EP1155178B1 - Method and device for producing a structured, voluminous non-woven web or film - Google Patents

Abstract

The invention relates to a method for producing a structured, voluminous non-woven web or velourised film from a thermoplastic by producing an unstructured web and subsequently processing this web using a pair of rollers (10a, 10b). The pair of rollers consists of a positive roller (10a) having numerous positive bodies distributed over the roll sleeve surface and a negative roller (10b) having equally as numerous cavities. During the rolling process, the positive bodies engage with the cavities and stretch the unstructured web in the area of the roller engagements in such a way that a deep-drawn web structure with numerous cavities is produced. After the web has passed through a roller gap, the deformed web, still bonded to the positive roller, is brought into contact with a perforating tool and perforated.

Description

The invention relates to a method for producing a structured, voluminous nonwoven web or velorized foil from a thermoplastic by producing an unstructured Path and post-processing of the unstructured path through a pair of rollers consisting of a positive roller with numerous positive bodies distributed over the surface of the roller and from a negative roller with just as many depressions exists, the positive body during the rolling process intervene in the depressions and the path in the area of Roller interventions stretch, so that a deep-drawn, numerous Path structure having recesses results.

The aforementioned method is used in particular for Production of structured, voluminous nonwovens (DE 195 47 319 A1). First, a raw fleece is made a variety of single filaments or staple fibers made from which a raw fleece is made. This Raw fleece is reworked by a second pair of rollers, the knobs engage in the recesses and the Stretch the raw fleece in the area of the roll interventions.

A similar procedure can also be applied to a unstructured film or on a velor film, such as according to DE 195 24 076 C1 is known.

A device is also known from DE 78 04 478 U1 to produce a moisture-permeable film in which a film of thermoplastic material so far is heated so that it has a deformation temperature close to that has thermoplastic temperature range of the material. At this temperature, the film is inserted into an embossing gap and while embossing while cooling deformed in the thermoplastic temperature range. The The embossing gap is between a cooled and an engraved one Metal cylinder and an elastic roller formed. Behind The foil is in contact with the embossing gap on the metal cylinder cooled further. Then the ends of the generated ones Expressions through brief heating on or over the the temperature applied during the deformation shrunk, the openings forming.

However, this known method only relates to smooth film and uses a precisely adjustable temperature and shrink cycle. This results on the one hand a restriction to a certain primary material, to the other complicated temperature control is required.

The task arises, one according to the known method manufactured film or web in the provided with recesses Areas at the bottom of these wells with an opening, Perforation or even just thinning that a vapor or liquid passage through these perforations or dilutions is possible.

The invention is thus in the field of technology Production of perforated, three-dimensional webs, as they are especially for disposable hygiene products be used. The main task here is already developed methods in a relatively simple manner expand to the extent that the manufactured by the method three-dimensional structured tracks in more reliable Perforations on the wells without changing the essential procedural steps Need to become.

This problem is solved by one in two main Embodiments manifesting invention, wherein in both cases results in a structured path that is more permeable is as the unstructured path.

On the one hand, the method mentioned at the beginning can be supplemented by this be that after passing the web through the nip the deformed and still adhering to the positive roller Membrane in the top area of the knobs with a perforating, contacted and perforated, in particular, tearing tool, in particular is torn open, at least in each case perforation or thinning in the area of the sole the depression is generated.

In this process, it is first deformed and then one Perforation created.

But it is also possible the other way round, first a perforation put on and tear open after the first perforation. For this purpose, it is proposed that the unstructured web through the nip the web in the later Perforation area of the knobs perforated with a tool or is diluted and at least one perforation each or thinning in the area of the later sole of the depression is generated, and that during the rolling process Positive bodies that engage in the depressions and the Stretch the path in the area of the roller interventions, the depressions Tear open further in their apex area and / or further dilute.

Both method options represent embodiments of the same Invention, namely the basic idea that in a already fluffy web, namely fleece or velor Foil, generally in the apex area with a recess a greater tension is generated, which is true in the course of the process and over a certain service life, however, at the moment of creation, a introduced crack or thinning increases or expands so that there is a perforation at the desired location or, depending on the choice of material, a thinning occurs.

