WO2017036931A1

WO2017036931A1 - A process of forming a film or laminate with a nap-like surface, a product made by this process, and apparatus to carry out the process

Info

Publication number: WO2017036931A1
Application number: PCT/EP2016/070128
Authority: WO
Inventors: Ole-Bendt Rasmussen
Original assignee: Ole-Bendt Rasmussen
Priority date: 2015-09-01
Filing date: 2016-08-25
Publication date: 2017-03-09
Also published as: JP2018528891A; GB201515479D0; CN108349152A; RU2018111323A; DE112016003981T5; EP3344436A1; AU2016313679A1

Abstract

A process of forming a fine stabilized transverse pleating or waving in a film or film assembly in a nip between two circularly or helically mutually intermeshing grooved roller (101) and (102), or such grooved rollers which are modified by indentations on the crests, in which the film or the assembly is stuffed into the nip by being supplied with a fine traverse pleating or waving either prior to or while entering the nip, such that the forces exerted by the intermeshing grooved rollers is adapted to produce the desired stabilization, whereas the stuffing of the film or film assembly is produced or assisted by an airjet through the nip acting essentially on the full width of the film as an airknife or as an array of closely spaced air filaments.

Description

A Process Of Forming A Film Or Film Laminate With A Nap-Like Surface, A Product Made By This Process, And Apparatus To Carry Out The Process.

The aim of the present invention is to provide a film or film laminate with a nap-like surface, thereby textilish look and feel.

During the last about 40 years, several methods of producing "napped film" has been proposed, but to the knowledge of the inventor, no such method has been industrialized. The inventors International Patent Application PCT/EP2015/054146 (WO2015128467)which was not published at the time when the present application was filed, describes and claims an improved method of making a "napped film", apparatus to carry out this method, and product obtained by the method. In that patent application, the disclosure relevant for the present invention is referred to as "the fifth aspect of the invention". The relevant claims are claims 27 - 39 and claim 50.

The present invention represent further improvements along the same lines of R&D. The method according to said "fifth aspect of the invention" is defined in claim 27 as follows:

"A process of orienting by sequentially stretching segments of a film or film assembly in a nip between two circularly or helically mutually intermeshing grooved roller (101 ) and (102), or such grooved rollers which are modified by indentations on the crests in which the film or the assembly is stuffed into the nip by being supplied with a fine traverse waving either prior to or while entering the nip, and by the sequential stretching, which takes place during the passage through the nip, the waving becomes fully or partly eliminated in the segments which become oriented by the stretching, whereas the waving is essentially maintained in segments which do not become oriented, and is stabilized by a contraction in the stretched segments."

Compared to other methods of producing a "napped film", the said method has the advantage that the "nap" contributes to the strength of the film. However, there are also certain limitations in the applicability of the described procedure. Thus, as it is mentioned in the said application, "...several measures have been tried in attempt to drag the film into the nip at the same velocity as the faster roller, but in all cases the result was negative, even when the faster roller was indented..." This has limited the nap-effect, but that limitation has now been overcome by the research leading to the present invention.

Another limitation concerns the step that "...the waving becomes fully or partly eliminated in the segments which become eliminated by the stretching, whereas the waving is essentially maintained in segments which do not become oriented by the stretching." This regional elimination of the waving softens the film product, and that is advantageous e.g. for textilish applications, but disadvantageous in other cases. According to the present invention, the stabilization of waving by regional stretching is optional.

The process according to the present invention is a process of forming a fine stabilized transverse pleating or waving in a film or film assembly in a nip between two circularly or helically mutually intermeshing grooved roller (101 ) and (102), or such grooved rollers which are modified by indentations on the crests, in which the film or the assembly is stuffed into the nip by being supplied with a fine transverse pleating or waving either prior to or while entering the nip, such that the forces exerted by the intermeshing grooved rollers is adapted to produce the desired stabilization, whereas the stuffing of the film or film assembly is produced or assisted by an airjet through the nip acting essentially on the full width of the film as an airknife or as an array of closely spaced air filaments.

It was found that the described air knife or array of closely spaced air filaments provides a very efficient means of stuffing the film or assembly of films into the nip between (101 ) and (102), such that the film, when desired, can enter the nip at a velocity, which is essentially higher than the circumferential velocity of each of the roller (101 ) and (102).

