EP3887117A1

EP3887117A1 - Method for producing solvent-based foils or films

Info

Publication number: EP3887117A1
Application number: EP19828186.7A
Authority: EP
Inventors: Karl Morgenbesser
Original assignee: Berndorf Band GmbH
Current assignee: Berndorf Band GmbH
Priority date: 2018-11-27
Filing date: 2019-11-25
Publication date: 2021-10-06
Also published as: WO2020107044A1; TW202030072A

Abstract

The invention relates to a method for producing a solvent-based foil or film (23), wherein the foil/film has a width of more than 1.9 m (in particular 2 m or 2.5 m or 4 m) in a finished state, wherein in a step a) at least one material (26) is applied to a moving surface of an endless belt (1) and in a step b) is at least partially dried and/or at least partially cured, wherein evaporating a solvent results in drying and/or curing of the material, and the at least partially dried and/or at least partially cured material is removed from the surface of the endless belt in a step c), wherein in step a) the material is applied to and uniformly distributed on the endless belt (1) across a width of more than 1.9 m, wherein after step c), in order to finish the foil/film, a portion of more than 1.9 m in width of the material applied to the endless belt (1) in step a) across a width of more than 2 m (preferably of more than 2.5 m or 4 m) is left in the foil or film, after an additional process for drying and/or curing the material, to form the finished foil/film.

Description

METHOD FOR PRODUCING A FOFIE OR FIFM

The invention relates to a method for producing a solvent-based film or a solvent-based film, the film or film in a finished state having a width of more than 1.9 m, in particular a width of more than 2 m, preferably a width of more than 2, 5m, particularly preferably more than 4m, wherein in a step a) at least one material is applied to a moving surface of an endless belt and in a step b) is at least partially dried and / or at least partially cured, wherein evaporation of a solvent results in drying and / or curing of the material, and the at least partially dried and / or at least partially cured material is removed in a step c) from the surface of the endless belt.

Processes of the type mentioned at the outset come, for example, in the production of films or films, for example polyvinyl alcohol films (PVOH films), as used for example in the pharmaceutical industry, or triacetate films (TAC films), which are used, for example, for the production of FCD films. Screens are used, or a polyimide (PI) film or an acrylic film.

An endless belt, which is used as a process belt for applying and transporting the film, usually runs between a drive roller and a deflection roller, between which the belt is clamped. In the known solutions, a starting material in liquid form is applied, in particular, poured onto the tape. The material then forms a homogeneous film on the belt surface, which is then subjected to further process steps, especially drying, stretching, trimming, etc.

In the following, the term “film” will also be used to represent films, and in general for any type of flat, in particular plate or band-shaped, single or multi-layered structures of solid materials, which can be made stretchy or inextensible elastic or inelastic, for reasons of easier fixing , used. One possible material mentioned here by way of example is cellulose triacetate (CTA), also known as triacetate or TAC film, which is a plastic which is obtained from cellulose in a reaction with acetic acid. In a continuous process, the CTA polymer, which is mixed with a solvent such as dichloromethane, can be applied to the surface of the metal strip and then moved through a drying oven together with the endless strip. The solvent evaporates and when the strength is sufficient, the dried film can be removed from the metal strip.

In order to achieve a high production speed, the films are usually pulled off the belt while they are still moist. In the case of solvent-based films, the term “moist” refers to the proportion of solvent still contained in the film. For example, the solvent percentage would be zero for a completely dried film. With conventional solutions, the removed film is stretched to the desired width.

A disadvantage of the known processes is that the material is always poured onto the endless belt over a narrowly limited width and the maximum width of the cast material used in the finished film is 1.9 m. This 1.9 m wide area is then expanded to the desired width of the finished film. For example, a 1.9m wide film can be stretched to produce a film that is many times wider. However, the conventional solutions have the problem that depending on the desired width of the finished film, different amounts of material have to be applied. If the resulting film is to have a very large width, the material must be stretched very much after being pulled off the endless belt. Since there is a reduction in the material thickness as a result of the stretching, a correspondingly thick application of material is necessary during the pouring onto the endless belt. With a high material application and the generation of large layer thicknesses, however, a longer drying time goes hand in hand until the material has the required strength to be able to survive the stretching process without damage, which in turn leads to a significant extension of the process time. It is therefore an object of the invention to overcome the disadvantages mentioned above and to improve the process of producing wide films and to optimize the process time.

