NL8500386A - Continuously consolidating non-bonded fibre web by heat and pressure - applied between heating calender roller with raised relief pattern and endless pressure belt passing around part of roller perimeter - Google Patents

Abstract

The method is intended for continuously consolidating non-bonded fibre web material by producing local fibre bonds through applicn. of heat and pressure between a calender roller with a given raised relief pattern and a pressure member. The member consists of an endless belt which passes around part of the roller perimeter and applies the pressure. This treatment may be repeated with the other side of the material in contact with the roller or in a similar second roller and belt unit immediately following the first pass.

Description

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Applicant! STORK BRABANT 3 '; V. in Boxmeer. #!

845149 / vdV / Ba / vL

Short designation: Method for strengthening unbound nonwoven material; installation for carrying out the method and reinforced nonwoven material

The invention relates to a method for the continuous local strengthening of unbonded nonwoven web material by the application of heat and the application of pressure, wherein the starting material to be treated is heat-fed between a desired pattern of surface elevations provided on the roller and a co-operating pressure member. is being fed.

Such a method is known.

In this known method, a fiber web material to be stiffened is passed between a heated roller provided with elevations and depressions 10 and a pressure roller co-operating therewith. The elevations on the surface of the heated roller and the smooth surface of the roller interacting with the heated roller are in the contact line between the two rollers.

At these contact points, by supplying heat and exerting pressure, a fusion of those fibers from the non-woven material will take place which have a melting or softening point that is lower than the temperature of the material to be treated in the contact zone 20 between the two rollers. reached.

The nonwoven material to be treated can consist entirely of this melting or softening fiber; the fiber web material to be treated may also consist in part of the fiber type mentioned at this operating temperature which melts or softens.

At the contact points between elevations of the heated roller and the pressure roller, a softening or melting will result in a connection between the softening or melting fibers or between these fibers and non-softening or melting fibers from the non-woven material. In both cases, this heat and pressure treatment creates a pattern of reinforcement sites in the nonwoven material.

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8500386 ---- -2- which gives the material the desired property of consistency and manageability. As indicated, the contact between the heated roller provided with elevations and depressions and the pressure roller is a line contact.

5 To ensure that the reinforcement pattern is applied with sufficient speed and effectiveness, especially at somewhat higher treatment speeds, the temperature of the central roller must be set high while the line pressure must also be high.

The high temperature in combination with the large line pressure leads to the material being compressed in the connection points in such a way that the material at that location acquires an almost plank-like character. The original fiber structure is partly lost; as a result, the material 15 loses its soft "grip".

Especially in the case of the light nonwoven fabrics, the damage caused by high temperature and high pressure plays a major role and a lower quality product is obtained.

The object of the present invention is to provide a method for the continuous local strengthening of unbonded nonwoven material of the above-mentioned type, which makes it possible, by using the method, to obtain a material which has an excellent soft "grip" and in which the material in the connection points still largely retains its original fiber structure and can also be made without problems even with very light non-woven fabric qualities.

According to the invention, this method is characterized for this purpose in that the starting material is fed into a zone which is formed between the roller and an endless belt, which at least partly wraps around this roller, is fed.

The consequence of the measure outlined above is that the contact between the material to be treated and the roller provided with elevations 35 and floors no longer takes place in BABiORlGfNA hair, which means that there is a treatment zone «no 3 fi fi» »-« * - 3- which can have a large size.

The treatment zone on the circumference of the central roller can generally be between 50 cm and 4 meters; noting that the calenders to be used are by no means limited to these dimensions and that larger and smaller zone lengths are possible. Due to the great length of the treatment zone, the great advantage is now obtained that the pressing force between the strip-shaped pressing member and the central heated roller is much lower than was the case in the prior art method.

In this way, an excellent locally-reinforced fiber web material is obtained, which in particular has an extremely soft "grip" and in which there is no longer any damage to the fibers due to a high pressing force. Advantageously, the method according to the invention is preceded by the second treatment following a second treatment in which the side of the material lying in the first treatment against the roller is turned away from the roller.

This embodiment of the method according to the invention is particularly attractive in those cases where a very thin, very delicate nonwoven material has to be treated.

For that purpose it may be advantageous to make the contact force between the band-shaped pressing member and the center of the elevated and depressed roller so low that only a superficial connection of the melting or softening fibers takes place.

In that case it is advantageous to allow the operation to take place a second time, wherein the part of the non-woven fabric that abuts the heated roller in the first operation faces away from the heated roller, the side facing outwards in the first treatment material side now rests against the heated roller.