The method is particularly suitable for that from DE 195 47 319 known method in which when using a Nonwoven web is first made of a raw nonwoven that consists of a There are a large number of individual filaments that are stretched and tangled down to a fiber layer, the initial Stretching the individual filaments only in the range of 50 to 70% of the maximum possible stretch is done, and then the fiber layer is pressed and welded and in this form is processed further. Further processing is then carried out by engaging knobs that the raw fleece in Stretch the area of the roller interventions and corresponding perforations leave.

But it is also possible, generally for perforating or thinning to use another roller that is the positive roller contacted after running the train while the train is still on. Here, needle or hot rollers are particularly suitable. The needle or hot rollers can with one temperature operated from 140 ° to 200 ° C in the contact areas.

The structuring of the method according to the invention manufactured product is improved in that the negative roller has an engraving that leads to an engraving of the positive roller is inverse, so that when the rollers roll, elevations, such as bars and knobs on the Surface of one of the rollers are arranged in compatible Grooves and troughs on the surface of the other roller intervention.

The positive bodies of the positive roller are advantageously in rows arranged knobs, and the surface of the negative roller has Lamellar webs arranged in the axial direction with intermediate ones Wells so that when rolling the rollers against each other, the slats in those kept free by the knobs Intervene alleys.

The rollers of the pair of rollers can be made of metal. In particular the metal has essentially that for both rolls same Rockwell hardness (HRC) greater than 50 HRC.

It is particularly advantageous as a positive and / or as a negative roller to use such a roller, which has a metal core has and the outer jacket by a plastic coating of the metal core is formed. Such a plastic outer jacket can be engraved in particular by means of a laser, which enables the roller to move quickly and inexpensively Patterns of any type can be provided. There a Engraving laser can be operated very precisely and fully automatically, the patterns can be applied with such high precision that it is possible to use the plastic-coated surfaces the positive and the negative roller with very fine intermeshing To provide patterns.

The height of the knobs is preferably between 0.8 and 2. mm. The focus is on the three-dimensional structure of the goods to be manufactured.

The mutual spacing of the knobs in a linear arrangement should be between 1 and 2.5 mm. The number of knobs on 100 cm ² roller surface is preferably between 2000 and 3000.

The knobs can end in different tip shapes, for example, they can be designed like an onion tower or in a pyramid with a tip angle of 90 ° ± 20 ° leak.

The rollers can also be of different heights during the process be tempered, preferably the temperature of the Negative roller at a temperature at least 20 ° C lower is set as that of the positive roller.

The following are suitable as starting materials for web production other polyethylene, polypropylene, polyamide, polyvinyl alcohol, Polyester, polyetherester or polycarbonate.

Essentially all thermoplastics are suitable from which structured foils according to the known methods have it made. Examples of such nonwovens are can be used from the aforementioned thermoplastics according to the Spunmelt process, the carding process, the airlaid process, the spunlaced process or the melt blown process were manufactured.

To improve stretching, it is proposed that during of all stretching and perforating processes to the side of the web Roll edges are kept taut.

Surprisingly, a nonwoven, a foil or a velor foil can be used, the due to a pair of rollers consisting of nub and matrix rollers is sent and after passing through the nip with the help of one pressed onto the pimples on the velor foil Hot roller, perforated if necessary with friction becomes. Manufacturing process for such a velor film are known from the patent DE 195 24 076. With the present method it is possible in the sole of the depression to create an opening so that the recess is practical represents a small funnel. It will be a full one Perforation of the fleece or another web achieved, wherein the three-dimensionality that has already been created or is yet to be created remains fully intact. It is astonishing that the production speed already at the experimental stage Could be increased 300 meters per minute. That speed can be particularly by using a higher temperature of the pimpled roller at a significantly lower Raise the temperature of the negative roller.

