DE102013014920A1 - Bicomponent fiber for the production of spunbonded nonwovens - Google Patents

Abstract

The invention relates to a bicomponent fiber (1), in particular for producing spunbonded nonwovens (4), having a first component (2) and a second component (3), wherein the first component (2) is a first polymer and the second component is a second polymer as a component. According to the invention, it is provided that the first component (2) has an additive, wherein the mass fraction of the additive in the second component (3) is smaller than in the first component (2).

Description

The invention relates to a bicomponent fiber, in particular for the production of spunbonded nonwovens, with a first component and a second component, wherein the first component comprises a first polymer and the second component comprises a second polymer as an ingredient. Furthermore, the invention relates to a spunbonded nonwoven with at least one bicomponent fiber of the aforementioned type.

Bicomponent fibers of the type in question usually have a first component of a first polymer and a second component of a second polymer. In this case, different types of bicomponent fibers can be distinguished, each having different characteristic distributions of the components in the fiber cross section. Bicomponent fibers in which the first component surrounds and thus encloses the second component in the cross-section of the fiber are referred to as core-sheath fibers. Bicomponent fibers in which both the first component and the second component form part of the fiber surface in the cross-section of the fiber are referred to as side-by-side fibers. Fibers having structures in which multiple strands of one component are embedded in a strand of the other component to form an image in cross-section reminiscent of a plurality of islands formed as a component are referred to as Iceland-in-the-Sea fibers designated. Bicomponent fibers in which in each case a plurality of regions of the respective component is present in cross-section and forms the outer fiber surface are referred to as segmented pie fibers, since the regions of the individual components in the cross-section regularly have a cake-like division. For the purposes of the present application, bicomponent fibers are expressly to be understood as meaning those fibers which have more than 2 components.

The purpose of the bicomponent fibers is to improve the properties of the fibers or the properties of spunbonded nonwoven webs. The properties of a spunbond depend on a variety of factors. Some of these influencing factors on the properties of a spunbonded fabric are properties of the fibers used in each case, such. B. their strength. A widely accepted and accepted at least in their basic theory is that the properties of the resulting bicomponent fiber then represent a combination of the properties of the individual components of the bicomponent fiber, in which the properties of the individual components complement each other to the extent that the benefits of the properties of both components be combined in the bicomponent fiber. If, for example, a fiber is desired which has both a high strength and exhibits advantageous behavior when bonding the fibers to one another in nonwoven production, it is advisable to have a first component with a high strength with a second component which has good bondability , to combine.

To improve the properties of the bicomponent fibers, additives are often added to the polymers. The additives can be a wide variety of substances. These can be used, for example, for dyeing, for thermal stabilization, for flame retardation, for hydrophilization or for hydrophobization or for UV stabilization. The additives are regularly distributed evenly throughout the phase.

However, a disadvantage of the use of these additives is that the additives can disrupt the production process, in particular if they exceed certain total concentration limits. Furthermore, the additives can be associated with high costs. Furthermore, additives may be hazardous to health or the environment, especially if they exceed certain total concentrations in the fibers.

The invention is based on the object of providing a bicomponent fiber, in particular for producing a spunbonded fabric, and a spunbonded fabric having at least one bicomponent fiber, in which the negative effects of the addition of additives do not occur or at least to a lesser extent.

The aforementioned object is achieved according to the invention essentially by a bicomponent fiber and a spunbonded nonwoven having the features of the independent claims. The features of the dependent claims relate to advantageous embodiments.

According to the invention, the first component has an additive for influencing or improving the properties. In this case, the mass fraction of the additive of the first component in the second component is preferably at most 66.6%, more preferably at most 50% and in particular at most 33.3% by mass of the additive in the first component. Most preferably, the additive is not present in the second component.

Preferably, the mass fraction of the first component of the bicomponent fiber is at most 50%, preferably 25%, more preferably 10%, most preferably 5%. The bicomponent fiber is particularly preferably one Core-sheath fiber, wherein the first component forms the sheath.

The advantage of concentrating the additives in the first component surrounding the second component is that it has been found that the amount of additive required in the second component may be lower than in the usual uniform distribution of the additive in the two components, if the same or improved effect of the additive to be generated.

Additive in this sense means additives which are added to the polymer in the respective component in order to modify and thereby improve the properties of the resulting fiber or of the spunbond obtained from the fiber.

The additives which are added to the polymers in low concentrations generally constitute a contamination of the polymer with respect to fiber production. In the case of impurities, there is always the risk that the behavior of the components in the production of the fiber will change as a result of these impurities. Therefore, unequal distribution of the additives in the components of the bicomponent fiber from the perspective of the person skilled in the art initially entails the risk that the quality of the bicomponent fiber or the stability of the manufacturing process will deteriorate. Moreover, from the point of view of the person skilled in the art, it is generally not important for an additive to be concentrated in a certain zone of the fiber. This is due to the small thickness of the fibers in question. Similarly, as with dyes or pigments, it does not make any obvious sense for additives as well from the professional viewpoint to enrich them in a particular zone of the fiber. For example, in a flame retardant anyway, the entire fiber will be affected by the combustion processes. Also, UV radiation will penetrate the entire fiber. Nevertheless, it has surprisingly been found that in some cases even particularly advantageous results can be achieved if the additive is not only reduced in the one component, but omitted entirely. In any case, an advantage of the concentration of the additives in the first component is the cost savings due to the lower amount of additive required.

