EP3569753B1 - Methods for producing spunbond nonwoven fabrics made from continuous fibres - Google Patents

Description

The invention relates to a spunbonded fabric made from continuous filaments made from thermoplastic material, the continuous filaments being in the form of multi-component filaments, in particular bi-component filaments with a core-sheath configuration. - According to the invention, the spunbonded webs have continuous filaments. Because of their almost endless length, such continuous filaments differ from staple fibers, which have much shorter lengths of, for example, 10 to 60 mm.

Spunbonded nonwovens of the type mentioned are known from practice in different variants. In the case of such spunbonded nonwovens, high strength or high tensile strength is generally desirable. For many applications, the spunbonded nonwovens should also have a smooth, soft feel. A soft hand of the spunbonded nonwovens on the one hand and high strength or tensile strength of the spunbonded nonwovens on the other hand is often not satisfactorily achievable in combination. Above all, a soft feel cannot be achieved at the same time as high productivity or system productivity.

Polypropylene spunbonded nonwovens have been known for a long time and are characterized by good running behavior on the associated system. In particular, relatively little soiling occurs. However, these spunbonded nonwovens are not particularly soft and the options for improving softness - for example with finer fibers - are limited and often not economical. The use of a lubricant to increase the softness of the spunbonded nonwoven fabric is possible, but does not change the relatively high flexural rigidity of the filaments and thus cannot give a satisfactory soft spunbonded nonwoven fabric. The use of such a lubricant has the The disadvantage is that the lubricant diffuses out of the filament melt or from the initially hot filaments during the spinning process and soils the system, so that productivity is ultimately reduced.

Polypropylene blends have been introduced to improve softness, for example blends of homo-polypropylene and polypropylene-based copolymers such as "Random CoPP". These mixtures result in flexible filaments, which, however, are usually characterized by a rather dull handle, which in turn requires the use of additional lubricants. These soft polypropylene blends have disadvantageously reduced strength. In addition, the pollution problems described above are also present here. - When using certain bicomponent filaments with a core-sheath configuration, a compromise between acceptable softness and sufficient strength can be achieved. A homo-polypropylene in the core improves the strength and soft polypropylene blends or the use of polypropylene copolymers in the sheath increase the softness of the filaments or the spunbonded nonwoven. However, the filament surfaces in question are also relatively dull. This necessitates the use of a lubricant, which in turn brings with it the problems associated with contamination described above.

With the high production speeds of modern systems for producing spunbonded nonwovens, a combination of a so-called jumbo roll winder and a rewinder-cutting machine is used, since direct winding is no longer possible at these high production speeds. Between the production of the spunbonded nonwoven and the associated production of the jumbo roll on the one hand and the point in time On the other hand, during the rewinding and cutting process, the jumbo rolls are temporarily stored, and this period can take several hours. During this time, a lubricant used can migrate to the surface of the filaments, so that the filaments or the spunbonded nonwovens become smoother and the rewinding behavior thus deteriorates. - There is therefore a need to adjust the filaments or spunbonded webs when using a lubricant in such a way that on the one hand positive end properties are retained, on the other hand the system is soiled as little as possible and the production speed, winding ability and process reliability remain optimized or can be optimized .

In the production of spunbonded nonwovens from continuous filaments, it is basically already known to mix softening additives or lubricants into the thermoplastic of the filaments. At the same time, the lubricant is introduced homogeneously into the filaments. However, these known measures have the disadvantage that the additives can evaporate from the filaments in the course of the production of the spunbonded fabric and soil the system or are reflected in particular in the air-conducting components of the system. These negative effects are of course undesirable.

US2011/165470 , U.S.6355348 and EP2034057 disclose continuous filament spunbond webs having a core-sheath configuration.

In contrast, the invention is based on the technical problem of specifying a spunbonded nonwoven of the type mentioned at the outset, which is characterized both by a smooth, soft feel and by sufficient strength, which can be produced easily and efficiently and in which, above all, evaporation of softening additives or evaporation of lubricants can be largely avoided.

To solve the technical problem, the invention also teaches, according to a first embodiment, a method for producing a spunbonded nonwoven from continuous filaments made of thermoplastic material, the continuous filaments being multi-component filaments, in particular bi-component filaments, with a core-sheath configuration, the filaments being at least one lubricant included, the proportion of the lubricant - based on the entire filament - 250 to 5500 ppm, preferably 500 to 5000 ppm, preferably 700 to 3000 ppm and very preferably 700 to 2500 ppm, the lubricant being exclusively or at least 90% by weight. %, preferably at least 95% by weight, is present in the core component and the surface of the spunbonded nonwoven is harder in the period up to 150 minutes after the spunbonded nonwoven production, in particular by more than 3%, preferably by at least 3.2% is at least 3.3% and in particular at least 3.5% harder than that Surface of a comparison spunbonded nonwoven otherwise produced under the same conditions with homogeneous distribution of the lubricant with respect to the filament cross section and wherein the surface of the spunbonded nonwoven has the same degree of hardness or softness or approximately the same degree of hardness or softness as the comparison spunbonded nonwoven after 96 hours, wherein the degrees of hardness then preferably differ by a maximum of 3%, preferably by a maximum of 2.9% and in particular by a maximum of 2.8%. In the context of the first embodiment, the mass ratio between the core component and the sheath component is preferably 40:60 to 90:10, expediently 60:40 to 85:15, in particular 65:35 to 80:20, preferably 65:35 to 75:25 and very preferably 67:33 to 73:27.

According to a highly recommended embodiment variant of the first embodiment, the jacket component is designed to be free of lubricants or essentially free of lubricants. - In the first embodiment, the jacket can also serve as a migration brake for the lubricant present in the core.