The second treatment can, if desired, take place after some time after the first treatment, so that only one treatment device has to be used, through which the material is simply passed twice;

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8500386 -4- Η

V

it goes without saying that the second treatment is also directly related to H

after the first treatment, an H

second identical installation in series with the first installation H

and pass the material to be treated in one pass through the first and second devices.

In material in this way to two very light

heat treatments subjected to very low compression I

is the desired degree of reinforcement and an extreme

good grip of the material present. I

With regard to the shape of the material, it can also be noted that the starting material consists of one or more layers of unbonded fibers, at least a part of which has a softening or melting point that is lower than the working temperature of the 2 roller and has a weight of 5-200. g / m and preferably 10-50 g / m2.

In order to obtain the correct degree of cohesion in the nonwoven material webs, it will be very advantageously ensured that the average mutual distance of the points to be joined is chosen after one or two treatments at least 20 less than the average fiber length of the material. In this way, it is ensured that each fiber present in the material is connected at least on one sheet of its length to other fibers located in the nonwoven fabric, so that a good firmness is obtained in the total nonwoven fabric.

For carrying out the method according to the invention it holds that during stiffening the local surface pressure exerted on the non-woven material is between 0.05 and 2 2 3 kg / cm and preferably between 0.10 and 0.15 kg / cm at 30 contact times. between 1 and 60 sec. and preferably 5-15 sec.

at temperatures between 25 and 300 ° C.

The invention is also embodied in an installation for carrying out the method according to one or more of the preceding claims, formed from one or more, from one with a Pattern of elevations corresponding to the desired connection pattern; heat supply means; -5- a belt which at least partially wraps around the roller; pressure rollers; a clamping roller; guiding rollers and synchronizing means, existing device (s).

In order to prevent adhesion of the nonwoven material to be treated with the heated roller provided with elevations and depressions and / or the endless belt which at least partly wraps around the roller, the installation according to the invention is characterized in that the central roller and / or the belt without end of the device (s) are provided with a layer consisting of inorganic or organic materials with adhesion-rejecting properties, the bond between the material to be treated and the roller or the belt, respectively.

Advantageously, the central roller and / or the endless belt are covered with a layer selected from polytetrafluoroethylene and silicones.

By using the installation according to the invention in which the central and / or the endless belt are provided with an adhesion-removing layer, the material to be reinforcing is prevented from sticking to the roller or the belt, respectively. It should also be noted here that the polytetrafluoroethylene or silicone product which is located on the central roller or the endless belt can be both in the form of a permanent layer and can be continuously in the form of, for example, a solution or mist during the treatment. supplied.

The invention is also embodied in locally stiffened nonwoven material obtained by applying the method according to the invention and using the installation according to the invention.

The invention will now be elucidated with reference to the drawing, in which: fig. 1 shows a perspective side-sectional view of a device in the installation according to the invention and

fig. 2 is a cross-sectional side view of a device from BAD ORIGINAL

8500386

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represents the installation according to the invention with an, in I

material feed direction, previously placed conventional I

nonwoven fabrication device. I

In fig. 1 a central roller (1) is shown with this one

5 roller, partially wrap-around endless belt (2). I

1 is indicated by a dotted line

whereas in this case the establishment has an internal I

heated central roller, of course heat can be supplied to the sa-I

central roller (1) and belt (2) can also be assembled in another suitable manner, such as, for example, with the aid of infrared radiators or other suitable heat supply devices.

Optionally, by separate heating outside the contact area with the central roller, the belt can be given the same temperature as the central roller.

This can be especially advantageous for the heavier fiber flake materials.

In the device according to Fig. 1, pressure rollers (3) and (3 ') are further present, with pressure roller (3) being the movable roller with which the pressing force 15 of the endless belt against the central roller surface at the location of the roller (3) is regulated while roller (3 ') is generally in a fixed position relative to belt and central roller surface. Furthermore, a roller (4) is indicated with which the pressing force between belt and central roller surface can be regulated. Furthermore, a roller (5) is provided which, as a steering roller, ensures a controlled running of the belt without end and which is also movable in the direction of arrow for this purpose, while the steering roller (5 ') is generally arranged in a fixed position.

During operation of the device, the nonwoven material to be treated is supplied to the device via the horizontal part of the endless belt (2) in the nip between the pressure roller (3 ') and the central roller (1) and is supplied with feed BAII. The pressure and pressure of the tape (2) is passed through the device in the direction of arrow 30 and exits this device again from the nip between the central roller (1) and the pressure roller (3).