• – Sterisch gehinderte Phenole, aromatische sekundäre oder tertiäre Amine, Aminophenole, aromatische Nitro- oder Nitrosoverbindungen als primäre Antioxidantien.
• – Organische Phosphite oder Phosphonate, Thioether, Thioalkohole, Thioester, Sulfide und schwefehaltige organische Säuren, Dithiocarbamate, Thiodipropionate, Aminopyrazole, metallhaltige Chelate, Mercaptobenzimidazole als sekundäre Antioxidantien.
• – Hydroxybenzophenone, Cinnamate, Oxalanilide, Salicylate, 1,3 Benzoldiol-Monobenzoate, Benzotriazole, Triazine, Benzophenone sowie UV-absorbierende Pigmente wie Titandioxid oder Ruß als UV-Absorber.
• – Metallhaltige Komplexe organischer Schwefel- oder Phosphorverbindungen, sterisch gehinderte Amine (HALS) als UV-Stabilisatoren.
• – Metallhydroxide, Borate, organische brom- oder chlorhaltige Verbindungen, organische Phosphorverbindungen, Antimontrixoid, Melamin, Melamincyanurat, Blähgraphit oder andere Intumeszenz-Systeme als Flammhemmer.
• – Quartäre Ammoniumsalze, Alkylsulfonate, Alkylsufate, Alkylphosphate, Dithiocar–bamate, (Erd)Alkalimetallcarboxylate, Polyethylenglykole sowie deren Ester und Ether, Fettsäureester, Ethoxylate, Mono- und Diglyceride, Ethanolamine als Antistatika.
• – Fettalkohole, Ester von Fettalkoholen, Fettsäuren, Fettsäureester, Dicarbonsäureester, Fettsäureamide, Metallsalze von Fettsäuren, Polyolefinwachse, natürliche oder künstliche Paraffine und deren Derivate, Fluorpolymere und Fluoroligomere, Antiblockmittel wie Kieselsäuren, Silikone, Silikate, Calciumcarbonat etc. als Gleitmittel.
• – Amide von Mono- und Dicarbonsäuren und deren Derivate, zyklische Amide, Hydrazone und Bishydrazone, Hydrazide, Hydrazine, Melamin und dessen Derivate, Benzotriazole, Aminotriazole, sterisch gehinderte Phenole in Verbindung mit komplexierenden Metallverbindungen, Benzylphosphonate, Pyridithiole, Thiobisphenolester als Metalldesaktivatoren.
• – Polyglycole, Ethoxylate, Fluorpolymere und Fluoroligomere, Montanwachse, insbesondere Stearate, als Hydrophilierungs-, Hydrophobierungs- oder Anti-Fogging-mittel.
• – 10,10'-Oxybisphenoxarsin (OBPA), N-(Trihalogen-methylthiol)phthalimid, Tributylzinnoxid, Zinkdimethyldithiocarbamat, Diphenylantimon-2-ethylhexanoat, Kupfer-8-hydroxychinolin, Isothiazolone, Silber und Silbersalze als Biozide.

Advantageously, the additive is a primary or secondary antioxidant, a UV absorber, a UV stabilizer, a flame retardant, an antistatic agent, a lubricant, a metal deactivator, a hydrophilizing agent, a hydrophobing agent, an antifogging additive and / or a biocide. Particularly preferred are the following classes of substances and mixtures thereof:

• Sterically hindered phenols, aromatic secondary or tertiary amines, aminophenols, aromatic nitro or nitroso compounds as primary antioxidants.
• - Organic phosphites or phosphonates, thioethers, thioalcohols, thioesters, sulfides and sulfurous organic acids, dithiocarbamates, thiodipropionates, aminopyrazoles, metal-containing chelates, mercaptobenzimidazoles as secondary antioxidants.
• Hydroxybenzophenones, cinnamates, oxalanilides, salicylates, 1,3-benzenediol monobenzoates, benzotriazoles, triazines, benzophenones and UV-absorbing pigments such as titanium dioxide or carbon black as UV absorbers.
• - Metal-containing complexes of organic sulfur or phosphorus compounds, sterically hindered amines (HALS) as UV stabilizers.
• - Metal hydroxides, borates, organic bromine or chlorine-containing compounds, organic phosphorus compounds, antimony trixoid, melamine, melamine cyanurate, expandable graphite or other intumescent systems as flame retardants.
• - Quaternary ammonium salts, alkyl sulfonates, alkyl sulfates, alkyl phosphates, Dithiocar bamate, (alkaline) alkali metal carboxylates, polyethylene glycols and their esters and ethers, fatty acid esters, ethoxylates, mono- and diglycerides, ethanolamines as antistatic agents.
• Fatty alcohols, esters of fatty alcohols, fatty acids, fatty acid esters, dicarboxylic acid esters, fatty acid amides, metal salts of fatty acids, polyolefin waxes, natural or artificial paraffins and their derivatives, fluoropolymers and fluoro-oligomers, antiblocking agents such as silicas, silicones, silicates, calcium carbonate, etc. as lubricants.
• - Amides of mono- and dicarboxylic acids and their derivatives, cyclic amides, hydrazones and bishydrazones, hydrazides, hydrazines, melamine and its derivatives, benzotriazoles, aminotriazoles, hindered phenols in conjunction with complexing metal compounds, benzyl phosphonates, pyridithiols, thiobisphenol esters as metal deactivators.
• Polyglycols, ethoxylates, fluoropolymers and fluoro-oligomers, montan waxes, in particular stearates, as hydrophilizing, hydrophobing or anti-fogging agents.
• 10,10'-oxybisphenoxarsine (OBPA), N- (trihalomethylthiol) phthalimide, tributyltin oxide, zinc dimethyldithiocarbamate, diphenyl antimony 2-ethylhexanoate, copper 8-hydroxyquinoline, isothiazolones, silver and silver salts as biocides.

For example, in carrying out a fire test according to EN 13501-1 note that in the inventive distribution of the additive in the components, a lesser amount of the additive as a whole, in this example a flame retardant, is sufficient to produce a positive Test result as if the flame retardant is evenly distributed in the fiber. In this test, within a fraction of a second, all of the fiber is caught by the flame, so the beneficial effect is not readily attributable to some sort of shielding effect of the cladding region of the fiber.

Advantageously, the difference in the melting points of the first component and the second component is less than or equal to 8 ° C. It should be pointed out that in the given intervals any individual intervals or individual values are included and must be regarded as disclosed essential to the invention, even if they are not specified in detail.

In connection with the advantageous choice of the melting points has surprisingly been found that in bicomponent fibers in which the two components have similar melting points, an improvement in the synergy between the properties of the two components can be achieved. This concerns in particular mechanical properties. For example, it is possible to increase both the specific breaking strength and the specific nail pull-out force in the case of a spunbonded nonwoven made from bicomponent fibers according to the invention. In conventional prior art fibers, measures taken in the production of spunbonded nonwoven fabrics from these fibers to increase specific tear forces have been routinely associated with a reduction in specific nail breakout forces. In the opposite case, measures to increase the specific nail pull-out forces regularly led to a decrease in the specific tear forces. These adverse effects can be avoided or at least mitigated with the advantageous bicomponent fibers.

