EP1138810B1 - Hydrophilic additive - Google Patents

Abstract

Reaction products (I) of 1 part polyethylene glycol (PEG) with 2 parts fatty acids having 10-12 carbon (C) atoms or their derivatives are used as additives for permanently hydrophilizing polyolefin-containing materials. Independent claims are also included for: (1) polypropylene fibers containing 0.5-10 wt.% (I); and (2) production of polypropylene fibers by mixing polyolefins with (I), heating the mixture to form a melt and spinning the melt to form fibers.

Description

The present invention relates to additives for the permanent hydrophilization of Polypropylene fibers.

In numerous cases, the surface of plastic products must have special effects that are either not at all or only during the shaping for technical reasons imperfectly or, for economic reasons, have it produced only disadvantageously. Such a Effects include improving wettability with polar liquids such as water - Technical applications are, for example, in the field of the production of Hygiene articles.

In the manufacture of hygiene articles, such as diapers or sanitary napkins, they become absorbent Materials used to absorb aqueous liquids. To have direct contact with the This will prevent absorbent material when worn and increase comfort Material covered with a thin, water-permeable nonwoven. Such nonwovens are usually made of synthetic fibers, such as polyolefin or polyester fibers, since these Fibers are inexpensive to produce, have good mechanical properties and are thermal are resilient. However, untreated polyolefin or polyester fibers are suitable for this Not intended for use because they are not sufficiently permeable due to their hydrophobic surface for aqueous liquids.

In principle, it is possible to coat the fibers with appropriate coatings Giving preparations the necessary hydrophilic properties or by adding suitable ones Additives in the production of the fibers to make them sufficiently hydrophilic. The latter is in the WO 95/10648 described, where diesters of polyethylene glycol with fatty acids or their Derivatives can be disclosed as suitable permanent additives. In the examples Reaction products of oleic acid with polyethylene glycol of molecular weight 400 as particularly advantageous described.

Surprisingly, it has now been found that selected diesters of polyethylene glycols better properties with regard to the hydrophilic finish of polyolefins containing Have materials than the compounds specifically disclosed in WO 95/10648.

The present invention relates to polypropylene fibers which are obtained by mixing polypropylene with an additive, then heating this mixture until it melts and spinning it into fibers by customary processes, characterized in that the additives are reaction products of 1 part of polyethylene glycol with a molecular weight of 400 2 parts of lauric acid or decanoic acid are selected.

In the context of the invention, the additives in polypropylene containing materials, preferably Fibers, fabrics such as nonwovens, foils and foams are used for permanent hydrophilization. All known polymer and copolymer types are suitable for this purpose Propylene.

Polymer types which are particularly suitable for the teaching according to the invention are set out below Compilation enumerated: poly (propylene) such as isotactic polypropylene; syndiotactic polypropylene; Metallocene-catalyzed polypropylene, impact-modified Polypropylene, random copolymers based on ethylene and propylene, block copolymers Based on ethylene and propylene; EPM (poly [ethylene-co-propylene]); EPDM (poly [ethylene-co-propylene-co-conjugated Diene]).

Other suitable types of polymer are polymer blends based on polyethylene and polypropylene.

Within the scope of the present invention, homopolymers and copolymers based on ethylene and Propylene is particularly preferred. In one embodiment of the present invention exclusively polypropylene, in a further embodiment copolymers based on ethylene and Propylene, a. Polyethylene glycols with a Molecular weight of 400, with lauric or decanoic acid by processes known per se, preferably in the presence of catalysts, implemented. The alcohol and the Acid components are reacted in a molar ratio of about 1 to 2. Mixtures of the acids can also be reacted with the polyethylene glycol become.

The fibers preferably contain the additives in amounts of 0.5 to 10% by weight, preferably 0.5 to 5 wt .-% and 1.0 to 2.5 wt .-% based on the fiber weight. Furthermore, a method for Production of hydrophilized polypropylene fibers claimed, polyolefins with the additives mixed as described above, then this mixture is heated until it melts and spins into fibers by conventional methods. The processes for spinning are known to the person skilled in the art and are described for example in WO 95/10648 or in US 3,855,046.

