DE19851687A1 - Process for the hydrophilic finishing of fibers based on polyolefins or polyester using alkyl ethoxylates - Google Patents

Abstract

The invention relates to a method for the hydrophilic finishing of fibres which consist exclusively or entirely of polyolefins or polyester. According to the invention a mixture containing (a) mostly polyolefins or polyester and (b) between 0.01 and 10 % by weight, in relation to the sum of polyolefin or polyester, of a composition containing at least one compound from the class of alkylethoxylates, is subjected at temperatures of between 180 and 320 DEG C and in the usual manner to a moulding process yielding fibres. The invention is characterized in that (i) no transition-metal compounds are added to the mixture subjected to the moulding process, either before or during said process; (ii) the alkylethoxylates (b) have the general structure R-O-(CH2-CH2-O)xH, where the rest R is an alkyl rest with between 8 and 14 carbon atoms and x is a number between 4 and 10; and (iii) in the individual wetting test the alkylethoxylates (b) require at least four wetting cycles until failure.

Description

Field of the Invention

The invention relates to a method for the hydrophilic finishing of fibers which finally or entirely contain polyolefins or polyester. Special Al kylethoxylate used.

State of the art

In numerous cases, the surface of plastic products must be treated with special Effects are provided that arise during the shaping either from technical Reasons not at all or only incompletely or only for economic reasons disadvantageously generated. One such effect is the improvement of Wettability with polar liquids such as water - technical applications here for example in the field of the production of hygiene articles.  

In the manufacture of hygiene articles, such as diapers or sanitary napkins, sorbent materials used to absorb aqueous liquids. To the di prevent direct contact with the absorbent material when worn and the This material is increased with a thin, water-permeable material Nonwoven wrapped. Such nonwovens are usually made of synthetic fibers, such as polyolefin or polyester fibers because these fibers are inexpensive to produce are, have good mechanical properties and are thermally resilient. Indeed untreated polyolefin or polyester fibers are not suitable for this purpose, because they are not sufficiently permeable to because of their hydrophobic surface have aqueous liquids.

For this purpose, the fiber surface must be hydro by an appropriate preparation phil are equipped. It is also desirable that the hydrophilic finish from water remains as long as possible without the water permeability of the nonwoven fabric is reduced. If such nonwovens are processed in diapers, for example, can be used several times without becoming impermeable to water. To this In this way the wearing time of the diapers is increased and that caused by worn diapers gentle waste reduced.

US-A-5,045,387 describes, for example, an agent for the hydrophilic finishing of polyolefin fibers which contains a mixture of an alkoxylated ricinoleic acid derivative, a hydrogenated ricinoleic acid derivative, a C ₁₈ fatty acid and a polyalkoxylated polymethylsiloxane. This agent must be applied from the outside to the surface of the fibers or films.

US Pat. No. 5,654,086 describes the hydrophilic finishing of otherwise hydrophobic fibers based on thermoplastic plastics, the hydrophobic fiber being treated with a mixture of five surface-active substances (surfactants). These are (A) polyoxyalkylene adducts of C _{28-50 alcohols} or alkyl amines or fatty acid amides based on C _30-50 fatty acids, (B) polyoxyalkylene adducts of fatty acid amides based on C _20-28 fatty acids , (C) fatty acid amides based on C _16-28 fatty acids and alkanolamines, (D) polyoxyalkylene adducts C _10-22 - alkyl phosphate salts and (E) C _12-16 alkyl sulfonate salts.

EP-A-400,622 describes a process for making non-woven materials that are hydrophobic Contain fibers to impart hydrophilic properties. A set is created tongue, which contains special polyoxyalkylated secondary or tertiary amines, before Ver spinning into a molten composition containing polyolefin.