This object is achieved according to the invention with a method of the type mentioned at the outset in that in step a) the material has a width of more than 1.9 m, in particular more than 2 m, preferably more than 2.5 m, particularly preferably of more than 4m in width, is applied to the endless belt and is evenly distributed, with a section of more than 1.9m, in particular more than 2m in width, preferably more than 2m, after step c) to complete the film or film , 5m width, particularly preferably of more than 4m width, in step a) over a width of more than 1.9m, in particular of more than 2m, preferably of more than 2.5m, particularly preferably of more than 4m width after a further drying and / or hardening of the material to form the finished film or film, the endless belt of material applied is left in the film or film.

The solution according to the invention makes it possible to significantly increase the process speed compared to conventional methods, since the wider width of the cast film compared to conventional solutions allows material to be applied with a substantially smaller thickness, and the lower layer thickness of the applied material means that it is essential faster drying of the film, compared to the known methods, in which the film is stretched to a great extent and a correspondingly thicker application of material is necessary to achieve the required layer thicknesses in order to achieve the desired final thickness of the film after stretching. Due to the large width of the film, stretching of the film can be dispensed with in the solution according to the invention. In addition, less waste arises in the solution according to the invention, since less material has to be cut off when trimming edges of the film. This is due to the fact that when the film is stretched using conventional methods, the film is fixed with clamps which have to encompass the film from its edges to relatively far to its center in order to avoid tearing the film. The areas in which the clamps engage are damaged during stretching and must be removed. In order to achieve captive edges that run in a straight line and parallel to one another, the film must therefore be cut to a width after stretching that is smaller than the engagement width of the clips in the film. According to an advantageous variant of the invention, it can be provided that in step a) the material is uniformly distributed on the endless belt at least over a width corresponding to the width of the dried or hardened film or the width of the dried and hardened film becomes. In this variant of the invention, there is no need to stretch the film entirely.

In a further development of the invention, which is characterized by a greatly shortened process time and a very high energy efficiency, it can be provided that the material in step a) is distributed to a uniform layer thickness, the layer thickness of the applied material by evaporation of the solvent is reduced to the layer thickness of the film or film in the finished state, in particular the layer thickness of the applied material is reduced to the layer thickness of the film or film in the finished state exclusively by evaporation of the solvent.

An endless belt is particularly preferably used, which has at least one weld seam running around a circumferential surface of the endless belt, wherein in step a) at least a section of the at least one circumferential weld seam is covered by the material. This variant of the invention ensures that an endless belt of sufficient width can be used, even if individual sections or sheets from which the endless belt is welded together are of smaller width than the endless belt.

An embodiment of the invention in which the endless belt has a width of over 2 m, preferably greater than 2.5 m, particularly preferably greater than 4 m, has proven particularly advantageous with regard to the production of wide films without stretching.

With regard to the drying of the material on the endless belt, it has proven to be particularly favorable if the endless belt has a circumferential length of 10 m to 300 m, in particular 50 m to 150 m.

In order to ensure the greatest possible parallelism and quality of the longitudinal edges of the film, it can be provided that after step c) before completion of the film or film, the film or film is brought to a width of the finished film or film by removing material along parallel longitudinal edges.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

Each show in a highly simplified, schematic representation:

1 shows a perspective illustration of an endless belt, as can be used in the method according to the invention;

2 shows a section through a first variant of an endless belt, as can be used in the method according to the invention;

3 shows a section through a second variant of an endless belt, as can be used in the method according to the invention;

4 shows a section through a third variant of an endless belt according to the invention;

5 shows a section through a fourth variant of an endless belt, as can be used in the method according to the invention;

6 shows a device for carrying out the method according to the invention;

7 shows a variant of an endless belt, as can be used in the method according to the invention;

8 shows a detail of an endless belt with helically running weld seams;

9 shows a cross section through the endless belt from FIG. 8 in the region of a weld seam;

and 10 shows a variant of a weld seam formation.

