EP3417098B1 - Nonwoven with an embossed mesh pattern - Google Patents

Description

Technical field

The invention relates to a nonwoven fabric with an embossed mesh pattern. The invention further relates to a method for producing such a nonwoven fabric and its use as a wipe for the household, the commercial sector and / or as a wiping material in a mop.

State of the art

Textile fabrics in the form of nonwovens are widely used as wipes and as a wiping material in mops. To achieve a higher durability, the fibers in such nonwovens are usually either thermally bonded by fusing existing thermoplastic fibers or by gluing or binding the fibers in by means of applied or incorporated chemical binder systems.

To further increase the bond and improve the mechanical properties, for example, in JP 60-194160 a thermal Pressing described using heated rollers. The result of this full-surface pressing, however, is thin, less flexible, paper-like and less absorbent fabrics.

Like in the EP 1 322 806 B1 described, wet baby wipes can also be partially embossed to increase the strength of the material, but this leads to an increase in the bending moment in the known methods and patterns and thus to an undesirable stiffness of the wipes. In order to nevertheless obtain moist disposable wipes that meet the requirements for softness, volume, absorption and mechanical strength, the cited document proposes to set a distance of at least half of the nominal fiber length between discrete (individual, unrelated) embossed areas. In addition, the embossed area should be between 4% and 8% of the total area.

According to the prior art described, flexibility and strength are opposing properties of thermally pressed (calendered) nonwovens. For use as a reusable wipe or as a wiping material in mops, the compromises of softness and strength to be achieved by embossing according to the prior art are not acceptable, so that, unlike in the area of disposable wet wipes, these have so far not been able to prevail.

Against this background, the invention is based on the object of specifying a nonwoven fabric which at the same time meets high requirements with regard to softness, flexibility and durability. In addition, the nonwoven fabric should have sufficient absorption properties and, in particular, should enable the production of wipes and wiping materials in mops with the abovementioned properties.

Presentation of the invention

The present invention achieves the aforementioned object by the features of patent claim 1.

It was recognized that with a certain arrangement and dimensioning of embossing grooves in relation to the fiber length, the durability of a nonwoven fabric as well as its softness and flexibility can be increased and the absorbent capacity of the nonwoven fabric is not significantly reduced by the embossing grooves introduced.

Implementation of the invention

The present invention relates to a nonwoven fabric comprising framework fibers and an at least partially fused thermoplastic material, in particular at least partially fused thermoplastic binder fibers, at least the framework fibers being staple fibers, the nonwoven fabric having a thermally embossed mesh pattern consisting of a plurality of intersecting embossing grooves, between which a large number is arranged by embossing elevations, the equivalent diameter of the embossing elevations being less than 50% of the fiber length of the framework fibers, the ratio of the width of the embossing grooves to the thickness of the nonwoven fabric in the region of the embossing elevations being less than or equal to 4/5 and the ratio of the width of the Embossing grooves for the thickness of the nonwoven fabric in the region of the embossing grooves is 0.5 to, characterized in that the proportion of the at least partially fused thermoplastic material is from 5% by weight to 30% by weight.

An essential aspect of the nonwoven fabric according to the invention is the presence of a thermally embossed mesh pattern made up of a plurality of intersecting embossing grooves. In this network pattern is between the A large number of embossing elevations are arranged in the embossing grooves. In the area of the embossing grooves, the nonwoven fabric is compressed in comparison to the embossing elevations and the thermoplastic material is at least partially fused, which stabilizes the embossed structure. The mesh pattern also has a positive effect on the stability and durability of the nonwoven as a whole. The pattern can be formed over the entire surface or only on partial areas of the nonwoven fabric. In a preferred embodiment of the invention, the mesh pattern is formed on at least 60%, preferably 70% to 100% and in particular 80% to 100% of the surface of the nonwoven fabric.

Another important aspect of the nonwoven fabric according to the invention is that the embossing grooves are arranged and dimensioned such that the equivalent diameter of the embossing elevations is less than 50% of the fiber length of the framework fibers.