Another object of the invention is the use of described above fibers for the production of textile fabrics. Preferably, the textile fabrics are Nonwovens. In a particularly preferred embodiment, these textile fabrics are for Use in diapers.

For the latter case, the use of textile fabrics in diapers, the individual Wetting test is a suitable simulation. Diapers are usually over a Period worn from 3 to 5 hours, with the inside averaging up to 3 times with urine is wetted. It must then be ensured that a hydrophilic nonwoven based on a otherwise hydrophobic plastic is sufficiently wettable so that the urine through the fleece penetrate and can be bound by the absorber material of the diaper.

Nonwovens can be produced using all of the methods known in the art for producing nonwovens, such as for example in Ullmann's Encyclopedia of Industrial Chemistry, Vol. A 17, VCH Weinheim 1994, Pages 572-581. Nonwovens are preferred, which are either were manufactured according to the so-called "dry laid" - or the spunbonded or spunbond process. The "dry laid" process is based on staple fibers, which are usually carded into single fibers separated and then using an aerodynamic or hydrodynamic process to be consolidated into the unconsolidated nonwoven. This is then, for example, by a thermal treatment combined to the finished fleece (the so-called "thermobonding"). there the synthetic fibers are either heated so far that their surface melts and the Individual fibers are connected to each other at the contact points, or the fibers are connected to one Additively coated, which melts during the heat treatment and so the individual fibers connects with each other. The connection is fixed by cooling. In addition to this procedure Of course, all other methods are also suitable which are known in the prior art for connecting Nonwovens are used. Spunbond formation, on the other hand, starts from individual filaments that are formed by the melt spinning process from extruded polymers, which under high Pressure is pressed through spinnerets. The filaments emerging from the spinnerets become bundled, stretched and laid down to form a fleece, which is usually "thermobonding" is solidified.

Examples

The following is the production of additives according to the specific disclosure of WO 95/10648 described (Examples 3 and 4) and the preparation of the additives according to the invention (Examples 1 and 2).

Example 1: Preparation of a polyethylene glycol 400 dilaurate

139 g (0.35 mol) of polyethylene glycol 400 are made in the presence of 1.45 g of Svedcat 5 (Sn-organic Svedstab catalyst) with 149.75 g (0.7 mol) of methyl laurate. The reaction mixture is heated to 100 ° C under nitrogen blanket. The methanol formed is gradually distilled off, thereby the bath temperature is increased to 180 ° C. If no more methanol is separated, the The pressure is reduced to 5 mbar and the remaining methanol is distilled off at 180 ° C. over 45 minutes. The The reaction is complete when no more methanol is deposited. OHZ: 20mgKOH / g

Example 2: Preparation of a polyethylene glycol 400 didecanoate

180g polyethylene glycol 400 are in the presence of 1.68g Svedcat 3 (Sn organic catalyst of Svedstab) with 155.6 decanoic acid. The reaction mixture is under nitrogen blanket heated to 100 ° C. The water formed is gradually distilled off, the bath temperature is up to increased to 180 ° C. If no more water is separated, the pressure is reduced to 5 mbar and the remaining water was distilled off at 180 ° C. for 45 minutes. The reaction is finished if none Water is deposited more. OHZ: 12 mgKOH / g, SZ: 8.7 g KOH / g

Example 3: Preparation of a polyethylene glycol 400 dipalmitate

140.7 g of polyethylene glycol 400 are in the presence of 1.65 g of Svedcat 5 (Sn organic catalyst from Svedstab) with 189.8 g of methyl palmitate. The reaction mixture is under Nitrogen protective gas heated to 100 ° C. The methanol formed is gradually distilled off, during which the bath temperature increased to 180 ° C. When no more methanol is deposited, the pressure drops reduced to 5 mbar and the remaining methanol was distilled off at 180 ° C. over 45 minutes. The reaction is ended when methanol is no longer separated. OHZ: 20mg KOH / g

