DE1560871A1 - Two-layer fibrous web made from non-woven fibers - Google Patents

Description

The invention relates to a two-ply sheet of non-woven fibers. Such a web, especially if it is very light, has particular advantages when used as a filling material for sanitary towels, as a cover material for cellulose diapers or cellulose towels, as a surface material for absorbent tampons and for numerous similar purposes. } ■ "■■ .- ■ Soap synthetic monofilaments and fibers made from them of pile length are known, numerous attempts have already been made to convert very thin and light layers of monofilaments or staple fibers of |

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low DenpLer-fert laei sanitary towels, cellulose diapers ■ / "

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o. The like. To be used. This is because it was found _for a Bahj | made of staple fibers (e.g. cotton) and! synthetic parsers are mif ■ a denier - ^ / ert of 0.5 to J (eg, | of viscose fibers, acetate fibers, lon%, polyester fibers, Alcryl-Fitril-Paeern and the like.).

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■ .separate the fibers into a substantial one in a stretching machine Extent aligned and arranged adjacent, has a much higher tensile strength after joining than usual carded tracks.

Highly curled webs can be processed on stretching machines

of fibers with staple length. Under the term "high-

¹ · · the

warped ¹¹ is understood to mean that approximately "80 ^ to 95 /" / fibers contained in the web are oriented in the machine direction. This high degree of orientation, which is also important to the present invention, differs from the orientation of the fibers with conventional carded webs, since there only about 50 to 70% of the fibers are parallel to the machine direction aligned. «■ ■

The use of warped, lightweight webs as cover layers for sanitary towels, diapers, tampons and the like. has not yet been able to establish itself in practice because it proved to be extraordinarily difficult! the synthetic ones to connect fibers with each other in such a way that the permeability, the supple grip and di <

Dimensional stability of the

Material is preserved. This is especially true when the synthetic fibers have only a low denier value, for example ^; wise have a denier of Oi5 to 3. Unbound

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Sheets that are only made of highly-insulated, very thin synthetic Fibers are extremely sensitive. Therefore, it is very difficult ·, '- such-webs during the application of a Use a suitable adhesive to hold it under even tension. In addition, because of the low weight Such webs require a considerable amount of adhesive to make the webs into a convenient handling Bring sufficient strength. As the amount of adhesive increases, the web becomes increasingly stiff, with the desired supple feel of the web is destroyed and also a significant reduction in liquid permeability entry. '-'

Attempts have already been made to reduce the high stretching produced fluffy webs directly with thermoplastic Adhesives to cover to increase the rigidity, which is due to the thermosetting used until then

to avoid
Materials adjusts These attempts did not lead to any result, namely "especially not because fibers are pulled out of the web because of the stickiness of the adhesive on the pressure roller, the high alignment of the individual fibers is destroyed and the uniform structure of the web is interrupted These disadvantages could be reduced somewhat if the web was temporarily bound with a subsequently exchangeable adhesive when it left the stretching machine, but the result was a product that only had a low level of strength.

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cross-machine direction and which also required the use of very high / tight adhesive. The adhesives penetrated the web up to both surface sides of the web and led to an uneven appearance and very poor permeability, quite apart from the deterioration in pliability and dimensional stability.

In contrast, the invention is intended to provide a fiber web of non-woven fibers which is excellent as a cover material for sanitary towels, as a cover material for cellulose diapers or cellulose towels, as a surface material for absorbent tampons and for numerous corresponding purposes, but having the disadvantages outlined above does not have.

This object is achieved according to the invention in that the base layer is a layer of creped cellulose wadding with an open structure and a basis weight (before creping) between 4 and 12 ibs / ream of 2880 ft, that the top layer is a highly warped layer of essentially in machine directionally oriented synthetic fibers of staple length, the denier of which is in the range of 0.5 to 3 , and that the two layers are connected by an elastomeric adhesive, preferably a plastisol, which is in a lattice-like manner, only up to about 25 ' The pattern covering the total area between the layers is distributed. It is preferable to

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seen that the adhesive is at least partially in the base layer penetrated while the fibers of the top layer are only partially embedded in the adhesive, whereby the outward facing! surfaces of the fibers are practically adhesive-free are.

