DE10257730B4 - Use of a mixture for producing hydrophilic polyolefin materials - Google Patents

Abstract

Use of a mixture comprising at least one polyolefin and at least one melt additive having the general formula R-CO-O-CH ₂ -CH ₂ -O-R ', wherein R is a straight or branched chain alkyl radical having 23 to 35 carbon atoms, and wherein R '= -CH ₃ , -C ₂ H ₅ , -C ₃ H ₇ , -C ₄ H ₉ is, for the production of fibers, filaments, nonwovens and / or nonwoven products.

Description

The The present invention relates to the use of a mixture for Preparation of hydrophilic polyolefin materials, especially fibers and / or filaments containing at least a polyolefin and a melt additive exhibit.

polyolefins are inherently hydrophobic in nature. Especially in the hygiene sector, for example in diapers, for recording serve urine, which is hydrophilic, it is therefore known nonwovens from polyolefins, which produce a hydrophilic Property with a order. Such an order is usually sprayed on or over appropriate roller method applied. It is also known that melt additives To add a polymer to subsequently hydrophilic fibers or To obtain filaments.

For example, goes from the WO 02/42530 A1 to use a hydrophilic oligomer having at least two ether groups. The disadvantage of this is that the ether groups of the hydrophilic oligomer in relation to the tail group is very large, which is why the oligomer has a reduced permanence. From the US 5,439,734 In turn, it is known to add a hydrophilic additive to a polyolefin, which may have two ester groups and additionally an ether group. However, the non-polar alkyl chains provided there at both ends of the oligomer, immediately adjacent to the ester groups, lead to an unequal ratio of the head to the tail group, which in particular reduces the adhesion of the additive to the polyolefin. The oligomer can therefore be partially washed out again.

DE 100 15 554 A1 in turn discloses a hydrophilizing additive obtained from one part of polyethylene glycol with two parts of fatty acids having 10 to 12 carbon atoms or derivatives thereof. Again, the alkyl chains of the fatty acids are too short to enter into a strong interaction with the polyolefin material, on the other hand, the chemical structure is very complex, so that steric effects do not fail.

task Therefore, it is the hydrophilic polyolefin materials of the present invention from a mix available to provide that do not have the aforementioned disadvantages.

This object is achieved by the use of a mixture comprising at least one polyolefin and further at least one melt additive having the general formula R-CO-O-CH ₂ -CH ₂ -OR wherein R is a straight or branched chain alkyl radical having 23 to 35 carbon atoms, and wherein R '= -CH ₃ , -C ₂ H ₅ , -C ₃ H ₇ , -C ₄ H ₉ is, for the production of fibers, filaments, nonwovens and / or nonwoven products.

Particularly preferred is R '= CH ₃ . R 'may furthermore represent both a primary or secondary propyl radical and also a primary, secondary or tertiary butyl radical. The mixture used according to the invention is melted to form a thermoplastic melt, from which fibers and / or filaments are subsequently produced in a conventional spinning process known from the prior art and, in turn, subsequently nonwovens or nonwoven products.

Especially advantageous to the invention used Mix is that On the one hand, the melt additive has an alkyl radical R, which has a has optimal number of C-atoms in order to be used Apply polyolefin material and sufficiently strong van der Waals To enter into interactions with the polyolefin, with preference R is a straight-chain alkyl radical having 25 to 30 carbon atoms. On the other hand, the rest practices R 'no negative steric influences to the ester and ether group of the melt additive, so that the melt additive a higher one Permanence, d. H. low leaching, as comparable, from Hydrophilicity additives known in the art. The ratio of Size of the head group (Rest R 'together Ester and ether group) to the tail group (alkyl radical R) of the melt additive is set up so that this in the thermoplastic melt with the polyolefin, from which then fibers etc. are produced, an optimal migration behavior in that the highly hydrophilic head group attached to the surface of the fibers produced etc. is located.

Preferably, the polyolefin is selected from a group comprising homo-, co-, random and / or Block (co) polymers of ethene and / or propene. However, copolymers with higher alkenes, in particular also butene, hexene and / or octene, are possible. The following polymers have proven to be particularly suitable:
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 weight polyethylene), VPE (cross-linked polyethylene), HPPE (high pressure polyethylene), poly (propylene) such as isotactic polypropylene; syndiotactic polypropylene; Metallocene-catalyzed polypropylene, impact-modified polypropylene, random copolymers based on ethylene, propylene and higher 1-olefins, block copolymers based on ethylene, and propylene; EPM (poly [ethylene-co-propylene]); EPDM (poly [ethylene-co-propylene-co-diene]).