In the introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component names, and the disclosures contained in the entire description can be applied analogously to the same parts with the same reference numerals or the same component names . The location information selected in the description, e.g. above, below, to the side, etc., referring to the figure described and illustrated immediately, and if the position is changed, these are to be applied accordingly to the new position.

All information on value ranges in the present description should be understood to include any and all sub-areas, e.g. the information 1 to 10 is to be understood in such a way that all sub-areas starting from the lower limit 1 and the upper limit 10 are included, i.e. all sub-areas begin with a lower limit of 1 or greater and end with an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

In Fig. 1, an endless belt 1, in particular an endless steel belt, is shown schematically simplified, which has an overall width 2 transverse to its longitudinal extent. The width of the endless belt 1 is greater than 2 m, preferably greater than 2.5 m and particularly preferably greater than 4 m. The endless belt 1 also preferably has a circumferential length of 10 m to 300 m, in particular 50 m to 150 m.

In order to achieve the desired overall width 2, the endless belt 1 is preferably formed in the direction of its longitudinal extension from a plurality of sub-belts 3, 4 arranged next to one another. The sub-bands 3, 4 are welded together on the longitudinal side edges. This is done by means of a weld 9, shown in simplified form, referred to as a longitudinal weld seam. The sub-bands 3, 4 are formed from prefabricated sheet metal sections, the longitudinal side edges being subjected to a preparation process which is suitable for the selected welding process before welding.

Furthermore, in order to produce the endless belt 1, this end face 5, 6, which faces one another, can be connected to a weld seam 7 referred to as a transverse weld seam. The procedure is usually such that first the two partial strips 3, 4 are welded to one another in their longitudinal extent and then the cross weld 7 is formed. In the exemplary embodiment shown here, the transverse weld seam 7 is arranged to run at a predetermined angle with respect to the outer longitudinal side edges 8, 10 of the endless belt 1. However, it would also be possible to choose a right-angled alignment of the transverse weld seam 7 with respect to the longitudinal side edges 8, 10.

Depending on the thickness of the endless belt 1 and the material used, the radius of the deflection of the endless belt 1 must be adjusted accordingly. In the case of a straight belt course of the endless belt 1, there is a distance 11 between deflection points spaced apart from one another. If further deflections of the endless belt 1 are provided, the distance 11 is shortened accordingly.

The two sub-bands 3, 4 can be formed with approximately the same width. Viewed in sum, the total width 2 of the endless belt 1 results from the belt widths of the sub-belts 3, 4. To connect the sub-belts 3, 4, the longitudinal side edges to be connected are arranged abutting one another on the end face and welded to one another in this position. The welding can take place, for example, with or without protective gas, by means of laser welding, TIG welding, plasma welding, MIG / MAG welding, ultrasonic welding or friction stir welding.

Fig. 7 shows a variant of an endless belt, as can be used in the present invention. The endless belt 1 here has more than one weld seam 9, which extends helically around the endless belt 1 and is inclined to a longitudinal direction of the endless belt 1. A preferred helical weld seam is also shown, for example, in AT283194B. Here the weld runs around the endless belt at least once. The method steps described below for producing the endless belt or features of the endless belt can be applied equally to endless belts according to FIG. 1 as well as to endless belts according to FIG. 7 or according to AT283194B. 2, a material 12 which reduces the thermal conductivity of the weld seam 9 can be introduced into a weld pool during the production of the weld seam 9.

The material 12 introduced into the weld pool can be a component of an alloy of a base material of a belt body 13 of the endless belt 1. Alternatively, however, a material 12 can also be selected which is not part of the base material of the belt body 13.

The following examples of possible materials for the belt body 13 refer to the standard designations according to EN 10027 Sheet 1 and Sheet 2. Examples here are the materials X10CrNil8-8 with the material number 1.4310, X5CrNil8-10 with the material number 1.4301, X5CrNiMol7-12-2 with the material number 1.4401,

X3CrNiMol3-4 with the material number 1.4313, CrNiCuTil5-7 or similar materials, Ck67 with the material number 1.1231, and Ti-II with the material number 3.7035, XlNiCrMoCu25-20-5. The material Ck 67 is also designated with a protected factory name "Ti 994-Ti-grade2".

