EP2660372A1 - Thermoplastic fibres with reduced surface tension - Google Patents

Abstract

Reducing the surface tension of thermoplastic based fibers or filaments, comprises adding at least one copolymer of at least one alpha -olefin and at least one acrylic ester or methacrylic ester of an aliphatic alcohol to the thermoplastic material, and spinning the copolymer by the melt spinning process. Independent claims are also included for: (1) fibers or filaments with a reduced surface tension which are obtainable by melt-spinning of thermoplastic materials, preferably thermoplastic materials of polyamide or polyester, which are additives with at least one copolymer of at least one alpha -olefin and at least one acrylic ester or methacrylic ester of an aliphatic alcohol; and (2) products, preferably fleece, nonwovens, clothes, woven fabrics or knitted fabric obtained from the thermoplastic materials based on fibers or filaments with a reduced surface tension.

Description

The present invention relates to a process for the production of thermoplastic fibers with reduced surface tension and from these thermoplastic fibers with reduced surface tension produced by the melt spinning process products, wherein the thermoplastic to be used with a copolymer of at least one α-olefin and at least one acrylic acid ester or methacrylic acid ester of an aliphatic alcohol becomes.

Products made of thermoplastic fibers from the group of polyamides or polyesters in the context of the present invention are nonwovens, nonwovens, fabrics, threads, yarns, ropes, felts, knits, scrims or knitted fabrics. Preferred products for the purposes of the present invention are nonwovens or nonwovens. A fleece consists of loosely connected fibers, which are not yet connected to each other. The strength of a fleece is based only on the fiber's own liability. However, this can be influenced by workup. To be able to process and use the fleece, it must be solidified, for which various methods can be used. Only a solidified nonwoven is to be called a nonwoven fabric. In colloquial language, this difference is not made.

Nonwovens are substantially different from woven, knitted, laid and knitted fabrics, which are characterized by the production of certain laying of individual fibers or threads. Nonwovens, on the other hand, consist of fibers whose position can only be described by statistical methods.

The fibers are confused with each other in the nonwoven fabric. The English term nonwoven (not woven) clearly distinguishes it from woven, crocheted , etc. Nonwovens are distinguished, inter alia, according to the fiber material (eg the polymer in man-made fibers), the bonding process, the type of fiber (staple or continuous fibers), the fiber fineness and the fiber orientation. The fibers can be deposited defined in a preferred direction or be completely stochastically oriented as the random nonwoven fabric.

If the fibers do not have a preferred direction of orientation, it is called an isotropic nonwoven fabric. If the fibers are arranged more frequently in one direction than in other directions, then this is called anisotropy.

Nonwovens are thus textile fabrics in which the surface formation does not take place by weaving, knitting, knitting or defined laying, but by depositing the fibers with subsequent fixation. Nonwovens still have high annual growth rates due to their versatility and comparatively low production costs compared to knitted and woven fabrics.

The advantages of these non-woven materials lie in a high specific surface, the production methods allow a high variability in density, fiber strength, pore size or thickness and lead to a broad surface isotropy. From these advantageous properties, numerous uses in medicine for hygiene products, especially surgical drapes, sheets, wound dressings, gauze, etc., arise in the household as wipes of all kinds and as decorative nonwovens, especially tablecloths, napkins, in the clothing industry as a deposit nonwovens, for technical Applications, in particular insulating mats, covering mats or as filter fleeces in the engine / motor vehicle sector (eg oil filters) or as separators / separating fleeces in batteries ( WO 2009/103537 A1 ).

For many of these applications, surface tension plays a significant role, so reducing the surface tension, e.g. lead to a more water-repellent behavior, which can play an important role in particular for applications in the clothing industry, but also in filter fleeces in the automotive sector.

In the production of spunbonded nonwovens, the direct linking of the spinning and web forming process takes place. Both melt and dry spinning processes and wet spinning processes are suitable for nonwoven on the basis of continuous fibers. As the starting material for the nonwoven fabrics, a variety of fiber-forming polymers are known. Inventive nonwovens of continuous materials are produced from thermoplastic polymers from the group of polyamides or polyesters, for example by melt spinning as so-called meltblown nonwovens. The method of melt spinning is used for example for polyester in EP 0 880 988 A1 or EP 1 473 070 A1 described. Nonwoven polyester will be in EP 2 090 682 A1 or EP 2 092 921 A1 described. The use of such nonwoven, produced by the meltblown process, as a filter medium is the subject of EP 0 466 381 B1 ,

While in thermoplastic fibers of polyolefins such as polypropylene or polyethylene fibers due to the intrinsic hydrophobic character of the polyolefins even without auxiliaries is a relatively low surface tension, it is in more polar thermoplastics, preferably in polyamides and polyesters, to do with higher surface tensions. This leads to numerous applications where one hand, on the one hand to low On the other hand, but - because of insufficient temperature or chemical stability of polyolefins - must resort to higher polymers such as polyamides or polyesters, to difficulties. This often results in the desire to also modify more polar thermoplastics, such as polyamides and polyesters to the effect that it achieves lower surface tensions while maintaining the known advantages such as temperature stability, mechanical strength and chemical resistance to fuels and oils.

To influence the properties of thermoplastic fibers to be spinned by the addition of the thermoplastic to be used is exemplified by polyesters in DE 19 937 729 A1 described in terms of tear strength. This is done there by addition of a copolyester which contains as monomer units, inter alia, acrylic acid ester or methacrylic acid ester.