The invention is therefore based on the. The idea of combining the highly warped layer of synthetic fibers with a carrier layer (base layer) to create a uniform finished product. This product has the necessary strength values, the required permeability and the desired flexibility and suppleness. At the same time, it enables the advance. draws that result from highly warped layers of synthetic fibers of low denier can be used to the full extent | - in the fact that such layers when using ί '\

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do not adhere to the surface of the body.

/ The ^ two-layer fiber web according to the invention leaves

"produce" themselves in a particularly favorable manner in that a ■ elastomeric adhesive in a grid-like pattern, a, ■ stretched web made of creped cellulose wadding

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is brought \ that on the side of the web of cellulose wadding provided with adhesive a web of highly warped, essentially oriented in the machine direction synthetic

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Fibers is laid on, and that the adhesive is then made to set, whereby both webs are tied under until the process is complete be maintained at a substantially uniform tension. It is expedient to proceed in such a way that the setting process is carried out Heating .des adhesive is effected and that in the Completion of the setting process, the web of highly warped synthetic fibers is pressed into the still warm adhesive up to a partial embedding of the synthetic fibers in the adhesive, in which the outward directed surfaces of the synthetic fibers practically glue-free stay. This process can be carried out at high working speeds without the very sensitive one Position of the individual fibers is disturbed

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Further details of the invention are provided below explained in more detail in an exemplary embodiment with reference to the drawings. In doing so, represent:

Fig. 1 schematically shows a machine that is used to manufacture • the two-layer fiber web according to the invention

suitable is,

Mg. 2 a section from the settlement of the Ar-. working surface of the machine according to Pig. 1 glue roller used,

Figure 3 shows, on a greatly enlarged scale, a cross-section of the two-layer fibrous web of the invention in the plane 3-3 of Fig. 4, and

Fig-. 4 is a photomicrograph of the surface the two-layer fiber web according to the invention.

The machine shown in Fig. 1 contains a supply roll 10, from which a creped wadding web 11 runs off. the Cotton web, which in a known manner by stretching and ironing on a conventional facial tissues corresponding suppleness was brought, comes from the roll 10 into the working gap, that between an adhesive roller 12 and a pressure roller 14 is formed. The size of the gap is set so that only very little pressure is exerted on the web 11. The adhesive « Fabric roller 12 is etched on its work surface with a deep

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Provided pattern, for example that shown in FIG. 2 , formed by grooves 16 honeycomb. However, other patterns can also be used for the working surface of the adhesive roller 12, provided that the requirement is met that the luster has a large open area. The total area that is taken up by the deeply scratched grooves of the pattern should not be more than 25? ' make up the entire working area of the glue roller and preferably only about 15 ^! .- 'or even less of the entire work surface, Y / furthermore, the pattern should preferably have a grid-like structure and in particular should not have any interruptions in the grooves extending in the transverse direction of the web 11.

In the operating state of the machine, the grooves 16 of the working surface of the adhesive roller 12 are continuously with a low-viscosity, thermoplastic adhesive 18 filled, namely by the fact that the lower region of the roller 12 in an adhesive trough 19 immersed. l?> evor the while dipping in the tub

19 wet with adhesive! Bearing the working surface of the roller 12 'but can reach the wad of cotton wool 11 is provided by a scraper

20 for the fact that only a predetermined amount of adhesive, namely the Amount of adhesive located in the grooves 16 onto which the cotton wool web 11 can be transferred. The transfer of the adhesive on the wad of cotton wool takes place essentially in the area of the gap between the rollers 12 and 14. Part of the adhesive penetrates something into the wad, while most of the adhesive remains on the surface of the wad.

