EP1094137B1 - Polyester fibres with reduced tendency to pilling formation and method for producing them - Google Patents

Description

The present invention relates to so-called pilling-resistant or low-pill polyester fibers, especially low-pill types with a greatly reduced tendency to pilling. The The invention further relates to a method for producing the aforementioned polyester staple fibers with reduced tendency to pilling.

Resistance to buckling is usually used to characterize the pilling behavior of fibers determined in the so-called wire scrub test. In doing so, individual Moving fibers back and forth over a thin wire under defined tension i.e. scrubbed until they break. Since the wire diameter is of the order of one Fiber diameter (20 - 40 µm) results in a strong bending stress combined with a grinding effect (see also "Textile tests" by Stefan Kleinheinz, June 1991, 4th edition, Akzo Fiber Division. Wuppertal; US Patent 5,858,529, Column 3, lines 54 to 65). Conventional polyethylene terephthalate fibers that are not are pilling resistant, usually have wire scrubbing tours of 3000 to 5000, while low-pill fibers reach values of <2000.

Polyester fibers are used for the manufacture of garments such as suits, Shirts or sweaters are advantageous because they have excellent wearing properties, Characterize dimensional stability, crease recovery and no ironing.

The high strength and good abrasion resistance of those made from these fibers However, textiles cause the garments to form during use tend to pills. In the case of textiles, the term pilling reduces the formation Understood fiber bales, i.e. of nodules or pills on the surface of the Garment. They arise from the fact that the surface of the garment protruding fiber ends or loose fiber parts tangle, and due to the high The strength of the fibers does not fall off and stick to the surface. This will the appearance of the clothing is severely impaired and the usability significantly restricted (see also DE-A-27 13 508).

There is therefore a need to be used in the manufacture of clothing Modify polyester staple fibers so that they have only a low tendency to pilling or pilling is almost completely avoided.

In order to eliminate or reduce the pilling or tendency to pilling, numerous procedures proposed.

A known method is to use a low molecular weight polyester, i.e. low solution viscosity (relative viscosity) to spin. The use of Glycol as an additive in the spinning extruder is described, for example, in US Pat. No. 4,359,557. By reducing the strength, the abrasion and bending resistance and thus the lifespan of the pills is significantly reduced. The connection between the Number average molecular weight of a polyester and resistance to buckling the fibers are approximately linear (Melliand Textilber. 1970, p. 181; chemical fibers + text. Application technology. Text.-Ind. 23 (1973), p. 811). In practice with this method Achievable effect of reducing the tendency to pilling by reducing the molecular weight can only be used to a limited extent. To get pill-free polyester fibers, the melt viscosity would have to be reduced so much that melt spinning of Threads are no longer possible (see International Textile Practice, April 1984, page 374). Therefore, this measure described above cannot turn into pill-free textiles Lead polyester fibers. An object of the invention was therefore to add additives which reduce the tendency to pilling without reducing the melt viscosity of the polyester to belittle too much.

Another known way of producing low-pill polyester fibers is by condensing of branching components. The polyester is included polyvalent carboxylic acids or alcohols, e.g. Trimethylolpropane (textile practice International 1993, p.29; DE-OS-2 046 121), pentaerythritol (Canad. Pat. No. 901716) or other branching agents modified. This chemical modification can while maintaining a high weight average molecular weight due to high melt viscosity the length of the macromolecules can be reduced what a reduction in the abrasion and bending resistance of the fibers and thus a Reduction in the tendency to pilling. The use of branching agents is described in a number of patents, such as FR-A-1 603 030. With these processes, however, there are considerable problems with regard to spinning safety, which are expressed, among other things, in short nozzle service lives. Problems continue to arise insufficient spinning cleanliness, which can be seen in further processing in the converter train disruptive. The production of low-pill fibers with fine titers in the range <3 dtex was therefore for the reasons described with the chemically modified So far, polyesters have only been possible with great difficulty.

Another known possibility is to add the polyester to the polymer chain special chemical bonds, mostly -Si-O- (hereinafter referred to as SiO bonds), to be installed, which are resistant to spinning and only in the later treatment be hydrolyzed in the presence of water or steam. This approach allows polyester with a necessary for melt spinning and good manufacture melt melt viscosity, the reduction of Molecular weight with the resulting reduction in the pilling tendency only after Spinning is done by hydrolysis. In a number of patents Condensing of di- and / or polyvalent Si-containing additives during the Polyester production described, using organic silicon compounds as modifiers, such as tetraethyl silicate or esters of silanetriol phosphoric acid be used.