Thus, the process may be carried out as specified in claim 2, in which circular roller (101 ) moves essentially faster than circular roller (102) and both have suitable indentations on the crests, as described in connection with figures 2a/b and 3a/b. The air knife or array of air filaments is adapted to press the film or assembly of films towards the crests on (101 ) and make it stick to these crests, until it is gripped in the nip by indentations on the crests of the slower roller (102). In an alternative embodiment of the present invention, the film or film assembly is first prepared for the stuffing into (101 ) and (102). This preparation, which is a separate step, consists in supplying the film or film assembly with embossment to let the airknife or array of closely spaced filaments get a good grip in the film or film assembly. Then the latter is carried into the nip at a velocity essentially higher than the circumferential velocity of each of the rollers. By these means, a particular high degree of stuffing can be achieved. In this case these rollers may be supplied with helical instead of circular grooves, provided that they move at the same circumferential velocity. The embossment carried out prior to the stuffing may consist in transverse waving with short waves and intervening plain film segments, which stabilize the waves.

No matter whether one or the other embodiment of the invention is chosen, the grooved rollers (101 ) and (102) should preferably have a diameter equal or lower than 70 mm, like in the abovementioned PCT application. Suitable means are described in connection with figure 1 .

The film or film assembly leaving rollers (101 ) and (102) will either be supplied with fine continuous transverse waves or pleats, or with fine interrupted transverse waves or pleats. If the waves or pleats are interrupted, the intervening regions will be transversely oriented. In any case, the process may be continued by transverse stretching in a tenter frame, either while maintaining some amount of waving/pleating, or to obtain a flat, transversely oriented film, very suitable e.g. for crosslamination.

The embossment carried out prior to the stuffing may consist in transverse waving with short waves and intermeshing plain film segments, which stabilize the waves. Like in the abovementioned PCT application, the stabilization between the grooved rollers (101 ) and (102) may consist in an essential regional contraction caused by stretching between the grooved rollers (101 ) and (102). This is preferred when a soft product is wanted.

Alternatively, the stabilization between (101 ) and (102) may consist in a full or partial flattening of the waves or pleats without any substantial regional contraction. The resultant product will not be a final product, but will be an intermediary product, suitable for further processing, as for instance the abovementioned tentering.

Another interesting use of this intermediary product is for extrusion coating or extrusion lamination, carried out while avoiding further permanent flattening of the film or film assembly. In this connection, reference is made to the drawing fig. 3 and corresponding description in European Patent Application 10747601 .2, which concerns special extrusion coating and extrusion lamination.

Especially for textile and textile like uses, the film or film assembly can be supplied with incorporated void forming particles. The grooved rollers (101 ) and (102) are then engaged sufficiently to form through going voids in regions which are stretched between (101 ) and (102) .

In an alternative or supplementary embodiment of the invention the grooved rollers (101 ) and (102) are engaged sufficiently to make the film or film assembly transversely splitable in the regions stretched between (101 ) and (102). Fibrillation of these regions is carried out subsequently under use of at least one rubber belt, with which the film or film assembly is engaged. The fibrillation takes place by longitudinal stretching of this belt.

No matter whether one or the other of these two embodiments is used, the process may be followed by extrusion coating with filaments while avoiding permanent flattening of the film or film assembly. Reference is again made to fig. 3 and corresponding description in European Patent Application 10747601 .2, however the molten film (B) in this drawing should be substituted by an array of directly extruded molten filaments. The present invention also comprises any apparatus suitable for carrying out the method, and any product made by use of the method. Thus, the product made under use of any of the claims is applicable for several types of bags. Here, the increased volume taken in relation to the weight, can have great importance for customer's evaluation of the bag.

The bulky structure can also have importance for manufacture of filing materials in pillows and similar. In that case, the film or assembly of films is cut to flake form.

However, it is in particular emphasized that the product, when it has been supplied with through going voids or has been regionally fibrillated, must be considered very suitable for manufacture of sanitary textiles, bed sheets, underwear and similar products.

For each particular product, the choice of polymer composition will be easy for a person skilled in the art. Examples of relatively cheap polymers suitable for several cheap end products are HDPE, LLDPE and PP. Examples of more expensive polymers suitable for finer end products are polyamides, polyesters and stretchable biodegradeable polymers.

The invention shall now be described in further detail with reference to the sketches, of which:

Fig. 1 illustrates a process line according to the invention. Indentations on the crests of the grooved rollers (101 ) and (102) are not shown.

Fig. 2a and 2b illustrate indentations on a faster grooved roller (101 ), fig. 2a showing the section b-b in fig. 2b, and fig. 2b showing the section a-a in fig. 2a.