In addition, to solve the technical problem, the invention teaches, according to a second embodiment, a method for producing a spunbonded nonwoven from continuous filaments made of thermoplastic material, the continuous filaments being multi-component filaments, in particular bi-component filaments, with a core-sheath configuration, the filaments being at least one lubricant included, wherein the proportion of the lubricant - based on the entire filament - is 250 to 5500 ppm, preferably 500 to 5000 ppm, preferably 700 to 3000 ppm and very preferably 700 to 2500 ppm, the lubricant being present in the sheath component, wherein in the Sheath component contains at least one additive that reduces the migration speed of the lubricant through the sheath component, the surface of the spunbonded nonwoven being harder in the period of up to 150 minutes after the spunbonded nonwoven was produced, in particular by more than 3%, preferably by at least 3.2%, preferably by is at least 3.3% and in particular at least 3.5% harder than the surface of a comparative spunbonded nonwoven otherwise produced under the same conditions without an additive that reduces the migration rate of the lubricant and the surface of the spunbonded nonwoven has the same hardness 96 hours after the spunbonded nonwoven was produced Degree of hardness or degree of softness or approximately the same degree of hardness or degree of softness as the comparative spunbonded nonwoven, the degree of softness then preferably differing by a maximum of 3%, preferably by a maximum of 2.9% and in particular by a maximum of 2.8%. In the first embodiment and the second embodiment, the surface of the spunbonded nonwoven is harder by more than 3% etc. than the surface of a comparative spunbonded nonwoven within a period of up to 150 minutes after the spunbonded nonwoven is produced means in particular that within the first 150 minutes after the production of the spunbonded nonwoven there is at least one point in time at which this tolerance limit is exceeded. Depending on the choice of raw material and depending on the lubricant or lubricant content, it can take 120 minutes, for example, for the tolerance limit to be exceeded. Under other conditions, however, the tolerance limit can already be exceeded after 15 minutes or the tolerance limit is exceeded over the entire period or essentially over the entire period. For example, the migration speeds depending on the raw material for the sheath or depending on the proportion of the sheath in the filament are relevant.

The time period of up to 150 minutes selected here is, on the one hand, adapted to the measuring device used described below and, on the other hand, also takes into account typical times from which the jumbo rolls can be rewound. A hardness measurement directly in the course of spinning is not possible with the chosen method. It is within the scope of the invention that such a measurement lasts about 15 minutes and therefore cannot run continuously. However, the specified period cannot be selected too long, so that it can still serve as a decision-making aid during production. Overall, this period enables the decision regarding the spinning behavior (system cleanliness) and the winding behavior.

In the context of the second embodiment, the mass ratio between the core component and the shell component is expediently 40:60 to 90:10, preferably 60:40 to 85:15, in particular 65:35 to 80:20, preferably 65:35 to 75:25 and very preferably 67:33 to 73:27.

It is within the scope of the invention that the degree of hardness of the spunbonded nonwoven (see patent claims 1 and 3) on the nonwoven surface using a TSA measuring device (from Emtec, Leipzig, Germany) as the volume at the peak maximum of the volume/frequency spectrum is approximately 6550 Hz is determined. This TSA meter returns the product property as a "TS7" value. The TS7 value correlates with the softness of the fleece. A spunbonded web made from rough/dull filaments has a higher TS7 value than a comparable spunbonded web made from smoother/softer filaments. According to the invention, the degree of hardness or the volume is measured in the period of up to 150 minutes after the production of the spunbonded nonwoven on the surface of the spunbonded nonwoven. The term spunbond production means the depositing of the filaments after they have been spun on the deposit or on the deposit sieve belt. The measurement is therefore carried out within a period of up to 150 minutes after the filaments have been deposited on the deposit or on the deposit sieve belt. It is within the scope of the invention for this measurement to be carried out after all pre-consolidation and/or consolidation measures that are carried out on the fleece--in particular on the deposit or on the deposit sieve belt. In particular, this also involves solidification by means of a calender with an engraved roller. The degree of hardness is therefore measured after this hardening, but with the proviso that it is carried out within a period of up to 150 minutes after the filaments have been deposited on the deposit or on the deposit sieve belt. The degree of hardness is expediently measured before the spunbonded nonwoven is wound up on a roll or after the spunbonded fabric is wound up on a roll, but always with the proviso that this measurement is carried out within a period of up to 150 minutes after the filament is deposited.

• Einspannen eines Teststückes des zu analysierenden Vlieses,
• Absenken des mit 8 Platten bestückten Standard-Rotors auf die Vliesoberfläche. Bei einer Kraft von 100 mN des Rotors auf die Vliesprobe dreht der Rotor mit einer Geschwindigkeit von 2/sec.
• Durch diese Rotation wird die Vliesprobe bzw. der Rotor zu Schwingungen/Geräuschen angeregt und ein Mikrofon zeichnet diese Reaktion auf. Die gemessenen Geräusche werden mittels FourierTransformation in ein Schallfrequenzspektrum umgewandelt.
• Die Lautstärke des lokalen Lautstärkemaximums im Bereich um etwa 6550 Hz wird als "TS7" von dem Messgerät ausgegeben.

It is within the scope of the invention for the degree of hardness to be measured using a commercially available measuring device TSA (Tissue Softness Analyzer) from Emtec, Leipzig, Germany. The following standard procedure is preferably carried out:

• Clamping a test piece of the fleece to be analyzed,
• Lowering the standard rotor equipped with 8 plates onto the fleece surface. When the rotor exerts a force of 100 mN on the nonwoven sample, the rotor rotates at a speed of 2/sec.
• This rotation causes the fleece sample or the rotor to vibrate/noise and a microphone records this reaction. The noises measured are converted into a sound frequency spectrum using Fourier transformation.
• The loudness of the local loudness maximum in the area around about 6550 Hz is output by the measuring device as "TS7".

This sound frequency spectrum depends on the overall structure of the fleece surface and the amplitude of the volume depends, among other things, on the height of the fleece structure and on the degree of hardness of the fleece surface or the filament surfaces. Properties such as surface topology in the range below 1000 Hz become clear and softness in the range around 6550 Hz. The percentages given there for differences in the degree of hardness therefore refer to this value. Appropriately, the volume or the degree of hardness of the comparison fleece is set equal to 100% and it is related to the volume or the degree of hardness of the spunbonded nonwoven according to the invention as a percentage Deviation determined. - A description of such a measuring method for the degree of hardness or for the degree of softness can be found in " Schloßer U., Bahners T., Schollmeyer E., Gutmann J.: Evaluation of the feel of textiles using sound analysis, Melliand Textilreports 1/2012, 43 to 45 ".