One of the positive effects of the present invention is that the proportion of recycled material that can be added to one of the components in making the bicomponent fiber increases over conventional fibers. It has been found that the use of components having combined melting points according to the invention makes the change in the properties of a component caused by the addition of recycled material much lower than with conventional fibers.

In this case, preferably the component with the lower melting point in the cross section of the fiber forms the outer surface of the fiber. Preferably, the lower melting point component surrounds the higher melting point component. This advantageous embodiment results in that the low-melting component in the cladding region of the fiber ensures better hardenability of the material, in addition improves the spinning stability and the extensibility of the fibers. This leads to an improvement of the softness and / or feel of the spunbonded fabric, furthermore the drapability of the fibers or of a spunbonded web obtained from the fibers is improved.

In the context of the invention, it is advantageous if the difference in the melting points of the first component and the second component is at most 6 ° C or between 1 ° C to 8 ° C, preferably between 1 ° C to 6 ° C. In these advantageous parameter ranges, the positive effects of the present invention occur significantly more.

Preferably, the mass fraction of the component with the lower melting point of the bicomponent fiber is at most 50%, more preferably at most 25%, preferably at most 10%, in particular at most 5%. More preferably, the bicomponent fiber is a core-sheath fiber, with the lower melting point component forming the sheath.

Advantageously, the difference between the melt flow indices of the first component and the second component is less than or equal to 25 g / 10 min, wherein the melt flow indices (hereinafter MFI) of the first component and the second component are each less than or equal to 50 g / 10 min are. The difference between the melt flow indices of the first component and the second component is preferably less than or equal to 20 g / 10 min, more preferably 15 g / 10 min and / or the MFIs of the first component and the second component are each less than or equal to 40 g / 10 min. Such an advantageous selection of the components according to the criterion of their MFIs surprisingly has a similar positive effect as the inventive selection of components based on their melting points.

The MFI is measured according to ISO 1133 with a test load of 2.16 kg and a test temperature of 230 ° C. The MFI is also referred to as the melt flow index or as the melt flow rate (MFR). The determination takes place after ISO 1133 in that the material is melted in a heatable cylinder and pressed by means of the test load through a defined nozzle. The MFI is a measure of the viscosity of the melt of the respective polymer-containing component. The viscosity, in turn, is related to the degree of polymerization, which corresponds to the average number of monomer units in each molecule of a polymer.

The positive influence of the beneficial differences of the MFIs essentially affects the specific tear strength and the specific nail pull-out force. These two characteristics one out of the fibers produced spunbonded fabric can be improved by the favorably selected MFIs. Even a simultaneous increase in both characteristic values is possible, but in any case one of the two characteristic values can be improved without the other characteristic value deteriorating. This also has a positive effect on the haptic properties. Thus, the specific breaking strength can be increased without the softness and the so-called "textile feel" being adversely affected. Textile grip is understood to mean a feeling of touch that is perceived as pleasant.

Preferably, the mass fraction of the component with the higher MFI on the bicomponent fiber is at most 50%, more preferably at most 25%, preferably at most 10%, in particular at most 5%. More preferably, the bicomponent fiber is a core-sheath fiber, with the higher MFI component forming the sheath.

Advantageously, the polymer of one of the two components has been polymerized with a metallocene catalyst and the polymer of the other component has been polymerized with a Ziegler-Natta catalyst and subjected to a subsequent visbreaking treatment. The polymer is preferably a polyolefin, in particular polypropylene, polyethylene or its copolymer or a mixture thereof. The other polymer is preferably also a polyolefin or a polyolefin copolymer. It is particularly advantageous if both polymers are composed of the same monomer or are at least predominantly composed of the same monomer.

Metallocene catalysts are structurally uniform catalysts containing transition metals coordinated by cyclopentadiene ligands. Such catalysts are detailed in the US 5,374,696 and the US 5,064,802 described. The relevant disclosure is expressly incorporated herein by reference. The advantage of these catalysts is that the polymers prepared with these catalysts have a narrow molecular weight distribution. The narrow molecular weight distribution leads to nonwovens with high elongation at break. In this case, the elongation at break is the elongation of the fibers, which results at the maximum of the breaking force, which is used when tearing a nonwoven strip. Above all, however, a narrow molecular weight distribution leads to an increase in process reliability in the production of the spunbonded nonwovens. The frequency of spinning disorders, such as fiber breakage, is reduced. Furthermore, a higher draw of the fibers is possible, higher spinning speeds can be achieved and the titers that can be achieved are lower. Lower titers mean a higher fineness of the fibers and / or of the yarns obtained from the fibers.

Another advantage of the metallocene catalysts or the polymers prepared by means of metallocene catalysts is that the residual content of the catalyst in the polymer is very low. The residual content of the catalyst in the polymer is an impurity of the polymer and can cause the properties of the polymer to be undesirably altered. For example, it can lead to discoloration in the processing of the polymer.

A disadvantage of the metallocene catalysts is their slightly higher price compared to the Ziegler-Natta catalysts. Furthermore, a thermal hardening of the fibers in the nonwoven production in the use of metallocene catalysts can be difficult. This may be the case if the possibilities opened up by the use of metallocene catalysts to increase the crystallinity and strength of the individual fibers by virtue of their higher drawability are utilized to a great extent.

Ziegler-Natta catalysts are heterogeneous mixed catalysts containing organometallic compounds of main group elements and transition metal compounds. In particular, elements of the first to third main groups are used as main group elements. The transition metal compounds in particular contain metals of the titanium group. There are a large number of variants of these catalysts. For the purposes of the present invention, the Ziegler-Natta catalysts are essentially defined by their delimitation from the metallocene catalysts.