Polyester-based fabrics are provided with oil and water repellency FR-OS 239 746 and US 3,378,609 described by applying to the finished fabric, an aqueous emulsion of a fluorine-containing polymer. The individual polyester fiber will be water repellent EP 0 196 759 A1 in that the polyester fibers are subsequently provided with a polyoxyalkylene glycol and a water-based and oil-repellent fluorine-based agent which essentially do not react with the polyester.

Disadvantage of all these solutions of the prior art is that the resulting in the oil and water repellent behavior change the surface tension are each realized only subsequently in an additional process step by application of excipients to the tissue. Subsequent application to the surface entails, apart from the increased process complexity, also an increased risk of desorption or leaching of the adjuvant, which on the one hand weakens the desired surface effect, but on the other hand can also be associated with problematic contamination of the environment, for example contamination of the filtrate for post-treated filter webs. In addition, it is often necessary to resort to fluorinated chemicals, which are not only very expensive, but also with regard to their toxic potentials, e.g. must be considered separately in the recovery by combustion.

It was therefore an object of the present invention to already modify the polyamide or the polyester in advance in such a way that it is possible to reduce the surface tension even without aftertreatment of the products made from the corresponding thermoplastic fiber. Further, the modification should be free of fluorochemicals, color neutral, and designed so that the process of fiber production per se is not unacceptably compromised. The fiber thus produced should in many ways become products, especially for nonwovens, nonwovens, woven, knitted, laid or knitted fabrics with reduced surface tension and concomitant medienabweisendem behavior can be further processed.

The object of the present invention is a process for reducing the surface tension of thermoplastic-based fibers, which comprises reacting a copolymer of at least one α-olefin with at least one methacrylic acid ester or acrylic acid ester of an aliphatic alcohol, preferably an aliphatic alcohol. 30 carbon atoms added to the thermoplastic and the mixture is then spun, preferably by the melt spinning method.

It has surprisingly been found that the addition of thermoplastics, preferably of thermoplastics based on polyamide or based on polyester, with the copolymer to be used according to the invention significantly reduces the surface tension of the thermoplastics then produced thermoplastic fibers and their derivatives and thus to a media repellent, in particular water-repellent finish of the thermoplastic-based fibers, preferably the polyamide fibers or polyester fibers, and their derivatives leads.

For the spinning process, mixtures based on 99.9 to 10 parts by weight, preferably 99.5 to 40 parts by weight, particularly preferably 99.0 to 55 parts by weight of at least one thermoplastic, are preferred
0.1 to 20 parts by weight, preferably 0.25 to 15 parts by weight, particularly preferably 0.5 to 10 parts by weight, very particularly preferably 0.75 to 6 parts by weight, in particular very particularly preferably 1 , 0 to 2.0 wt .-% of at least one of the above-mentioned copolymers used.

Preferred thermoplastic based fibers are fibers based on thermoplastic polymers from the group of polyamides or polyesters.

Particularly preferred thermoplastic-based fibers from the group of polyamides to be used are fibers based on aliphatic polyamides.

Particularly preferred thermoplastic based fibers from the group of polyesters are fibers based on the polyalkylene terephthalates.

The thermoplastic polyamides to be spun according to the invention can be prepared by various processes and synthesized from very different building blocks. They are used in special applications alone or in combination with processing aids, stabilizers, polymeric alloying partners, in particular elastomers. Are suitable also blends with proportions of other polymers, preferably blends with polyethylene, polypropylene or ABS, wherein optionally one or more compatibilizers can be used. The properties of the polyamides can be improved by adding elastomers, for. B. in view of the tensile strength of z. B. especially low-viscosity polyamides. The multitude of possible combinations enables a very large number of products with different properties.

For the preparation of polyamides, a variety of procedures have become known, depending on the desired end product different monomer units, various chain regulators for setting a desired molecular weight or monomers with reactive groups are used for later intended post-treatments.

The technically relevant processes for the preparation of polyamides usually run via the polycondensation in the melt. In this context, the hydrolytic polymerization of lactams is understood as a polycondensation.

Preferred polyamides (PA) are partially crystalline polyamides which can be prepared starting from diamines and dicarboxylic acids and / or lactams with at least 5 ring members or corresponding amino acids.

Suitable starting materials are aliphatic and / or aromatic dicarboxylic acids such as adipic acid, 2,2,4- and 2,4,4-trimethyladipic acid, azelaic acid, sebacic acid, isophthalic acid, terephthalic acid, aliphatic and / or aromatic diamines such as e.g. Tetramethylenediamine, hexamethylenediamine, 1,9-nonanediamine, 2,2,4- and 2,4,4-trimethylhexamethylenediamine, the diamino-dicyclohexylmethane isomeric diamines, diaminodicyclohexylpropanes, bis-aminomethylcyclohexane, phenylenediamines, xylylenediamines, aminocarboxylic acids, e.g. Aminocaproic acid, or the corresponding lactams into consideration. Copolyamides of several of the monomers mentioned are included.

Particularly preferred are caprolactams, most preferably ε-caprolactam is used.

Especially suitable are most compounds based on PA6, PA66 and other aliphatic or / and aromatic polyamides or copolyamides in which 3 to 11 methylene groups are present on a polyamide group in the polymer chain.

The polyamides prepared according to the invention can also be used in a mixture with other polyamides and / or further polymers.