EP-B-372 890 describes fibers based on polyolefin or polyester with a Surface arrested lubricant. This lubricant comprises a mixture of (1) fatty acid diethanolamide, (2) a polyether-modified silicone, (3) a Sorbi tan fatty acid esters and (4) a metal salt of an alkyl sulfonate; the com components (1) to (4) in special proportions. According to page 3, lines 20-26 the mixture of components (1) to (4) is applied to the surface. This Technique of applying the mixture containing the four components to the top The surface of finished fibers is also explained in more detail on page 4, lines 6-9. There are mentioned as application techniques: a) the use of rollers, b) spraying and c) immersion. It is therefore a procedure in which a Mi components (1) to (4) in an additional processing step Surface of molded polyolefin parts is applied. The one in claim 1 of EP-B-372 The term 890 used "adhered to the fiber surface" is therefore from the specialist to understand clearly in such a way that it is only a relaxed and  temporary liability - for example due to relatively weak adhesive forces - is not an option but for permanent anchoring.

EP-B-616 622 relates to extrudable, compostable polymer compositions, um including an extrudable, thermoplastic polymer, copolymer or mixtures of which is a mining-promoting system consisting of an auto-oxidative component and a Contains transition metal. The autooxidative system comprises a fatty acid, a substituted fatty acid or derivatives or mixtures thereof, the fatty acid 10 to Has 22 carbon atoms and at least 0.1 wt .-% of unsaturated compounds and min contains at least 0.1% by weight of free acid. The transition metal is in the composition tion in an amount of 5-500 ppm in the form of a salt and selected from the group of cobalt, manganese, copper, cerium, vanadium and iron. The composition is said to be in the form of a film approximately 100 microns thick at 60 ° C and a relative Moisture of at least 80% oxidatively to embrittlement within 14 days be buildable.

WO 98/42898 describes the use of amphiphiles for permanent hydrophilicity sation of the surfaces of polyolefin-based moldings, fibers and foils. Here subjecting a mixture comprising (a) predominantly one or more polyolefins, (b) 0.01 to 10 wt .-% - based on the polyolefins - one or more migratable amphiphiles and (c) 0.01 to 1000 ppm of one or more transition metal Compounds - Metal content of the transition metal compounds based on the Po lyolefins - at temperatures in the range of 180 to 320 ° C in the usual way one shaping processing such as extrusion, calendering, injection molding and same. According to the technical teaching of WO 98/42898, the hy drophilized polyolefin moldings that all three features (a), (b) and (c) be observed, d. H. that a transition metal Compound to be regarded as a catalyst is used.  

It is also known to achieve special properties of the plastic surface Effects by, for example, oxidative aftertreatment processes such as corona or To improve plasma treatment. Here the plastic is in the presence of gases and surface discharges are oxidized or chemically modified, causing have certain surface properties of the plastic modified. These methods However, in addition to high energy consumption, they always require an additional operation and lead to ozone emissions in the manufacture of plastic parts. Are next to it chemical pretreatment processes such as B. treatment with fluorine or chlorine gas, with chromosulfuric acid or fluorosulfonic acid, etc. has been known for a long time.

Description of the invention

The object of the present invention was to provide tools with which Fa s based on polyolefins or polyester and derived materials such as Nonwovens endowed with a hydrophilic finish and multiple wetting by aqueous Media - for example urine - can be made accessible.

The concept of hydrophilization - more recently, people often speak of hydrophi lation - is well known to the expert. This is done in the well-known standard work "Lexicon for textile finishing" (Editor: Hans-Karl Rouette; Volume 1; Dülmen 1995, pages 859-862) stated that hydrophobic fibers for Water can be made wettable, which is about better washability Synthetic fiber articles as well as for a better wearing comfort of such articles is. Examples of metrological indicators of successful hydrophilization are such as wetting (the surface spread of a liquid) or the height of rise (a Measure of the speed with which water in textile fabrics opposes the Gravity is transported).  