US-A-3,335,211 describes the production of polyester staple fibers with improved Pilling resistance, whereby one of anhydrous polyethylene terephthalate with a Melt viscosity starts from 100 - 600 Pas (at 275 ° C), which 0.10 to 0.75 g Contains Si atoms per mole of glycol. Silicate esters, such as tetraethyl silicate, which in Glycol are dissolved, are condensed into the polymer chain. EP-A-0 262 824 also recommends the modification of polyester fibers with the help of tetraethyl silicate followed by treatment in the presence of water.

DE-A-17 20 647 also recommends esters and / or salts of compounds such as Silanetriolethanphosphonsäure and especially of trimethoxysilanethanephosphonsäurediethylester condense into the polyester chain.

DE-A-27 13 508 and DE-A-24 53 231 recommend 0.008 to 2% by weight of diphenylsilanediol, based on dimethyl terephthalate, as a co-component in the polyethylene terephthalate einzukondensieren.

DE-A-41 11 066 describes a process for producing SiO groups modified polyethylene terephthalate according to the continuous direct esterification process described starting from terephthalic acid. Here, methoxyethyl or Propyl silicate added in such an amount that 300 to 700 ppm in the polymer Silicon content results. This happens continuously during the polycondensation by introducing methoxyethyl silicate or propyl silicate at a time when the prepolymer has a weight average molecular weight between 9,000 and 16,000 g / mol and has a polydispersity index between 1.5 and 2, and which it is a temperature between 260 and 290 ° C and under a pressure between 1.5 and 2.5 bar located. The duration of the reaction between silicate and prepolymer is at least 5 min.

Commercially available pill-free fibers are made according to the process described Condensation of hydrolysis-sensitive silicon compounds during polycondensation manufactured. Because of the sensitivity to hydrolysis was in practice So far almost exclusively the transesterification process was one of the continuous processes starting from dimethyl terephthalate, while the use of direct esterification process more widely used today for the purpose described is extremely difficult due to the water generated during the esterification. The There are other problems associated with the manufacturing process. To a certain level of melt viscosity of the polyester and in the finished fiber to obtain a relative final viscosity reduced by a certain amount, the Polyester set to a defined degree of polymerization before spinning and at the same time a defined number of hydrolysis sensitive SiO bonds in the Polyester can be installed. The number of SiO bonds condensed in based on the The number of macromolecules determines the degradation of the relative viscosity after Spinning. This requires a very exact management of the process parameters and one precise control of the amount of modifier added during polyester production. In addition, the polyester must be kept absolutely water-free before spinning. The Polyesters containing SiO bonds can therefore often only be produced using the direct spinning process (i.e. without intermediate granulation), or an additional one must be processed specific work step can be applied.

An alternative route is set out in US 5,858,529. There is a polyester fiber with high pilling resistance is described, in which a polyester with 1-7 wt special polyalkylene glycol block copolymer with hydrophobic polyoxypropylene core and chemically modified polyoxyethylene groups adhering to the core. The procedure to produce the staple fibers is the mixture of the normal polyester with the Block copolymers before spinning.

A disadvantage of all the methods described above is that they are either a special one Modification of the polyester or special post-treatment processes of the fiber or of the tissue.

The chemical modification of the polyester described above with, for example Trimethylolpropane, pentaerythritol, ethylene oxide-propylene oxide block copolymers or the Incorporation of SiO bonds in the polymer chain have the additional disadvantage that the chemical modifiers added during or before the polyester condensation Need to become. This will contaminate the reactors with the modifiers. Therefore, the production line cannot easily manufacture other types of polyester be used. For large-scale continuous polycondensation systems like this are common today for polyester production (up to 600 t / d) Operating mode not economical, because changing the recipe too much there is no usable transition material.

One way to influence the pilling behavior of polyester without chemical Modification during the polymerization process is preceded by the addition of additives or in the spinning process. So silicone oils, e.g. Polydimethyl or Polymethylphenylsiloxane, used as additives to the polymer in the spinning process (see Textilpraxis International, April 1984, pages 374, 375). In the above Publication were the polysiloxanes (viscosity range 100 to 500 mPas, at 20 ° C) in an amount of 0.1-2% by weight into the feed hopper of a melt extruder commercial matted polyester granules metered, and this mixture was at Nozzle temperatures of 290 to 295 ° C extruded and spun. there has been a Significant reduction in the resistance to kinking was observed. As the cause of this it is stated that the modified PES single fiber due to the buckling abrasion spliced into individual fibrils. This splitting leads to a premature one Fracture of the individual fibrils. Because silicone oils are stored as inert substances in the polyester matrix the textile mechanical properties change only insignificantly. The Elongation at break, tensile strength at break and the initial modulus of these fibers remained almost unchanged unaffected. Measurements on polyester / polysiloxane mixtures (with up to 1.8% by weight Polysiloxane) showed a reduction of compared to pure polyester melts less than <5% in melt viscosity.