As part of the production of the spunbonded nonwoven according to the invention, the filaments are preferably deposited on a tray, in particular on a tray sieve belt. It is within the scope of the invention for the degree of hardness to be measured on the surface of the spunbonded nonwoven fabric that faces away from the deposit or from the deposit sieve belt. If the nonwoven web or spunbonded nonwoven is bonded using a calender with an engraved roller, the measurement of the degree of hardness is expediently carried out on the surface of the spunbonded nonwoven that faces the engraved roller and is preferably the surface of the spunbonded nonwoven that is exposed to the deposit or facing away from the deposit sieve belt. It is within the scope of the invention that the spunbonded nonwoven according to the invention on the one hand and the comparative nonwoven on the other hand are manufactured under the same conditions, in particular are manufactured with the same system or spunbond system and are deposited on the same tray or the same tray sieve belt. Furthermore, it is within the scope of the invention that the spunbonded nonwoven and the comparison nonwoven are bonded in the same way, in particular with the same calender or the like, and that the filaments of the spunbonded fabric on the one hand and the comparison nonwoven on the other hand have the same titer.

The following stipulations apply to all embodiments (first and second embodiment):
Raw material mixtures which are preferably compatible in each case can be used in the core component and/or in the shell component. In the context of the invention, core-mantle configuration means that the mantle component completely or essentially completely surrounds the core component. - The continuous filaments of the spunbonded fabric preferably have a titer of 1.0 to 2.5 denier and particularly preferably a titre of 1.2 to 2.2 denier for all embodiments of the invention.

It is within the scope of the invention that the core-shell configuration can be an eccentric core-shell configuration. A spiral-crimped filament then preferably results through a suitable choice of the raw materials or the plastic components.

In the context of the first and second embodiment, it is recommended that the core component and/or the shell component contain at least 90% by weight, preferably at least 95% by weight and preferably at least 96% by weight of at least one component from the group “polyolefin, polyolefin Copolymer, mixture of polyolefin and polyolefin copolymer". It is particularly preferred that the core component and/or the shell component contain at least 90% by weight, preferably at least 95% by weight and preferably at least 96% by weight of at least one component from the group “polypropylene, polypropylene copolymer, mixture made of polypropylene and polypropylene copolymer". The core component and/or the sheath component expediently consists/consist essentially of a polyolefin and/or essentially of a polyolefin copolymer and/or essentially of a mixture of polyolefin and polyolefin copolymer. According to the highly recommended variant of the first and second embodiment, there is/are the core component and/or the sheath component consists essentially of a polypropylene and/or essentially of a polypropylene copolymer and/or essentially of a mixture of a polypropylene and a polypropylene copolymer. The limitation "substantially" in the embodiment variants described above takes into account the fact that the core component and/or the shell component contains additives, in particular the lubricant and optionally an additive that reduces the migration speed of the lubricant. Preferably, the proportion of the additives (lubricant, optionally the additive that reduces the migration speed of the lubricant and any other additives, such as color additives) - based on the entire filament - is at most 10% by weight, expediently at most 8% by weight, preferably at most 6 wt% and very preferably a maximum of 5 wt%. The polypropylene copolymer used within the scope of the invention is, moreover, designed as an ethylene-propylene copolymer in accordance with an expedient embodiment. It is recommended that the ethylene-propylene copolymer used has an ethylene content of 1 to 6%, preferably 2 to 6%. It is advisable for the polypropylene copolymer preferably used to have a melt flow rate (MFI) of from 19 to 70 g/min, in particular from 20 to 70 g/min, preferably from 25 to 50 g/min. It has proven useful for the polypropylene copolymer to have a molecular weight distribution or molar mass distribution (M _w /M _n ) of from 2.5 to 6, preferably from 3 to 5.5 and very preferably from 3.5 to 5.

A recommended embodiment variant of the first and the second embodiment of the invention is characterized in that the core component essentially consists of a homo-polyolefin, in particular essentially of a homo-polypropylene. It has been proven that the core component at least 80% by weight, preferably at least 85% by weight, preferably at least 90% by weight and particularly preferably at least 95% by weight of the homopolyolefin, in particular of the homopolypropylene. - A recommended embodiment of the first and the second embodiment is further characterized in that the sheath component consists essentially of a polyolefin copolymer, in particular essentially of a polypropylene copolymer and/or essentially of a mixture of a polyolefin or homo-polyolefin with a polyolefin copolymer, in particular essentially consisting of a mixture of a polypropylene or homo-polypropylene with a polypropylene copolymer.

Both in the first and in the second embodiment of the invention, the substances specified below are preferably used as lubricants. At least one fatty acid derivative and preferably at least one substance from the group “fatty acid ester, fatty acid alcohol, fatty acid amide” is expediently used as the lubricant. A recommended embodiment of the invention is characterized in that at least one stearate - in particular glycerol monostearate - and/or a fatty acid amide such as e.g. B. erucic acid amide and / or an oleic acid amide used. For example, the use of distearylethylenediamide is also possible. According to a proven embodiment, the erucic acid amide product SL05068PP from Constab is used as the lubricant masterbatch.

A variant of the first embodiment of the invention is characterized in that both the core component and the sheath component of the endless filaments of the spunbonded nonwoven according to the invention consist of a homo-polyolefin, preferably of a homo-polypropylene or essentially exist. In this variant of the first embodiment, the mass ratio between the core component and the shell component is expediently 40:60 to 90:10 and preferably 67:33 to 75:25. In the first embodiment, the at least one lubricant is recommended to be admixed only to the core component or the lubricant is present in the core component to an extent of at least 95% by weight, preferably at least 98% by weight. In this embodiment, it is recommended that a proportion or an average proportion of the lubricant of 250 to 5000 ppm and preferably of 1000 to 5000 ppm be present in the entire continuous filament. - A higher proportion of the sheath of the filaments with a core-sheath configuration impedes the migration of the lubricant from the core more effectively, on the other hand, the proportion of the lubricant in the core must continue to increase for the end effect. Here are the lower limits of the core portion z. B. given by the extruder used or by feeding back a recyclate in the core.