In the context of the present invention, hydrophilization becomes synonymous with this the term "hydrophilic finish" is used in the following - understand the that polyolefin or polyester surfaces that a wetting with water form an angle of more than 90 ° - ie "hydrophobic" interfaces - through a special Measure are modified so that their critical angle is too small after this measure values are shifted towards this. This is a rather dynamic interaction gen appropriately modified polymer surfaces with molecules or substrates that not immobilized, but in flexible contact with the polymer surface hen. In this regard, the effects that come under the concept of hydrophilic limit sation fall explicitly from phenomena in which molecules or substrates in permanent fixation are in contact with the polymer surface, as is the case with Be layers and bonds or when dyeing and printing.

The invention relates to a process for the hydrophilic finishing of fibers which contain all or all of polyolefins or polyesters, a mixture comprising (a) predominantly polyolefins or polyesters and (b) 0.01 to 10% by weight based on the sum of polyolefin and polyester - a composition which contains at least one compound from the class of alkyl ethoxylates, is subjected to shaping processing into fibers at temperatures in the range from 180 to 320 ° C. in the customary manner, where

• a) before or before the mixture which is subjected to the shaping processing no transition metal compounds during this shaping processing added,
• b) the alkyl ethoxylates (b) have the general structure RO- (CH ₂ -CH ₂ -O) _x H, in which the radical R is an alkyl radical with 8 to 14 carbon atoms and x is a number in the range from 4 to 10 and that
• c) the alkyl ethoxylates (b) in the individual wetting test at least four cycles to need to fail.

The "individual wetting test" is carried out as follows:

• 1. 600 g of high-molecular polypropylene granules are mixed (commercial pro product "Eltex PHY 671" from Solvay) with 9.0 g (= 1.5% by weight) of - with regard to a hydrophilic finish - substance to be tested. This mix is made by introduced a hopper into an extruder (twin screw extruder DSK 42/7 der Brabender OHG / Duisburg). An extruder is - as the skilled person suffices known - a plastic processing machine, which for continuous Mi rinsing and plasticizing both powder and granular thermoplastics suitable is. There is a water cooling system under the filling funnel to prevent premature melting of the granules or powder, also a ge smooth twin screw, which is divided lengthwise into three heating zones. The The temperature of the heating zones and the speed of the twin screw can be controlled via egg regulate data processing Plast-Corder PL 2000 via a PC interface is connected to the extruder. The heating zones I, II and III are set to one Temperature set at 200 ° C, the three heating zones being air-cooled to keep the temperature constant. The mixture of polyopropylene Granules and test substance are automatically created by the counter-running dop Fur screw drawn into the extruder and transported along the screw. The Speed is set to 25 revolutions per minute to ensure a good through to ensure mixing and homogenization. This homogeneous and practical Bubble-free mixture finally gets into a nozzle, which is a fourth heating zone represents. The temperature of this nozzle is set to 200 ° C - at this temperature The mixture then leaves the extruder. The nozzle is chosen so that the average diameter of the strand after emerging from this nozzle in the range of  is about 2-3 mm. This strand is granulated, i.e. H. cut into small pieces, setting lengths of about 2-4 mm. The granules obtained are left at 20 ° C cooling down. This granulate is processed in a melt spinning plant temperature of 280 ° C (i.e. both the melting star temperature and also the temperature of the spinneret to 280 ° C on) gravimetrically (i.e. by Gravity) converted into fibers. The fibers obtained have a sertiter in the range of about 10-30 dtex to (1 dtex corresponds to 1 g fiber per 10000 m Fiber length). Then 500 m of this fiber on a roll with a Diameter of 6.4 cm coiled. This fiber is wound on the roll withdrawn from the roll and the withdrawn circular structure by center Knotting stabilized, resulting in a structure that has the shape of an "8"; this structure is referred to below as "strands".
• 2. A 1-1 measuring cylinder (glass cylinder with an inner diameter of 6.0 cm) with distilled water at 20 ° C up to the 1000 ml mark. Now you hold the strand to be tested in such a way that its longitudinal direction with the Vertical of the measuring cylinder coincides, d. H. that the string as vertical "8" appears. On the bottom part of this "8" you now hang a weight made of copper Wire exists, the mass of the Cu wire 0.2064 g Cu per gram of strands is. This copper wire is attached to the strand in the form of turns, wherein the diameter of the copper wire turns is about 1 to 2 cm; then These copper wire turns become owing by lightly pressing between the thumbs and forefinger pressed together. Now hold the string with the copper Weight over the water surface of the measuring cylinder so that the lower one Immerse part of the Cu weight in the water and the lowest part of the strand is about 2 mm above the water surface. Then you let go of the strand and uses a stopwatch to measure the time in seconds that the string takes from the 1000 ml mark to the 200 ml mark. Beginning and  The end of the measuring time are defined by the fact that the lowest end of each strand because the 1000 ml or 200 ml mark passes. In the present experiment order means that the strand on its way between the above Marks a diving distance of 28.3 cm. This first measurement is called the C1 value ("value of the first wetting cycle").
• 3. The strand is taken immediately after determining the C1 value from the measuring cylinder, blotted with cellulose and dried for 1 hour in a forced-air cabinet (type UT 5042 EK from Heraeus) at 40 ° C. Then step 2 is repeated. The value now obtained in seconds of the 28.3 cm sink time is referred to as the C ₂ value ("value of the second wetting cycle"). Drying and determination of the 28.3 cm sink time are now repeated again, the C3 value ("value of the third wetting cycle") being obtained. Drying and determination of the 28.3 cm sink time are now repeated again, giving the C4 value ("value of the fourth wetting cycle"). Drying and determination of the 28.3 cm sink time are now repeated again, giving the C5 value ("value of the fifth wetting cycle"). If desired, the described procedure can also be repeated several times, so that if necessary, C5, C6, C7, etc. values can also be determined.
• 4.If 28.3 cm sink times (C1 to C5 values) are above 180 seconds, the respective cycle is ended.
• 5. If on the strand, predominantly in its upper part, when immersed in the Air bubbles get stuck in the measuring cylinder Wire or removed by briefly touching with a finger.

