NH-R2 (iii) R1-(CO)-NH-R3-NH-(CO)-R2. 2. Non-woven fabric (21) according to claim 1, characterized in that a. R1 is an aliphatic hydrocarbon chain with a length of at least 10 carbons, preferably at least 12 carbons, preferably at least 15 carbons; or b. R2 is an aliphatic hydrocarbon chain with a length of at least 10 carbons, preferably at least 12 carbons, preferably at least 15 carbons; or c. R 3 is an aliphatic hydrocarbon chain of 1 to 3 carbons in length. 3. Non-woven fabric (21) according to any one of the preceding claims, characterized in that a. R1 is an aliphatic hydrocarbon chain with a maximum length of 30 carbons, preferably a maximum of 25 carbons, preferably a maximum of 20 carbons, and/or b. R2 is an aliphatic hydrocarbon chain with a maximum length of 30 carbons, preferably a maximum of 25 carbons, preferably a maximum of 20 carbons. 4. Non-woven fabric (21) according to any one of the preceding claims, characterized in that a. R 1 is an unbranched aliphatic chain; or b. R 2 is an unbranched aliphatic chain; or c. R 3 is an unbranched aliphatic chain. 5. Non-woven fabric (21) according to any one of the preceding claims, characterized in that a. R 1 is a saturated aliphatic chain; or b. R 2 is a saturated aliphatic chain; or c. R 3 is a saturated aliphatic chain. 6. Non-woven fabric (21) according to any one of the preceding claims, characterized in that the first component contains at least 0.15% by weight of additives, preferably at least 0.20% by weight of additives, preferably at least 0.25% by weight of additives . 7. The nonwoven fabric (21) according to any one of the preceding claims, characterized in that the first component contains no more than 10% additive, better no more than 5% additive, preferably no more than 1% additive. 8. The non-woven fabric (21) according to any one of the preceding claims, characterized in that the additive is N,N'-Ethylenebis(stearamide). 9. Nonwoven fabric (21) according to any of the preceding claims, characterized in that the first component forms at least 70% of the fiber surface, better at least 85% of the fiber surface, better at least 90% of the fiber surface, preferably at least 95% of the fiber surface. 10. The non-woven fabric (21) according to any one of the preceding claims, characterized in that the first component forms a sheath in a core-sheath bicomponent fiber type. - 19 CZ 2021 - 234 A3 11. The non-woven fabric (21) according to any one of claims 1 to 9, characterized in that the first component forms one of the sides in a side/side bicomponent fiber type. 12. Non-woven fabric (21) according to any one of the preceding claims, characterized in that the continuous fibers contain at least 90% by mass of polymeric components, preferably at least 95% by mass, of polymeric components, preferably at least 99% of polymeric components. 13. The non-woven textile (21) according to any one of the preceding claims, characterized in that the first component contains a mixture of aliphatic polyesters with different values of heat of cold crystallization. 14. The non-woven textile (21) according to any one of the preceding claims, characterized in that the first component contains PLA or a combination of at least two types of PLA with a different value of heat of cold crystallization. 15. Non-woven textile (21) according to any one of the preceding claims, characterized in that the first component consists of a mixture of PLA and another aliphatic polyester. 16. The nonwoven fabric (21) according to any one of the preceding claims, characterized in that it contains a second component, the first component having a lower melting point than the second component. 17. Non-woven textile (21) according to claim 16, characterized in that the second component contains at least one aliphatic polyester, preferably PLA or a mixture of different types of PLA with different values of heat of cold crystallization. 18. A method of producing a non-woven fabric (21), which includes the following steps: a) a material for the production of continuous fibers is prepared, which contains at least 80% by mass of polymer components, while this material contains the components of the first component of continuous fibers, which contains at least one aliphatic polyester and an additive in an amount of at least 0.1% by mass, of the total amount first component, wherein the additive contains an amide group and corresponds to the general formula (i) or (ii) or (iii) (i) R1-(CO)-NH2 (ii) R1-(CO)-NH-R2 (iii) R1 -(CO)-NH-R3-NH-(CO)-R2 b) melt and mix at least the components of the first component, c) at least the first component is fed to the nozzles of the spinning head (1), with the help of which continuous fibers are formed, at least 55% of the surface of which is made up of the first component, after which the fibers formed in this way are cooled and elongated and then deposited on the passing belt, d) whereupon the thus formed layer (21a) of fibers is thermally bonded. 19. The method according to claim 18, characterized in that in step d) the layer (21) of fibers is joined by calendering and/or the action of hot air.