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Fig. 2 shows how a device from the installation according to the invention cooperates with fibrous fabrication equipment arranged for it.

In the figure, reference numeral (6) schematically indicates a carding machine in which the web to be treated is manufactured in its basic form by means of a carding operation, after which it is deposited on a roller which cooperates with a so-called electric depositing comb (7) with which the web formed is placed on a conveyor belt (8) and from there it is fed directly to the horizontal part of the endless belt ('2) of the device which forms part of the installation according to the invention. The treated material (10) carried the pressure roller (3) out of the device and then either stored or stored to be subjected to a second reverse treatment later, or directly to the second device, which is part of the installation, to be fed to immediately undergo the second treatment on the other side of the fleece.

The invention will now be further elucidated on the basis of an example.

20 Example 1 2

A nonwoven fabric weighing 25 g / m was treated in an installation consisting of 2 devices, as described above. The throughput speed in the installation was 24 m / min. which in the installation in question up to a contact time per device of approx. 8 sec. agreed.

The nonwoven fabric to be treated consisted of one layer composed of 60% polyester fibers and 40% polypropylene fibers.

The temperature during operation of the device, at the point of contact between the elevations of the central roller and the endless belt, was of the order of 165 ° C.

The calculated surface pressure between the central roller and the endless belt 2 was 0.14 kg / cm.

In this manner, a two-sided fiber web product was obtained which exhibited a very good "grip" and an outer cohesion.

The exchange used in the implementation of this example

85 0 0 3 8 S

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rollers had a hexagonally arranged elevation pattern on I.

the surface, with the elevations in the major directions I.

were present in a number of 16 / cm.

Example 2 I

5 In an installation as in example 1, where I

only 1 device with central roller and pressure band available I

fibrous web material consisting of I.

a 2-layer material, one layer 2 consisting of a 20 g / m fiber web of polyester fibers and the other 2 layer consisting of a 35 g / m high density polyethylene fiber web. The material was introduced so that the polyethylene fleece portion abuts the raised roll. The temperature at the elevations reached by the web was 130 ° C.

The contact pressure and contact time were as in the previous example.

A one-sided treated web, which excelled by an excellent "grip" and a very good cohesion, was obtained.

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Claims (9)

1. A method for the continuous local strengthening of unbonded nonwoven web material by the application of heat and the application of pressure, wherein the starting material to be treated is fed according to a desired pattern under a heat supply between a roller provided with surface increases and a co-operating pressure member with the feature that the starting material is fed into a zone formed between the roller (1) and an endless belt (2) which at least partially wraps around this roller (1). Method according to claim 1, characterized in that the first treatment is followed by a second treatment in which the side of the material turned away from the roller in the first treatment against the roller stop. Method according to claim 2, characterized in that the second treatment follows without interruption after the first treatment. Method according to claims (1) - (3), characterized in that the starting material consists of one or more layers of unbonded fibers, at least a part of which has a softening or melting point that is lower than the operating temperature of the roller (1) and has a weight of 5-200 g / m and 2 preferably 10-50 g / m. 5. Method according to claims 1 to 4, characterized in that the average distance between the points to be joined after one or two treatments is chosen to be at least smaller than the average fiber length of the material. 6. Method according to one or more of claims 1 to 5, characterized in that during stiffening the local surface pressure exerted on the non-woven material is between 0.05 and 3 kg / cm and preferably between 0.10 2 and 0.15 kg / cm for contact times between 1 and 60 sec. and preferably 5-15 sec. at temperatures between 25 and 300 ° C. Installation for carrying out the method according to one or more of the preceding claims, formed from one or more W8Te 6 v -10-I more, from a central roller (1) with a pattern of elevations corresponding to the desired connection pattern; heat H feed means; a belt (2) at least partially surrounding the roller (1)? pressure rollers (3, 3 '); a clamping roller (4); guiding rollers (5, 5 ') and synchronizing means, existing device (s), characterized in that the central roller (1) and / or the endless belt (2) of the device (s) of one, the adhesion between the material to be treated (10) and the roller (1) and the belt (2), respectively, consisting of inorganic or organic materials with adhesion-rejecting properties, are provided. I Installation according to claim 7 with h. It is characterized in that the central roller (1) and / or the endless belt 15 (2) are covered with a layer selected from polytetrafluoroethylene and silicone-containing substances. J 9. Locally reinforced nonwoven material obtained by applying the method according to one or more of claims 1 to 6 and with the aid of the installation according to claims 7 and 8. BAD ORIGINAL