The individual wetting test is passed if the values for C1, C2 and C3 be a maximum of 50 seconds or less. This is equivalent to the fact that  when using a test substance suitable according to the invention, d. H. an alkyl ethoxylate (b), for the hydrophilic finishing of the polypropylene at the earliest when passing through the fourth cycle (C4 value) a value above 50 seconds is reached. An alkyl Ethoxylate (b) is suitable for the purposes of the present invention if a failure, So a 28.3 cm sink rate value above 50 seconds, at the earliest at the C4 value entry.

The alkyl ethoxylates (b) to be used according to the invention are structurally - as already mentioned - characterized by the general structure RO- (CH ₂ -CH ₂ -O) _x H, in which the radical R is an alkyl radical with 8 to 14 C atoms and x is a number in the range from 4 to 10 mean. The radical R can be saturated or unsaturated, straight-chain or branched. These compounds can be used both individually and in combination with one another.

In a preferred embodiment, such alkyl ethoxylates of the general structure RO- (CH ₂ -CH ₂ -O) _x H are used, in which the radical R is an alkyl radical having 12 to 14 carbon atoms. In a further embodiment, x is a number in the range from 4 to 7. Particularly preferred compounds of this class are addition compounds of 4 to 7 moles of ethylene oxide to 1 mole of lauryl alcohol, myristyl alcohol or mixtures of these alcohols. The compounds mentioned are used in particular in technical quality.

In a particularly preferred embodiment of the invention, such Ver bindings (b), which in the individual wetting test at least six cycles up to Need failure. With these connections, all values are C1, C2, C3, C4 and C5 in the individual wetting test described above under 50 seconds.