Example 4: Preparation of a polyethylene glycol 400 dioleate

122.3 g of polyethylene glycol 400 are in the presence of 1.88 g of Svedcat 5 (Sn organic catalyst from Svedstab) with 177.9 g of methyl oleate. The reaction mixture is under Nitrogen protective gas heated to 100 ° C. The methanol formed is gradually distilled off, during which the bath temperature increased to 180 ° C. When no more methanol is deposited, the pressure drops reduced to 5 mbar and the remaining methanol was distilled off at 180 ° C. over 45 minutes. The reaction is ended when methanol is no longer separated. OHZ: 9.3 mg KOH / g

1. Man vermengt 600 g eines hochmolekularen Polypropylen-Granulates (Handelsprodukt "Eltex PHY 671" der Firma Solvay) mit 9,0 g (=1,5 Gew.-%) der - hinsichtlich einer hydrophilen Ausrüstung - zu prüfenden Substanz. Diese Mischung wird durch einen Trichter in einen Extruder eingebracht (Doppelschneckenextruder DSK 42/7 der Firma Brabender OHG / Duisburg). Ein Extruder ist - wie dem Fachmann hinlänglich bekannt - eine Kunststoff-Verarbeitungsmaschine, welche zum kontinuierlichen Mischen und Plastifizieren sowohl von pulver- als auch granulatförmigen Thermoplasten geeignet ist. Unter dem Einfülltrichter befindet sich neben einer Wasserkühlung, die ein verfrühtes Schmelzen des Granulates bzw. Pulvers verhindern soll, auch eine gegenläufige Doppelschnecke, die der Länge nach in drei Heizzonen aufgeteilt ist. Die Temperatur der Heizzonen und die Drehzahl der Doppelschnecke lassen sich über einen Datenverarbeitungs-Plast-Corder PL 2000 regeln, der über eine PC-Schnittstelle mit dem Extruder verbunden ist. Dabei werden die Heizzonen I, II und III auf eine Temperatur von jeweils 200°C eingestellt, wobei die drei Heizzonen luftgekühlt werden, um die Temperatur konstant zu halten. Die Mischung von Polypropylen-Granulat und Prüfsubstanz wird automatisch durch die gegeneinander laufende Doppelschnecke in den Extruder eingezogen und entlang der Schnecke befördert. Die Drehzahl wird auf 25 Umdrehungen pro Minute eingestellt, um eine gute Durchmischung und Homogenisierung zu gewährleisten. Diese homogene Mischung gelangt schließlich in eine Düse, die eine vierte Heizzone darstellt. Die Temperatur dieser Düse wird auf 200 °C eingestellt - bei dieser Temperatur verläßt also die Mischung den Extruder. Die Düse wird so gewählt, daß der mittlere Durchmesser des Stranges nach dem Austritt aus dieser Düse im Bereich von etwa 2 - 3 mm liegt. Dieser Strang wird granuliert, d.h. in kleine Stücke geschnitten, wobei man Längen von etwa 2-4 mm einstellt. Das erhaltene Granulat läßt man auf 20 °C abkühlen. Dieses Granulat wird in einer Schmelzspinnanlage bei einer Verarbeitungstemperatur von 280 °C (d.h man stellt sowohl die Schmelzsterntemperatur als auch die Temperatur der Spinndüse auf 280 °C ein) gravimetrisch (d.h. durch Schwerkrafteinwirkung) in Fasern überführt. Die erhaltenen Fasern weisen einen Fasertiter im Bereich von etwa 10 - 30 dtex auf (1 dtex entspricht 1 g Faser pro 10000 m Faserlänge). Anschließend werden 500 m dieser Faser auf eine Rolle mit einem Durchmesser von 6,4 cm aufgewickelt. Diese auf die Rolle aufgewickelte Faser wird von der Rolle abgezogen und das abgezogene kreisförmige Gebilde durch mittiges Verknoten stabilisiert, wobei ein Gebilde erhalten wird, das die Form einer "8" hat; dieses Gebilde wird nachfolgend als "Strängchen" bezeichnet.