As used herein, the term "equivalent diameter of the embossment elevations" means the diameter of the smallest circle that circumscribes (i.e., can be drawn and / or include around) the entire embossment elevation. Rewriting the symbol means that at least two points of the embossing elevation touch the circle tangentially and no section of the embossing elevation intersects the circle to the outside. Of course, a real circle does not have to be drawn or marked on the nonwoven fabric for rewriting. For the purposes of the present invention, equivalent symbol diameters were determined as shown in the Test Methods section below.

Another important aspect of the nonwoven fabric according to the invention is that the ratio of the width of the embossing grooves to the thickness of the nonwoven fabric in the area of the embossed elevations is less than or equal to 4/5 and the ratio the width of the embossing grooves to the thickness of the nonwoven in the area of the embossing grooves is from 0.5 to 2.

The width of the embossing grooves is defined as the distance between two turning points W of the transitions of an embossing groove into the adjacent embossing elevations. For the purposes of the present invention, the width of the embossing grooves was determined as shown in the Test Methods section below. Furthermore, the thickness of the nonwoven fabric in the area of the embossing surveys was measured in accordance with DIN EN ISO 9073-2: 1997 and the thickness of the nonwoven fabric in the area of the embossing grooves as shown below in the section on test methods.

It has been found that with this special arrangement and dimensioning of the embossing grooves in coordination with the fiber length of the framework fibers, a very good property profile can be achieved from high strength and abrasion resistance as well as high absorbency and flexibility of the nonwoven, which is advantageous for use as a wipe and / or wiping material in a mop.

In particular, the special arrangement and dimensioning of the embossing grooves in relation to the fiber length enables a high proportion of scaffold fibers that have been tied multiple times, for example twice, ie scaffold fibers that are tied at at least two different locations in the compressed area of the embossing grooves. As a result, the durability and strength of the nonwoven fabric can be improved and less fiber loss can be achieved when using and washing the nonwoven fabric. In addition, the nonwoven fabric according to the invention is surprisingly distinguished by a high degree of flexibility or a low bending moment, which makes the nonwoven fabric extremely supple and, as a result, pleasant to the touch gives. Furthermore, the specific mesh pattern gives the nonwoven a good cleaning performance even for coarse dirt particles.

Without wishing to be bound by theory, it is assumed that in the specific arrangement and dimensioning of the embossing grooves and fiber lengths according to the invention, the individual framework fibers are strongly connected to one another in a three-dimensional structure by the thermoplastic material in the embossing grooves, and thus in their mutual position and possibility of movement are limited, but the embossing grooves are just so far apart that the embossed areas can serve as joints to a certain extent, thereby increasing the flexibility of the nonwoven.

This effect overcompensates the tendency that an embossing process usually dramatically increases the bending moment of the materials. Nevertheless, due to the intensive connection of the scaffold fibers, high durability, strength and dimensional stability are achieved during use and during washing.

In practical tests, it has proven to be particularly advantageous if the equivalent diameter of the embossing elevations is 5% to 50%, more preferably 5% to 40%, even more preferably 7% to 40% and in particular 8% to 30% of the fiber length of the framework fibers .

Furthermore, it has proven to be particularly favorable if the ratio of the width of the embossing grooves to the thickness of the nonwoven in the region of the embossing elevations is from 4/5 to 1/5, more preferably from 4/5 to 1/3 and in particular from 2/3 to Is 1/3.

It has also proven to be particularly favorable if the ratio of the width of the embossing grooves to the thickness of the nonwoven fabric in the region of the embossing grooves is from 0.5 to 1.5 and in particular from 0.75 to 1.25.

The proportion of the surface of the embossed elevations on the total surface of the nonwoven can be adjusted depending on the desired properties of the nonwoven. In principle, the fluffiness and absorbency of the nonwoven can be increased by increasing the proportion of the surface of the embossed elevations in the total surface of the nonwoven. Against this background, it has proven to be advantageous to set the total surface area of the embossing elevations to more than 50%, preferably from 55% to 85%, more preferably from 60% to 80%, based on the total surface area of the nonwoven fabric. In the event that the mesh pattern is only present on partial areas of the nonwoven, then only the partial area provided with the mesh pattern is regarded as the total surface of the nonwoven for determining the proportion of the surface of the embossed elevations.