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There is also some migration of the adhesive to the side, but this is not harmful if the amount of the of the adhesive transferred to the wad of cotton wool is dimensioned in such a way that that - according to the above-mentioned requirement - the the area of the Y / attebahn covered by the adhesive even after one sideways' migration of the adhesive is not greater than approximately 25 ^ (and preferably less than about $ 15) of the total area the cotton wool pad. This open-plan structure of the adhesive on the cotton wool web, as will be explained below, the desired flexibility and suppleness of the end product ensured '.

The cotton web 11 provided with adhesive runs off Gap between the rollers 12 and 14 from zu'einer deflection roller 24, which is arranged close to a stretching machine 26. From the stretching machine 26, a web 28a is discharged from almost fully machine-oriented synthetic Fibers whose denier is in the range of 0.5 to 3. This web 28 is produced in that in the stretching machine a number of slivers 28 made of synthetic fibers of Stack length are severely warped. The fuses 28 must contain a sufficient amount of fibers so that the high degree of warping results in a closed and even

moderate Balin 28a leads. The track 28a, the weight of which preferably is about 2.5 to 20g / m, the output of the Stretching machine 26 off under constant tension

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placed on the side of the cotton wool web 11 previously with the Adhesive pattern has been provided.

The two-layer fiber web formed by placing the web 28a on the wadding web 11 runs from the deflecting roller 24 from over a further deflection roller 30 and is then wrapped around a heating roller 32. The heat roller 32 completes the setting of the adhesive located between the webs 11 and 28a, so that the adhesive when running off the two-layer Paserbahn from the heating roller 32 no longer has a sticky state. As can be seen from the graphic representation, while the adhesive is setting, the upper layer, consisting of the synthetic fibers, lies on the surface the roller 32-on. This is the preferred form of implementation the setting process. Alternatively, however, the creped cotton layer of the two-layered can also be used during the setting process Fit the paserbahn on the surface of the heating roller. In each Pail it is practical to use the two-layer paserbahn as large a part of the surface of the Ileizwalze 32 as possible To bring plant. In order to achieve this, a calender roll can be installed at the outlet of the two-layer paserbahn from the heating roll 32 34 provided leg that, based on the axis of rotation of the V / alze 32, in a considerable and far beyond 180 ° V / inkel to the inlet of the two-layer Paserbahn lies. The calender roller 34 forms a press nip 35 'with the Ileizwalze 32' so that at the end of the rotation the Jalze 32 progressive setting process the layer off

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synthetic fibers are pressed into the adhesive. Incidentally, in addition to the illustrated heat roller 32 further heating devices, such as additional IIeizwalzen _r Convection .ströme, radiant heaters can ο. Like. Are used, which are arranged either in front of or behind the calender roller 34 (based on the running direction of the two-layer fiber web) and bring about an acceleration of the setting process or ensure the complete termination of the setting process.

Bach the setting process runs the two-layer Paserbahn over guide rollers 36 and 38 and over another roller 40 to an end roll 13 · The end roll'13 is on a spindle 42 is formed, which is mounted on a frame 44 pivotable about an axis 46. ·

The base layer of the two-layer fiber web, that is the Vfatteschicht 11 is during its entire course of the Supply roll 10 to the end roll 13 under a uniform chip, held by the fact that the rollers. 12, 34 and 40 are driven. The web 28a of synthetic fibers discharged from the stretching machine 26 is up to the inlet of the two-layered Fiber web to the heating roller 32 "held under an equal tension, so that during the bonding of the web 11 with the Panel 28a still has practically all of the fibers of panel 28a in its state aligned parallel to the machine direction.

The alignment of the individual fibers 48 of the web 28a in the finished product, which is practically completely retained can be clearly seen in the microphotography according to FIG.