A further variant of the first embodiment of the invention is characterized in that the core component consists or essentially consists of a homo-polyolefin, in particular of a homo-polypropylene, and that the sheath component consists of a mixture of a homo-polyolefin, in particular of a homo- Polypropylene and a polyolefin copolymer, in particular a polypropylene copolymer consists or essentially consists. According to an expedient embodiment, the homo-polyolefin, in particular the homo-polypropylene in the core component, is identical to the homo-polyolefin or homo-polypropylene in the sheath component. The proportion of the homopolyolefin, in particular the homopolypropylene, in the sheath component is preferably 40 to 90% by weight, preferably 70 to 90% by weight and preferably 75 to 90% by weight 85% by weight (relative to the sheath component). The proportion of polyolefin copolymer or polypropylene copolymer in the shell component is expediently 50 to 10% by weight, preferably 30 to 10% by weight and preferably 25 to 15% by weight (based on the shell component). The polyolefin copolymer used, in particular the polypropylene copolymer, is recommended to have a melt flow rate (MFI) of from 5 to 30 g/10 min, preferably from 5 to 25 g/10 min. In the context of the invention, the melt flow rate (MFI) is measured in particular according to ISO 1133, specifically for polypropylene and polypropylene copolymer at 230° C. and 2.16 kg. The polyolefin copolymer or the polypropylene copolymer preferably has an ethylene content of 2 to 20%, preferably 4 to 20%. With regard to the carbon atoms, the polyolefin copolymer or the polypropylene copolymer of this embodiment is preferably characterized by an average C2 content in the range from 2 to 6%. Exxon Vistamaxx 3588 and/or Exxon Vistamaxx 6202 or a polypropylene with similar properties are preferably used as the polypropylene copolymer. The polypropylene copolymer is mixed with the homo-polyolefin or homo-polypropylene for the sheath component as described above. Preferred specifications for the homo-polypropylene are listed further below.

In the course of the production of the spunbonded nonwoven according to the invention, recyclate recycling can be used with regard to the thermoplastic material used. In this case, the recyclate stream is expediently used exclusively or primarily for the core component, particularly in the first embodiment of the invention. A lubricant-loaded recycled recyclate is then only fed back into the core component and the sheath component is guaranteed to be lubricant-free or essentially remains free of lubricants. - In the case of recyclate recycling with copolymer shares in the recyclate stream, the copolymer is then also converted into the core component. Nevertheless, the sheath remains lubricated or substantially lubricated.

In the first embodiment of the invention, the at least one lubricant is present exclusively or for the most part in the core component. The second embodiment of the invention is explained in more detail below. According to the second variant, lubricant is present in the jacket component. According to one embodiment, the lubricant can only be contained in the jacket component. In principle, however, lubricant can also be present in the core component in this second embodiment.

In the second embodiment of the invention, the core component can consist or essentially consist of a homopolyolefin and in particular of a homopolypropylene. According to another embodiment variant, the core component in this second embodiment has at least 75% by weight, preferably at least 80% by weight, preferably at least 85% by weight and particularly preferably at least 90% by weight of the homo-polyolefin, in particular the homo -polypropylene.

A recommended variant of the second embodiment of the invention is characterized in that the jacket component or the jacket component containing the lubricant consists or essentially consists of a polyolefin copolymer, in particular of a polypropylene copolymer. It should be noted that the lubricant may be or is contained in the sheath component and (additionally) the Additive that reduces the migration speed of the lubricant is included. In the second embodiment, a polyolefin copolymer or a polypropylene copolymer is preferably selected for the sheath component which has a melt flow rate (MFI) of 20 to 70 g/10 min, preferably 25 to 50 g/10 min. An ethylene-propylene copolymer with an ethylene content of 1 to 6%, preferably 2 to 6%, is expediently used. The polyolefin copolymer or polypropylene copolymer selected for the sheath component is recommended to have a narrow molar mass distribution and preferably a molecular weight distribution or molar mass distribution (M _w /M _n ) of from 2.5 to 6, preferably from 3 to 5.5 and very preferably from 3.5 to 5. The molecular weight distribution M _w /M _n is determined in the context of the invention by gel permeation chromatography (GPC) according to ISO 16014-1:2003, ISO 16014-2:2003, ISO 16014-4:2003 and ASTM D 6474-12. - It is recommended to use a random polypropylene copolymer containing a nucleating agent or otherwise modified for a high crystallization rate, such as Borealis RJ377MO or Basell Moplen RP24R. This latter random polypropylene copolymer has z. B. a melt flow rate of 30 g/10 min and a Vicat temperature of 120 °C (ISO 306/A50, 10 N).

In the context of the second embodiment of the invention, at least one additive that reduces the migration speed of the lubricant is used in the sheath component of the endless filaments. This additive is at least one nucleating agent and/or at least one filler. According to a particularly preferred embodiment of the invention, at least one nucleating agent is used. The nucleating agent is expediently present in a proportion of 500 to 2500 ppm - based on the entire filament - included in the filaments. A nucleating agent from the group "aromatic carboxylic acid, salt of an aromatic carboxylic acid, sorbitol derivative, talc, kaolin, quinacridone, pimelic acid salt, suberic acid salt, dicyclohexyl-naphthalenedicarboxamide, organophosphate, triphenyl compound, triphenyldithiazine" has proven particularly useful. used. A sorbitol such as dibenzyl sorbitol (DBS) or 1,3:2,4-bis-(p-methylbenzylidene) sorbitol (MDBS) or 1,3:2,4-bis(3,4 -dimethylbenzylidene) sorbitol (DMDBS) can be used. A preferred nucleating agent is a salt of an aromatic carboxylic acid, especially an alkali metal salt of benzoic acid, such as sodium benzoate.