In particular through the additional pressing of the already deformed The opening on the forming positive roller becomes the path widened and displaced remaining fibers there or melted down. The opening structure of the fleece or the Web is thereby improved.

A roller assembly as part of an implementation device the above process modifications is thereby characterized in that the positive roller provided with positive bodies combs with a negative roller and the roller pair one further positive roller is connected, the positive areas with the rotation of the rollers with the depressions of the Negative roller coincides.

The pair of rollers can also be followed by a needle roller, with which the web, which is still resting on the positive bodies and is already provided with depressions, can be perforated. This requires a particularly dense needle roller that carries at least 5 to 50 needles per cm ^{2 of} roller surface.

The already mentioned second version of the method is the opposite Path. Here is a precisely structured, heated needle roller required to deliberately pre-perforate the To cause web. In the following roller circulation, the Intervention of the positive roller in each case existing perforation expanded and stabilized. A die roller takes that In the middle of the roller stand. The positive roller is underneath arranged. There is a heatable needle roller at the top of the roller stand attached, which is equipped with single needles or tufts of needles is. The locations of the individual needles or tufts of needles are in the rotation of the rollers with the increases in Positive roller compatible. The needle roller runs with the positive roller synchronous and perforated a web as it passes in a first step where, in the further course of the Path processing recesses arise.

The temperature of the needle roller at the top of the Needle brought to 140 ° and 250 ° C if it is polyethylene or polypropylene. For polyesters and others This temperature is higher for plastics, for example 180 ° to 300 ° C.

The needle roller mechanically perforates or melts the web Fibers or film so that a stable pre-perforation is created. The web peeled off the positive roller also shows after the recess has been made, a clear and defined opening. The three-dimensionality is retained. First is the hole formed by the needle roller is very small, for example 0.05 to 0.1 mm diameter. It will then be on one Diameter from 0.5 to 1.4 mm brought by the targeted Intervention of the knob roller. The web is stretchable accordingly of their material selection.

Fig. 1

schematisch den Herstellungsprozeß einer dreidimensional strukturierten und mit öffnungen versehenen Vliesstoffes oder Folie;

Fig. 2

ein vergrößertes Detail aus der Figur 1, nämlich eine Walzenanordnung;

Fig. 3

eine Walzenanordnung in veränderter Ausführungsform;

Fig. 4

eine weitere Ausführungsform einer Walzenanordnung;

Fig. 5

eine weitere Ausführungsform einer Walzenanordnung;

Fig. 6

ein Beispiel einer dreidimensionalen strukturierten Folie in schematisierter Darstellung;

Fig. 7

eine andere Folienstruktur im Schnitt.

Embodiments of the invention are explained with reference to the drawing. The figures in the drawing show in detail:

Fig. 1

schematically the manufacturing process of a three-dimensionally structured and provided with openings non-woven fabric or film;

Fig. 2

an enlarged detail of Figure 1, namely a roller assembly;

Fig. 3

a roller arrangement in a modified embodiment;

Fig. 4

a further embodiment of a roller arrangement;

Fig. 5

a further embodiment of a roller arrangement;

Fig. 6

an example of a three-dimensional structured film in a schematic representation;

Fig. 7

another film structure in the cut.

In Figure 1, the career of a structured, voluminous fleece is shown schematically. A storage silo 1 contains a thermoplastic granulate, for example made of a polyethylene, polypropylene, polyamide, polyvinyl alcohol, polyester, polyether ester or polycarbonate which can be processed into a nonwoven. It passes into a heatable extruder 2, where it is plasticized and conveyed from the extruder screw 2 'to the nozzle 3 of the extruder. The extrudate is then fed into a spinneret via a guide trunk 4 and, in accordance with the so-called spunlaced method, is cooled and stretched as a filament in an attenuator 18. The single fiber is not fully drawn here. Only a degree of stretching of 60 to 70% for polyethylene and polypropylene or of 50 to 70% for polyesters or for polyamide is advantageous. This is in contrast to the usual stretching conditions, which prefer full process stretching for reasons of material savings. In a so-called disperser 19, the threads are tangled and cooled (cooling fan 22). The stretched spinning strand 6 is placed on a net conveyor 7, which is underlaid with a vacuum frame 8, so that the tangled fiber lies flat on the net conveyor 7. It is then compressed between a first pair of rollers, namely calender rollers 91, 9b. After processing, a raw nonwoven web 12 is obtained. This still has a basis weight of approximately 20 g / m ² and is only a few millimeters thick.