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At the same time, this photomicrograph shows that the orientation of the individual fibers 48 through the honeycomb adhesive lines 15 is securely fixed. With a relatively small proportion of fibers, the fiber ends are not bound by the adhesive, so that they can take a freely relaxed position. This results in a somewhat fluffy surface that becomes the desired contributes to the soft, supple feel of the end product.

The representation of Fig. 3, as a section along the line 3 - 3 in Fig. 4 and thus can be viewed as a section along an adhesive line 15, shows in enlarged Scale and, in a bitschenmtie.ch.or form, the location of the individual Fibers 48 in the finished product. ~? s can be seen that the adhesive line 15 penetrated deep into the layer of cotton wool 11 is that, however, the fibers 48 are only partially embedded in the adhesive 15. The outward-facing surfaces the fibers 48 are practically free of glue, so that the finished Product a smooth and - as mentioned above - something has a fluffy surface. This makes the finished product particularly suitable as a cover material for sanitary napkins Cover material for cellulose diapers or cellulose tissues, as a surface material for absorbent tampons and for many corresponding purposes.

For gluing the strips. 11 and 28a a none various adhesives can be used. The use of plastisols, i.e. colloidal dispersions, is advantageous

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- ¹ '- 1580871

synthetic plastics in a suitable organic eater plasticizer. Particularly suitable have been found while those Plas-tisole which contain as plastic component polyvinyl chloride or copolymers of vinyl chloride with other Vinylkunatstoffen and _f by organic phthalates Sebeazinate, adipates or phosphates are softened. Adhesives of this type are characterized by a fast setting capacity, a relatively low viscosity, a weak tendency to migrate within the 7 / atteschicht, and only low volatility. In addition, they remain soft and flexible after setting, which contributes to the desired supple, soft feel of the finished product.

The base layer consisting of the creped cellulose wadding preferably has a basis weight of about 4 to 12 lbs / ream of 2880 feet prior to creping. When creping this layer (during the removal from the dry section of the paper machine), a creping ratio of about 1.1 to 2.5 is expediently set. Furthermore, the wet strength of the base layer can be increased in the usual way, for example by adding IJelamin-formaldehyde resins, ilarnea-formaldehyde resins, polyalkylene-polyamine resins or similar plastics to the paper pulp, although such a treatment is by no means absolutely necessary . If a treatment has taken place to increase the leak strength, it can be appropriate. oein, continue to carry out a treatment with conventional irritants in order to avoid the possible increase in the wetness

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strength to compensate for any reduction in the absorption capacity of the base layer *

The Baaisschioht should preferably be one have an open, perforated structure so that the finished, two-layered one Paserbahn can be penetrated well and quickly by liquids. To achieve this, you can use the cotton wool pad in the paper machine on a patterned or in special Woven screen fabric or perforated with a needle roller after its production. The usage however, a solid, open layer of cotton wool is not essential necessary;. Rather, a normal can also be used in a normal Use wise made cotton sheets without further ado.

Furthermore, the basic fabric should be finished after creping Be stretched and ironed to the point of reduction

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the crepe ratio to about 1.1 to 11.5. Through this in the Manufacture of (Jeöicht cloths commonly used Tech- J nik, the base layer gets a soft, supple feel, which in addition to the properties of absorption capacity, permeability and the strength is very ^ desirable.

The top layer of the two-layer fiber fabric, so the layer 28a, instead of the fibers 48, can be made of monofilaments exist, whereby the monofilaments should preferably also have a denier value in the range of 0.5-3. If how in the preferred embodiment, fibers are used these should be stacked in length or about 10 - 75 mm or more in length, with the main

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part of the fibers is about 25 mm long. The basic weight The path 28a should appropriately be as small as possible be. The lower limit of this basis weight is through the Given the workability of the web 28a on the stretching machine. In practice, tracks from the aforementioned Synthetic lasers with a basis weight of about 2.5 to 20 g / m can easily be produced. These lanes can be used with a Working speed from about 20 ft / out to over 500 ft / min can be applied to the base layer. .