By nucleating the sheath component, in particular the polyolefin copolymer or the polypropylene copolymer of the sheath component, with at least one nucleating agent, the migration rate of the lubricant in the sheath is reduced and thus, with regard to solving the technical problem, the problem-free use of lubricants in the sheath component is made possible . - At least one filler in the shell component can also reduce the migration speed of the lubricant. At least one metal salt and particularly preferably at least one substance from the group “titanium dioxide”, calcium carbonate, talc” is preferably used as the filler.

In the context of the second embodiment of the invention, random polypropylene copolymers with a narrow molar mass distribution can advantageously be used as polypropylene copolymers for the sheath component. Polypropylene copolymers, which are known from the injection molding sector and often contain antistatic agents and contain nucleating agents. Such antistatic agents (eg fatty acid esters such as glycerol monostearate or ethoxylated fatty amines or alkylamines) can often already be sufficient as lubricants and would fall under the amount of lubricant claimed according to the invention. - Optionally, additional lubricant can be metered into the core component and/or shell component if the proportion already present from the copolymer is not sufficient. The copolymer of the sheath component can be blended with homo-polypropylene. It is within the scope of the invention that the viscosity of these mixtures is lower than the viscosity of a homo-polypropylene. The following explanations again relate both to the first embodiment and to the second embodiment of the invention: If a homo-polypropylene is used in the first or in the second embodiment of the invention, it is preferably a homo-polypropylene with the following properties. The melt flow rate (MFI) is expediently 17 to 37 g/10 min, preferably 19 to 35 g/10 min. The homo-polypropylene is recommended to have a narrow molar mass distribution in the range from 3.6 to 5.2, in particular in the range from 3 8 to 5 on. The measurement of the molar mass distribution has already been specified above. According to a preferred embodiment of the invention, at least one of the following products is used as homo-polypropylene: Borealis HF420FB (MFI19), HG455FB (MFI25), HG475FB (MFI25), Basell Moplen HP561R (MFI25) and Exxon 3155 PP (MFI35).

In the first as well as in the second embodiment, according to a particularly recommended embodiment of the invention, homo-polypropylene and/or polypropylene copolymer, in particular ethylene-propylene copolymer, is used for both the core component and the shell component and/or mixtures thereof are used. The PP materials have proven particularly useful in the context of the invention.

It is within the scope of the invention that, both in the first embodiment and in the second embodiment, a spunbonded nonwoven according to the invention is produced using a spunbond process. First, multi-component filaments or bi-component filaments with a core-sheath configuration are spun as continuous filaments using at least one spinneret and then these continuous filaments are cooled in at least one cooling device and the continuous filaments then pass through a stretching device to stretch the filaments. The stretched filaments are laid down as a spunbonded nonwoven on a deposit, in particular on a sieve belt.

A particularly recommended embodiment of the invention is characterized in this context in that the unit consisting of the cooling device and the stretching device is designed as a closed unit, with no further air being supplied to the closed unit apart from the supply of cooling air in the cooling device. This closed design has proven particularly useful within the scope of the invention when producing a spunbonded nonwoven according to the invention.

At least one diffuser is expediently arranged between the stretching device and the deposit or the deposit sieve belt. The continuous filaments emerging from the stretching device are guided through this diffuser and then deposited on the tray or on the tray sieve belt. A recommended embodiment variant of the invention is characterized in that at least two diffusers, preferably two diffusers, are arranged one behind the other in the filament flow direction between the stretching device and the deposit are arranged. At least one secondary air inlet gap for the entry of ambient air is expediently present between the two diffusers. The embodiment with the at least one diffuser or with the at least two diffusers and the secondary air inlet gap has also proven itself particularly with regard to the production of the spunbonded nonwovens according to the invention.

After the filaments have been deposited to form the spunbonded nonwoven, this spunbonded nonwoven is bonded, prebonded according to a preferred embodiment and then finally bonded. The pre-consolidation or consolidation of the spunbonded fabric is expediently carried out with at least one calender. In this case, two interacting calender rolls are preferably used. According to a recommended embodiment, at least one of these calender rolls is designed to be heated. The embossing area of the calender is expediently 8 to 20%, for example 12%. - If, within the scope of the invention, the degree of softness is determined for a spunbonded nonwoven according to the invention on the one hand and for a comparison nonwoven on the other hand, the same preconsolidation or strengthening of the spunbonded nonwoven takes place in both nonwovens.

The invention is based on the finding that the spunbonded nonwovens according to the invention have an optimal, smooth, soft feel and nevertheless have high strength. This results in soft spunbonded nonwovens with good tensile strength. This applies above all to the preferred use of polypropylenes or polypropylene copolymers for the core component and/or sheath component of the continuous filaments of the spunbonded nonwoven according to the invention. It is also important that, compared to known solutions, the evaporation of lubricant from the filaments can be effectively reduced, thereby avoiding undesirable deposits in the system. Consequently the cleanliness of the system can be increased compared to the known measures and thus the efficiency and availability of the system can also be increased. In particular, the system running time can be increased. In this respect, the invention is also based on the knowledge that inhomogeneous introduction of the lubricant into the filaments contributes effectively to solving the technical problem according to the invention. - As will be demonstrated with the following exemplary embodiments, a comparable strength of the nonwovens can be achieved in comparison to the measures known from practice when producing the spunbonded nonwovens according to the invention and in particular when solidifying the spunbonded nonwovens with less energy expenditure - especially at lower calender temperatures. Due to the high strength of the spunbonded webs achieved according to the invention, material can also be saved in the production of the endless filaments, in particular in comparison to other raw material combinations, such as PP/PE. Furthermore, when producing the spunbonded nonwovens according to the invention, the components can be easily recycled in the production process. Due to the compatibility of the raw materials used, a high proportion of recyclate can be returned without any problems. This also results in a significant cost advantage compared to z. B. a PP / PE combination. The result is soft, smooth and strong spunbonded nonwovens that can be produced at relatively low cost.