DD 104 089 describes that the addition of silicone resins (methyl-phenyl-polysiloxanes) with molar masses <4000 g / mol to increase the melt viscosity leads what should allow the trouble-free spinning of low molecular weight polyester and thereby the production of low-pill polyester fibers at a DST level of approx. 900 allows. DD 104 089 describes silicone resins with several esterifiable substances OH groups added in the polycondensation, which leads to the formation of branched Structures and thus an increase in the weight average molecular weight of the Leads macromolecules. The effect of reducing the pilling tendency described in DD 104 089 is therefore on the effects already described above during the introduction branched modification agents attributable.

Polysiloxanes without OH groups capable of esterification have the considerable disadvantage that that they are purely inert additives in the course of further processing on the fiber surface can migrate and interfere with the dyeing process, for example impact. In addition, washing out the additive and thus losing the Antipillig effect cannot be prevented. Ramifications through use polyfunctional silicone oils (i.e. with more than 2 esterifiable OH groups) have an adverse effect, since branching devices, as described above, cause problems with regard to of spinning security and spinning cleanliness.

Another well-known additive for polyester is silicon dioxide, which has not yet been described as a means of reducing the tendency to pilling without further measures. In practice, synthetic SiO ₂ powder is usually used for thixotropy, as a dispersant, thickener (increase in melt viscosity) and antiblocking agent (for films).

According to DE-A-29 09 188 silicon dioxide or colloidal silica particles with a diameter of 1 to 100 nm can be incorporated in polyester in order to Fix unevenness in the spun polyester fiber.

According to JP-A-55 112-313, silicon dioxide (silica; particle size ≤80 nm) in Amounts of 0.5 to 10 wt .-% are used, whereby the pilling tendency of special co-polyester fibers in which 0.1-10% of the ester bonds are phosphoric acid esters are reduced. With this special procedure, however, an aftertreatment of the Polyester fiber with hot water, steam and / or a solvent required.

In the patents DE 1 237 727 and DD 104 089 the use of colloidal Silicon dioxide in the form of a suspension described as an additive in the polycondensation. With complete exclusion of moisture until spinning is a result Melt viscosity increase described. Here too is analogous to that described above Process of chemical modification with the incorporation of hydrolytically cleavable SiO bonds aftertreatment of polyester fiber with hot water in polyester, Steam and / or a solvent as described.

In no process described so far, SiO ₂ powder is added directly to the polyester melt or, alternatively, to the polyester granulate without the exclusion of moisture, in order thereby to obtain low-pill polyester fibers. The use of SiO ₂ powder in pure form for the modification of standard polyester with the aim of reducing the tendency to pilling is described for the first time in the present invention. The use of SiO ₂ of the Aerosil® type described in DE-A-4041042 was used exclusively for the purpose of increasing the spinning speed in POY spinning.

The object of the invention is an economical process for the production of low pill or pill-free polyester fibers, in particular commercially available Standard polyesters, especially those based on terephthalic acid and ethylene glycol, by adding small amounts of suitable additives during the spinning process are to be modified in an advantageous manner so that the spun from it Polyester fibers are largely pill-free. The manufacturing process of the fiber is said to be deviate only slightly from the usual procedure, i.e. such fibers are said to easily with the usual machine equipment of a fiber manufacturer can be produced.

The object is achieved according to the invention by providing pill-resistant or low-pill polyester fibers, especially fibers of high-pillar type (with strong reduced pilling tendency) according to claim 1 and their production according Claim 14. The polyester fibers according to the invention with a reduced tendency to pilling have the composition defined in claim 1. Essential here is that by using three modifiers in combination in unexpected resistance to pilling can be significantly improved.

1. ein Diol, aus der Gruppe Ethylenglykol, Diethylenglykol und Triethylenglykol,

2. Siliconöl, und

3. Siliciumdioxid- oder Kieselsäure-Pulver.

The three additives to be used together with the standard polyester according to the invention are:

1. a diol from the group consisting of ethylene glycol, diethylene glycol and triethylene glycol,