The proportion of the surface of the embossed elevations in the total surface of the nonwoven fabric can be determined by coloring the embossed elevations and subsequent optical evaluation, as shown below in the section on the test methods.

By increasing the proportion of the surface of the embossing grooves in the total surface of the nonwoven fabric, the durability, strength and dimensional stability of the nonwoven fabric can be increased. Against this background, the proportion of the surface of the embossing grooves in the total surface of the nonwoven fabric is preferably more than 15%, for example from 15% to 45%, more preferably from 20% to 40%. In the event that the mesh pattern is only present on partial areas of the nonwoven fabric, only that with is used to determine the proportion of the surface of the embossing grooves Partial area provided with the mesh pattern is regarded as the total surface of the nonwoven.

The proportion of the surface of the embossing grooves on the total surface of the nonwoven fabric can also be determined by coloring the embossing elevations and visual evaluation, as shown below in the section on the test methods.

According to the invention, the nonwoven contains an at least partially fused thermoplastic material, in particular thermoplastic binding fibers. As a result, the framework fibers can be consolidated in the nonwoven. The thermoplastic material can comprise thermoplastic binding particles, in particular binding powder, and / or binding fibers. Binding fibers are preferred according to the invention since they are particularly easy to process and can be distributed homogeneously in the nonwoven fabric.

In order to allow easy melting of the thermoplastic material in the manufacture of the nonwoven, the melting point of the thermoplastic material is advantageously at least 30 ° C, for example from 30 ° C to 150 ° C, more preferably at least 40 ° C, for example from 40 ° C to 150 ° C and in particular at least 45 ° C for example from 45 ° C to 130 ° C below the melting point or decomposition point of the framework fibers.

As explained above, the at least partially fused thermoplastic material enables the embossed mesh pattern and the nonwoven fabric to be stabilized overall. This material can be melted in the manufacture of the nonwoven in a simple manner, for example by using heated embossing rollers.

At least partially fused thermoplastic materials which are particularly preferred according to the invention contain polyolefin, in particular polypropylene and / or polyethylene, and also polyester, polyamide, polylactide, and / or mixtures and copolymers thereof.

In order to obtain sufficient stabilization of the mesh pattern and of the nonwoven fabric overall, it has proven to be expedient to increase the proportion of the at least partially fused thermoplastic material to 5% by weight to 30% by weight, preferably 15% by weight. up to 25% by weight, based on the total weight of the nonwoven. A setting of more than 30% is disadvantageous since the flexibility of the nonwoven fabric is undesirably restricted.
The nonwoven contains structural fibers as a further component. According to their function as framework fibers, these are preferably either not fused or at least significantly less fused compared to the at least partially fused thermoplastic material. In a preferred embodiment of the invention, the framework fibers are selected from non-thermoplastic materials, for example natural fibers, preferably cellulosic fibers, in particular viscose or cotton fibers and / or mixtures thereof.
However, the use of thermoplastic fibers as framework fibers is also conceivable, provided that their melting point is at a sufficient distance from the melting point of the at least partially fused thermoplastic material. Polyester, polyamide, polylactide fibers and / or mixtures thereof are particularly suitable for this.

According to the invention, particular preference is given to the use of mixtures of non-thermoplastic and thermoplastic fibers as framework fibers, since this enables a particularly good property profile to be achieved for use as a wipe and / or wiping material in a mop.

According to the invention, the framework fibers are staple fibers. In contrast to filaments, which at least theoretically have an unlimited length, staple fibers have defined lengths. The average length of the framework fibers is preferably 15 mm to 85 mm, more preferably 20 mm to 60 mm, in particular 25 mm to 55 mm. It has been shown that the combination of the aforementioned fiber lengths and the specific network pattern makes it possible to achieve a double fiber setting and yet to ensure a sufficient amount of unbound fiber surface and free fiber ends in order to achieve a high cleaning performance of the nonwoven.