The invention is explained in more detail using exemplary embodiments:
Subsequently, spunbonded webs were produced from bicomponent filaments with a core-sheath configuration by the spunbond process described above. Homo-polypropylene and polypropylene copolymers were used as the material for the two components (core and jacket). The In all exemplary embodiments, the spunbonded nonwoven laid down on the sieve belt was consolidated using a calender which had an engraving U5714A (12% embossed area, round engraved points, 25 figures/cm ² ). The fineness of the filaments of all examples was about 1.6 to 1.8 denier. All samples were produced with a spinning system at the same or similar throughputs.

Comparative example:

Monocomponent filaments were made from homo-polypropylene (Borealis HG455FB with MFI25). The calendering took place at a surface temperature of the calender rolls of approx. 148.degree. The spunbonded fabric produced has good strength, but does not have a satisfactory soft hand compared to the following exemplary embodiments.

Example 1:

A spunbonded web of bicomponent filaments was produced according to the first embodiment of the invention, with both the core component and the sheath component made of homo-polypropylene (Borealis HG455FB with MFI25) with 8% of a polypropylene from Idemitsu "L-MODU X901S" as a soft additive polypropylene passed. The mass ratio between the core component and the sheath component was 70:30. Only the core contained the lubricant SL05068PP from Constab based on erucic acid amide. The content of the lubricant was 2000 ppm with respect to the whole filament. The spunbonded web was calendered at a surface temperature of the calender rolls of about 142°C. The spunbonded fabric produced from these continuous filaments had a smooth, soft handle after one day's storage time.

Example 2:

The spunbonded fabric of this embodiment was also produced according to the first embodiment of the invention. The bicomponent filaments of this spunbonded web contained homo-polypropylene (Basell Moplen HP561R with MFI25) with 10% by weight of a soft additive co-polypropylene (Exxon Vistamaxx VM 6202) both in the core component and in the sheath component. The mass ratio between the core component and the sheath component was 70:30 here as well. SL05068PP from Constab based on erucic acid amide was again used as the lubricant. This lubricant was contained only in the core, and the content of the lubricant was 2500 ppm based on the whole filament. The spunbonded nonwoven was calendered at a surface temperature of the calender rolls of 132.degree. The handle of the filament produced initially had to be classified as dull, after one day of storage a smooth, soft handle developed. This shows the delayed migration of the lubricant.

Example 3:

This spunbonded nonwoven fabric was produced according to the second embodiment of the invention. The bicomponent filaments contained homo-polypropylene (Borealis HG475FB) in the core and polypropylene copolymer (Basell Moplen RP248R with MFI 30) in the sheath. The mass ratio between the core component and the sheath component was 70:30. The polypropylene copolymer of the sheath contains a nucleating agent and an antistatic agent. The spunbonded nonwoven was calendered at a surface temperature of the calender rolls of 121.degree. The hand of the spunbonded nonwoven produced had to be initially classified as dull, after a day's storage time, the nonwoven had a smooth, soft hand. This in turn shows delayed migration of the lubricant or, in this case, the antistatic agent.

Example 4:

The spunbonded fabric was produced according to the second embodiment of the invention. The core component of the bicomponent filaments consisted of homo-polypropylene (Borealis HG475FW with MFI25) and the sheath component consisted of polypropylene copolymer (Basell Moplen RP248R with MFI30). The mass ratio between the core component and the sheath component was 50:50. The polypropylene copolymer contained a nucleating agent and an antistatic agent. The solidification took place with calender rolls with a surface temperature of 121 °C. The handle of the spunbonded fabric produced was initially dull and after a day's storage time, a smooth, soft handle then set in. This in turn shows the delayed migration of the stearate used as a lubricant. Compared to Example 3, the fleece has reduced strength (see table below), which is due to the larger proportion of polypropylene copolymer compared to homo-polypropylene.

Example 5:

The bicomponent filaments of this spunbonded nonwoven had homo-polypropylene (Borealis HG475FB with MFI25) in the core and polypropylene copolymer in the sheath. The mass ratio of the core component to the shell component was 70:30. The polypropylene copolymer used is comparable to the Moplen RP248R copolymer, but has no nucleating agent and no antistatic agent. The spunbonded nonwoven was consolidated using calender rolls with a surface temperature of 121.degree. Even after a three-day storage time, the spunbonded fabric produced in this way did not achieve the smooth, soft feel of exemplary embodiment 3. This shows that the use of polypropylene copolymer alone is not sufficient and a migrating one Lubricant is required to realize the properties of the invention.

The table below gives the basis weights of the spunbonded nonwovens in g/m ² and the strengths in the machine direction (MD) and transversely to the machine direction (CD) for the above examples, specifically in N/5 cm. The strengths were measured according to EDANA ERT 20.2-89 with a clamping length of 100 mm and a pull-off speed of 200 mm/min. Comparative example V is compared here with exemplary embodiments 1 to 5: example basis weight Strength MD Strength CD "V" 22 49 35 1 22 44 28 2 22 39 31 3 20 55 31 4 20 48 30 5 20 55 35

It should be emphasized that the spunbonded nonwovens of Examples 3 to 5 were consolidated at a significantly lower calender temperature than in Comparative Example V. Nevertheless, comparable strengths can be observed, so that the energy consumption in the production of the spunbonded nonwovens according to Examples 3 to 5 could be reduced. The lower calender temperature supports the soft handle and thus enables a reduction in the amount of additional lubricant to be added.