Suitable are also graft copolymers and polymer blends, d. H. mixtures of polymers in which inter alia the aforementioned polymers are included, for example, polymer blends based on polyethylene and polypropylene.

Prefers are further copolymers of ethene and / or propene with higher olefins and / or Diolefins.

Especially a preferred polyolefin is a homopolymer of ethene or propene. In a preferred embodiment The invention uses a mixture containing 0.5 to 10% by weight, more preferably 0.5 to 3% by weight, more preferably 1 to 2.5 Wt%, of the melt additive. Furthermore, the mixture can in particular from 0.05 to 2% by weight, preferably from 0.1 to 0.5% by weight, of titanium dioxide exhibit. Preferably used mixtures have 96 to 99 wt% Homopolypropylene or homopolyethylene, 0 to 1% by weight of titanium dioxide and 1 to 3% by weight of the melt additive. Such mixtures could used without problems, for example for the production of a spunbonded fabric despite the predominance in the thermoplastic melt high temperatures in a range between 190 and 310 ° C. For the production The thermoplastic melt can first of all be used according to the invention Mixture in the unmelted state mixed together and then melted However, it may also be the melt additive and optionally other additives such as titanium dioxide by means of side feeders fed into an extruder of the polyolefin melt.

By the inventive Use can be made of fibers, filaments, nonwovens and / or nonwoven products produce. In particular, you can Also bicomponent fibers are produced. For example, a Core-shell structure in the production of fibers or filaments be created. According to one embodiment only the jacket has the polyolefin material with the melt additive on. The core is not equipped with melt additive. A another embodiment provides that the core is a homopolypropylene, the coat in turn has a homopolyethylene, which with the Enamel additive equipped is. Such structures allow the melt additive only in those Areas in which it is required to develop its hydrophilic Property is necessary. In addition to a core-shell structure can a fiber or filament cross-section also other multi-component distributions exhibit. For example, you can this segment structures, crescent structures, non-circular geometries or other structures.

The Nonwoven produced using the mixture according to the invention, is in addition to the application in a so-called "top sheet" also used as so-called "acquisition layer ". Due to its permanently hydrophilic property, it can do so manufactured fleece in addition to the use in hygiene and / or medical articles also be used where there is a quick fluid intake arrives. This is the case for example in the filter area.

So For example, a filter layer may comprise the hydrophilic nonwoven wherein the liquid is transported to a further underlying layer. particle in the liquid can retained by the fleece, however. Due to the fast fluid intake it is avoided that forms a liquid jam in front of the fleece.

The under use according to the invention fabric produced preferably has a penetration time (strike through time) according to the test method EDANA 150.3-96 of less than 4 seconds up. To determine the Penetration time according to EDANA 150.3-96 becomes one defined amount of synthetic urine (0.9% saline) applied to the fleece to be examined. The fleece lies on it a special filter paper. To the behavior of the fleece too to be able to characterize with repeated contact with moisture is made a repeated determination of the penetration time. Of the The test is usually three times at intervals of one Minute repeated (repeated strike through time).

Further Preferably, the fleece has only a very small, if any, Leaching of the melt additive on. In this case, the surface tension is preferably of for the Auswaschtest used water after a trial run more than 65 mN / m. The produced using the invention Fleece thus has no pronounced leaching of the melt additive from the polyolefin material used. By the synonymous with multiple Moire the fleece consistently high hydrophilicity of the same through the the nonwoven remaining in the nonwoven is the nonwoven in particular for recording, even repeated recording, larger amounts of liquid and moisture particularly suitable. Furthermore, the nonwoven is in view of this outstanding penetration values particularly suitable, in combination with other fleece or other layers, depending on the application, to be used.

These and further advantageous embodiments and further developments of The present invention will be apparent from the following examples explained in more detail. The thereby set out features with the further described above lead to additional developments, the but in detail not be executed here. They show in detail:

1 a section of a hygiene product;

2 a section of an oil suction filter;

3 a section of a liquid-receiving product;

4 a bicomponent fiber in cross section; and

5 a fiber that is divided into segments.