The compounds (b) to be used according to the invention are capable of migration. This means that these compounds are able to  position of the fibers by, for example, extrusion processes on the surface of the right resulting polyolefin or polyester molded body. You enrich yourself there through on the surface or near the surface of the plastic matrix at what by successively removing surface layers on the order of in each case a few nanometers and subsequent scanning techniques by the applicant was verified.

The polyolefin or polyester fa accessible by the process according to the invention and textile fabrics that can be made from them - such as nonwovens - are characterized by excellent wettability by aqueous media.

The technical action in the sense of the teaching according to the invention is on the one hand ensured that the desired improved and lasting surface hydrophilicity is achieved, on the other hand, that this without affecting other material parameters succeed.

The alkyl ethoxylates (b) are incorporated into the plastic matrix as part of the process usual shaping processing processes such as extrusion processes and the like. It may be desirable to use a pre-assembled mixture of components a) and b) use. Other common auxiliary substances used, which are used in the processing processing of plastics have generally proven and which are known to the expert, for example slip agents, antistatic agents, lubricants, release agents, UV stabilizers, anti oxidants, fillers, fire retardants, mold release agents, nucleating agents and an tiblock agents can be pre-assembled accordingly in separate form and from final mixing of the finished products are added. But it can - at for example when using extrusion technology - the components should also be desired ten b) and / or other additives in whole or in part directly into the polymer melt on Meter the extruder so that the mixture of components a) and b) - and give if necessary, other auxiliaries - not already available from the start as pre-assembled  but is only present in the extruder itself. Such a technique is available, for example Instruct if the compounds b) to be metered into the polymer melt flow into present form and an injection of this component is easier than a pre packaging.

It may also be desirable, although to achieve the effect of the invention not necessary - following the use of components a) according to the invention and b) to carry out a corona or plasma treatment in the customary manner.

Polyolefins are preferred as component a) in the context of the invention. All known polymer and copolymer types based on ethylene or propylene are suitable here. Mixtures of pure polyolefins with copolymers are also generally suitable. Polymer types particularly suitable for the teaching according to the invention are listed in the following compilation:
Poly (ethylene) such as HDPE (high density polyethylene), LDPE (low density polyethylene), VLDPE (very low density polyethylene), LLDPE (linear low density polyethylene), MDPE (medium density polyethylene), UHMPE (ultra high molecular polyethylene), VPE (cross-linked polyethylene), HPPE (high pressure polyethylene); 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-copropylene-co-conjugated diene]).

Other suitable types of polymers are: poly (styrene); Poly (methylstyrene); Butt ly (oxymethylene); Metallocene catalyzed alpha olefin or cycloolefin copolymers such as norbornene-ethylene copolymers; Copolymers containing at least 80% ethylene and / or styrene and less than 20% monomers such as vinyl acetate, acrylic acid reester, methacrylic acid ester, acrylic acid, acrylonitrile, vinyl chloride. Examples of such  Polymers are: poly (ethylene-co-ethyl acrylate), poly (ethylene-co-vinyl acetate), Po ly (ethylene-co-vinyl chloride), poly (styrene-co-acrylonitrile). Pfropfco are also suitable polymers and polymer blends, that is, mixtures of polymers in which under other the aforementioned polymers are included, for example polymer blends Basis of polyethylene and polypropylene.

In the context of the present invention, homopolymers and copolymers are based on Ethylene and propylene are particularly preferred. In one embodiment of the present Accordingly, invention is used as a polyolefin exclusively polyethylene; in another embodiment exclusively polypropylene, in another version Rungsfrom copolymers based on ethylene and propylene.

In a very particularly preferred embodiment of the invention, component a) Polypropylene.

Another object of the invention is the use of be according to the above described method prepared hydrophilized and wetted by aqueous media feasible fibers based on polyolefin or polyester for the production of textile fabrics. The textile fabrics are preferably nonwovens. In a particularly be preferred embodiment are these textile fabrics for use in diapers certainly.