The average titer of the framework fibers is preferably between 0.1 dtex and 2.6 dtex, more preferably from 0.3 dtex to 2.4 dtex, in particular from 0.6 dtex to 2.2 dtex. If there is a mixture of fibers of different titers, fiber titers greater than 6.7 dtex are not taken into account for the determination of the average titre. It has been shown that fibers with the aforementioned fiber titers on the one hand enable a high cleaning line and on the other hand a good hand feel.

The basis weight of the nonwoven fabric is preferably in the range between 50 g / m ² and 300 g / m ² , more preferably from 100 g / m ² to 250 g / m ² , in particular from 120 g / m ² to 220 g / m ² . It has been shown that with the above-mentioned basis weights, on the one hand, due to a sufficient volume, a high absorption capacity and, on the other hand, a satisfactory and pleasant flexibility of the nonwoven can be achieved.

The volume weight of the area of the nonwoven fabric compressed by the embossing grooves can be calculated from the thickness of the nonwoven fabric in the area of the embossing grooves and from the basis weight of the nonwoven fabric and is preferably less than 0.0005 g / mm ³ , more preferably 0.00015 g / mm ³ to 0.00045 g / mm ³ .

In the area of the embossing elevations, the nonwoven fabric has a lower density than in the area of the embossing grooves and is therefore more voluminous and absorbent than in the area of the embossing grooves.

The volume weight of the area of the nonwoven fabric which is not compressed by the embossing grooves can be calculated from the thickness of the nonwoven fabric in the area of the embossed elevations and the basis weight of the nonwoven fabric and is preferably less than 0.00015 g / mm ³ , more preferably 0.00008 g / mm ³ to 0.00012 g / mm ³ .

As explained above, the nonwoven fabric according to the invention surprisingly has a low bending moment at least in one direction. This bending moment is preferably less than the bending moment of a nonwoven fabric of the same structure without embossing grooves.

The bending moment of a nonwoven according to the invention is preferably less than 90% in at least one direction, more preferably between 70% and 90%, in particular between 75% and 85% of a nonwoven fabric of the same structure without embossing.

As explained above, the nonwoven fabric can be thermally bonded via the at least partially fused thermoplastic material. The partially fused thermoplastic material is at least in the Areas of the embossing grooves. In a preferred embodiment, the at least partially fused thermoplastic material is also present in the areas of the embossed elevations, which enables the nonwoven to be further stabilized. As explained above, the at least partially fused areas can be formed by the embossing process. However, it can also be advantageous to carry out an additional thermal consolidation in which the thermoplastic material melts at least in part.

In addition to thermal bonding, the nonwoven fabric can also have a bonding agent for bonding, advantageously at least some of the fibers being bound with a bonding agent. Any binder customary for chemical consolidation of textile materials can be used, the binder preferably being selected from the group consisting of an aqueous copolymer dispersion of vinyl acetate and ethylene.

It is also conceivable that the nonwoven fabric is also additionally consolidated by needling.

The shape of the embossing grooves can be linear or non-linear, for example wavy or zigzag, provided that a network pattern is formed as a result.

It is also conceivable that the embossed grooves have interruptions and, for example, form dashed and / or dotted grooves. This can have an advantageous effect on the absorbency of the nonwoven.

In an advantageous embodiment of the invention, the mesh pattern is designed as a diamond pattern, honeycomb pattern, fish scale pattern, waffle pattern, linen pattern, and / or butterfly pattern.

According to the invention, this is preferred, for example, in FIGS Figures 2 and 4 to 6 fish scale pattern shown. The mesh pattern is preferably aligned such that the embossing grooves run diagonally to the machine direction. This enables the strength values (measured as maximum tensile force) to be homogenized in the longitudinal and transverse directions.

