WO2013164452A1

WO2013164452A1 - Thermoplastic fibres with reduced surface tension

Info

Publication number: WO2013164452A1
Application number: PCT/EP2013/059259
Authority: WO
Inventors: Jochen Endtner; Wolfram Littek; Matthias Bienmüller; Wolfgang Wambach
Original assignee: Lanxess Deutschland Gmbh
Priority date: 2012-05-04
Filing date: 2013-05-03
Publication date: 2013-11-07
Also published as: JP6290183B2; HUE057122T2; EP2844788B1; EP2844788A1; CN104350188A; JP2015520806A; US20150084231A1; EP2660372A1; KR20150003392A; KR101965471B1

Abstract

The present invention relates to a method for producing thermoplastic fibres with reduced surface tension and to products to be produced from such thermoplastic fibres with reduced surface tension according to the melt-spinning method, wherein the thermoplastic to be used is mixed with a copolymer made of at least one α-olefin and at least one acrylic acid ester or methacrylic acid ester of an aliphatic alcohol.

Description

Thermoplastic fibers with reduced surface tension

The present invention relates to a process for the production of thermoplastic fibers with reduced surface tension and products to be produced from said thermoplastic fibers with reduced surface tension by the melt spinning process, wherein the thermoplastic to be used comprises a copolymer of at least one α-olefin and at least one acrylic ester or methacrylic acid ester of an aliphatic alcohol, preferably a 2-Ehtylhexanols is added.

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, by the fiber material (e.g., 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 in 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. Because of the versatility and the comparison Nonwovens still show high annual growth rates for knitted and woven fabrics with comparatively low production costs.

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

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 nonwoven 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. Nonwovens of continuous materials according to the invention are made of thermoplastic polymers from the group of polyamides or polyesters, e.g. produced by melt spinning as so-called meltblown nonwovens. The process of melt-spinning is described, for example, for polyesters in EP 0 880 988 A1 or EP 1 473 070 A1. Polyester nonwoven fabrics are described in EP 2 090 682 A1 or EP 2 092 921 A1. The use of such nonwovens, produced by the meltblown process, as a filter medium is the subject of EP 0 466 381 B 1.

While relatively low surface tension is present in thermoplastic fibers of polyolefins such as polypropylene or polyethylene fibers due to the intrinsically hydrophobic nature of the polyolefins, even without auxiliaries, higher surface tensions are encountered in more polar thermoplastics, preferably in polyamides and polyesters. This leads to difficulties in many applications in which, on the one hand, one has to rely on low surface tensions, but on the other hand, because of too low temperature or chemical stability of polyolefins, for example, to resort to polymers of higher value such as polyamides or polyesters. This often results in the desire, even more polar thermoplastics, such as polyamides and Polyester, to be modified so 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 thermoplastics fibers to be spinned by the addition of the thermoplastic to be used for this purpose is described with reference to the tensile strength of polyesters in DE 19 937 729 A1. This is done there by addition of a copolyester which contains as monomer units, inter alia, acrylic acid ester or methacrylic acid ester. A similar aspect has WO2005 / 040257 AI, where ethylene alkyl acrylate copolymers are used in polyester films, tapes, and melt spinning fibers to demonstrate their mechanical properties, e.g. to improve the tensile strength. Preferably, copolymer additions above 5% are mentioned there.

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

WO 2009/152349 A1 describes, among other hygiene wipes which are equipped with fluorochemicals based on perfluorinated alkyl groups having up to four carbon atoms as a repellent additive. For example, copolymers of such perfluorinated substances with acrylate esters or methacrylate esters are listed. JP 2003 193331 A describes polyester monofilaments for reinforcing rubbers which are used i.a. are equipped with copolymers of ethylene with glycidyl methacrylate.

WO 2005/087868 A1 discloses ethylene copolymer-modified polyamide products, which products may be melt-spun fibers equipped with E / X / Y copolymers wherein E is ethylene, X and the like. for alkyl acrylate and Y for u.a. Glycidyl acrylate, glycidyl methacrylate or glycidyl vinyl ether.