2. silicone oil, and

3. Silicon dioxide or silica powder.

The Trevira®350 fiber can be seen as a benchmark for an anti-pilling fiber. The quality level of Trevira®350 fiber with regard to resistance to pilling, which is below 700 DST values, was achieved for the first time in an advantageous and economical way simply by adding additives to standard polyester. This indicates different mechanisms of action of the additives silicone oil and SiO ₂ , which therefore achieve a synergistic effect. In this way, according to the invention, a low-pill DST level was achieved both with a titer of 2.4 dtex and with the finer titer 1.7 dtex, as shown in Table 1 (Examples 16 and 18 from Table 5 below): Fineness (titer) 2.35 dtex 1.69 dtex strength 2.92 cN / dtex 2.90 cN / dtex strain 52% 48% DST 618 696

Extensive spinning tests have shown that the addition of the above additives 1 to 3 to commercially available standard polyester, neither on their own, still with a combination of 1. with 2. or 1. with 3. to high-pillar polyester fibers leads with DST <700. With these additive combinations not described in the prior art can be justified economically and with regard to spinning security Additive amounts only reduce the tendency to pilling of the polyester fibers up to a DST level of around 1000 can be achieved.

With ethylene glycol as the only additive, there is an improvement in pilling resistance to DST values of maximum 1200 possible, considering the limit of spinnability reached. The DST value depends on the amount of ethylene glycol (EG) introduced approximately linear from (Fig. 1).

A number of silicone oils are known, primarily as lubricants and lubricants Find use. Common silicone oils are e.g. Polydialkylsiloxanes, polydiarylsiloxanes and Polyalkylarylsiloxanes. In the present invention, these are silicone oils preferably polydimethylsiloxane, e.g. Baysilon®M1000. Preferred are further Silicone oils with terminal esterifiable hydroxyl groups, especially preferably polydimethylsiloxanes with terminal esterifiable OH groups.

In the present invention, in order to exclude cross-links, it is preferred Variant silicone oil, preferably polydimethysiloxane, with two esterifiable OH groups, particularly preferably used with two terminal OH groups. On Silicone oil of this type is Struktol®Polydis3999, a dihydroxy-terminated polydimethylsiloxane by Schill & Seilacher, Hamburg. The examples shown in Fig. 2 set the increased effect of this silicone oil on the pilling resistance of the polyester fiber in the Comparison to the use of a polydimethysiloxane without OH groups Struktol® silicone oil was also added compared to other silicone oil types achieved an improvement in spinning security and spinning cleanliness. Furthermore was found that when using silicone oils alone or together with glycol as an addition to the polyester, the effect on the tendency to pilling and the DST value increasing amount of silicone oil decreases drastically (Fig. 2).

With silicone oil of the type particularly preferred according to the invention, e.g. Struktol®, can with simultaneous degradation of the polyester with ethylene glycol wire scrubbing tours (DST values) in the range of 1000 can be achieved (see FIG. 2). This only through large The level of additives that can be achieved does not yet meet the requirements of one low-pill fiber. Even at the highest addition amounts of Struktol® together with 0.1% by weight ethylene glycol do not achieve DST values below about 900.

Analogous to the correlation between the DST value and the amount of silicone oil added, it was also observed when using SiO ₂ as an additive that the effect on the DST values flattened significantly with the amount used and could not be further increased by higher concentrations. Even with ethylene glycol together with the highest amount of SiO2 realized in FIG. 3, the level of the DST values is not less than approx. 1000. This level, which can only be achieved by large amounts of SiO ₂ , does not yet meet the requirements of a low-pill fiber. The use of large amounts of SiO ₂ has the disadvantage that it is difficult to incorporate large amounts in the necessary finely divided form into the polyester. This can lead to increased pressure build-up on the spinneret and thus to shorter nozzle life or problems with spinneret clogging. It is therefore preferred according to the invention to keep the amount of SiO ₂ below 1% by weight, preferably in the range between 0.05 and 0.3% by weight, and for very good incorporation of the SiO ₂ powder into the To ensure polyester through appropriate mixing elements.

It could thus be found that the correlation of the DST value with the SiO ₂ content or the silicone oil content when dosed alone to the polyester and also with the simultaneous addition of glycol is not linear. In the case of the additive combinations EG and SiO ₂ as well as EG and silicone oil, the same basic relationship between the amount used and the effect on the DST value was observed. Above a certain content of the additives in the fiber, their effect on the DST value is very small with further increases (FIGS. 2 and 3). Achieving a DST level with values below 1000 is only possible with large amounts of SiO ₂ (and EG) or silicone oil (and EG), which in the first case leads to a deterioration in the spinning properties and further processing, and in both cases to a disproportionate amount Would increase the price of the product.

The above object is further achieved by the method according to the invention Production of these polyester fibers with reduced tendency to pilling according to claim 14 solved. The invention therefore also relates to a method in which the production homo- or copolyesters commonly used by normal textile fibers suitable introduction of modifiers into the polyester melt or suitable Application of the additives to the dry granulate before melting in one Extruder, is modified so that a low-pill or pill-free polyester fiber results. For The term "late addition technology" was also introduced for such a process (see US-A-5,858,529).