The special configuration of the nonwoven fabric according to the invention enables a homogeneous property profile. The MD / CD ratio of the maximum tensile force is preferably more than 0.65, for example from 0.65 to 0.95, more preferably from 0.75 to 0.95. At these ratios, the nonwoven fabric according to the invention has a homogeneous strength profile, which has proven to be favorable in use.

The nonwoven fabric can be constructed in one or more layers. It is preferably constructed in one layer. As a result, the embossed mesh pattern can be formed on both sides of the nonwoven in one process step. Delamination is also difficult.

The nonwoven fabric according to the invention is outstandingly suitable as a wipe for the household and / or the commercial sector and / or as a wiping material in a mop.

• Bereitstellen eines Faserflors umfassend Stapelfasern als Gerüstfasern und ein thermoplastisches Material, insbesondere thermoplastische Bindefasern;
• Verfestigen des Faserflors mittels Vernadelung, Bindemittel und/oder thermischer Beaufschlagung;
• Thermisches Einprägen eines Netzmusters unter zumindest teilweisem Verschmelzen des thermoplastischen Materials wobei das Netzmuster
  • eine Vielzahl sich kreuzender Prägenuten aufweist, zwischen denen eine Vielzahl von Prägeerhebungen angeordnet ist,
  • der äquivalente Durchmesser der Prägeerhebungen kleiner ist als 50 % der Faserlänge der Gerüstfasern,
  • das Verhältnis der Breite der Prägenuten zur Dicke des Vliesstoffs im Bereich der Prägeerhebungen kleiner oder gleich 4/5 ist,
  • das Verhältnis der Breite der Prägenuten zur Dicke des Vliesstoffs im Bereich der Prägenuten von 0,5 bis 2 liegt.

The nonwoven fabric according to the invention can be produced, for example, by a process comprising the following process steps:

• Providing a pile of fibers comprising staple fibers as framework fibers and a thermoplastic material, in particular thermoplastic binding fibers;
• Solidification of the fibrous web by means of needling, binding agents and / or thermal exposure;
• Thermal embossing of a mesh pattern with at least partial fusion of the thermoplastic material, the mesh pattern
  • has a multiplicity of intersecting embossing grooves, between which a multiplicity of embossing elevations is arranged,
  • the equivalent diameter of the embossing elevations is less than 50% of the fiber length of the framework fibers,
  • the ratio of the width of the embossing grooves to the thickness of the nonwoven in the area of the embossing elevations is less than or equal to 4/5,
  • the ratio of the width of the embossing grooves to the thickness of the nonwoven in the region of the embossing grooves is from 0.5 to 2.

Thermal embossing can be carried out in a simple manner, for example by using heated embossing rollers.

According to the invention, the solidification preferably takes place at least by means of needling and, if appropriate, additionally by means of binders and / or thermal action, for example using a calender or an oven. It is advantageous with the needling that it can reorient the fibers in the nonwoven and thus enables a further adjustment of the property profile of the nonwoven.

The specific mesh pattern can be obtained by suitable selection of the embossing bars on the embossing rollers.

Brief description of the drawing

Fig.1

die schematische Ansicht eines Ausschnitts aus dem Querschnitt eines erfindungsgemäßen Vliesstoffs,

Fig.2

die schematische Darstellung der Draufsicht eines erfindungsgemäßen Vliesstoffs, sowie die vergrößerte Ansicht eines Ausschnitts hiervon,

Fig.3

eine CT-Aufnahme eines Ausschnitts aus dem Querschnitt eines erfindungsgemäßen Vliesstoffs,

Fig.4

eine CT-Aufnahme eines Ausschnitts aus der Draufsicht eines erfindungsgemäßen Vliesstoffs,

Fig.5

eine REM-Aufnahme eines Ausschnitts aus der Draufsicht eines erfindungsgemäßen Vliesstoffs,

Fig.6

eine weitere CT-Aufnahme eines Ausschnitts aus der Draufsicht eines erfindungsgemäßen Vliesstoffs.