Example 6:

This embodiment relates to the difference in hardness or referred to in relation to the hardness measurements. Measurements of the degree of hardness were carried out on a spunbonded nonwoven S1 according to the invention and on a comparative nonwoven C1 using a commercially available measuring device TSA (Tissue Softness Analyzer) from Emtec, Leipzig, Germany. The measurement method has already been explained above. The measuring head was pressed against the fleece surface with a force of 100 mN. It was measured here on the surface of the spunbonded nonwoven facing away from the sieve belt. The measuring head was equipped with eight rotating or rotatable measuring blades and the speed during the measurement was 2/sec. A volume/frequency spectrum was recorded for the spunbonded nonwoven according to the invention and for the comparison nonwoven and the volume of the peak maximum (TS7 value) at 6550 Hz was determined therein. In each case, 5 individual measurements were averaged. The two spunbonded webs were made using the same spunbond apparatus, preconsolidated in the same manner (ie, under the same calender bonding conditions), and both spunbonded webs had filaments of the same 1.8 denier. The difference between the filaments of the two spunbonded webs was the distribution of the lubricant in the polymer melt as it exited the spinning plate prior to spinning to form the respective filament. In the case of the spunbonded nonwoven S1 according to the invention, the filaments consisted of a homogeneous mixture of homo-polypropylene and polypropylene copolymer. The raw materials for the bicomponent filaments were selected analogously to example 2 above, the proportion of lubricant based on the entire filament was 2000 ppm and a calender engraving "U2888" with a surface proportion of 19% was used. The proportion of the core was 50% (mass ratio between core component and sheath component 50:50). Correspondingly, 4000 ppm of lubricant were metered into the core component of the bicomponent filaments. A spunbonded nonwoven with filaments made from the same components was used as comparison nonwoven V1, but the lubricant was distributed homogeneously over the filament cross section at 2000 ppm. The volume values (TS7 values) were determined for both webs S1 and V1, specifically for three points in time, namely 15 minutes, 2 hours and 96 hours after the filaments had been deposited on a sieve belt. Loudness values for the spunbonded nonwoven S1 according to the invention and for the comparative nonwoven C1 are shown in the table below: L (dBV ^2rms ) in % S1 V1 S1 V1 15 minutes 4:31 3.98 108.2 100 2 hours. 4.42 4:16 106.3 100 96 hours 3.93 3.84 102.2 100

The only figure shows the volume values TS7 (in dBV ² rms) of the peak maximum at 6550 Hz as a function of the time of measurement. The TS7 value that was determined 15 minutes after the filament was laid is shown on the far left and the TS7 value that was determined 2 hours after the filament was laid is shown on the right. The TS7 value is shown on the far right, which was determined 4 days or 96 hours after filament laying. The solid line characterizes the TS7 values for the spunbonded nonwoven S1 according to the invention and the dashed line shows the TS7 values for the comparative nonwoven C1. It can be seen here that the spunbonded nonwoven S1 according to the invention initially (after 15 minutes and after 2 hours) has a significantly higher volume value and thus a lower degree of softness or softness. has a higher degree of hardness than the comparison fleece V1. This results from the fact that the lubricant in the filaments of the spunbonded nonwoven S1 according to the invention moves or migrates much more slowly towards the filament surface. In the case of the comparison nonwoven, on the other hand, migration takes place relatively quickly, so that high degrees of softness or low degrees of hardness are achieved here relatively early on. The slope of the curve between 15 minutes and 2 hours for both spunbonded nonwovens is explained by the first post-crystallization of the polypropylene blend, which stiffens the filaments. This shape of the curves may be considered typical for this combination of raw materials. As expected, both lubricant migration and post-crystallization simultaneously affect softness. Since migration speeds can also change depending on the respective crystallinity, there is no generally applicable curve here, it is specific to the raw material. - After 96 hours, the volume values and thus the degrees of softness or hardness of the spunbonded nonwoven S1 according to the invention on the one hand and the comparison nonwoven V1 on the other hand match or almost match. The delayed migration of the lubricant to the filament surface in the spunbonded nonwovens according to the invention has the advantage that significantly less outgassing of lubricant from the filaments takes place in the course of the production of the filaments and the system components are correspondingly less soiled. At the same time, the winding behavior is positively influenced. - The percentages in the table also show that the volume value of the spunbonded nonwoven according to the invention within the first 150 minutes after filament deposition is more than 3% higher than the volume value of the comparison nonwoven C1 and the degree of hardness of the spunbonded nonwoven S1 according to the invention is accordingly more than 3% higher than the degree of hardness of the comparison fleece V1. It can also be seen that regardless of a the finished spunbonded nonwovens have become softer as a result of the post-crystallization that is taking place, which proves the effect and purpose of the lubricant.

Example 7:

The combination of raw materials was selected according to exemplary embodiment 5 with the same system and consolidation as in exemplary embodiment 6, but with a lubricant. A homo-polypropylene Moplen HP561R was used in the core and the random CoPP with MFR 30 from example 5 was used in the jacket. A core-case ratio of 70:30 was set and the same calendering temperature was used as in example 6 In the spunbonded nonwoven S2 according to the invention, 2900 ppm of lubricant were added only to the core. In comparison nonwoven C2, 2000 ppm of lubricant were added both to the core and to the sheath. Here, too, a similar relationship of the TS7 values is established as in exemplary embodiment 6, although the casing raw material used here, with its different basic softness and crystallization or migration speed, results in a different time course. The TS7 difference is particularly evident here after 2 hours. L (dBV ^2rms ) S2 v2 15 minutes 5.03 4.91 2 hours. 5.64 4.86 96 hours 4.3 4:19

Here, too, the seasoned spunbonded nonwoven is softer (lower TS7 value) than the freshly produced spunbonded nonwoven.

The following table shows the TS7 ratio of spunbonded nonwovens S according to the invention to the comparative nonwovens V (examples 6 and 7) after 15 minutes, 2 hours and 96 hours, as well as the strength values after production and the basis weights of the spunbonded nonwovens. Strengths and basis weights were determined according to the methods explained above, a pull-off speed of 200 mm/min being used for the strength measurement. template V1 S1 v2 S2 TS7 (15min) [%] 100 108.2 100 102.4 TS7 (2 hours) [%] 100 106.3 100 116.1 TS7 (96 hours) [%] 100 102.2 100 102.5 Strength MD [N/5cm] 41.6 39.4 44.2 42.3 Strength CD [N/5cm] 23.7 23 28.1 28.4 Weight per unit area [gr/m ² ] 20.6 20.3 20.6 20.3

It shows a strength advantage of embodiment 7 compared to embodiment 6. It shows the advantage and the possibilities of the bi-component technology.