The polyamides may contain conventional additives such as e.g. Mold release agents, stabilizers and / or flow aids be admixed.

The invention preferred over thermoplastic polyamides to be spun Thermoplastic polyesters are particularly preferably partially aromatic polyesters.

Particularly preferred polyester to be spun are selected from the group of derivatives of the polyalkylene terephthalates. Very particular preference is given to polyesters to be spun selected from the group of polyethylene terephthalates, polytrimethylene terephthalates and polybutylene terephthalates, more preferably polybutylene terephthalate and polyethylene terephthalate, most preferably polybutylene terephthalate, or mixtures of these terephthalates.

Partly aromatic polyesters are understood as meaning materials which, in addition to aromatic moieties, also contain aliphatic moieties.

Polyalkylene terephthalates in the context of the invention are reaction products of aromatic dicarboxylic acids or their reactive derivatives, in particular dimethyl esters or anhydrides, and aliphatic, cycloaliphatic or araliphatic diols and mixtures of these reactants.

Preferred polyalkylene terephthalates can be prepared from terephthalic acid (or its reactive derivatives) and aliphatic or cycloaliphatic diols having 2 to 10 carbon atoms by known methods ( Plastics Handbook, Vol. VIII, p. 695 FF, Karl-Hanser-Verlag, Munich 1973 ).

Preferred polyalkylene terephthalates contain at least 80 mol%, preferably 90 mol%, based on the dicarboxylic acid, terephthalic acid residues and at least 80 mol%, preferably at least 90 mol%, based on the diol component, ethylene glycol and / or 1,3-propanediol and / or butanediol-1,4-radicals.

In addition to terephthalic acid esters, the preferred polyalkylene terephthalates may contain up to 20 mol% of radicals of other aromatic dicarboxylic acids having 8 to 14 carbon atoms or radicals of aliphatic dicarboxylic acids having 4 to 12 carbon atoms, in particular radicals of phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid , 4,4'-diphenyldicarboxylic acid, succinic, adipic, sebacic, azelaic, cyclohexanediacetic, cyclohexanedicarboxylic.

In addition to ethylene or 1,3-propanediol or 1,4-butanediol glycol, the preferred polyalkylene terephthalates may contain up to 20 mol% of other aliphatic diols having 3 to 12 C atoms or cycloaliphatic diols having 6 to 21 C atoms included, in particular. Residues of 1,3-propanediol, 2-ethylpropanediol-1,3, neopentyl glycol, pentanediol-1,5, hexanediol-1,6, cyclohexane-dimethanol-1,4, 3-methylpentanediol-2,4, 2-methylpentanediol 2,4, 2,2,4-trimethylpentanediol-1,3 and -1,6,2-ethylhexanediol-1,3 2,2-diethylpropanediol-1,3, hexanediol-2,5, 1,4-di (β-hydroxyethoxy) benzene, 2,2-bis (4 -hydroxycyclohexyl) -propane, 2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane, 2,2-bis (3-.beta.-hydroxyethoxyphenyl) -propane or 2,2-bis (4-hydroxypropoxyphenyl ) -propane ( DE-A 24 07 674 (= US Pat. No. 4,035,958 ) DE-A 24 07 776 . DE-A 27 15 932 (= US 4,176,224 )).

The polyalkylene terephthalates can be prepared by incorporation of relatively small amounts of 3- or 4-hydric alcohols or 3- or 4-basic carboxylic acids, as described, for example, in US Pat DE-A 19 00 270 (= US-A 3,692,744 ) are branched. Examples of preferred branching agents are trimesic acid, trimellitic acid, trimethylolethane and -propane and pentaerythritol.

It is advisable to use not more than 1 mol% of the branching agent, based on the acid component.

Particularly preferred are polyalkylene terephthalates which are prepared solely from terephthalic acid and its reactive derivatives, in particular their dialkyl esters, and ethylene glycol and / or 1,3-propanediol and / or 1,4-butanediol, in particular polyethylene and polybutylene terephthalate, and mixtures of these polyalkylene terephthalates.

Preferred polyalkylene terephthalates are also copolyesters which are prepared from at least two of the abovementioned acid components and / or from at least two of the abovementioned alcohol components; particularly preferred copolyesters are poly (ethylene glycol / butanediol-1,4) terephthalates.

The polyalkylene terephthalates generally have an intrinsic viscosity of about 0.3 dl / g to 1.5 cm ³ / g, preferably 0.4 dl / g to 1.3 dl / g, particularly preferably 0.5 dl / g 1.0 dl / g each measured in phenovo-dichlorobenzene (1: 1 parts by weight) at 25 ° C.

The thermoplastic polyesters preferably to be spun according to the invention can also be used in a mixture with other polyesters and / or further polymers. Very particular preference is given to using polyethylene terephthalate (PET), polypropylene terephthalate or polybutylene terephthalate (PBT) or mixtures thereof, in particular polybutylene terephthalate.

Furthermore, recycled polyester from post or pre-consumer recycled materials can be used alone or in the mixture, with polyester recyclates from beverage bottles, so-called PET copolyesters, being preferred. An example is the PET Plus80 ^® from. PET plastic recycling GmbH, Beselich-Obertiefenbach, Germany.