The drawing shows:

Fig. 1

the schematic view of a section of the cross section of a nonwoven fabric according to the invention,

Fig. 2

2 shows the schematic representation of the top view of a nonwoven fabric according to the invention, as well as the enlarged view of a section thereof,

Fig. 3

a CT image of a section from the cross section of a nonwoven fabric according to the invention,

Fig. 4

1 shows a CT image of a detail from the top view of a nonwoven according to the invention,

Fig. 5

1 is a SEM image of a detail from the top view of a nonwoven fabric according to the invention,

Fig. 6

another CT image of a detail from the top view of a nonwoven fabric according to the invention.

Figure description

Figure 1 shows the schematic view of a section from the cross section of a nonwoven fabric 1 according to the invention with an embossing groove 2 which has a width 3. In the area of the embossing groove 2, the nonwoven fabric 1 has a thickness 4. Two embossing elevations 5 and 5 'adjoin the embossing groove 2 on the left and right. at. In the area of the embossed elevations 5 and 5 ', the nonwoven fabric 1 has a thickness 6 in each case.

Figure 2 shows the schematic view of the top view of a nonwoven fabric 1 according to the invention comprising a multiplicity of embossed elevations 5. The smallest circle, which describes the entire embossed elevation 5, is shown as an example on an embossed elevation 5. The diameter of this circle is the equivalent diameter 7 of this embossing elevation 5.

Figure 3 shows a CT image of a section from the cross section of a nonwoven fabric 1 according to the invention.

Figure 4 shows a CT image of a detail from the top view of a nonwoven fabric 1 according to the invention.

Figure 5 shows an SEM image in 50-fold enlargement of a detail from the top view of a nonwoven fabric 1 according to the invention.

Figure 6 shows a further CT image of a detail from the top view of a nonwoven fabric 1 according to the invention. The smallest circle, which circumscribes the entire embossing survey 5, is shown as an example on an embossing survey 5. The diameter of this circle is the equivalent diameter 7 of this embossing elevation 5.

Test method

When selecting the areas used for the test methods, it is essential to ensure that representative sections with the predominant pattern are selected.

Equivalent diameter of the embossing elevations

The equivalent diameter of the embossing surveys is determined as follows: As a basis, a computed tomography image of the top view of the nonwoven fabric with the entire pattern repetition unit is used.

In the evaluation (in the present case by means of Volume Graphics VG Studio Max ), a circular template is used for the embossed surveys in the network pattern in order to measure the diameter of the smallest circle that can circumscribe the complete embossed elevations (i.e. which is drawn around it and enclose it) may) (as described above with reference to the definition of the equivalent diameter of the embossing elevations). The measurement should be accurate within +/- 0.6 mm. The diameter of the circumscription circle is the equivalent diameter of the embossing elevations.

After determining the equivalent diameter of the embossing in the mesh pattern, the numerical value of the diameter is taken as the average of at least five individual measurements.

Any very small embossed elevations, ie embossed elevations with an equivalent diameter of less than 5% of the fiber length, are not taken into account.

Thickness of the nonwoven in the area of the embossing grooves and width of the embossing grooves

To determine the thickness of the nonwoven fabric in the area of the embossing grooves, a cross-sectional computed tomographic image of the nonwoven fabric is used.

The thinnest points are optically determined by at least five embossing grooves (in this case using Volume Graphics VG Studio Max ), and the mean value is formed. This gives the thickness of the nonwoven in the area of the embossing grooves.

To determine the width of the embossing grooves, the thickness of the nonwoven is first determined. This corresponds to the thickness of the nonwoven in the area of the embossed elevations.

The arithmetic mean is then calculated from the thickness of the nonwoven in the area of the embossing grooves and the thickness of the nonwoven in the area of the embossing elevations. The resulting value corresponds to the thickness of the nonwoven in the area of the turning points W, which can now be optically drawn in the computed tomography image. If one measures the shortest distance between two turning points W delimiting the same groove, the width of this embossing groove results. This measurement is repeated for at least five embossing grooves and the average is formed.