The raw strand then arrives at a roll stand 20. In the Roll stands are arranged three rolls one above the other. First the raw fleece 12 passes between the nip 21 the two rollers 10a and 10b. The roller 10a is one Positive roller with numerous, over the surface of the roller distributed knobs, as can be seen, for example, from FIG. 2. The knobs can have a truncated pyramid or truncated cone shape have, but they can also taper to a point, for example in a pyramid with an acute angle of 90 ° ± 20 °. After passing the web 12 through the nip 21 is the deformed and still on the positive roller 10a adhesive web in the crown area of the knobs in turn another nip 41 introduced where another negative roller 31 is arranged, but which is set so that the corresponding positive parts against the outside of the knob press and a perforation in the crown area of the knobs in the preformed web 12 which cause expanded due to the existing tension. The slide will then peeled off overhead and represents a three-dimensional structured foil with defined openings. The foil is therefore again on the shaping knob roller pressed on, which results in the fleece opening and widened. Any remaining fibers are displaced or melted off.

Instead of a raw fleece, a velor foil can also be used become. Figure 3 shows an example of processing a such foil. The film runs as an unstructured web 32 with a material thickness of 60 µm with its velor top against the nub roller 10a in the nip 21 on. The unstructured web 32 is formed in the roll gap 21 and a three-dimensional structure with numerous fine ones Cylinders pulled out. The structure corresponds in detail the respective roller surface.

A 190 ° hot steel roller 23 is placed against the roller 10a and driven slightly friction against the roller 10a. The heating roller, which runs non-stick on its surface is moving against the passing roller 10a and causes the shrinking film to open and tear open in the area of the sole of the depression. It follows a small funnel with an opening at the bottom. After the second forming, the perforated and three-dimensionally formed film pulled off the roller 31, chilled and wrapped. The surface shows an even, very fine velor effect. The production of the film as such is described in the patent specification DE 195 24 076th

In particular, the multi-layer process mentioned in the cited document used. The top layer is 40 µm and that Back layer 20 µm thick. The top film is a mixture of two made by the metallocene process HDPE products. The film also contains lubricants, Pigments, stabilizers and release agents. For the On the back, an HDPE is used, the lower one Has melt index. The film can be made according to the known Chill-roll processes are made and with a velor effect be provided. The resulting from the velor effect Knobs can also be stretched. Instead of the steel roller 23 can also be a very dense brush roller with steel tips be provided. Here is a slide in first the nip 21 is inserted, then the brush roller processed still lying on the knobs, so that thinners and perforations in the already deformed film result. Then the pre-structured deepening pressed in again and thus a very clear three-dimensional structure with openings in the Soles of the wells created.

In the present example, the negative roller 10b has a temperature from 40 to 60 ° C, the middle roller has a temperature of about 150 ° C and the upper negative roller 31 again a temperature from only 40 to 60 ° C. The brush roller can also brought to a temperature of 120 to 150 ° C.

A roller arrangement is shown in FIG the unstructured web 32 into a nip 25 is introduced, with the help of a needle roller 24 before Passing the unstructured path 32 through the other Roller gap 21 in the later apex area of the knobs 11 these Roller 24 perforated or thinned the material and each at least one perforation of the dilution in the area of the later sole of the depression is generated. The continued Film then passes into the nip 21, where during the Rolling the positive body, that is nubs 11, in the Intervening recesses and the web 32 in the area of the roller interventions stretch. The recesses in their Peak area further torn open and / or further thinned. The structured and perforated web is from the roller 10a deducted and sent for further processing.