Although the Ziegler-Natta catalysts are less expensive than the metallocene catalysts, the polymers produced with the Ziegler-Natta catalysts have a significantly broader molecular weight distribution than polymers prepared with metallocene catalysts. To improve the drawability of the fibers, which serves in particular to increase the process reliability, the polymers produced with Ziegler-Natta catalysts are therefore usually aftertreated. This aftertreatment is called "visbreaking". In the process of visbreaking polymer chains are cleaved, which reduces the molecular weight of the individual molecules and increases the number of molecules. This also reduces the width of the molecular weight distribution. The cleavage of the polymer chains is brought about by heat, irradiation, the addition of peroxide, or by similar means. Examples of such visbreaking treatments include in the US 4,282,076 and the US 5,723,217 described.

By such a visbreaking treatment, however, neither the narrow molecular weight distribution of the polymers produced with metallocene catalysts, nor the good drawability of the fibers obtained from these polymers can be achieved. Also, polymers produced with Ziegler-Natta catalysts have a higher level of impurities than polymers made with metallocene catalysts. This is due to the fact that in the production of the polymer with a Ziegler-Natta catalyst, a comparatively higher catalyst content is required, which requires a relatively higher proportion of catalyst residues in the polymer and on the other to auxiliaries, which were added as part of the visbreaking treatment which provides an additional source of impurities in the final polymer.

The advantage of polymers produced using Ziegler-Natta catalysts followed by a visbreaking treatment is above all their favorable price and their high availability on the market. Another advantage is the good thermal connectivity of the fibers produced from these polymers.

It has now surprisingly been found that the advantageous choice of polymers, based on the catalysts used in their preparation, results in the resulting bicomponent fibers allowing a combination of the advantages of using the respective types of catalysts. Thus, it is possible to reduce the costs compared to using pure polymer fibers produced by means of metallocene catalysts, while at the same time realizing the advantages of using metallocene catalysts. In addition, it is still possible to achieve a better bondability of the fibers in comparison to fibers of polymers which have been produced exclusively using metallocene catalysts.

Preferably, the mass fraction of the component whose polymer has been polymerized with a metallocene catalyst, at the bicomponent fiber is at most 50%, more preferably at most 25%, preferably at most 10%, in particular at most 5%. In this case, the bicomponent fiber is particularly preferably a core-sheath fiber, wherein the component whose polymer has been polymerized with a metallocene catalyst forms the sheath.

Advantageously, the first polymer and / or the second polymer is a polyolefin or a polyolefin copolymer, preferably a polymer and / or copolymer of ethylene, propylene, butylene, hexene or octene and / or a mixture and / or a Blend it. It has been found that these polymers are particularly well suited for producing the bicomponent fibers according to the invention from them. A copolymer in this context is to be understood as meaning a polymer which has been prepared from at least two different types of monomers, the mass fraction of the monomer which is decisive for the name of the copolymer being at least 50%.

Preferably, the bicomponent fiber is a core-sheath fiber, wherein the mass fraction of the core is 50% to 98%, preferably 60% to 95%, more preferably 70% to 95%, most preferably 80% to 90%. It has been found that the advantages of the bicomponent fiber according to the invention, if this is a core-sheath fiber, occur to a particular extent in these advantageous mass parts of the core.

If the bicomponent fiber is a side-by-side fiber, segmented pie fiber or islands-in-the-sea fiber, the mass ratio of the two components is in the range of 10:90 to 90:10, preferably in the range of 70:30 to 30:70, more preferably in the range of 60:40 to 40:60. In these types of fibers it has been shown that the advantages of the bicomponent fiber according to the invention can be achieved particularly well for the component ratios listed.

In another preferred embodiment, the bicomponent fiber is a multilobal, in particular a tetralobal or trilobal fiber. Due to their cross-sectional geometry, these fibers have a higher specific surface area than comparable fibers with circular cross-sections. In conjunction with these, the advantages of the fibers according to the invention can be utilized particularly efficiently, in particular if the different properties of the components which are to be optimized by the bicomponent fiber according to the invention are properties which relate to the surface of the fiber.

Advantageously, the diameter of the bicomponent fiber is between 1 μm and 50 μm, preferably between 5 μm and 30 μm, particularly preferably between 8 μm and 20 μm. It has been found that, especially with fiber diameters which lie in these advantageous ranges, the combination of two components in a bicomponent fiber leads to a particular extent to synergy effects.

Furthermore, the invention relates to a spunbonded nonwoven with bicomponent fibers according to the invention. Two properties which play a special role in spunbonded nonwovens are the specific breaking strength of the spunbonded nonwoven and the specific nail breaking strength of the spunbonded nonwoven. It will be a desirable high specific tensile strength achieved by fibers with high strength.

In this sense, good bondability is to be understood as meaning that the mobility of the fibers in the spunbonded fabric can be set as defined as possible during the joining of the fibers during the production of a spunbonded nonwoven. The targeted adjustment of the mobility of the fibers in the nonwoven, which depends on the strength of the connection of the fibers with each other, is the prerequisite for the production of a spunbonded fabric with high specific tear strength and high specific Nagelausreißkraft.

In practice, there may be the problem that suitable high strength fibers have poor bondability and fibers with good bondability have low strength. Therefore, just in the case of producing a spunbonded fabric, which should have both a high specific tensile strength and a high specific nail breaking strength, the use of a bicomponent fiber makes sense. In this case, the bicomponent fibers according to the invention are particularly suitable for allowing a high specific breaking strength and a high specific nail breaking strength of a spunbonded fabric, since the bicomponent fibers according to the invention can be optimized with regard to a combination of good connectivity and high strength.

Such a nonwoven produced from the fibers of the invention is suitable for numerous applications, for example in medicine, in the hygiene sector, in the automotive industry, in the clothing sector, in home and technical textiles and in particular in the construction sector and agriculture. Possible applications also include the use in filters and membranes, battery separators and as a backing for laminates and as a carrier for coatings of all kinds.