2. Man füllt einen 1-I-Meßzylinder (Glaszylinder mit einem Innendurchmesser von 6,0 cm) mit destilliertem Wasser von 20 °C und zwar bis zur 1000-ml-Markierung. Nun hält man das zu prüfende Strängchen in der Weise, das seine Längsrichtung mit der Vertikale des Meßzylinders übereinstimmt, d.h. daß das Strängchen als vertikale "8" erscheint. An den untersten Teil dieser "8" hängt man nun ein Gewicht, das aus Cu-Draht besteht, wobei die Masse des Cu-Drahtes 0,2064 g Cu pro Gramm Strängchen beträgt. Dieser Cu-Draht wird in Form von Windungen an dem Strängchen befestigt, wobei der Durchmesser der Cu-Draht-Windungen etwa 1 bis 2 cm beträgt; anschließend werden diese Cu-Draht-Windungen durch leichtes Drücken zwischen Daumen und Zeigefinger zusammengepreßt. Nun hält man das Strängchen mit dem Cu-Gewicht über die Wasseroberfläche des Meßzylinders und zwar so, daß der untere Teil des Cu-Gewichtes in das Wasser eintaucht und der unterste Teil des Strängchens sich etwa 2 mm über der Wasseroberfläche befindet Dann läßt man das Strängchen los und mißt mit einer Stoppuhr die Zeit in Sekunden, die das Strängchen benötigt, um vollständig einschließlich seiner Oberkante ins Wasser einzutauchen (vollständige Eintauchzeit). Beginn und Ende der Meßzeit sind dadurch definiert, daß das unterste Ende des Strängchens jeweils die 1000-ml- und das obere Ende des Strängchens ebenfalls die 1000 ml- Marke passiert. Dieser erste Meßwert wird als C1-Wert ("Wert des ersten Benetzungscyclus") bezeichnet.

3. Das Strängchen wird unmittelbar nach Bestimmung des C1-Wertes aus dem Meßzylinder genommen, mit Zellstoff abgetupft und 1 Stunde in einem Umlufttrockenschrank (Typ UT 5042 EK der Firma Heraeus) bei 40 °C getrocknet. Anschließend wird Schritt 2 wiederholt. Der jetzt erhaltene Wert in Sekunden der vollständigen Eintauchzeit wird als C2-Wert ("Wert des zweiten Benetzungscyclus") bezeichnet. Trocknung und Bestimmung der vollständigen Eintauchzeit werden nun erneut wiederholt, wobei man den C3-Wert ("Wert des dritten Benetzungscyclus") erhält. Sofern die vollständige Eintauchzeit (C1- bis C3-Werte) oberhalb von 180 Sekunden liegen, wird der jeweilige Cyclus beendet.

Polypropylene test specimens equipped with different test substances (A and B = examples according to the invention; V1 to V2 = comparative tests) were subjected to a wetting test which is carried out as follows:

1. 600 g of high-molecular polypropylene granules (commercial product "Eltex PHY 671" from Solvay) are mixed with 9.0 g (= 1.5% by weight) of the substance to be tested with regard to a hydrophilic finish. This mixture is introduced into an extruder through a funnel (twin-screw extruder DSK 42/7 from Brabender OHG / Duisburg). As is well known to the person skilled in the art, an extruder is a plastic processing machine which is suitable for the continuous mixing and plasticizing of both powder and granular thermoplastics. In addition to water cooling to prevent premature melting of the granules or powder, there is also a counter-rotating twin screw below the feed hopper, which is divided lengthwise into three heating zones. The temperature of the heating zones and the speed of the twin screw can be controlled via a PL 2000 data processing plast corder, which is connected to the extruder via a PC interface. The heating zones I, II and III are set to a temperature of 200 ° C each, the three heating zones being air-cooled in order to keep the temperature constant. The mixture of polypropylene granulate and test substance is automatically drawn into the extruder by the twin screw running against each other and transported along the screw. The speed is set to 25 revolutions per minute to ensure thorough mixing and homogenization. This homogeneous mixture finally arrives in a nozzle, which is a fourth heating zone. The temperature of this nozzle is set to 200 ° C - at this temperature the mixture leaves the extruder. The nozzle is selected so that the mean diameter of the strand after it emerges from this nozzle is in the range of approximately 2-3 mm. This strand is granulated, ie cut into small pieces, with lengths of about 2-4 mm being set. The granules obtained are allowed to cool to 20 ° C. These granules are gravimetrically (ie by gravity) converted into fibers in a melt spinning system at a processing temperature of 280 ° C (ie both the melt star temperature and the temperature of the spinneret are set to 280 ° C). The fibers obtained have a fiber titer in the range of about 10-30 dtex (1 dtex corresponds to 1 g fiber per 10000 m fiber length). Then 500 m of this fiber are wound on a roll with a diameter of 6.4 cm. This fiber wound on the roll is withdrawn from the roll and the withdrawn circular structure is stabilized by central knotting, whereby a structure which has the shape of an "8" is obtained; this structure is referred to below as "strands".