Particularly preferred for the melt-spinning process to be used polyesters are poly (C _2-4 -alkylene) terephthalates containing up to 15 mol% of other dicarboxylic acids and / or diols, especially isophthalic acid, adipic acid, diethylene glycol, polyethylene glycol, 1,4-cyclohexanedimethanol, or the each other C _2-4 alkylene glycols. Preferred is polyethylene terephthalate having an intrinsic viscosity (IV) in the range of 0.5 to 1.4 dl / g, polypropylene terephthalate having an IV of 0.7 to 1.6 dl / g or polybutylene terephthalate having an IV of 0.5 to 1 , 8 dl / g, with polyethylene terephthalate having an intrinsic viscosity (IV) in the range of 0.6 to 1.0 dl / g or polybutylene terephthalate having an IV of 0.6 to 0.9 dl / g is particularly preferred.

To reduce the surface tension, the thermoplastics to be spun according to the invention contain random copolymers of at least one α-olefin with at least one methacrylic ester or acrylic acid ester of an aliphatic alcohol. Preferred α-olefins as a constituent of the copolymer preferably have between 2 and 10 carbon atoms and can be unsubstituted or substituted with substituted one or more aliphatic, cycloaliphatic or aromatic groups. Preferred α-olefins are selected from the group comprising ethene, propene, 1-butene, 1-pentene, 1-hexene, 1-octene, 3-methyl-1-pentene. Particularly preferred α-olefins are ethene and propene, most preferably ethene. Also suitable are mixtures of the described α-olefins.

The content of the α-olefin in the copolymer is between 50 and 90% by weight, preferably between 55 and 75% by weight.

The copolymer is further defined by the second component besides the α-olefin. As the second component, alkyl or arylalkyl esters of acrylic acid or methacrylic acid are suitable whose alkyl or arylalkyl group is formed from 5-30 carbon atoms and no or only a low concentration of reactive functions selected from the group comprising epoxides, oxetanes, anhydrides, imides, aziridines , Furans, acids, amines. The alkyl or arylalkyl group may be linear or branched and may contain cycloaliphatic or aromatic groups, but may also be substituted by one or more ether or thioether functions. Suitable methacrylic or acrylic esters in this context are also those synthesized from an alcohol component based on oligoethylene glycol or oligopropylene glycol having only one hydroxyl group and at most 30 carbon atoms.

The alkyl or arylalkyl group of the methacrylic or acrylic ester is preferably selected from the group comprising methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, 1-pentyl, 1-hexyl, 2 Hexyl, 3-hexyl, 1-heptyl, 3-heptyl, 1-octyl, 1- (2-ethyl) hexyl, 1-nonyl, 1-decyl, 1-dodecyl, 1-lauryl or 1-octadecyl. Particularly preferred are alkyl or arylalkyl groups having 6-20 carbon atoms. Branched alkyl groups are particularly preferred which lead to a lower glass transition temperature T _G compared to linear alkyl groups of the same number of carbon atoms.

Particular preference is given according to the invention to copolymers in which the α-olefin is copolymerized with 2-ethylhexyl acrylate or with n-butyl acrylate.

Also suitable are mixtures of the described acrylic acid esters or methacrylic acid esters.

The content of acrylic acid esters or methacrylic acid esters in the copolymer is between 10 and 50% by weight, preferably between 25 and 45% by weight.

Particularly suitable copolymers are selected from the group of materials supplied by Messrs. Arkema under the trade name Lotryl EH ^® or Lotryl ^® BA, which are in part also as a hot melt adhesive use.

The e.g. amount of the copolymer to be added by spinning to be processed polyamide or polyester mixture has already been stated above, with usually addition amounts of ≦ 6% by weight being sufficient. Preferably, the concentration of the copolymer in the range 0.75 to 6.0 wt .-%, depending on the desired take-off speed (> 700-1500 m / min) is chosen so that the birefringence of the fiber <3.5 · 10-3 is. Such birefringence in the fiber allow draw ratios of 1: 5 and ensure the desired high thread strengths regardless of the spinning take-off speed of up to 1500 m / min at Aufspulgeschwindigkeiten of well over 3800 m / min.

Usual additives, preferably dyes, other hydrophobizing agents, matting agents, stabilizers, antistatic agents, lubricants, branching agents, can be added to the thermoplastic-copolymer mixtures according to the invention in amounts of from 0.001 to 5.0% by weight without any disadvantage.

Preferred dyes to be used are disperse dyes, in particular those based on azo dye or those based on very finely divided carbon blacks

Preferably used matting agents are microcrystalline anatase having an average particle size [d50] of 0.25 to 0.35 μm, which may optionally also be provided with an organic or inorganic surface treatment.

Examples of preferred stabilizers are aromatic polycarbodiimides such as Stabaxol P from Rheinchemie in Mannheim, Germany, but also heat stabilizers based on organically derivatized phosphites.

Preferably used antistatic agents are in particular finely divided conductive carbon blacks or carbon nanotubes.

Lubricating agents which are preferably to be used are, in particular, long-chain fatty acids, preferably stearic acid or behenic acid, their salts, preferably Ca or Zn stearate, and also their ester derivatives, and low molecular weight polyethylene or polypropylene waxes. According to the invention, montan waxes are mixtures of straight-chain, saturated carboxylic acids having chain lengths of 28 to 32 carbon atoms. Preferred lubricants and / or mold release agents are compounds from the group of low molecular weight polyethylene waxes and from the group of amides or esters of saturated or unsaturated aliphatic carboxylic acids having 8 to 40 carbon atoms with aliphatic saturated amines or alcohols having 2 to 40 carbon atoms. Ethylene bisstearylamide and pentaerythritol tetrastearate (PETS) are very particularly preferred according to the invention, pentaerythritol tetrastearate (PETS) is particularly particularly preferred.