Advantageously, the weight per unit area of the spunbonded nonwoven is between 1 g / m ² and 300 g / m ² , preferably between 5 g / m ² and 200 g / m ² , particularly preferably between 8 g / m ² and 200 g / m ² . It has been found that at basis weights which lie in these advantageous ranges, the use of a high strength biocomponent fiber according to the invention and at the same time good bondability leads in particular to a combination of high specific tensile strength and high specific Nagelausreißkraft of the nonwoven fabric made from these fibers ,

Advantageously, the specific breaking strength of the spunbonded web is at least 1.8 N / g x 5 cm in the machine direction and / or at least 1.3 N / g x 5 cm in the cross direction, preferably 2.0 N / g x 5 cm in the machine direction and / or at least 1.5 N / g × 5 cm in the transverse direction, preferably at least 2.2 N / g × 5 cm in the machine direction and / or at least 2.0 N / g × 5 cm in the transverse direction, more preferably at least 2.4 N / g · 5 cm in the machine direction and / or at least 1.9 N / g · 5 cm in the transverse direction. Here, the machine direction refers to the direction in which the spunbonded fabric has been transported in its manufacture in the machine, so regularly the length direction of a spunbonded web. The transverse direction designates the direction at right angles to this direction, in which the spunbond flat expands, that is to say regularly the width of a spunbonded web. The specific breaking force is measured after EN 12311-1.

It has been found that these advantageous minimum values for the specific breaking strength of the spunbonded fabric should in any case be striven for when bicomponent fibers according to the invention are used for the production of the spunbonded nonwoven. The bicomponent fibers according to the invention make it possible to achieve these advantageous minimum values for the specific breaking strength without the specific nail pull-out force falling disproportionately.

Advantageously, the spunbond specific nail pull-out force is at least 1.0 N / g in the machine direction and / or at least 1.2 N / g in the transverse direction, preferably at least 1.4 N / g in the machine direction and / or at least 1.5 N / g in Transverse direction, preferably at least 1.6 N / g in the machine direction and / or at least 2.16 N / g · cm in the transverse direction, more preferably at least 1.8 N / g in the machine direction and / or at least 2.1 N / g in the transverse direction.

The specific nail pull-out force is the maximum force that occurs when tearing a nonwoven strip when the nonwoven strip already has a given damage, namely a nail pushed through the nonwoven fabric. Measured is the specific nail pull-out force EN 12310-1 , It has been found that the stated minimum values for the specific nail pull-out force of the spunbonded fabric can be achieved without the specific breaking strength of the spunbonded fabric falling disproportionately when bicomponent fibers according to the invention are optimized correspondingly with regard to their connectivity and strength. In particular, it is also possible to realize a combination of said specific advantageous nail pull-out forces and the aforementioned advantageous specific minimum breaking forces.

The combination of these two advantageous minimum parameters leads to a spunbonded nonwoven, which in view of its mechanical properties for a variety of applications suitable is. Such a spunbonded fabric can be used, for example, well in the construction sector, where often attachment of the spunbonded nonwoven webs by nailing, tacking or screwing must be possible. The spunbonded fabric must not tear or tear when it is fastened, for example, on a roof. It is also possible to use these advantageous spunbonded nonwovens as geotextiles. In any case, geotextiles must have a high tolerance for punctual damage, such as may be caused by sharp stones.

In practice, a high specific nail tear resistance is often associated with a good feel. The softness and the textile feel of such spunbonded fabrics therefore also open up applications, for. B. Applications in the hygiene or medical sector. The reason for the good feel is the high mobility of individual fibers, which is regularly associated with the occurrence of high nail pull-out forces. Fibers that behave in this way regularly also have a tactile and pleasant feel. The fiber segment mobility allows fibers to "collect" as the nail moves through the web in the nail by avoiding the nail moving through the web rather than tearing it immediately. This leads to a zone of increased fiber density, ie a zone of increased strength around the nail.

It will be understood that the invention also extends to threads or articles made therefrom having one or a plurality of bicomponent fibers of the aforementioned type. In particular, the invention also relates to a spunbond fabric made from bicomponent fibers according to the invention. A spunbonded nonwoven according to the invention is a structure, in particular a textile fabric, of bicomponent fibers according to the invention, in particular continuous filaments, which have in some way been joined together to form a nonwoven and joined together in some way.

The invention also relates to a process for producing the bicomponent fibers according to the invention and to a process for producing a spunbonded nonwoven fabric from the bicomponent fibers according to the invention.

Advantageously, the two components of the bicomponent fiber are melted separately. The polymer melts thus produced form the starting material for the fibers. It is advantageous to combine the melt streams thus produced only in a spinning plate. In such a spinning plate, the melt streams are extruded through spinnerets into bicomponent fibers. Advantageously, the spinnerets have a hole diameter of 0.1 mm to 10 mm, preferably a hole diameter of 0.2 mm to 5 mm, more preferably a hole diameter of 0.5 mm to 3 mm. Spinnerets whose hole diameter is within the stated preferred ranges have been found to be particularly suitable for the production of bicomponent fibers.

It is advantageous to mechanically stretch the extruded fibers after their extrusion. Preferably, the fibers are peeled off via godets. Godets are special rolls used in the production of synthetic threads and fibers for transporting and / or stretching and / or thermally treating the fibers or threads.

Advantageously, the cooling rate of the fibers can be regulated by the temperature of the godets. Due to the defined cooling rate, in particular during the drawing of the fibers, their mechanical properties can be further improved.

In a likewise advantageous manner, stretching of the fibers is possible by means of an air flow guided along the fiber. Preferably, the cooling rate of the fibers is controlled by the temperature of the air stream and / or the amount of air.

To produce a spunbonded nonwoven, it is advantageous to fluidize the fibers, which are also referred to as filaments in this context, after they have cooled and drawn. The fibers thus receive a random arrangement. In this case, parts of the fibers are reoriented in the machine direction in the transverse direction, so that an overall isotropic nonwoven can be obtained. Subsequently, the fibers can be deposited on a sieve belt.

The layer of fibers produced in this way can then be solidified, preferably thermally. When solidifying the individual fibers are joined together, whereby the actual fleece is formed. The thermal solidification can be carried out by flowing through hot air or steam, in a particularly advantageous manner it is done by calendering. Calendering is understood to mean solidification using hot or heated rolls. Advantageously, the calendering can be done with a smooth and an engraved roller. In this case, the engraved roller is preferably designed so that a proportionate pressing surface of at least 5% and at most 25%, preferably at least 8% and at most 20%, more preferably at least 12% and at most 20%, results due to the engraving of the roller. As a result, the connection of the fibers with each other and thus the mobility of the fibers can be selectively influenced.