Fig. 3a and 3b illustrate indentations on a slower roller (102), fig. 3a showing the section b-b in fig. 3b, and fig. 3b showing the section a-a in fig. 3a. In fig. 1 , the film (3) to be supplied with transverse fine waves or pleats is supplied to the nip between the circular grooved rollers (101 ) and (102) from a set of rollers (or similar) which is not shown. The film (3) may be generally unoriented or mainly oriented in one direction, which may be longitudinal or on bias. It is supplied at practically the same velocity as the faster one of the two grooved rollers. As an example (101 ) may move double so fast as (102). A jet in form of a sharp "air-knife" presses the film towards indentations on the crests of (101 ) so that the film sticks to this roller. This "air-knife" is formed by the exit slot (4) on air-chamber (5), which is fed with pressurized air through the inlet (6). The exit (4) may e.g. be 0.1 - 0.2mm wide. Alternatively, (4) may be row of closely spaced holes to form a row of "air- filaments" instead of an "air-knife". The jet is directed mostly towards the faster roller (101 ). It proceeds between the crests on the rollers, then losing its effect to stick the film to (101 ). As exemplified in figs. 2a/b and 3a/b, the crests on (101 ) are supplied with mildly acting indentations and those on (102) with much sharper indentations. Therefore, in the nip (101 ) losses its grip of the film. Preferably it is taken over to follow the velocity of (101 ). Having left the nip, the film is pulled off by suitable means (not shown) and may be further processed as stated in the claims and in the general description.

The intermeshing between the crests of (101 ) and (102) may be very low, so that practically no regional stretching occurs, only a temporary stabilization of the fine waving or pleating. Then the product can be further processed by one of the mentioned means.

In order to get the exit (4) of the air chamber (5) as close to the nip as possible, the diameters of (101 ) and (102) should be as short as possible. A subclaim has indicated a limit of 7cm. To apply this over a reasonable roller length (101 ) and (102) can be supported by small and short rollers (2). These are only sketchy shown, but reference is made to the inventor's earlier application PCT/EP2010/056220, see especially the photo fig. 2 and the description in this connection. When the crests of (101 ) and (102) have indentations, the support rollers can be supplied with crests which fit into the grooves of (101 ) and (102). To minimize wear, the crests on (7) and/or the bottom of the grooves on (101 ) and (102) can be covered by a wear resistant polymer, e.g. Teflon.

The procedure here described can be varied. Thus (101 ) and (102) may move at the same velocity, may be without indentations, and may be supplied with helical instead of circular grooves. In that case the (not shown) roller means which supply the film (3) moves the film at a velocity substantially higher than the velocity at which any of the rollers (101 ) and (102) or the two together move. Then the stuffing can be established by the air jet. Prior to the shown process steps, the film is preferably supplied with some embossment to give the air a better grip in the film.

The surface profiles of the circular grooves rollers shown in fig. 2a, fig. 2b, fig. 3a and fig. 3b are profiles which experimentally have been found advantageous to carry out the "stuffed ring rolling". The width of each groove is 1 .6mm. The width of each crest on the slower roller (fig. 3a and fig. 3b) is 1 .2mm, while the width on the faster roller is 0.8mm, at the top narrowed down to 0.5mm. It is believed that tips on the faster roller preferably should be narrower than the tips of the slower roller.

The crests on the faster roller are supplied with very smooth indentations (15) of a substantially waved shape. They must be very smooth, otherwise they would tear the film, since they move much faster than the film. As here shown, the top of the crests may be flat, and on both sides of this flat top, the surface-portions may form an angle of about 30° to the flat top. Quite good results have been obtained by giving the indentations on the slower roller the same shape as shown in fig. 2a and fig. 2b, but in order to obtain the most even pattern of the film, the shape shown in fig. 3a and fig. 3b is preferred. Accordingly, the depth of indentations is 0.25mm and the indentation is essentially straight radial. In this way, the film gets the same velocity as the slower roller. In the former case, it will still move faster than the slower roller at the end of the nip.

Claims

1 . A process of forming a fine stabilized transverse pleating or waving in a film or film assembly in a nip between two circularly or helically mutually intermeshing grooved roller (101 ) and (102), or such grooved rollers which are modified by indentations on the crests, in which the film or the assembly is stuffed into the nip by being supplied with a fine traverse pleating or waving either prior to or while entering the nip, such that the forces exerted by the intermeshing grooved rollers is adapted to produce the desired stabilization, whereas the stuffing of the film or film assembly is produced or assisted by an airjet through the nip acting essentially on the full width of the film as an airknife or as an array of closely spaced air filaments.

2. The process according to claim 1 , where at least a part of the stuffing is carried out while the film or the assembly enters the nip, by choosing the grooved rollers (101 ) and (102) as circular grooved rollers with indentations on the crests modified for adequate frictional control, and rotating one of the rollers (101 ) at a circumferential velocity essentially higher than a circumferential velocity of the other roller (102), and at the entrance to the nip frictionally engaging the film or the assembly with the faster roller (101 ) by directing and controlling the jet such that the film approaches the nip essentially at the same velocity as that of (101 ) , while crests of the slower roller (102) are supplied with indentations sufficient to reduce the velocity of the film or the assembly, preferably to bring the film or the assembly to follow the velocity of the slower roller (102).