2. A 1 liter measuring cylinder (glass cylinder with an inner diameter of 6.0 cm) is filled with distilled water at 20 ° C up to the 1000 ml mark. Now hold the strand to be tested in such a way that its longitudinal direction corresponds to the vertical of the measuring cylinder, ie that the strand appears as vertical "8". A weight consisting of Cu wire is now attached to the lowest part of this "8", the mass of the Cu wire being 0.2064 g Cu per gram of strands. This Cu wire is attached to the strand in the form of turns, the diameter of the Cu wire turns being approximately 1 to 2 cm; Then these copper wire turns are pressed together by gently pressing between the thumb and forefinger. Now hold the strand with the Cu weight over the water surface of the measuring cylinder in such a way that the lower part of the Cu weight is immersed in the water and the lowest part of the strand is about 2 mm above the water surface. Then the strand is left go and use a stopwatch to measure the time in seconds that the strand takes to completely immerse itself in the water, including its top edge (complete immersion time). The start and end of the measuring time are defined by the fact that the bottom end of the strand passes the 1000 ml mark and the top end of the strand also passes the 1000 ml mark. This first measured value is referred to as the C1 value (“value of the first wetting cycle”).

3. The strand is removed from the measuring cylinder immediately after determining the C1 value, dabbed with cellulose and dried for 1 hour in a forced-air drying cabinet (type UT 5042 EK from Heraeus) at 40 ° C. Then step 2 is repeated. The value now obtained in seconds of the complete immersion time is referred to as the C2 value ("value of the second wetting cycle"). Drying and determination of the complete immersion time are now repeated again, the C3 value (“value of the third wetting cycle”) being obtained. If the complete immersion time (C1 to C3 values) is above 180 seconds, the respective cycle is ended.

The wetting test is passed if C1 to C3 are less than 5 seconds.

The test results are summarized in Table 1; the complete immersion times are given (in seconds). Additive (1.5% by weight each) in PP fiber (Eltex PHY 677) C1 [sec] (after spinning) C2 [sec] (24h after C 1, drying at RT) C3 [sec] (24h after C 2, drying at RT) A PEG-400 dilaurate 1.1 1.6 1.5 B PEG-400 didecanoate 1.5 2.4 2.5 V1 PEG-400 dioleate > 180 > 180 > 180 V2 PEG-400 dipalmitate 6.5 6.6 50.2

It is clear from the results that the additives proposed according to the invention are clear allow better hydrophilization of the PP fibers than they disclosed from WO 95/10648 Links.

Claims (3)

1. , Polypropylene fibres obtained by mixing polypropylene with an additive, heating the resulting mixture until it melts and spinning the melt to fibres by conventional methods, characterized in that reaction products of 1 part of polyethylene glycol with a molecular weight of 400 with 2 parts of lauric acid or decanoic acid are selected as additives.
2. Polypropylene fibres as claimed in claim 1, characterized in that the polypropylene fibers contain the additive in quantities of 0.5 to 10% by weight, preferably 0.5 to 5% by weight and more particularly 1.0 to 2.5% by weight.
3. The use of the polypropylene fibres claimed in claims 1 and 2 for the production of flat textile materials.