Preferably, the temperature of the rollers is at most 70 ° C, preferably at most 50 ° C less than the temperature of the melting point of the component with the lower melting point. These minimum temperatures of the rollers ensure a good connection of the fibers. The contact pressure of the rollers in the nip is advantageously 10 N / mm to 250 N / mm, preferably 25 N / mm to 200 N / mm, particularly preferably 50 N / mm to 150 N / mm. In particular, in combination with the aforementioned advantageous temperatures, it makes sense to adjust the contact pressure in the aforementioned advantageous ranges. It has been found that the connections between the fibers resulting from the use of these parameter combinations result in a spunbonded web having good mechanical properties when the bicomponent fibers according to the invention are used.

The solidification of the fiber layer can alternatively be done mechanically. In this case, the nonwoven can for example be needled or solidified by means of water jet. Another possible advantageous alternative is the chemical hardening of the fiber layer. In this case, a binder, for example by soaking or spraying, applied to the fiber layer. This binder is cured, thereby bonding the fibers to the spunbonded web. The curing of the binder can be done for example by annealing, photo-induced or moisture-induced crosslinking, cooling, evaporation of a solvent or similar measures.

It is expressly understood that the features set forth in the aforementioned separate paragraphs can each be combined in combination with the basic idea of the present invention without necessarily requiring features from further of the aforementioned paragraphs for realizing the invention.

Furthermore, it is expressly pointed out that all the intervals mentioned above and below contain all the intermediate intervals and also individual values contained therein and that these intermediate intervals and individual values are to be regarded as essential to the invention, even if these intermediate intervals or individual values are not specified in detail.

Other features, advantages and applications of the present invention will become apparent from the following description of exemplary embodiments with reference to the drawing and the drawing itself. In this case, all described and / or illustrated features, alone or in any combination, the subject of the present invention, regardless of their Summary in the claims or their dependency.

It shows:

1 a cross-sectional view of an embodiment of a bicomponent fiber according to the invention as a core-sheath fiber,

2 a cross-sectional view of an embodiment of a bicomponent fiber according to the invention as a core-sheath fiber with a thin sheath,

3 a cross-sectional view of another embodiment of a bicomponent fiber according to the invention as core-sheath fiber with eccentrically arranged core,

4 a cross-sectional view of another embodiment of a trilobal bicomponent fiber according to the invention as a core-sheath fiber,

5 a cross-sectional view of another embodiment of a bicomponent fiber according to the invention as a side-by-side fiber,

6 a cross-sectional view of another embodiment of a bicomponent fiber according to the invention as a side-by-side fiber with a low proportion of the second component,

7 Cross-sectional views at various points along another embodiment of a bicomponent fiber as a mixed-type core-sheath fiber and side-by-side fiber,

8th a cross-sectional view of another embodiment of a bicomponent fiber according to the invention as a side-by-side fiber,

9 Cross sections at various points along a further embodiment of a bicomponent fiber according to the invention as a mixed type of a side-by-side fiber and a core-sheath fiber,

10 a cross-sectional view of another embodiment of a trilobal bicomponent fiber according to the invention as a side-by-side fiber,

11 a cross-sectional view of another embodiment of a trilobal bicomponent fiber according to the invention as a side-by-side fiber,

12 a cross-sectional view of another embodiment of a trilobal bicomponent fiber according to the invention as a side-by-side fiber with an alternative arrangement of the components,

13 a cross-sectional view of another embodiment of a tretralobal bicomponent fiber according to the invention as a side-by-side fiber with a component arrangement similar to that in 12 represented fiber,

14 a cross-sectional view of another embodiment of a bicomponent fiber according to the invention as a segmented pie fiber,

15 a cross-sectional view of another embodiment of a bicomponent fiber according to the invention as Iceland-In-The-Sea fiber,

16 a cross-sectional view of another embodiment of a bicomponent fiber according to the invention with a strip-like arrangement of the components, and

17 a part of an exemplary spunbonded nonwoven fabric according to the invention.

The 1 to 16 show cross-sectional views of exemplary bicomponent fibers of the invention 1 , The illustrated bicomponent fibers 1 each have a first component 2 and a second component 3 on. In the in the 1 and 4 illustrated core-sheath fibers surrounds the first component 2 the second component 3 and thus forms the outer surface of the fiber. In this case, in the 1 to 3 shown bicomponent fibers 1 in cross-section one, at least approximately, circular or -round geometry. In the 4 On the other hand, the shown bicomponent fiber shows a trilobal cross section. Such trilobal cross-sections, as well as other multilobal cross-sections, result in the fiber having a larger outer surface in relation to its mass than is the case with circular cross-section fibers. In "core dumbbell fibers" in which the proportion of the cladding component is very small, for example, at about 2%, but also in "core-sheath fibers" with a higher proportion of sheath, it may happen that the sheath Has defects. That is, the sheath does not completely surround the core, but is broken in some places, so that the core at these points also forms the outer surface of the fiber. Also such fibers are "core dumbbell fibers". In particular, in such fibers, the open-shell component within the meaning of the present invention forms the outer surface of the fiber.

The 5 . 6 . 8th and 10 to 13 show bicomponent fibers that are designed as side-by-side fibers. These side-by-side fibers are characterized in that both the first component 2 as well as the second component 3 a part of the outer surface of the bicomponent fiber 1 forms. Even with side-by-side fibers are circular or at least approximately circular cross-sections, as in the 5 . 6 and 8th are as possible as multilobal cross sections, as in the 10 to 13 are shown. Depending on which fiber properties or fleece properties are to be achieved, the first component 2 and the second component 3 be combined in different proportions and in different spatial arrangement to each other. For example, as in the 8th is shown, a component, in the example shown, the second component 3 , are arranged so that they account for only a small proportion of the outer surface of the bicomponent fiber relative to their mass fraction 1 forms. Also, as it can in the 12 and 13 in the case of a multilobal bicomponent fiber 1 a component, in the examples shown, the first component 2 , in particularly exposed areas of the bicomponent fiber 1 be arranged. In the 12 and 13 is the first component 2 at the tips of the multilobal cross section of the bicomponent fiber 1 arranged.