Preferred branching agents are fusible modified bisphenol-A epichlorohydrin resins, such as e.g. Araldite GY764CH or Araldite GT7071 from Huntsman in Everberg, Belgium.

The mixing of the copolymer to be used according to the invention with the polyamide or with the polyester (= matrix polymer) takes place by compounding, preferably by means of mixing elements in an extruder, using static mixers or by means of other suitable devices which can mix the two or more components together. The melt can optionally be discharged into a strand, cooled and granulated.

Also so-called masterbatch techniques are possible, wherein the copolymer is mixed as a concentrate or pure substance with the polyester granules.

und die Verweilzeit $$\mathrm{t}=\frac{{\mathrm{V}}_2\cdot \epsilon \cdot \delta .60}{\mathrm{F}}$$

wobei

F =

Fördermenge des Polymeren (g/min)

V₂ =

Innenvolumen des Leerrohres (cm³)

R =

Leerrohrradius (mm)

ε =

Leervolumenanteil (bei Sulzer-SMX-Typen 0,84 bis 0,88)

δ =

Nenndichte der Polymermischung in der Schmelze (etwa 1,2 g/cm³).

However, the mixing of the individual components can also be carried out directly in the spinning or meltblown system, wherein the components can be introduced physically premixed via a metering point or separately via a plurality of metering points. Also, the addition to a partial flow of the matrix polymer, which is then mixed into the main stream of the matrix polymer is practicable. Advantageously, a defined distribution is set there by specific choice of the mixer and the duration of the mixing process, before the melt mixture is passed through product distribution lines to the individual spinning stations and spinnerets. Mixers with a shear rate of 16 to 128 sec ^-1 have proven themselves. The product of shear rate (sec ^-1 ) and the power of 0.8 of the residence time (in sec) should preferably be 250 to 2500, particularly preferably 350 to 1250. Values over 2500 are generally avoided to keep the pressure drop in the piping limited. For clarification, it should be noted that the Here, the shear rate is defined by the shear rate in the empty tube (sec ^-1 ) times the mixer factor, wherein the mixer factor is a characteristic characteristic of the mixer type. For Sulzer SMX types, for example, this factor is about 7-8. The shear rate γ in the empty pipe is calculated according to $$\gamma =\frac{4\cdot {10}^3\cdot \mathrm{F}}{\pi \cdot \delta \cdot {\mathrm{R}}^3\cdot 60}\left[{\sec }^{-1}\right]$$

and the residence time $$\mathrm{t}=\frac{{\mathrm{V}}_2\cdot \epsilon \cdot \delta .60}{\mathrm{F}}$$

in which

F =

Flow rate of the polymer (g / min)

V ₂ =

Inner volume of the empty tube (cm ³ )

R =

Empty pipe radius (mm)

ε =

Void volume fraction (for Sulzer SMX types 0.84 to 0.88)

δ =

Nominal density of the polymer blend in the melt (about 1.2 g / cm ³ ).

Both the mixing of the polymers and the subsequent spinning of the polymer mixture takes place at temperatures, depending on the matrix polymer, preferably in the range from 5 to 85 ° C., particularly preferably from 30 to 70 ° C., in each case above the melting temperature of the matrix polymer. For PET, preferably temperatures of 265 to 340 ° C are set, for PA6 and PBT preferably 225 to 300 ° C.

The production of nonwovens from the thermoplastics to be used according to the invention takes place, for example, in a meltblown plant. There, the components are heated in an extruder and brought to a high pressure. The melt is then pressed after optional pre-filtration through a suitable filter package in exact dosage by means of the spinning pumps through a die, the so-called spin bar (Spinerette). The polymer exits the die plate as a fine fiber - also called filament in textile terminology - in molten form. It is cooled by a stream of air and still stretched out of the melt. The air flow conveys the filaments to, for example, a conveyor belt, which is designed as a sieve or on a porous drum or on an incoming substrate such. Eg paper. To be sucked under the sieve belt fixed the threads. This fiber fabric is a random nonwoven that must be consolidated. The solidification can be done for example by two heated rollers (calender) or by a vapor stream. When solidified by a calender, one of the two rolls is usually provided with an engraving consisting of points, short rectangles or diamond-shaped points. At the contact points, the filaments merge to form the nonwoven fabric. Lighter nonwovens can be produced exclusively in this way (thermobonded), heavier nonwovens are produced with a second incorporated low-melting polymer, which is melted in a passage through a so-called fixing oven, the hot melt adhesive and the matrix fibers are usually glued together at their crossing points and thus ensures the desired nonwoven strengths become. A further possibility of solidification is hydroentanglement, in which water jets impinge on the still unconsolidated web with water pressures of up to 400 bar.