Claims (14)

1. Method for producing a spunbonded nonwoven from continuous filaments of thermoplastic material, wherein the continuous filaments are produced as multicomponent filaments, in particular as bicomponent filaments having a core-sheath configuration, wherein the filaments contain at least one lubricant, wherein the fraction of the lubricant - relative to the entire filament - is 250 to 5500 ppm, preferably 500 to 5000 ppm, more preferably 700 to 3000 ppm and very preferably 700 to 2500 ppm, wherein the lubricant is present in the core component in an amount of at least 90 wt.%, preferably at least 95 wt.%,

   wherein the degree of hardness of the surface of the spunbonded nonwoven is measured, wherein the TS7 value of a TSA measuring device (Emtec, Leipzig, Germany), i.e. the loudness at the peak maximum of the loudness/frequency spectrum at about 6550 Hz is used as the degree of hardness of the spunbonded nonwoven at the nonwoven surface,

   wherein the surface of the spunbonded nonwoven in the time interval up to 150 minutes after production of the spunbonded nonwoven has a higher degree of hardness, in particular a degree of hardness more than 3% higher than a comparative spunbonded nonwoven having a homogeneous distribution of the lubricant relative to the filament cross-section produced under otherwise the same conditions and wherein the surface of the spunbonded nonwoven after 96 hours has the same degree of hardness or approximately the same degree of hardness as the comparative spunbonded nonwoven, wherein the degrees of hardness then preferably differ by a maximum of 3%.
2. Method according to Claim 1, wherein the mass ratio between core component and sheath component is 67:33 to 73:27 and preferably 70:30 or about 70:30.
3. Method for producing a spunbonded nonwoven from continuous filaments of thermoplastic material, wherein the continuous filaments are produced as multicomponent filaments, in particular as bicomponent filaments having a core-sheath configuration, wherein the filaments contain at least one lubricant, wherein the fraction of the lubricant - relative to the entire filament - is 250 to 5500 ppm, preferably 500 to 5000 ppm, more preferably 700 to 3000 ppm and very preferably 700 to 2500 ppm, wherein the lubricant is present in the sheath component, wherein at least one additive which reduces the migration speed of the lubricant through the sheath component is contained in the sheath component,

   wherein the degree of hardness of the surface of the spunbonded nonwoven is measured, wherein the TS7 value of a TSA measuring device (Emtec, Leipzig, Germany), i.e. the loudness at the peak maximum of the loudness/frequency spectrum at about 6550 Hz is used as the degree of hardness of the spunbonded nonwoven at the nonwoven surface,

   wherein the surface of the spunbonded nonwoven in the time interval up to 150 minutes after production of the spunbonded nonwoven has a higher degree of hardness, in particular a degree of hardness more than 3% higher than a comparative spunbonded nonwoven without an additive which reduces the migration speed of the lubricant, produced under otherwise the same conditions and wherein the surface of the spunbonded nonwoven 96 hours after production of the spunbonded nonwoven has the same degree of hardness or approximately the same degree of hardness as the comparative spunbonded nonwoven, wherein the degrees of softness then preferably differ by a maximum of 3%.
4. Method according to one of Claims 1 to 3, wherein the core component and/or the sheath component have at least 90 wt.%, preferably at least 95 wt.% and more preferably at least 96 wt.% of at least one component from the group "polyolefin, polyolefin copolymerisate, mixture of polyolefin and polyolefin copolymerisate".
5. Method according to one of Claims 1 to 4, wherein the core component and/or the sheath component have at least 90 wt.%, preferably at least 95 wt.% and more preferably at least 96 wt.% of at least one component from the group "polypropylene, polypropylene copolymerisate, mixture of polypropylene and polypropylene copolymerisate".
6. Method according to one of Claims 1 to 5, wherein the core component consists or substantially consists of a homopolyolefin, in particular consists or substantially consists of a homopolypropylene or wherein the core component has at least 80 wt.%, preferably at least 85.wt %, more preferably at least 90 wt. % and particularly preferably at least 95 wt.% of the homopolyolefin, in particular of the homopolypropylene.
7. Method according to one of Claims 1 to 6, wherein the sheath component consists or substantially consists of a polyolefin copolymerisate, in particular of a polypropylene copolymerisate and/or a mixture of a polyolefin with a polyolefin copolymerisate, in particular of a polypropylene with a polypropylene copolymerisate.
8. Method according to one of Claims 1 to 7, wherein the polyolefin copolymerisate, in particular the polypropylene copolymerisate has a molecular weight distribution or molar mass distribution (M_w/M_n) of from 2.5 to 6, preferably from 3 to 5.5 and very preferably from 3.5 to 5.
9. Method according to one of Claims 1 to 8, wherein at least one fatty acid derivative and preferably at least one substance from the group "fatty acid ester, fatty acid alcohol, fatty acid amide" is used as lubricant.
10. Method according to one of Claims 1 to 9, wherein at least one stearate and/or at least one erucic acid amide and/or at least one oleamide is used as lubricant.
11. Method according to one of Claims 3 to 10, wherein the lubricant is contained in the sheath component and according to one embodiment only in the sheath component.
12. Method according to one of Claims 3 to 10, wherein at least one nucleating agent and/or at least one filler, preferably at least one nucleating agent is contained in the sheath component as an additive that reduces the migration speed of the lubricant.
13. Method according to one of Claims 3 to 12, wherein at least one additive from the group "aromatic carboxylic acid, salt of an aromatic carboxylic acid, sorbitol derivative, talc, kaolin, quinacridone, pimelic acid salt, suberic acid salt, dicyclohexyl naphthalene dicarboxamide, organophosphate, triphenyl compound, triphenyl dithiazine" is used as the additive that reduces the migration speed of the lubricant.
14. Method according to one of Claims 12 or 13, wherein at least one metal salt or at least one substance from the group "titanium dioxide, calcium carbonate, talc" is used as filler.

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