Determination of the proportion of the embossing surveys and the embossing grooves in the total surface

To determine the proportion of the embossing surveys on the total surface of the nonwoven, the same is glued flat on a metal plate of the same dimensions (8 x 4 cm) and a total weight of 114 g ± 10 g and circling without additional pressure using a commercially available stamp pad (ten times in and ten times against clockwise). This embosses the embossed areas. This sample can then be scanned or photographed and evaluated using image processing software (in the present case using Adobe Photoshop ). The proportion of the embossed elevations in the total surface can be determined on a pixel basis by means of the color difference between the colored areas and the non-colored area. There is at least one triple determination.

The difference measurement from the total surface and the proportionate area of the embossing elevations gives the proportion of the area of the embossing grooves in the total area of the nonwoven.

Thickness of the nonwoven

Based on the test specification DIN EN ISO 9073-2: 1997, the thickness of the nonwoven is measured with a precision thickness measuring device with 25 cm ² test area and 0.5 kPa pre-pressure. At least ten places on the sample are measured and then the mean value is formed.

Basis weight

Based on the test specification DIN EN ISO 9073-1: 1989, at least ten samples with a sample size of 100 mm x 100 mm are punched out to determine the basis weight, these samples are weighed and the measured values are multiplied by 100. The mean value is formed from these individual values.

Length of the staple fibers

Depending on the type of fiber, the individual fiber length measurement is carried out using the one or two-tweezers method based on DIN 53808-1: 03. Deviating from the test standard, the number of measurements is n = 50.

It is important to ensure that the fibers are not shortened when they are removed from the nonwoven. This applies especially to thermally bonded and embossed nonwovens.

Determination of the melting point

The determination of the melting point of the thermoplastic material is determined according to the test specification DIN EN ISO 11357-3: 2013.

Determination of tensile strength

The maximum tensile force is determined according to the test specification DIN EN ISO 9073-3: 1992.

Determination of the bending length

The bending length is determined based on the test specification DIN EN ISO 9073-7: 1998. The sample size is 250 x 50 mm. Three individual measurements are carried out and the mean in mm is formed. The smaller the bending length, the lower the bending stiffness.

The invention is explained in more detail below using an example.

example

In an exemplary nonwoven fabric according to the invention, the production takes place in the dry-laying process. In this version, a fiber mixture of 50% viscose fibers (1.7 dtex, 50 mm), 30% polyester fibers (0.9 dtex, 38 mm) and 20% polypropylene hot melt adhesive fibers (2.2 dtex, 40 mm) is mixed homogeneously and laid over a carding machine to a pile. After the pile layers have been doubled, they are consolidated by needling before this nonwoven fabric is additionally heat-set in an oven. A nonwoven stretch is also interposed. The subsequent embossing process embosses a fish-scale mesh pattern on the nonwoven. In addition, a design print can be applied to the nonwoven fabric before or after the embossing unit.

The nonwoven fabric according to the invention has a weight per unit area of 145 g / m ² , the thickness in the area of the embossing elevations is 1.4 mm, the thickness in the area of the embossing grooves is 0.7 mm. The equivalent diameter of a mesh sample unit is 6.5 mm. This means that the fibers are thermally set on average at at least two points. Furthermore, the ratio of the width of the embossing grooves and the thickness of the nonwoven fabric in the area of the embossing elevations is 1/2, which has a positive effect on the bending stiffness of the Nonwoven affects, as well as the ratio of the width of the embossing grooves and the thickness of the nonwoven in the area of the embossing grooves, which assumes a value of 1 in this advantageous embodiment.

A computer tomographic 3D model of the nonwoven fabric was created to measure and calculate the dimensions of the embossing grooves and embossing grooves. The determination of the thickness of the nonwoven in the area of the embossing, the measurement of the weight per unit area of the nonwoven as well as its strength and bending stiffness was carried out according to the above-mentioned test regulations.

The special design of the mesh pattern, which covers 30% of the total surface (measured by coloring the raised areas and software-based, pixel-based evaluation), leads to a homogenization of the tensile strengths in the longitudinal and transverse directions and, on the other hand, to a reduction in the bending length in at least one direction ( measured in accordance with the test specification DIN EN ISO 9073-7: 1998) to less than 10 mm of the nonwoven.