The first additive: The polyester fibers of the invention typically have one relative viscosity from 1.37 to 1.58, preferably from 1.40 to 1.55, particularly preferred from 1.42 to 1.48 (1% in m-cresol). For the sake of better spinning performance one goes according to the invention from higher molecular weight polyester, for example with a relative viscosity RV = 1.65, which is obtained by adding a diol such as ethylene glycol, Diethylene glycol or triethylene glycol, to the desired relative viscosity of the fiber is broken down. A corresponding one is used for the respective degradation of the polyester required amount of the aliphatic or alicyclic diol used. With ethylene glycol Depending on the initial viscosity of the polyester, the amounts used are usually in Range between 0.03 and 0.28% by weight. The diol is used when granules are used in the Extruder feed zone or metered into the melt line during direct spinning. In a particularly preferred embodiment of the invention is ethylene glycol (EG) as the diol used.

According to the invention, in addition to the diol used, the polyester is as follows 2. and 3. Additive components added:

For the second additive: addition of 0.003 to 2.0% by weight, preferably 0.05 to 0.5% by weight, of a silicone oil, based on the mass of the polyester used. A commercially available silicone oil without ester groups capable of esterification is, for example, Baysilon® M 1000 from Bayer with a dynamic viscosity of 1400 mPas at 20 ° C. In order to be able to use silicone oils particularly advantageously in practice to reduce the tendency to pilling in polyester fibers, as described above, silicone oil with two terminally esterifiable OH groups is preferably used in the present invention. A dihydroxy-terminated polydimethylsiloxane with terminal OH groups with the formula: HO- [Si-O (CH ₃ ) ₂ ] _n -OH with n = 8-60, particularly preferably with n = 40.
(n = average of the repeating monomer units)

The polymer degradation caused by the addition of such a silicone oil is negligible low. By esterifying at least part of the esterifiable Hydroxyl groups with the polymer matrix is achieved in that it is too pure Do not migrate inert polysiloxanes to the surface during further processing and have no disruptive effect, for example on the coloring of the fibers. Also the This eliminates the risk of washing out the additives.

An example of a particularly preferred commercially available silicone oil with terminal esterifiable OH groups is Struktol® Polydis 3999 from Schill & Seilacher, D-Hamburg, with a degree of polymerization n = 40 and a dynamic viscosity of 82 mPas at 20 ° C. Surprisingly, by adding this silicone oil, the Spinning performance, i.e. spinning security and spinning cleanliness are significantly improved (compared to spinning tests without the use of Struktol®). This indicates that this silicone oil has an excellent internal effect Exerts lubricant. The high spinning delay, i.e. the ratio between the take-off godet speed and the exit velocity from the nozzle bore with a high probability to a particularly advantageous fibril-like Arrangement of the low molecular weight silicone oil type Struktol® within the fiber, whereby a splicing of the individual fibrils of the fibers is particularly promoted, which leads to the leads to a particularly marked improvement in resistance to pilling.

For the 3rd additive: addition of 0.003 to 1.0% by weight, preferably 0.05 to 0.3% by weight, finely dispersed SiO ₂ powder, with primary particle sizes of <30 μm. These are synthetic, porous SiO ₂ powders, which are produced either by pyrogenic processes (flame hydrolysis, electric arc, plasma) or by wet processes (precipitated silicas, silica gels). Fumed silica with a primary particle size of <100 nm is particularly preferred.

A particularly preferred commercially available product is, for example, Aerosil®200, or Aerosil® 300, or Aerosil®130 from Degussa, Frankfurt, which is produced by flame hydrolysis. Another commercial product is Syloid® from Grace, a micronized synthetic silica (average primary particle size 3-4 µm). The mode of action of SiO ₂ in the present invention is not, as described and used so far, an increase in the melt viscosity, but rather the formation of predetermined breaking points within the fiber, which lead to breakage under tensile and torsional stress.

Alternatively, a masterbatch with 1-20% by weight SiO ₂ , preferably 5-15% by weight, can also be used. The masterbatch and the additives are advantageously metered into the extruder or into the polyester melt using suitable devices, or are added to the granulate in advance.