For the latter case, the use of textile fabrics in diapers the individual wetting test represents a suitable simulation Usually worn over a period of 3 to 5 hours, with its inside is wetted with urine up to 3 times on average. It must then be ensured that a hydrophilically finished fleece based on an otherwise hydrophobic plastic because it is sufficiently wettable so that the urine penetrate through the fleece and from the Ab sorber material of the diaper can be bound.  

Nonwovens can be made by all nonwoven methods known in the art position, as for example in Ullmann's Encyclopedia of Industrial Chemistry, Vol. A 17, VCH Weinheim 1994, pages 572-581 the. Nonwovens are preferred, either according to the so-called "dry laid" or the spunbond or spunbond process were produced. The "dry laid" process starts from staple fibers, which are usually separated into individual fibers by carding and then using an aerodynamic or hydrodynamic method rens can be folded into the unconsolidated nonwoven. This will then become an example connected by thermal treatment to the finished fleece (the so-called "thermobonding"). The synthetic fibers are either heated to the extent that whose surface melts and the individual fibers ver together at the contact points be bound, or the fibers are coated with an additive, which in the Heat treatment melts and connects the individual fibers. By After cooling, the connection is fixed. In addition to this procedure, of course, everyone is other methods suitable in the prior art for connecting nonwovens be used. Spunbond formation, on the other hand, starts from individual filaments, which are formed by the melt spinning process from extruded polymers, wel be pressed under high pressure through spinnerets. Those from the spinnerets emerging filaments are bundled, stretched and deposited into a fleece, which ches is usually solidified by "thermobonding".

Examples

With different test substances (B1 = example according to the invention; V1 to V3 = Comparative tests) equipped polypropylene test specimens were described above subject to individual wetting test. The test results are in the table 1 compiled; the 28.3 cm sink times (in seconds) are given one, two, three, four and five wetting cycles (columns C1 to C5).

Table 1

It is clear that the values C1, C2 and C3 of example B1 are clearly below the kri table value of 50 seconds and the corresponding values of the comparison games V1 to V3 are clearly superior.

Claims (8)

1. A process for the hydrophilic finishing of fibers containing only or entirely polyolefins or polyesters, a mixture comprising (a) predominantly polyolefins or polyesters and (b) 0.01 to 10% by weight, based on the sum me of polyolefin and polyester - a composition which contains at least one compound from the class of alkyl ethoxylates, at temperatures in the range from 180 to 320 ° C in a customary manner a shaping processing into fibers, characterized in that

• a) no transition metal compounds are metered into the mixture which is subjected to the shaping processing before or during this shaping processing,
• b) the alkyl ethoxylates (b) have the general structure RO- (CH ₂ -CH ₂ -O) _x H, in which the radical R is an alkyl radical having 8 to 14 carbon atoms and x is a number in the range from 4 to 10 and that
• c) the alkyl ethoxylates (b) need at least four cycles in the individual wetting test to fail.

2. The method according to claim 1, wherein polypropylene is used as component a). 3. The method according to claim 1 or 2, wherein as component b) Anlagungspro products from 4 to 7 moles of ethylene oxide with 1 mole of lauryl and / or myristyl alcohol puts. 4. The method according to any one of claims 1 to 3, wherein one in the shaping Ver usual additives for processing plastics and / or as an additional further processing step in the usual way a coro na or plasma treatment.   5. Process around non-woven materials, the fibers of polyolefin or polyester contain, impart hydrophilic properties and make them suitable for aqueous media to make casual, characterized in that one according to the method one of claims 1 to 4 produced hydrophilic fibers based of polyolefin or polyester in the usual way - for example to nonwovens - processed further. 6. Use of the according to the method according to any one of claims 1 to 4 herge made hydrophilized fibers wettable by aqueous media on polyols Fin or polyester base for the production of textile fabrics. 7. Use according to claim 6, wherein the textile fabrics are nonwovens. 8. Use according to claim 6 or 7, wherein the textile fabrics are used are intended in diapers.