Finally, WO 2008/083820 A1 discloses soft yarns based on polyamide or polyesters which can be equipped with plasticizer polymers of ethylene alkyl acrylates. Listed are methyl acrylate, ethyl acrylate and butyl acrylate. 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 must also be considered separately with regard to their toxic potentials, for example in the case of incineration.

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, whereby a reduction of the surface tension is achieved with as little material as possible should. 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. Furthermore, the modification to reduce the surface tension should be such that added auxiliaries can be limited due to their effectiveness to an addition amount that does not or not significantly affect the melt spinning process. The fiber thus produced should be able to be further processed in many ways into products, in particular nonwovens, nonwovens, woven, knitted, laid or knitted fabrics with reduced surface tension.

The solution of the object and subject of the present invention is a process for reducing the surface tension of thermoplastic-based fibers, characterized in that at least one E / X copolymer of an α-olefin and a methacrylic acid ester or acrylic acid ester of an unsubstituted aliphatic alcohol, preferably an unsubstituted aliphatic Alcohol having 6-30 carbon atoms, more preferably a 2-ethylhexanol 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 the thermoplastics polyamide or polyester with the present invention to be used E / X copolymer reduces the surface tension of the corresponding thermoplastic fibers and their derivatives with high efficiency and thus, for example, a water-repellent finish of the thermoplastic fibers, preferably the polyamide or Polyester fibers, and their derivatives leads. The effectiveness of the copolymer to be used according to the invention already permits a low concentration strong lowering of the surface tension, so that the melt spinning process is not or not decisively influenced.

For the spinning process, preference is given to mixtures based on from 99.9 to 10 parts by weight, preferably from 99.5 to 40 parts by weight, more preferably from 99.0 to 55 parts by weight, of at least one thermoplastic and

0.1 to 20 parts by wt., Preferably 0.25 to 15 parts by wt., Particularly preferably 0.5 to 10 parts by wt. Very particularly preferably 0.75 to 6 parts by wt., Very particularly preferably 1 , 0 to 2.0 wt .-% of the above-mentioned E / X copolymer 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. Also suitable are blends with proportions of other polymers, preferably blends with polyethylene, polypropylene or ABS, it being possible where appropriate to use one or more compatibilizers. 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 isomeric diamino-dicyclohexylmethanes, 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 thermoplastic polyesters to be spun according to the invention 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, particularly particularly preferably polybutylene terephthalate and polyethylene terephthalate, in particular very particular preference 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 (Kunststoff-Handbuch, 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 propanediol-1 , 3- and / or butanediol-1,4-residues.

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 C atoms or radicals of aliphatic dicarboxylic acids having 4 to 12 C atoms, in particular radicals of phthalic acid, isophthalic acid, naphthalene-2, 6-dicarboxylic acid, 4,4'-diphenyldicarboxylic acid, succinic, adipic, sebacic, azelaic, cyclohexanediacetic, cyclohexanedicarboxylic acid.

The preferred polyalkylene terephthalates, in addition to ethylene or propanediol-1,3- or butanediol-l, 4-glycol radicals up to 20 mol% of> other aliphatic diols having 3 to 12 carbon atoms or cycloaliphatic diols having 6 to 21 Contain C atoms, 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-1,3,1,6,2-ethylhexanediol-1,3 2,2-diethylpropanediol-1,3-hexanediol-2,5,1,4-diol (β-hydroxyethoxy) benzene, 2,2-bis (4-hydroxycyclohexyl) propane, 2,4-dihydroxy-1,1,3,3-tetramethylcyclobutane, 2,2-bis (3-β - Hydroxyethoxyphenyl) propane or 2,2-bis (4-hydroxypropoxyphenyl) propane (DE-A 24 07 674 (= US 4 035 958), DE-A 24 07 776, DE-A 27 15 932 (= US 4 176 224)).

The polyalkylene terephthalates can be branched by incorporation of relatively small amounts of 3- or 4-hydric alcohols or 3- or 4-basic carboxylic acids, as described, for example, in DE-A 19 00 270 (= US Pat. No. 3,692,744). 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. Particular preference is given to 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. 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 phenol / o-dichlorobenzene (1: 1 parts by wt.) 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.