Applying the specific mesh pattern makes the nonwoven more stable and flexible at the same time and is therefore ideal as a wipe and / or wiping material in mops.

Claims (13)

1. Non-woven fabric (1) comprising structural fibres and an at least partially fused thermoplastic material, in particular at least partially fused thermoplastic bonding fibres, wherein at least the structural fibres are staple fibres, and wherein the non-woven fabric (1) has a thermally embossed mesh pattern from a multiplicity of intersecting embossed grooves (2), a multiplicity of embossed elevations (5) being disposed therebetween, wherein

   - the equivalent diameter (7) of the embossed elevations (5) is less than 50% of the fibre length of the structural fibres;

   - the ratio of the width (3) of the embossed grooves (2) to the thickness (6) of the non-woven fabric in the region of the embossed elevations (5) is less than or equal to 4/5; and

   - the ratio of the width (3) of the embossed grooves (2) to the thickness (4) of the non-woven fabric in the region of the embossed grooves (2) is 0.5 to 2,

   characterized in that the proportion of the at least partially fused thermoplastic material is 5% by weight to 30% by weight.
2. Non-woven fabric (1) according to Claim 1, characterized in that the proportion of the surface of the embossed grooves (2) in terms of the overall surface of the non-woven fabric (1) comprises more than 15% of the overall area of the non-woven fabric (1) .
3. Non-woven fabric (1) according to one or a plurality of the preceding claims, characterized in that the structural fibres have a mean length of 15 mm to 85 mm.
4. Non-woven fabric (1) according to one or a plurality of the preceding claims, characterized in that the structural fibres have a yarn count between 0.1 dtex and 2.6 dtex.
5. Non-woven fabric (1) according to one or a plurality of the preceding claims, characterized by an area weight between 50 g/m² and 300 g/m².
6. Non-woven fabric (1) according to one or a plurality of the preceding claims, characterized in that at least part of the structural fibres are present as needle-bonded and/or bonded by a bonding agent.
7. Non-woven fabric (1) according to one or a plurality of the preceding claims, characterized in that the embossed grooves (2) have interruptions.
8. Non-woven fabric (1) according to one or a plurality of the preceding claims, characterized in that said non-woven fabric (1) is of single-ply construction.
9. Non-woven fabric (1) according to one or a plurality of the preceding claims, characterized in that the mesh pattern is configured as a diamond pattern, a honeycomb pattern, a fish scale pattern, a waffle pattern, a linen pattern, and/or a butterfly pattern.
10. Non-woven fabric (1) according to one or a plurality of the preceding claims, characterized by a machine-direction/cross-direction ratio of the maximum tensile force of more than 0.65.
11. Method for producing a non-woven fabric (1) according to one or a plurality of the preceding claims, comprising the following method steps:

    - providing a fibrous pile comprising staple fibres and a thermoplastic material, in particular thermoplastic bonding fibres;

    - consolidating the fibrous pile by means of needle-bonding, bonding agents, and/or thermal impingement;

    - thermally embossing a mesh pattern while at least partially fusing the thermoplastic material, wherein the mesh pattern

    - has a multiplicity of intersecting embossed grooves (3), a multiplicity of embossed elevations (7) being disposed therebetween;

    - the equivalent diameter of the embossed elevations (7) is less than 50% of the fibre length of the structural fibres;

    - the ratio of the width of the embossed grooves (3) to the thickness of the non-woven fabric (1) in the region of the embossed elevations (6) is less than or equal to 4/5.
12. Method according to Claim 11, characterized in that the consolidating is performed at least by means of needle-bonding and optionally additionally by means of a bonding agent and/or thermal impingement, for example using a calender or an oven.
13. Use of a non-woven fabric (1) according to one or a plurality of Claims 1 to 10 as a mopping cloth for the domestic and/or the commercial sector, and/or as mopping material in a mop.

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