• Faserdurchmesser 0,1 µm bis 20 µm, bevorzugt 1 bis 10µm
• Vliesbreite bis zu 5000 - 6000 mm
• Lufttemperatur 230 bis 400 °C, bevorzugt 290° bis 370°C
• Luftgeschwindigkeit 0,5 - 0,8 -fache Schallgeschwindigkeit
• Flächengewicht 8 bis 350 g/m², typischerweise 20 bis 200 g/m²
• Bohrungen im Düsenbalken (Spinnerette) 0 100 to 500 µm mit 1 bis 6 Bohrungen / mm

The meltblown method typically uses the following parameters:

• Fiber diameter 0.1 .mu.m to 20 .mu.m, preferably 1 to 10 .mu.m
• Fleece width up to 5000 - 6000 mm
• Air temperature 230 to 400 ° C, preferably 290 ° to 370 ° C.
• Air speed 0.5 - 0.8 times the speed of sound
• Basis weight 8 to 350 g / m ² , typically 20 to 200 g / m ²
• Drill holes in the nozzle bar (Spinnerette) 0 100 to 500 μm with 1 to 6 holes / mm

The production of high-strength filaments from the thermoplastic-based mixtures to be used according to the invention, preferably the polyamide or polyester mixtures, is preferably carried out by spinning at take-off speeds of> 700 m / min, more preferably 750 to 1000 m / min, and stretching, thermofixing and winding with a appropriate speed. This is done using known spinning devices.

Typical of high-strength filaments made of polyamide or polyester is that they are produced by the melt spinning process in large direct melt spinning plants, in which the melt is distributed over heated product lines on the individual spin lines and within the lines on the individual spinning systems. Here, a spinning line represents a juxtaposition of at least one row of spinning systems, and a spinning system represents the smallest spinning unit with a spinning head containing at least one spinneret pack including spinneret plates. The melt in such systems is subject to high thermal stress Residence times up to 35 min. Due to the high thermal stability of the copolymer, the effectiveness of the copolymer to be used according to the invention for reducing the surface tension does not lead to any appreciable limitations of its action, so that, depending on the desired reduction of the surface tension, small addition amounts of the additive, for example ≦ 2.0% and in many cases even ≤ 1.5% despite high thermal load.

The nozzle block to be used according to the invention preferably has at least 20, preferably 150 to 1500 and more preferably 500 to 1000 nozzle holes per meter of nozzle width. With regard to the diameter of the nozzle holes, diameters of 0.05 to 1 mm and especially of 0.3 to 0.5 mm are preferred.

The nozzle exit velocity is preferably 1 to 20 m / min, but more preferably 3 to 10 m / min. Due to the applied hot flow, the extruded filaments are preferably drawn to 50 to 800 times their length after the nozzle exit, resulting in spinning speeds of up to 10,000 m / min.

The present invention also relates to the use of at least one copolymer of at least one α-olefin and at least one acrylic ester or methacrylic acid ester to reduce the surface tension of thermoplastic-based fibers or filaments, preferably polyester-based fibers or filaments or polyamide-based fibers or filaments, particularly preferably polyester-based fibers or filaments.

The present invention further relates to fibers or filaments having reduced surface tension obtainable by melt-spinning thermoplastic-based fibers or filaments whose thermoplastic before processing to the fiber or filament, preferably before spinning with at least one copolymer of at least one α-olefin and at least one acrylic acid ester or methacrylic acid ester aliphatic alcohol was added.

The present invention furthermore relates to products, preferably nonwovens, nonwovens, woven fabrics, knitted fabrics, fabrics or knitted fabrics, in particular nonwovens or nonwovens obtainable from inventive thermoplastic fibers or filaments with reduced surface tension, preferably polyester-based fibers or filaments or polyamide-based fibers or filaments each with reduced Surface tension, the underlying thermoplastic before spinning by at least one copolymer of at least one α-olefin and at least one acrylic acid ester or methacrylic acid ester was additivated.

For clarification, it should be noted that in the context of the present invention, all the general or preferred definitions and parameters mentioned above are included in any combination.

In general, the surface tension of fibers can be determined by their wettability with liquids of different polarity. A further possibility for determining the surface tension of fiber products produced according to the invention is the consideration of the absorption kinetics of a liquid medium absorbed by the fiber product (for example water or cyclohexane) with the aid of a suitable tensiometer.

Examples

The lowering of the surface tension of the materials according to the invention is shown quantitatively on injection-molded plates, which serve as a model system for more accurate determination of the surface surface tension, and on the other hand qualitatively produced by the meltblown process webs.

Determination of the reduced surface tension on injection molding plates:

For exemplifying the reduction of the surface tension described according to the invention, first of all corresponding plastic molding compounds were prepared by compounding. For this purpose, the individual components were mixed in a twin-screw extruder (ZSK 26 Mega Compounder from Coperion Werner & Pfleiderer (Stuttgart, Germany)) at temperatures between 250 and 285 ° C., discharged as a strand, cooled to granulation capability and granulated. After drying (usually 2-6 h at 80 ° C in a vacuum oven), the processing of the granules to test specimens.

The test specimens (rectangular plates measuring 60 × 40 × 4 mm or 150 × 105 × 1.0 mm) for the tests listed in Tables 1 and 2 were cast on an Arburg 320-210-500 injection molding machine at a melt temperature of about 260 ° C and a mold temperature of about 80 ° C sprayed.

The surface tension of the rectangular plates obtained from the materials produced according to the invention was determined in a simple and reproducible manner according to DIN ISO 8296 with test inks.

The surface tensions according to DIN ISO 8296 can generally not be compared with the values according to ASTM D 2587-84. The values of the surface tension are given in nN / m (= dyn / cm).