Especially preferred for the melt spinning process to be used polyesters are poly (C ₂ _4-alkylene) terephthalate 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 respectively 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 comprise random E / X copolymers of E at least one α-olefin with X or a methacrylic ester or acrylic acid ester of an unsubstituted aliphatic alcohol. Preferred α-olefins as constituent E of the copolymers preferably have between 2 and 10 carbon atoms. Atoms and can be unsubstituted or substituted with 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 E / X copolymer is between 50 and 90% by weight, preferably between 55 and 75% by weight.

The E / X 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 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 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 unsubstituted alkyl or arylalkyl groups having 6-20 carbon atoms, more preferably having 8-20 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.

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 offered by the company Arkema under the brand name Lotryl® EH, some of which are also used as hot melt adhesives.

Particularly preferred according to the invention therefore is a process for reducing the surface tension of polyester-based fibers or polyamide-based fibers, characterized in that an E / X copolymer of ethylene and an acrylic ester of an unsubstituted aliphatic alcohol having 6 to 30 carbon atoms, preferably from ethylene and ethylene X is an acrylic acid ester having 6 to 20 carbon atoms, more preferably from ethylene and X 2-ethylhexyl acrylate is added to the thermoplastic and then spun the mixture by the melt spinning process.

Particularly preferred according to the invention is therefore a process for reducing the surface tension of polyester-based fibers, characterized in that an E / X copolymer of ethylene and an acrylic ester of an unsubstituted aliphatic alcohol having 6 to 30 carbon atoms, preferably from ethylene and X is an acrylic ester with 6 to 20 carbon atoms, more preferably from E ethylene and X 2-ethylhexyl acrylate is added to the thermoplastic and then spun the mixture by the melt spinning process.

Particularly preferred according to the invention is therefore a process for reducing the surface tension of polyamide-based fibers, characterized in that an E / X copolymer of ethylene and an acrylic acid ester of an unsubstituted aliphatic alcohol having 6 to 30 carbon atoms, preferably from E ethylene and X is an acrylic ester with 6 to 20 carbon atoms, more preferably from E ethylene and X 2-ethylhexyl acrylate is added to the thermoplastic and then spun the mixture by the melt spinning process. The amount of the copolymer to be added to the polyamide or polyester mixture to be processed, for example, by spinning, has already been indicated above, with addition amounts of <6% by weight usually 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 the inventive Thermoplastic copolymer mixtures in amounts of 0.001 to 5.0 wt .-% are added without any disadvantage.

Preferably used dyes are disperse dyes, especially those based on azo dyes or based on very finely divided carbon blacks are preferably microcrystalline anatase having an average particle size [d50] of 0.25 to 0.35μιη, which optionally also with an organic or inorganic surface treatment can be equipped.

Preferred stabilizers to be used are e.g. aromatic polycarbodiimides, e.g. Stabaxol P from Rheinchemie in Mannheim, Germany, but also heat stabilizers based on organically derivatized phosphites.

Preference is given to using antistatics which are preferably finely divided carbon blacks or carbon nanotubes (English: "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-bis-stearylamide 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.

However, the mixing of the individual components can also be carried out directly in the spinning or meltblown apparatus, wherein the components can be introduced physically premixed via a metering point or else 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 term thermoplastic in the context of the present invention is also described with polymer. 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 parameter 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

and the residence time

V ₂ - ε _L 5 _L 60

t

F

in which

F = flow rate of the polymer (g / min)

Inner volume of the empty pipe (cm) R = Empty pipe radius (mm)

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

Nominal density of the polymer blend in the melt (about 1.2 g / cm). 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 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 e.g. a conveyor belt which is designed as a sieve or on a porous drum or on an incoming substrate such. Eg paper. The threads are fixed by suction under the sieve belt. This fiber fabric is a random nonwoven that must be consolidated. The solidification may e.g. by two heated rollers (calender) or by a steam flow. 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 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.

In the meltblown process, the following parameters are typically used: Fiber diameter 0.1 μιη to 20 μιη, preferably 1 to ΙΟμιη 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

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.