The in the 14 shown bicomponent fiber 1 is designed as a segmented pie fiber. This fiber structure has a relationship to the side-by-side fiber structures in that both the first component 2 as well as the second component 3 a part of the outer surface of the bicomponent fiber 1 forms. The same applies to the in the 16 illustrated structure of the local bicomponent fiber 1 in which the first component 2 and the second component 3 alternated in a layer structure in cross section. The in the 14 and 16 However, as opposed to the "classical" side-by-side structures, the structures shown are common in that they each have a variety of areas that are made up of the first component 2 or the second component 3 are formed.

In contrast, the in 15 shown bicomponent fiber 1 with their islands-in-the-sea structure as a modification of a core-clad fiber, in which a plurality of cores from the second component 3 is available. The individual cores from the second component 3 are from a common coat of the first component 2 surround.

Furthermore, mixed forms between core-sheath fibers and side-by-side fibers are possible, as exemplified in US Pat 7 and 9 are shown. In the 7 shown bicomponent fiber 1 has along the fiber partially cross-sections, in which the first component 2 the second component 3 similar to a core-sheath fiber surrounds and alone the outer surface of the bicomponent 1 forms. At other places along the fiber forms the second component 3 also part of the outer surface of the bicomponent fiber 1 , The first component 2 surrounds the second component 3 not complete in cross section. This also applies to the in the 9 shown bicomponent fiber 1 , this merely shows a different, alternative geometry compared to that in the 7 shown bicomponent fiber 1 on. Also, such mixed forms are referred to as core-sheath fibers in the context of the present application, as long as the first component forms more than 50% of the outer surface of the fiber.

In 17 is shown as a variety of exemplary bicomponent fibers 1 a spunbonded fabric 4 forms. In this case, the spunbonded web forms a web with a transverse direction X, a thickness direction Y and a length direction Z, which is also referred to as the machine direction.

An exemplary spunbonded fabric 4 became from bicomponent fibers 1 prepared, which were thermally consolidated by means of a calender. The bicomponent fibers 1 are core-sheath fibers, with a sheath of the first component 2 with polypropylene as the first polymer and a core of the second component 3 with polypropylene as the second polymer. The basis weight of the spunbonded nonwoven 4 is 70 g / m ² . The mass fraction of the second component 3 on the bicomponent fiber 1 is 80%. The MFI of the first components 2 in the jacket is 30 g / 10 min and the MFI of the second component 3 in the core is 25 g / 10 min. As an additive, the bicomponent fibers 1 a flame retardant (NOR-HALS) on. The additive concentration is 1.5% in the first component and 0.5% in the second component. The fire behavior of the spunbonded nonwoven 4 in a small burner test EN 13501-1 leads to classification in class E.

Another exemplary spunbonded fabric 4 became from bicomponent fibers 1 prepared, which were thermally consolidated by means of a calender. The bicomponent fibers 1 are core-sheath fibers, with a sheath of the first component 2 with polypropylene as the first polymer and a core of the second component 3 with polypropylene as the second polymer. The basis weight of the spunbonded nonwoven 4 is 70 g / m ² . The mass fraction of the second component 3 on the bicomponent fiber 1 is 80%. The MFI of the first components in the jacket is 30 g / 10 min and the MFI of the second component in the core is 25 g / 10 min. As an additive, the bicomponent fibers 1 a flame retardant (NOR-HALS) on. The additive concentration is in the first component 2 3% and in the second component 3 0%. The fire behavior of the spunbonded nonwoven 4 in a small burner test EN 13501-1 leads to classification in class E.

Another exemplary spunbonded fabric 4 became from bicomponent fibers 1 prepared, which were thermally consolidated by means of a calender. The bicomponent fibers 1 are core-sheath fibers, with a sheath of the first component 2 with PET as the first polymer and a core of the second component 3 with PET as the second polymer. The basis weight of the spunbonded nonwoven 4 is 70 g / m ² . The mass fraction of the second component 3 on the bicomponent fiber 1 is 70%. As an additive, the bicomponent fibers 1 an antioxidant (trade name Irganox 1010, manufacturer BASF) on. The additive concentration is in the first component 2 0.15% and in the second component 3 0.04%. When checking the thermal stability of the spunbonded nonwoven 4 achieves the specific breaking strength of the spunbonded fabric 4 after 3 weeks storage at 150 ° C still 54% of the initial value.

Another exemplary spunbonded fabric 4 became from bicomponent fibers 1 prepared, which were thermally consolidated by means of a calender. The bicomponent fibers 1 are core-sheath fibers, with a sheath of the first component 2 with PET as the first polymer and a core of the second component 3 with PET as the second polymer. The basis weight of the spunbonded nonwoven 4 is 70 g / m ² . The mass fraction of the second component 3 on the bicomponent fiber 1 is 70%. As an additive, the bicomponent fibers 1 an antioxidant (trade name Irganox 1010, manufacturer BASF) on. The additive concentration is in the first component 2 0.25% and in the second component 3 0%. When checking the thermal stability of the spunbonded nonwoven 4 achieves the specific breaking strength of the spunbonded fabric 4 after 3 weeks of storage at 150 ° C still 61% of the initial value.

Another exemplary spunbonded fabric 4 became from bicomponent fibers 1 prepared, which were thermally consolidated by means of a calender. The bicomponent fibers 1 are core-sheath fibers, with a sheath of the first component 2 with polyethylene as the first polymer and a core of the second component 3 with polypropylene as the second polymer. The basis weight of the spunbonded nonwoven 4 is 70 g / m ² . The mass fraction of the second component 3 on the bicomponent fiber 1 is 90%. As an additive, the bicomponent fibers 1 a UV stabilizer (trade name Uvinul 5050, manufacturer BASF) on. The additive concentration is in the first component 2 0.4% and in the second component 3 0.23%. When checking the spunbonded fabric 4 In the case of outdoor weathering, in which outdoor samples are oriented at a 30 ° angle to the floor to the south, the specific breaking strength after 16 weeks of outdoor exposure still reaches 59% of their initial value.