Here, the temperature of the roller 10a is about 140 to 160 ° C, while the roller 10b only a temperature of 40 ° C. The needle roller 24 is at a needle tip temperature heated from 160 ° C. The roller stand can be used 4 for nonwovens or films.

Figure 5 shows a further variant. Here is a structured one or textured or velorized, but otherwise unstructured Web 32 in the nip 21 between one Positive roller 10a and a negative roller 10b introduced and thereby subjected to a first structuring. With help a hot roller 26, which is at a temperature of 120 ° to Is brought to 130 ° C and works with low friction the web lying on the knobs 11 torn, that is provided with thinners and perforations. Subsequently the web is again in a gap 25 between a negative roller 27 and the positive roller 10a inserted and again deep drawn and stretched. This roller has a temperature of 60 ° C. Here again the film material is stretched, see above that the already latent thinnings and perforations, which are still relatively fine, are enlarged and become a uniform three-dimensional structure with openings the respective trough soles. The structured film 33 is withdrawn via a film trigger 34 and a bearing fed. A base film is used for this the base of polyethylene with elastic properties that is produced as a two-layer film. The film is 2.5% Provide titanium dioxide and lubricant. The starting film has for example, a thickness of 50 microns and can then can be used well for hygiene applications. It shows one quick penetration for moisture and exhibits due to excellent three-dimensionality rewetting values on. By filling with kaolin, chalk or titanium dioxide the film gets a very "dry grip".

In Figure 6 is an enlarged view and schematic shown a film structure. It can be seen that the Troughs 120 have an approximately pyramid-like shape and with Perforations 122 are provided on the trough sole. The hollows are separated from one another by webs 121. The proportions are illustrated by the "1 cm" scale.

Figure 7 shows a similar structure. Here is a velor foil have been used, each with very fine cylindrical Troughs are provided, which are in their respective bases are open.

Claims (20)