It is typical for high-strength filaments made of polyamide or polyester that they are produced by the melt-spinning process in large direct-melt spinning plants in which the melt is distributed via heated product lines to the individual spinning lines and within the lines to 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 is subject in such systems a high thermal load at 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 e.g. <2.0% and in many cases even <1, 5% are sufficient despite high thermal stress.

The nozzle block to be used according to the invention preferably has at least 20, preferably 150 to 1500 and particularly 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 for reducing 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 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.

The present invention additionally relates to products, preferably nonwovens, nonwovens, woven fabrics, knits, fabrics or knitted fabrics, in particular nonwovens or nonwovens obtainable from inventive thermoplastic fibers having reduced surface tension, preferably polyester-based fibers or filaments or polyamide-based fibers or filaments each having a reduced surface tension, which have been additized by at least one copolymer of at least one α-olefin and at least one acrylic acid ester or methacrylic acid ester.

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 on the one hand quantitatively on injection-molded plates, which serve as a model system for more accurate determination of the surface surface tension, and on the other qualitatively produced according to 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 assessment 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 stays longer unchanged for two seconds, repeat the measurement with inks of higher surface tension until the two seconds have been 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 300μιη an average fiber thickness of about Ι μιη 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).

The experiments used:

Component AI: linear polybutylene terephthalate (Pocan® B600, from Lanxess Deutschland GmbH, Leverkusen, Germany) having an intrinsic viscosity of about 69 cffiVg (measured in phenol: 1,2-dichlorobenzene = 1: 1 at 25 ° C.) Component A2: linear polybutylene terephthalate (Pocan ^u B1300, from Lanxess Deutschland GmbH, Leverkusen, Germany) having an intrinsic viscosity of about 94 cffiVg (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 Bl: copolymer of ethene and acrylic acid 2-ethylhexyl ester with an ethene 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]

Table 1 Reduction in surface tension in polyester fibers shown on the model system of an injection molding plate [60 x 40 x 4mm]

Table 2 Reduction of surface tension in polyamide fibers shown on the model system of an injection molding plate [150 x 105 x 1 mm]

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. The examples show that the surface tension can only be reduced to a limit value of 30 mN / m, the value 30 mN / m represents a saturation. In the prior art (component B2 in Comparative Example 5), this limit is only achieved with 6% by weight copolymer of ethylene and butyl acrylate. When using only 3% by weight, the surface tension can only be reduced to 34 mN / m. A comparison of the surface tensions of component Bl and components B2 shows that with component B1, a copolymer of ethylene and 2-ethylhexyl acrylate, a very low surface tension of only 30 mN / m can be achieved even at a low dosage of, for example, 3% by weight.

Table 3 Surface tension reduction on polyester webs

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. Already 1 wt .-% of the component Bl are sufficient to increase the hydrophobicity crucial.

Claims

claims

Process for reducing the surface tension of thermoplastic-based fibers or filaments, characterized in that at least one E / X copolymer of an α-olefin and an acrylic or methacrylic acid ester of an unsubstituted aliphatic alcohol having 6 to 30 carbon atoms is added to the thermoplastic and spun by the melt spinning process, being used as a thermoplastic polyamide or polyester.

A process according to claim 1, 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.

A method according to claim 1, characterized in that are used as polyamides aliphatic polyamides.

A process according to claims 1 to 3, 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 the copolymer.

Process according to claims 1 to 4, characterized in that the α-olefins have between 2 and 10 carbon atoms and can be unsubstituted or substituted by one or more aliphatic, cycloaliphatic or aromatic groups.

A process according to claim 5, 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, as well as mixtures of these a-olefins.

Process according to claims 5 or 6, 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 7, 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 .-% are added.

9. Process according to claims 1 to 8, characterized in that an E / X copolymer of ethylene and an acrylic ester of an unsubstituted aliphatic alcohol having from 6 to 30 carbon atoms, preferably from ethylene and X, an acrylic acid ester having from 6 to 20 Carbon atoms, more preferably from E ethylene and X 2 -ethylhexyl acrylate is added to the thermoplastic.

10. Use of at least one E / X copolymer of an α-olefin and an acrylic 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.