Another exemplary spunbonded fabric 4 became from bicomponent fibers 1 prepared, which were thermally consolidated by means of a calender. The bicomponent fibers 1 are core-sheath fibers, with a sheath of the first component 2 with polyethylene as the first polymer and a core of the second component 3 with polypropylene as the second polymer. The basis weight of the spunbonded nonwoven 4 is 70 g / m ² . The mass fraction of the second component 3 on the bicomponent fiber 1 is 90%. As an additive, the bicomponent fibers 1 a UV stabilizer (trade name Uvinul 5050, manufacturer BASF) on. The additive concentration is in the first component 2 0.7% and in the second component 3 0.1%. When checking the spunbonded fabric 4 In the event of UV resistance due to outdoor weathering, in which outdoor samples are oriented at a 30 ° angle to the ground to the south, the specific breaking strength after 16 weeks of outdoor exposure still reaches 72% of their initial value.

LIST OF REFERENCE NUMBERS

1

bicomponent

2

First component

3

Second component

4

spunbond

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5374696 [0026]
• US 5064802 [0026]
• US 4282076 [0030]
• US 5723217 [0030]

Cited non-patent literature

• EN 13501-1 [0014]
• ISO 1133 [0022]
• ISO 1133 [0022]
• EN 12311-1. [0045]
• EN 12310-1 [0048]
• EN 13501-1 [0088]
• EN 13501-1 [0089]

Claims (11)

Bicomponent fiber ( 1 ), in particular for the production of spunbonded nonwovens ( 4 ), with a first component ( 2 ) and a second component ( 3 ), the first component ( 2 ) comprises a first polymer and the second component comprises a second polymer as constituent, characterized in that the first component ( 2 ) has an additive, wherein the mass fraction of the additive in the second component ( 3 ) is smaller than in the first component ( 2 ). A bicomponent fiber according to claim 1, characterized in that the mass fraction of the first component of the bicomponent fiber is less than 50%, preferably less than 25%, more preferably less than 15%, in particular less than 10%, more particularly 5%. Bicomponent fiber according to claim 1 or 2, characterized in that the mass fraction of the additive in the second component ( 3 ) at most 66.6%, preferably at most 50%, in particular at most 33.3%, of the mass fraction of the additive in the first component ( 2 ) is. A bicomponent fiber according to any one of the preceding claims, characterized in that the additive is a primary or secondary antioxidant, a UV absorber, a UV stabilizer, a flame retardant, an antistatic agent, a lubricant, a metal deactivator, a hydrophilizing agent, a hydrophobing agent , an anti-fogging additive, and / or a biocide. A bicomponent fiber according to any one of the preceding claims, characterized in that the additive is selected from the group of: hindered phenols, aromatic secondary or tertiary amines, aminophenols, aromatic nitro or nitroso compounds, organic phosphites or phosphonates, thioethers, thioalcohols, thioesters, sulfides and sulfurous organic acids, dithiocarbamates, thiodipropionates, aminopyrazoles, metal-containing chelates, mercaptobenzimidazoles, hydroxybenzophenones, cinnamates, oxalanilides, salicylates, resorcinol monobenzoates, benzotriazoles, triazines, benzophenones, titanium dioxide, carbon black, metal-containing complexes of organic sulfur or phosphorus compounds, sterically hindered amines (HALS ), Metal hydroxides, borates, organic bromine or chlorine-containing compounds, organic phosphorus compounds, antimony trixoid, melamine, melamine cyanurate, expandable graphite or other intumescent systems, quaternary ammonium salts, Al alkyl sulfates, alkyl sulfates, alkyl phosphates, dithiocarbamates, (alkaline) alkali metal carboxylates, polyethylene glycols and their esters and ethers, ethoxylates, mono- and diglycerides, fatty alcohols, esters of fatty alcohols, fatty acids, fatty acid esters, dicarboxylic acid esters, fatty acid amides, metal salts of fatty acids, polyolefin waxes, natural or artificial Paraffins and their derivatives, fluoropolymers and fluoro-oligomers, antiblocking agents such as silicas, silicones, silicates, calcium carbonate, amides of mono- and dicarboxylic acids and their derivatives, cyclic amides, hydrazones and bishydrazones, hydrazides, hydrazines, melamine and its derivatives, benzotriazoles, aminotriazoles, steric hindered phenols in conjunction with complexing metal compounds, benzyl phosphonates, pyridithiols, thiobisphenol esters, polyglycols, ethoxylates, fluoropolymers, and fluoro oligomers montan waxes, particularly stearates, 10,10'-oxybisphenoxarsine (OBPA), N- (trihalo-met hylthiol) phthalimide, tributyltin oxide, zinc dimethyldithiocarbamate, diphenyl antimony 2-ethylhexanoate, copper 8-hydroxyquinoline, isothiazolones, silver and silver salts as biocides or mixtures thereof. Bicomponent fiber according to one of the preceding claims, characterized in that the difference of the melting points of the first component ( 2 ) and the second component ( 3 ) the difference of the melting points of the first component ( 2 ) and the second component ( 3 ) is less than or equal to 8 ° C, preferably not more than 6 ° C or between 1 ° C to 8 ° C, more preferably between 1 ° C to 6 ° C. A bicomponent fiber according to claim 6, characterized in that the component ( 2 . 3 ) with the lower melting point in the cross-section of the fiber, the outer surface of the bicomponent fiber ( 1 ), preferably the component ( 2 . 3 ) completely surrounds with the higher melting point. Bicomponent fiber according to one of the preceding claims, characterized in that the difference of the melt flow indices of the first component ( 2 ) and the second component ( 3 ) is less than or equal to 25 g / 10 min, preferably less than or equal to 20 g / 10 min, particularly preferably 15 g / 10 min, and that the melt flow indices of the first component ( 2 ) and the second component ( 3 ) are each less than or equal to 50 g / 10 min, preferably less than or equal to 40 g / 10 min, are. Bicomponent fiber according to one of the preceding claims, characterized in that the polymer of one of the two components ( 2 . 3 ) has been polymerized with a metallocene catalyst and that the polymer of the other components ( 2 . 3 ) was polymerized with a Ziegler-Natta catalyst and subjected to a subsequent visbreaking treatment. A bicomponent fiber according to any one of the preceding claims, characterized in that the first polymer and / or the second polymer is a polyolefin or a polyolefin copolymer, preferably a polymer and / or copolymer of ethylene, propylene, butylene, hexene or Octene and / or a mixture and / or a blend thereof. Spunbonded fabric ( 4 ) with at least one bicomponent fiber ( 1 ) according to any one of the preceding claims.

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