1 shows a section of a hygiene product 1 , The hygiene product 1 has a top layer 2 , a distribution situation 3 and a core 4 on. The top layer 2 is of a nonwoven that is highly hydrophilic due to the addition of the melt additive. The hydrophilic nonwoven picks up liquid and forwards it to the distribution layer 3 , From the distribution situation 3 can the liquid to the core 4 be passed on. At the core 4 the liquid is stored. In addition to the hydrophilic property of the top layer 2 can also the distribution situation 3 be prepared using the mixture according to the invention and thus be highly hydrophilic. The distribution situation 3 However, it can also be made of another thermoplastic material. For example, the top layer 2 a spunbonded fabric, while the distribution layer 3 is a meltblown web. Preferably, the distribution layer 3 a higher hydrophilicity, preferably at least about 10%, more preferably at least about 20% higher than the top layer 2 , In this way, a suction effect from a surface of the top layer 2 towards the distribution position 3 achieved.

2 shows a section of an oil filter 5 , The oil filter 5 has a suction layer 6 on. The suction layer 6 on the one hand serves to receive oil that comes into contact with the absorbent layer. On the other hand, the suction layer is used 6 also as a filter against particles contained in the oil, which should not be transported further. The suction layer 6 closes in this example another, not necessarily necessary filter layer 7 at. The filter layer 7 is preferably finer pored than the suction layer 6 , The suction layer 6 serves as a pre-filter for the filter layer 7 , The oil filter 5 may for example be provided for permanent use, or even be used only when needed. The suction layer 6 is formed by a prepared according to the invention using the mixture, hydrophilic-equipped fleece. The underlying filter layer 7 , which may also have suction properties, may also be made of a hydrophilically finished nonwoven produced using the mixture according to the invention. The suction layer 6 can also serve individually as oil suction. This is used, for example, where escaping oil from machines o. Ä. Is to be collected.

3 shows a use of a prepared according to the invention using the mixture for liquid absorption, in which a hydrophilic fleece 8th in a product 9 , here arranged between two further layers, is contained. The hydrophilic fleece 8th is able to moisture in the product 9 to record and save in oneself. For example, the product 9 used in the hydrophilic nonwoven 8th to release stored moisture when needed. The release, for example, by heating the product 9 respectively.

4 shows a cross section of a nonwoven fiber 10 , The fleece fiber 10 is a bicomponent fiber with a core-shell structure. According to one embodiment, a core 11 a different polymer material than a jacket 12 the nonwoven fiber 10 , The coat 12 is made from the mixture used in the invention for hydrophilic adjustment of the nonwoven fiber 10 , According to a further embodiment, the core 11 and the coat 12 also have the same polymer material, wherein the jacket 12 is prepared using the hydrophilic mixture according to the invention, the core 11 However not. A further development provides that there is a hydrophilic gradient and thus one of the melt additive over a cross section of the fiber. For example, the core 11 have a lower proportion of melt additive than the shell 12 , Also, a steady increase in the amount of melt additive to the surface of the nonwoven fiber 10 according to another embodiment.

5 is a cross section through a fleece filament 13 , The fleece filament 13 here has a total of four segment sections 14 on. However, there may also be more than four, but at least two segment sections. The segment sections 14 may differ according to an embodiment in the polymer material used. According to another embodiment, the segment sections can 14 , also in addition, differ by the melt additive used. For example, some segment sections of the nonwoven filament 13 be made more hydrophilic, while other segment sections are less hydrophilic. According to a further embodiment, some of the segment sections may also be hydrophobic, the others may be hydrophilic.

Examples

Different polyolefin blends were prepared and made from these using the Lurgi-Docan spunbond process a nonwoven having a basis weight of 30 g / m ² . Specifically, the nonwovens were made from the following materials:

reference

When Reference was made to a spunbonded web made of 100% by weight homopolypropylene (Basell company, Moplen HP 460R), which is a standard ground stabilization for the Extrusion process has.

Mixture 1

Mixture 1 comprised 98% by weight of the homopolypropylene according to the reference and additionally 2% by weight of the melt additive C ₂₅ H ₅₁ -CO-O-CH ₂ -CH ₂ -O-CH ₃ .