1. Process for producing a voluminous non-woven web or velourised sheeting from a thermoplastic material by producing an unstructured web and by post-processing the unstructured web (12) through a roller pair (10a, 10b) which consists of a positive roller (10a) with numerous positive bodies (11) distributed over the roller outer surface and of a negative roller (10b) with equally numerous recesses (14), wherein during the rolling process the positive bodies engage in the recesses and stretch the unstructured web (12) in the region of the roller engagements so that a deep-drawn web structure comprising numerous depressions is produced,
   characterised in that after the web (12) has passed through the roller gap the deformed web, which still adheres to the positive roller, is contacted in the peak region of the nubs by a perforating, in particular tearing, tool and is perforated, in particular torn open, wherein in each case at least one perforation or thinned area in the region of the bottom of the depression is produced so that the non-woven web or velourised sheeting is more porous than the unstructured web.
2. Process for producing a structured voluminous non-woven web or velourised sheeting from a thermoplastic material by producing an unstructured web and by post-processing the unstructured web (12) through a roller pair (10a, 10b) which consists of a positive roller (10a) with numerous positive bodies (11) distributed over the roller outer surface and of a negative roller (10b) with equally numerous recesses (14), wherein during the rolling process the positive bodies engage in the recesses and stretch the unstructured web (12) in the region of the roller engagements so that a deep-drawn web structure comprising numerous depressions is produced,
   characterised in that before the unstructured web passes through the roller gap, the web is perforated or thinned by a tool in the region which will become the peak of the nubs and in each case at least one perforation or thinned area is produced in the region which will become the bottom of the depression and that during the rolling process the positive bodies, which engage in the depressions and stretch the unstructured web (32) in the region of the roller engagements, tear open and/or thin the depressions still further in their peak region so that the non-woven web or velourised sheeting is more porous than the unstructured web.
3. Process as claimed in claim 1 or 2,
   characterised in that when using a non-woven web a raw non-woven fabric is first produced which consists of a large number of individual filaments which are stretched and are randomly laid down to form a fibre layer, wherein the initial stretching of the individual filaments takes place only in the region of 50 to 70% of the maximum possible extension, and subsequently the fibre layer is pressed and bonded and further processed in this form.
4. Process as claimed in claim 1, characterised in that a needle roller is used as a perforating or thinning tool, this needle roller coming into contact with the positive roller after passage of the web but while the web is still lying thereon.
5. Process as claimed in claim 4, characterised in that the needle roller is operated at a temperature at the needle points between 140 to 200°C.
6. Process as claimed in any one of claims 1 to 5, characterised in that the negative roller (10b) has engraving which is the reverse of engraving (10a) on the positive roller (10a) so that, as the rollers (10a, 10b) roll against each other, ridges and nubs (11), which are disposed on the surface of one of the rollers (10a, 10b), engage in matching grooves and recesses (14) on the surface of the respective other roller, wherein the positive bodies of the positive roller are nubs (11) disposed in rows, and the surface of the negative roller has rib-like ridges (13) disposed in the axial direction with recesses (14) lying therebetween, so that when the rollers roll against each other the ribs engage into the channels left free by the nubs.
7. Process as claimed in claim 6, characterised in that the outer surfaces of the rollers (10a, 10b) consist of metal.
8. Process as claimed in claim 6, characterised in that at least one of the rollers (10a, 10b) has an outer surface formed from a laser-cut synthetic material coating.
9. Process as claimed in claim 6, characterised in that the rollers (10a, 10b) are tempered to a different level.
10. Process as claimed in claim 9, characterised in that the temperature of the negative roller is set to a temperature which is at least 20°C lower than the positive roller.
11. Process as claimed in at least one of the preceding claims, characterised in that when processing a non-woven fabric during the second stretching procedure the raw non-woven fabric is kept at a temperature which is substantially equal to the temperature which prevailed during the first stretching procedure.
12. Process as claimed in at least one of the preceding claims, characterised in that a polyethylene, polypropylene, polyamide, polyvinyl alcohol, polyester, polyether ester or polycarbonate is used as the starting material to produce the web.
13. Process as claimed in at least one of the preceding claims, characterised in that the non-woven fabrics used should be those which have been produced according to the spun-melt process, the carding process, the air-laid process, the spun-laced process or the melt-blown process.
14. Process as claimed in at least one of the preceding claims, characterised in that during the stretching procedures the web (12) is laterally held taut at the roller edges.
15. Process as claimed in at least one of the preceding claims, characterised in that the starting material used is a non-woven fabric, sheeting or velour sheeting, which is caused to pass through a roller pair consisting of a nub roller and a bottom roller and which, after passing through the roller gap, is perforated with the aid of a heated roller pressed against the velour sheeting at the nubs, if necessary with frictioning.
16. Process as claimed in claim 15, characterised in that the velour side is directed towards the axis of the nub roller.
17. Roller arrangement as part of a device for carrying out the process as claimed in at least one of the preceding claims, characterised in that the positive roller (10a) provided with positive bodies meshes with a negative roller (10b) and a further positive roller is connected downstream of the roller pair (10a, 10b), the positive regions of which coincide, during rotation of the rollers, with the recesses of the native roller.
18. Roller arrangement as part of a device for carrying out the process as claimed in at least one of the preceding claims 1 to 17,
    characterised in that the positive roller (10a) provided with positive bodies meshes with a negative roller (10b) and a needle roller is connected downstream of the roller pair (10a, 10b), with which needle roller the web, which is already provided with depressions and which is still lying on the positive bodies, can be perforated.
19. Roller arrangement as part of a device for carrying out the process as claimed in any one of the preceding claims 17 and 18,
    characterised in that a needle roller, which is fitted with individual needles or bunches of needles and on which the locations of the individual needles or bunches of needles match with raised areas of the positive roller when the rollers rotate, runs synchronously with the positive roller and, when an unstructured web passes through, this web can be perforated in a first working step in the regions were depressions are produced as the web processing is continued.
20. Roller arrangement as claimed in claim 18 or 19, characterised in that the points of the individual needles and bunches of needles can be heated to a temperature between 140° and 250°.

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