The test method is based on the evaluation of the wetting of inks with different surface tension on the polymer surface to be examined. The brush located on the bottle cap is dipped into the test ink, stripped off the edge of the bottle and the ink is immediately applied to the surface to be tested. The stroke length should be at least 100 mm. The behavior of the line edge is evaluated at a length of about 90%, so that slight inhomogeneities are not taken into account. If the ink stroke contracts in less than two seconds, repeat the measurement with a lower surface tension ink until the edges stop for two seconds. If the ink stroke remains unchanged for more than two seconds, the measurement is with Repeat higher surface tension inks until the two seconds are reached. The value indicated on the bottle then corresponds to the surface energy of the test plate. The test shall be carried out in standard climate 23/50, ie at an air temperature of 23 ° C +/- 2 ° C and a relative humidity of 50% +/- 10%.

In the context of the present experiments, test inks of the company Softal Electronic GmbH, (see Softal Report No. 108), Hamburg, Germany, were used.

Determination of the surface tension on nonwovens:

To reduce the surface tension on thermoplastic fibers according to the invention, nonwovens having a basis weight of about 55 g / m ² were produced by means of a meltblown system. In the experiments, the melt temperature was about 275 ° C, the hot air flow about 360 ° C. The ratio of melt throughput and air flow was chosen so that at a nozzle diameter of 300 .mu.m, an average fiber thickness of about 1 .mu.m was obtained. The nonwovens described in the examples and comparative examples differ only in the polymer compositions used in each case, while all other parameters and associated nonwoven characteristics such as basis weight, pore size, fiber orientation and fiber thickness are kept constant for each example and comparative example.

For qualitative evaluation of the surface tension, the nonwoven fabric was subjected to a water drop. A rapid wetting of the water droplet on the nonwoven indicates a high surface tension (hydrophilic behavior), while the retention of the droplet shape on the surface indicates a low surface tension. For further differentiation, the drop was exposed to an air stream. If the drop leaves a trace of a water film, it can be assumed qualitatively of a higher surface tension, the drop moves over the fleece without leaving a visible trace of water, then a lower surface tension can be assumed (see Table 3).

• Komponente A1: Lineares Polybutylenterephthalat (Pocan^® B600, der Fa. Lanxess Deutschland GmbH, Leverkusen, Deutschland) mit einer intrinsischen Viskosität von ca. 69 cm³/g (gemessen in Phenol : 1,2-Dichlorbenzol = 1:1 1 bei 25°C)
• Komponente A2: Lineares Polybutylenterephthalat (Pocan^® B1300, der Fa. Lanxess Deutschland GmbH, Leverkusen, Deutschland) mit einer intrinsischen Viskosität von ca. 94 cm³/g (gemessen in Phenol : 1,2-Dichlorbenzol = 1:1 bei 25°C) Komponente A3: PET Copolymerisat mit einer intrinsichen Viskosität von ca. 80cm³/g (PETplus 80 der PET Kunststoffrecycling GmbH, Beselich-Obertiefenbach, Deutschland)
• Komponente A4: Polyamid 6 (Durethan^® B40F, Fa. Lanxess Deutschland GmbH, Leverkusen, Deutschland)
• Komponente B1: Copolymerisat aus Ethen und Acrylsäure-2-ethylhexylester mit einem Ethen-Anteil von 63 Gew.-% und einem MFI von 550 (Lotryl^® 37 EH 550 der Arkema, Puteaux, Frankreich) [CAS-Nr. 26984-27-0]
• Komponente B2: Lotryl^® 35 BA 320: Copolymerisat aus Ethen und Acrylsäsure-n-butylester mit einem Ethen-Anteil von 65 Gew.-% und einem MFI von 320 (Lotryl^® 35 BA 320 der Arkema, Puteaux, Frankreich) [CAS-Nr. 25750-84-9]

Tabelle 1 Reduzierung der Oberflächenspannung in Polyesterfasern gezeigt am Modellsystem einer Spritzgussplatte [60 x 40 x 4mm] Beispiel Vgl. 1 Bsp. 1 Bsp.2 Vgl. 2 Bsp. 3 Bsp. 4 Bsp. 5 Vgl. 3 Bsp. 6 Vgl. 4 Bsp. 7 Bsp. 8 Komponente A1 [%] 100 99 96 Komponente A2 [%] 100 97 94 94 50 48,5 47 Komponente A3 [%] 100 97 50 48,5 47 Komponente B1 [%] 1 4 3 6 3 3 6 Komponente B2 [%] 6 Oberflächenspannung [mN/m] 38 36 30 40 30 30 30 36 30 36 30 30 Tabelle 2 Reduzierung der Oberflächenspannung in Polyamidfasern gezeigt am Modellsystem einer Spritzgussplatte [150 x 105 x 1mm] Beispiel Vgl. 5 Bsp. 9 Bsp. 10 Komponente A4 [%] 100 99 95 Komponente B1 [%] 1 5 Oberflächenspannung [mN/m] 54 36 <34 The experiments used:

• Component A1: Linear polybutylene terephthalate (Pocan ^® B600, the company Lanxess Germany GmbH, Leverkusen, Germany.) Having an intrinsic viscosity of about 69 cm ³ / g (measured in phenol: 1,2-dichlorobenzene = 1: 1 1 at 25 ° C)
• Component A2: Linear polybutylene terephthalate (Pocan B1300 ^®, the company Lanxess Germany GmbH, Leverkusen, Germany.) Having an intrinsic viscosity of about 94 cm ³ / g (measured in phenol: 1,2-dichlorobenzene = 1: 1 at 25 ° C) Component A3: PET copolymer with an intrinsic viscosity of about 80 cm ³ / g (PETplus 80 of PET Kunststoffrecycling GmbH, Beselich-Obertiefenbach, Germany)
• Component A4: polyamide 6 (Durethan B40F ^®, from Lanxess Germany GmbH, Leverkusen, Germany.)
• Component B1: copolymer of ethene and acrylic acid 2-ethylhexyl ester having an ethylene content of 63 wt .-% and an MFI of 550 (37 Lotryl ^® EH 550 of Arkema, Puteaux, France) [CAS-No. 26984-27-0]
• Component B2: ^® Lotryl 35 BA 320: copolymer of ethene and Acrylsäsure-n-butyl ester with an ethene content of 65 wt .-% and an MFI of 320 ^(® Lotryl 35 BA 320 of Arkema, Puteaux, France) [CAS No. 25750-84-9]

<b><u> Table 1 </ u></b> Surface tension reduction in polyester fibers shown on the model system of an injection molding plate [60 x 40 x 4mm] example See 1 Example 1 Ex.2 See 2 Example 3 Example 4 Example 5 See 3 Example 6 See 4 Example 7 Ex. 8 Component A1 [%] 100 99 96 Component A2 [%] 100 97 94 94 50 48.5 47 Component A3 [%] 100 97 50 48.5 47 Component B1 [%] 1 4 3 6 3 3 6 Component B2 [%] 6 surface tension [MN / m] 38 36 30 40 30 30 30 36 30 36 30 30 example See Fig. 5 Ex. 9 Ex. 10 Component A4 [%] 100 99 95 Component B1 [%] 1 5 surface tension [MN / m] 54 36 <34

A high value stands for a high surface tension and thus for a hydrophilic behavior, while the material becomes increasingly more hydrophobic with decreasing surface tension. <b><u> Table 3 </ u></b> Reducing Surface Tension on Polyester Webs example See 1 Example 1 Ex.2 Component A1 [%] 100 99 96 Component B1 [%] 1 4 Behavior of a drop of water on the fleece Drop wets the surface and spreads there Drops hardly wet the surface and remains as a nearly spherical drop Drops hardly wet the surface and remains as a nearly spherical drop Behavior of a water drop on the fleece after exposure to an air flow. Drops wet the surface so much that it can not practically be blown off Drops can be blown away, but leaves a highly visible trace of water. Drops can be blown away without leaving any visible water residue on the fleece surface. The strongly decreasing adhesion of the water drop with increasing concentration of component B1 is a measure of the strongly decreasing wettability of the nonwoven with water and thus indicates the reduction of the surface tension in the polyester fibers used for the nonwoven.

Claims (12)

Process for reducing the surface tension of thermoplastic-based fibers or filaments, characterized in that at least one copolymer of at least one α-olefin and at least one acrylic acid ester or methacrylic acid ester of an aliphatic alcohol is added to the thermoplastic and this is spun by the melt spinning process. A method according to claim 1, characterized in that the polyamide or polyester is used as a thermoplastic. A process according to claims 1 or 2, characterized in that the polyesters used are polyalkylene terephthalates, preferably polyethylene terephthalates, polytrimethylene terephthalates or polybutylene terephthalates, particularly preferably polybutylene terephthalate and polyethylene terephthalate, in particular very particular preference polybutylene terephthalate, or mixtures of these terephthalates. Process according to claims 1 or 2, characterized in that aliphatic polyamides are used as polyamides. A process according to claims 1 to 4, characterized in that mixtures are used for spinning on the basis of 99.9 to 10 parts by weight of at least one thermoplastic and 0.1 to 20 parts by weight of at least one copolymer. Process according to claims 1 to 5, characterized in that the α-olefins have between 2 and 10 carbon atoms and may be unsubstituted or substituted by one or more aliphatic, cycloaliphatic or aromatic groups. A process according to claim 6, characterized in that α-olefins are selected from the group comprising ethene, propene, 1-butene, 1-pentene, 1-hexene, 1-octene, 3-methyl-1-pentene, preferred α-olefins are ethene and propene, most preferably ethene, and mixtures of these α-olefins. Process according to claims 6 or 7, characterized in that the content of the α-olefin in the copolymer is between 50 and 90% by weight, preferably between 55 and 75% by weight. A process according to claims 1 to 8, characterized in that conventional additives, preferably dyes, further hydrophobizing agents, matting agents, stabilizers, antistatic agents, lubricants, branching agents, the thermoplastic copolymer mixture in amounts of 0.001 to 5.0 wt .-% added become. Use of at least one copolymer of at least one α-olefin and at least one acrylic acid ester or methacrylic acid ester for reducing the surface tension of fibers or filaments based on thermoplastics, preferably based on thermoplastics from the group of polyamides or polyesters. Fibers or filaments with reduced surface tension obtainable by melt spinning of thermoplastics, preferably thermoplastics from the group of polyamides or polyesters, which are additized with at least one copolymer of at least one α-olefin and at least one acrylic acid ester or methacrylic acid ester of an aliphatic alcohol. Products, preferably nonwovens, nonwovens, woven, knitted or knitted fabrics, obtainable from the thermoplastic-based fibers or filaments with reduced surface tension according to claim 11.