The SiO ₂ powder can be added to the PET, for example, using the so-called "melt conditioning" process for the continuous modification of polyester melts (DE 40 39 857 C2). According to the "melt conditioning" process, part of the melt, which can come directly from the polycondensation or from a melt, is branched off from the main melt stream. This partial stream is fed into a side-stream extruder, where it is charged with the SiO ₂ additive and then dispersed. The dispersed and mixed melt concentrate is then fed into the main melt line and there diluted to the final concentration using a static mixer. Silicone oil and ethylene glycol are added in liquid form. The two liquid additives can be metered into the main melt line before the static mixer.

Furthermore, it is also possible, if one starts directly from standard PET granules and melts them in a spinning extruder, to meter the SiO ₂ powder as well as the silicone oil and ethylene glycol directly into the PET granules into the spinning extruder, where the additives are mixed with the polyethylene terephthalate and then spin the mixture.

As already stated above, the additive or the additive combination according to the invention can both as a pure substance or mixture of substances and also in Masterbatch form can be added. In addition, other additives can also be used and additives are incorporated and spun. The polyethylene terephthalate itself can also use conventional additives such as matting agents (titanium dioxide), stabilizers, Contain catalysts etc. In the present application one understands "Polyethylene terephthalate" (PET) or "polyester" polyester which is at least 90 mol% Contain polyethylene terephthalate units and a maximum of 10 mol% units by a diol other than ethylene glycol, such as diethylene glycol, Tetramethylene glycol or a dicarboxylic acid other than terephthalic acid, for example Isophthalic acid, hexahydroterephthalic acid, dibenzoic acid are derived.

You can optionally with small amounts of polyethylene terephthalate branching agents already mentioned above, such as trimethylolpropane, trimethylolethane, Pentaerythritol, glycerol, trimesic acid, trimelitic acid or pyromelitic acid, modify. The starting polyester can also contain known additives to the Ability to modify the coloring, e.g. Sodium 3,5-dicarboxybenzenesulfonate.

The process according to the invention also has the great advantage that the polycondensation plant are always operated with the same standard settings can. It can be standard textile granulate according to the direct esterification process or Transesterification processes can be used. The necessary for the special requirement Additives are only added after the polycondensation, before spinning, what allows a high degree of flexibility and economy. According to the invention found such additives that lead to the desired effect within a short time Residence time in which highly viscous polyester melt can be incorporated, none Polycondensation conditions (vacuum to remove low molecular weight fission products) require and do not affect the spinnability. The additives are also stable and will not be washed out.

The fibers and the method according to the invention will now be explained in more detail by the following examples and figures. Common, known to those skilled spinners and stretching methods were used for staple fiber production, for example in Ullmann's Encyclopedia of Industrial Chemistry, ^5th Ed like them. Vol.

A10, Fibers, 3. General Production Technology, pages 550 to 561.

Figur 1 die für die verschiedenen Beispiele gemessenen DST-Werte in Abhängigkeit von der Ethylenglykolzugabe; der DST-Wert wurde an Polyesterfasern mit einem Titer von 2,4 dtex gemessen;

Figur 2 die Abhängigkeit des DST-Wertes von der Zugabe des Siliconöls (Struktol® bzw. Baysilon®). Weiterhin ist in Figur 2 die Korrelation der DST-Werte mit der eingebrachten Struktol®-Menge bei gleichzeitiger Zugabe von 0,10 Gew.-% Ethylenglykol dargestellt;

Figur 3 die für die verschiedenen Beispiele gemessenen DST-Werte der Fasern mit einem Titer von 2,4 dtex in Abhängigkeit vom SiO₂-Gehalt bei gleichzeitiger Zugabe von 0,10 bzw. 0,14 Gew.-% Ethylenglykol;

Figur 4 die für die verschiedenen Beispiele gemessenen DST-Werte für einen Fasertiter von 2,4 dtex in Abhängigkeit von Ethylenglykol-Zugabe, SiO₂- und Siliconölgehalt, wobei die im DST-Bereich zwischen 500 und 700 eingetragenen Messpunkte dem besonders bevorzugten Erfindungsbereich entsprechen.

Show it:

1 shows the DST values measured for the various examples as a function of the ethylene glycol addition; the DST value was measured on polyester fibers with a titer of 2.4 dtex;

Figure 2 shows the dependence of the DST value on the addition of silicone oil (Struktol® or Baysilon®). FIG. 2 also shows the correlation of the DST values with the amount of Struktol® introduced with the simultaneous addition of 0.10% by weight of ethylene glycol;

3 shows the DST values of the fibers measured for the various examples with a titer of 2.4 dtex as a function of the SiO ₂ content with the simultaneous addition of 0.10 or 0.14% by weight of ethylene glycol;

FIG. 4 shows the DST values measured for the various examples for a fiber titer of 2.4 dtex as a function of ethylene glycol addition, SiO ₂ content and silicone oil content, the measurement points entered in the DST range between 500 and 700 corresponding to the particularly preferred range of the invention.