The invention is to be explained below using a detailed numerical example.

A creped wad of cotton wool that was made before creping a

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Basis weight of about 6.5 lbs / ream of 2880 ft and a crepe

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The ratio of 2.2 was obtained by stretching and ironing brought a final crepe ratio of about 1.2. This web was made in a V / Aben pattern with a plastisol adhesive printed, which consisted of 100 parts by weight of polyvinyl chloride, dispersed in 60 parts by weight of dioctyl phthalate and with Raw alcohol were diluted. The glue was in the tight of just over 5 g / m applied and covered-about $ 21 the total area of the track. On the Y / attebahn provided with adhesive was a top layer of highly distorted synthetic Pasern applied. This layer had a basis weight of about 5.9 g / m 2 and contained viscose fibers about 25 mm long with a denier of 1.5. The lines were about 90% parallel aligned to the Hanchine direction. The resulting two

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layered fiber web is led around under tension around a heat roll, which was operated at a temperature between about 160 and 165 G ^0. Virtually complete setting of the adhesive resulted on this heating roller. The synthetic topsheet _'x was pushed at the completion of the setting process by a calender roll in the above beochriebenen way into the adhesive.

The two-ply Paserbahn described above was tested for tensile strength on an Instron testing machine. Your breaking point was in the mat? machine direction 2.93 lbs / inch and cross machine direction at 0.21 lbs / inch.

A similar two-layer fiber web was produced as a comparison material, but instead of this as a top layer of the highly drawn web of synthetic fibers, a web carded only in the usual way was used, in which only about 60 $ of the fibers were oriented in the machine direction. The basis weight of the carded web was about 6.1 g / m. The two-layer fibrous web made with this carded web had a tensile strength in the machine direction of 1.04 pounds per inch and a cross-machine direction tensile strength from 0 | 28 lbs / inch.

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Claims (6)

1580871 Expectations: ί / Two-layer fiber web of non-woven fibers, characterized _f in that the base layer is ft, a layer of creped cellulose wadding with an open structure and having a basis weight (prior to creping) 4-12 Mbs / egg of 2880, that the upper layer a hochverzogene Is a layer of staple length synthetic fibers oriented essentially in the machine direction, the denier of which is in the range from 0.5 to 3, and that the two layers are connected by an elastomeric adhesive, preferably a plastisol, which is formed in a lattice-like, only about up to $ 25 the total area is distributed between the layers covering the pattern. . 2. fiber web according to claim 1, characterized in that; the adhesive has at least partially penetrated into the base layer, while the fibers of the top layer are only partially embedded in the adhesive, the according to 'i outwardly facing surfaces of the fibers are practically free of adhesive _{. ^ · '-. j 3. A fibrous web according to claim 1 or 2, characterized in _t that the synthetic fibers have a length of about mm 25th ^: . ■■■■■■ "■■■■. - - ί 209833/0832 ■ - BAD ORK J * 4. A method for producing a two-layer Paeerbahn according to one of the preceding claims ^ fiekennaelohnet that an elastomeric adhesive is applied in a grid-like pattern to a tensioned web of creped cellulose wadding, that on the adhesive side of the cream made of cellulose wadding a web of highly warped synthetic fibers oriented substantially in the machine direction, and that the adhesive is then caused to set, with both webs being held under substantially uniform tension until the setting process. 5. The method according to claim 4, characterized in that the setting process is effected by heating the adhesive und'daß in the! Completion of the setting process, the web of highly warped synthetic fibers is pressed into the still warm adhesive until the synthetic fibers are partially embedded in the adhesive, in which the outward-facing surfaces of the synthetic fibers remain practically adhesive-free, 6. The method according to claim 4 and 5, characterized in that the application of the adhesive to the web of cellulose wadding takes place in a measured amount by a printing process. KRE / Ki 209833/0832 _BAD ff-.