Mixture 2

mixture 2 showed 97.6% by weight of homopolypropylene according to the reference, 2% by weight of Melt additive according to the mixture 1 and in addition 0.4% by weight of a titanium dioxide masterbatch (Clariant, Remfin RCLAP, Grain size 2.2 to 2.6 mm).

Both the reference and Blends 1 and 2 were made into a spunbond under identical process conditions. Subsequently, the breakthrough time according to EDANA 150.3-96 and the wash-out was based on US 5,945,175 determined the spunbonded nonwoven fabric.

The wash-out was determined by the following test method:
It is determined before immersing the spunbonded in the water whose surface tension according to DIN 53914. From the nonwoven fabric samples are punched out (about 2.5 × 22 cm, about 0.17 g) and dipped for 30 minutes in 80 ml of water. Subsequently, the surface tension of the water is measured again. Table 1 Surface tension (mN / m) Mixture 1 Mixture 2 Before the test 72.5 72.5 After the test 65.5 66.8

Usually, in polyolefins with a subsequent hydrophilic finish after the "wash-out" test, the surface tension is lowered significantly below 60 mN / m. However, as shown by the test results for Mixture 1 as well as Mixture 2, the surface tension remains approximately constant in the mats produced using the mixture according to the invention. From this it can be concluded that a washing out of the melt additive is omitted. Mixtures 1 and 2 as well as other erfindungsge According to used mixtures enable a permanently hydrophilic nonwoven production. In particular, the melt additive is added in an amount such that the water after the wash-out test has a surface tension that changes by less than 15% from the original one. Preferably, the change in the surface tension of the water is in a range that is below 2%. An advantageous surface tension of the water after leaching of the nonwoven lies in a range between 60 mN / m and 70 mN / m.

The breakthrough time according to EDANA 150.3-96 is shown in Table 2. Table 2: Time (s) reference Mixture 1 Mixture 2 1st run > 60 2.3 3.8 2nd run > 60 2.9 3.3 3rd run > 60 2.8 2.9

The Reference fleece rejected the for Polyolefins have typical hydrophobic properties. The used synthetic urine (0.9% saline) was unable to to penetrate the fleece. Therefore, the test was after more than 60 Seconds each canceled. Each with the melt additive produced nonwovens according to the mixtures However, 1 and 2 showed breakthrough times below 4 Seconds lay. As can be seen from Table 1, were the Times at the fleece from mixture 1 slightly below the times of Fleece from mixture 2. While in the case of the nonwoven after mixture 1, the hydrophilic properties of the nonwoven slight decreases after the first run, the hydrophilic property increases the fleece from the mixture 2, however, in the further runs.

As from the times to be taken from Table 2 is to be seen is the nonwoven equipped with the melt additive not only in the first Run able for a fast permeability of the applied artificial To provide urine. Rather, this property is beyond with multiple wetting. This is particularly important when using such a nonwoven as a top layer in a diaper, bandage or incontinence products. at this product usually has not only a single fluid thrust rather, it is required that such a fluid intake and distribution is also repeatable.

Around the wearing comfort of such a hygiene article for the user to increase, the web advantageously has a penetration time which even after the triple test run is less than 4 seconds.

Claims (7)

Use of a mixture comprising at least one polyolefin and at least one melt additive having the general formula R-CO-O-CH ₂ -CH ₂ -O-R ', wherein R is a straight or branched chain alkyl radical having 23 to 35 carbon atoms, and wherein R '= -CH ₃ , -C ₂ H ₅ , -C ₃ H ₇ , -C ₄ H ₉ is, for the production of fibers, filaments, nonwovens and / or nonwoven products. Use according to claim 1, characterized in that the Polyolefin selected is from a group comprising homo, co, random and / or block (co) polymers of ethene and / or propens. Use according to one of the preceding claims, characterized in that the Polyolefin is a homopolymer of ethene or propene. Use according to one of the preceding claims, characterized in that the Mixture 0.5 to 10% by weight of the melt additive. Use according to one of the preceding claims, characterized in that the Mixture further comprises 0.2 to 2% by weight of titanium dioxide. Use according to claim 1, characterized in that a Nonwoven is made, which has a breakthrough time (strike through time) according to EDANA 150.3-96 of less than 4 s. Use according to claim 7, characterized in that the surface tension of the water after a Auswasieht the fleece larger than 60 mN / m.