3. The process according to claim 1 , in which the grooved rollers (101 ) and (102) have a diameter equal to or lower than 70 mm.

4. A process according to claim 1 , in which prior to the steps of claim 1 , the film is supplied with embossment to assist the jet in its conveying effect, and by virtue of the jet, the film is carried into the nip at a velocity essentially higher than the circumferential velocity of each of the rollers (101 ) and (102).

5. A process according to claim 4, in which the embossment consists in transverse waving with short waves and intervening plain film segments which stabilize the waves.

6. A process according to claim 1 , in which the claimed steps are followed by transverse stretching in a tenter frame.

7. A process according to claim 1 , in which the stabilization between the grooved rollers (101 ) and (102) consists in an essential regionals contraction caused by stretching between the grooved rollers (101 ) and (102).

8. A process according to claim 1 , in which the stabilization between the grooved rollers (101 ) and (102) consists in a full or partial flattening of the waves or pleats without any substantial regional contraction.

9. A process according to claim 7 or claim 8, which is supplemented by extrusion lamination while avoiding further permanent flattening of the film or film assembly.

10. A process according to claim 1 , in which the film or film assembly has been supplied with incorporated void forming particles, and the grooved rollers (101 ) and (102) are engaged sufficiently to form through going voids in regions which are stretched between (101 ) and (102).

1 1 . A process according to claim 1 , in which the grooved rollers (101 ) and (102) are engaged sufficiently to make the film or film assembly transversely splitable in the regions stretched between (101 ) and (102), and fibrillation of these regions is carried out subsequently under use of at least one rubber belt, with which the film or film assembly is engaged, the fibrillation taking place by longitudinal stretching of this belt.

12. A process according to claims 10 or 1 1 , which is followed by extrusion coating with filaments while avoiding permanent flattening of the film or film assembly.

13. Process or process use according to any of the claims 1 -12, in which the film or film assembly is made from HDPE, LLDPE, PP, polyamide, polyester or stretchable biodegradable polymer.

14. Use of the process according to claims 10, 1 1 or 12 for manufacture of sanitary textiles, bedsheets or underwear.

15. Use of the process according to any of the claims 1 -13 for manufacture of filling material in pillows or similar, after cutting to flake form.

16. Use of the process according to any of the claims 1 -13 in the manufacture of bags.

17. A product of a process of any of claims 1 -13, that is a sanitary textile, a bed sheet, underwear, filling material for pillows in flake form or a bag.

18. Apparatus for pleating a film or film assembly comprising two mutually intermeshing circularly or helically grooved rollers (101 and 102), one or both of which rollers optionally having indentations in the crests, said grooved rollers forming a nip into which said film or film assembly is stuffed with a transverse pleating, further comprising means for supplying an airjet (4) through the nip and across the width of the film, whereby the an airknife is formed or an array of closely spaced air filaments is formed.

19. Apparatus according to claim 18, wherein the means for supplying the airjet comprises an airchamber (5) into which is fed pressurized air through inlet (6) having an exit slot (4), which is preferably 0.1 to 0.2 mm wide.

20. Apparatus according to claim 18 or claim 19, wherein the grooves of both rollers are circular, the crests have indentations, and one of the rollers (101 ) is rotatable at a higher circumferential velocity than the other roller (102).

21 . Apparatus according to claim 20, wherein the crests of roller (101 ) have smooth indentations of a substantially waved shape.

22. Apparatus according to claim 20 or 21 , wherein the tips of the crests of roller (101 ) are narrowed, and wherein the crests on faster roller (101 ) are narrower than the crests on the slower roller (102).

23. Apparatus according to claim 22, wherein the width of the crests of the faster roller (101 ) is 0.8 mm, with the tips narrowed to 0.5 mm, and the width of the crests of the slower roller (102) is 1 .2 mm.

24. Apparatus according to any of claims 20 to 23, wherein the indentations have a depth of 0.25 mm.

25. Apparatus according to claim 24, wherein the indentations in the crests of the slower roller (102) are essentially straight radial.

26. Apparatus according to any of claims 18 to 25, wherein the grooved rollers (101 , 102) each have a diameter equal to or lower than 70 mm.

27. Apparatus according to any of claims 18 to 26, further comprising, upstream of the nip, embossing means for supplying transverse waving and intervening plain film segments.

28. Apparatus according to any of claims 18 to 27, further comprising, downstream of said grooved rollers, a tenter frame for transverse stretching of the film or film assembly.

29. Apparatus according to any of claims 18 to 28, further comprising, downstream of said grooved rollers, a longitudinally stretchable rubber belt for engaging with the film or film assembly and for providing longitudinal stretching and fibrillation of the film or film assembly.

30. Apparatus according to claim 29, further comprising, downstream of said rubber belt, an extruder for extrusion coating of filaments longitudinally onto the film or film assembly.