Examples 1 to 20 Substances used:

Polyethylene terephthalate (PET):

Standard PET in textile quality with rel. Viscosity 1.65 (measured 1% in m-cresol at 20 ° C) with 0.3% Ti0 ₂

Silicone oil:

Dihydroxy-terminated polydimethylsiloxane with n = 40 (trade name Struktol® Polydis 3999 from the company Schill and Seilacher, Hamburg) Polydimethylsiloxane without terminal OH groups: Trade name Baysilon® M 1000 from Bayer, Leverkusen

diol:

Ethylene glycol (EG)

SiO ₂ :

Silicon dioxide, (Aerosil® 200 from Degussa)

DST-value determination:

The DST value was determined in accordance with US-A-5,858,529, Sp. 3, lines 54-65.

Experimental procedure:

Standard PET granules matted with 0.3% TiO ₂ and having a relative viscosity of 1.65 (1% in m-cresol / 20 ° C.) were melted on a melt spinning machine and mixed with the indicated additives in accordance with Table 2. Threads were pressed out at a melt temperature of 258 ° C with a throughput of 599 g / min from a nozzle plate with 845 holes and 0.35 mm hole diameter, cooled by central blowing, drawn off at 891 m / min and placed in a jug. The spun cables were then stretched about 3.2 times on a fiber line, crimped, heat-set and cut into staple fibers.

The liquid components (silicone oil and EG) were dosed directly into the granulate inlet of the spinning extruder. The SiO ₂ powder was mixed with the granules using a metering device (from Koch Maschinentechnik GmbH, D-Ispringen / Pforzheim). In most variants, the SiO _{2 was used} as a masterbatch (10% by weight SiO ₂ in polyester carrier material). Examples Titer [dtexl EC silicone oil Final SiO ₂ concentration in PET 1 2.40 0.14% 2 2.40 0.14% 0.40% Struktol® 3 2.40 0.14% 0.50% SiO ₂ 4 2.40 0.14% 0.40% Struktol® 0.50% SiO ₂ 5 2.40 0.14% 0.40% Struktol® 0.20% SiO ₂ 6 2.40 7 2.40 0.40% Struktol® 8th 2.40 0.90% Struktol® 9 2.40 0.10% 10 2.40 0.10% 0.40% Struktol® 11 2.40 0.10% 0.90% Struktol® 12 2.40 0.10% 0.20% SiO ₂ 13 2.40 0.10% 0.50% SiO ₂ 14 2.40 0.14% 0.40% Struktol® 0.50% SiO ₂ 15 2.40 0.16% 0.40% Struktol® 0.50% SiO ₂ 16 2.40 0.16% 0.40% Struktol® 0.20% SiO ₂ 17 2.40 0.14% 0.20% SiO ₂ 18 1.67 0.16% 0.40% Struktol® 0.20% SiO ₂ 19 2.40 0.60% Baysilon® 20 2.40 0.40% Baysilon®

The main goal of the investigations was to achieve the quality level of Trevira® Trevira®350 fiber with regard to pilling resistance. The properties of this fiber are shown in Table 3 and serve as a benchmark for comparison with the fibers according to the invention measured using the same methods. Comparative values of the Trevira ® 350 fiber (measured according to the method as in Tab. 1) TREVIRA ® 350 TREVIRA ® 350 Titer [dtex] 2.36 1.64 Strength [cN / dtex] 2.69 2.64 Strain [%] 50.84 28.46 DST 545 655

In the experiments of the present invention, the following viscosity values were measured for the extruded threads under the spinneret: Viscosities (relative viscosity) of Examples 1 to 20 example RV, 1% measured in m-cresol 1 1,471 2 1,458 3 1,456 4 1,446 5 1.445 6 1,650 7 1.641 8th 1,630 9 1,500 10 1,497 11 1,493 12 1,490 13 1.479 14 1,440 15 1.436 16 1,432 17 1,467 18 1,427 19 1,638 20 1,631

Example 6 shows a zero variant without any additive. Textile data of the finished fibers example Titer [dtex] Strength [cN / dtex] Strain % DST 1 2.34 3.38 48.37 1382 2 2.31 3.36 48.66 932 3 2.43 2.93 53.45 997 4 2.30 3.00 49,25 673 5 2.40 3.07 54.27 715 6 2.42 4.02 48.79 3008 7 2.41 3.98 54,50 1451 8th 2.41 4.00 52.27 1304 9 2.44 3.61 52.86 1649 10 2.31 3.68 53.01 990 11 2.47 3.60 51.33 905 12 2.35 3.36 52.15 1208 13 2.37 3.21 54.97 1140 14 2.31 2.90 53.01 622 15 2.47 2.69 55.33 511 16 2.35 2.92 52.15 618 17 2.43 3.09 54.72 1045 18 1.69 2.90 47.97 696 19 2.37 3.90 52.10 2170 20 2.41 3.95 51.89 2273

It should be noted that compared to Trevira fiber Examples 14 to 16 for the 2,4-dtex type and example 18 for the 1,7-dtex type meet all requirements (like already shown in Table 1).

Claims (16)

1. Polyester fibers having a reduced tendency to pilling, comprising

   (1) a polyester as filament-forming polymer consisting of at least 90 mol-% of polyethylene terephthalate units, and

   (2) a diol from the group of ethylene glycol, diethylene glycol and triethylene glycol in a quantity having degraded the polyester to a relative viscosity in the range of 1.37 - 1.58 (measured by 1 % in m-cresol), and

   (3) 0.003 to 1.0 % by weight of silicon dioxide particles or silica particles finely distributed in the polyester material, relative to the filament-forming polymer, and

   (4) 0.003 to 2.0 % by weight of silicone oil, relative to the filament-forming polymer, wherein in the case of reactive groups present in the silicone oil said groups are at least partially chemically bonded to the polyester macromolecules, and

   (5) optionally additional common, known processing- or use-specific additives,

   wherein the polyester fibers have a relative viscosity of 1.37 to 1.58 measured by 1 % in m-cresol.
2. Polyester fibers according to patent claim 1, characterized in that the silicon dioxide is a finely dispersed porous silicon dioxide powder.
3. Polyester fibers according to patent claim 1, characterized in that the silicon dioxide has primary particle sizes of < 30 µm, preferably < 100 nm.
4. Polyester fibers according to one of the preceding claims, characterized in that the silicon dioxide is used in the form of a masterbatch on polyester basis with 1 to 20 % by weight of SiO₂, preferably 5 to 15 % by weight SiO₂.
5. Polyester fibers according to claim 1, characterized in that the silicone oil is a polydialkyl siloxane, polydiaryl siloxane or polyalkylaryl siloxane, preferably polydimethyl siloxane.
6. Polyester fibers according to claim 5, characterized in that a silicone oil having reactive hydroxyl groups, preferably two terminal reactive hydroxyl groups per molecule, is used.
7. Polyester fibers according to claims 5 or 6, characterized in that the silicone oil is a polydimethyl siloxane having two terminal hydroxyl groups.
8. Polyester fibers according to one of the preceding claims, characterized in that they have wire abrasion stroke cycles values of less than 700.
9. Polyester fibers according to one of the preceding claims, characterized in that they have wire abrasion stroke cycles values of less than 600.
10. Polyester fibers according to one of the preceding claims, characterized in that polyethylene terephthalate is used as filament-forming polymer.
11. Polyester fibers according to one of the preceding claims, characterized in that the silicon dioxide particles or the silica particles, respectively, are used in quantities of 0.05 to 0.3 % by weight relative to the filament-forming polymer, and that the silicone oil is used in quantities of 0.05 to 0.5 % by weight.
12. Polyester fibers according to one of the preceding claims, characterized in that the polyester fibers have a relative viscosity of 1.40 to 1.55 measured by 1 % in m-cresol.
13. Polyester fibers according to claim 12, characterized in that they have a relative viscosity of 1.42 to 1.48 measured by 1 % in m-cresol.
14. Method of producing polyester fibers according to one or more of the preceding claims, characterized in that the combination of additives (2), (3) and (4) is dosed into the polyester granulate prior to the melting or, respectively, into the melt prior to the spinning and is mixed or dispersed, respectively, therein and the melt mixture is subsequently subjected to spinning.
15. Method according to claim 14, characterized in that, for the continuous modification of the polyester melt, a part of the melt is taken from the main melt stream, said partial stream is fed into a side stream extruder, supplied with the silicon dioxide or silica powder and dispersed therein, the dispersed and mixed melt concentrate is passed back into the main melt line and is diluted to form the final concentration by means of a static mixer, the diol and the silicone oil are dosed before the static mixer in a liquid state and the melt mixture is subsequently subjected to spinning.
16. Polyester fiber according to claim 1, characterized in that a polyester having a relative viscosity of > 1.55 is taken as a basis, which is degraded to the desired target viscosity (relative viscosity measured by 1 % in m-cresol) in the range of 1.40 to 1.55, preferably to 1.42 to 1.48 by adding an aliphatic or alicyclic diol.

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