In the case of the materials for the band body 13 described in detail below, these are formed with the individual alloy elements for the respective material. The information in Table 1 is given in percent by weight, unless another unit is specified.

Table 1:

12-2 (1.4401) is used for the strip body 13, the thermal conductivity of the weld seam 9 can be reduced by adding Cr or Ni to the weld pool, which are already contained in the alloy of the base material of the strip body 13. In this case, as much Cr or Ni is preferably added to the weld pool that the Cr or Ni content in the

Weld seam 9 is at least between 5% and 20% higher than in the base material of the strip body 13. If the weld seam 9 Cr is added as material 12, the Cr content of the weld seam 9 can, according to the above examples, depending on the base material used, for example over 18% and are below 24%.

By adding Co into the weld pool, the thermal conductivity of the weld seam 9 in the above examples can be reduced by an element not contained in the alloy of the base material of the band body 13. The amount of Co that is added to the weld 9 in this case is preferably such that the content of Co in the weld is between 5% and 20%.

By adding the material 12, the thermal conductivity of the weld seam 9 can be adapted to the thermal conductivity of an area of the strip body 13 directly adjacent to the weld seam 9. According to FIG. 3, the thermal conductivity in the area 14 of the endless belt 1 directly adjacent to the weld 9 can be increased by changing a material composition in this area. Thus, an indentation 15 of the strip surface opposite the weld seam 9 can be produced on the endless belt 1 in the area 14 directly adjacent to the weld seam 9. This can be done, for example, by removing material in the area 14. The recess 15 can be filled with a material 16 which has a higher thermal conductivity than the weld 9. In this way, the thermal conductivity of the region 14 can be increased and thus the thermal conductivity of the weld seam 9 can be approximated. For example, Cu can be used as material 16.

A galvanic process, for example tampon galvanizing, can be used to apply the material 16.

As shown in FIG. 4, the area 14 adjoining the weld seam 9 can be reshaped by applying further weld seams 17, 18, 19. The further weld seams 17, 18, 19 are applied above and next to the weld seam 9, with immediately adjacent weld seams 17, 18, 19 at least partially overlapping. Since the weld seams 17, 18, 19 have a higher thermal conductivity than the base material of the strip body 13, the arrangement of the additional weld seams 17, 18, 19 increases the thermal conductivity in the region 14, so that there is a difference between the thermal conductivity - Speed of the area 14 and the thermal conductivity of the weld 9 is reduced.

5, a thickness of the at least one weld seam 9 in the direction of a thickness of the belt body 13 of the endless belt 1 can be reduced by removing material. A depression 21 created by the removal can be filled with a material 20 which has a lower thermal conductivity than the weld seam 9. For example, a plastic, in particular Teflon, can be used as material 20.

For all of the above-mentioned exemplary embodiments, the endless belt 1 can be reworked, for example polished, in particular mirror-polished, after the weld seams 7, 9 have been produced. The weld seams 7, 9 can also be reworked on their own, for example ground and / or polished. A thickness adjustment of the Continuous belt 1 are performed so that it has a substantially constant thickness over its entire circumferential length.

It is preferred if the ratio between the thermal conductivity of the belt body 13 of the endless belt 1 formed by a partial belt 31 on the belt surface in the central region of the partial belt 31 and the thermal conductivity of the weld seam 9 on the belt surface in the central region of the weld seam 9 is at most 1, 5, preferably at most 1.3, particularly preferably at most 1.1. This is particularly preferred at an angle a (angle of inclination of the helically extending weld seam 9 to the longitudinal extent a of the endless belt) greater than 5 °.

In an exemplary embodiment, the endless belt 1 has a width 2 of 3,000 mm and is constructed by a circumferential part belt 31 with a width b2 of 1,800 mm. The partial belt 31, shown narrower in FIG. 8, is connected via one or more circumferential weld seams 9. Several sub-bands can also be welded together. The weld seam 9 forms an angle a of 6.1 ° with the longitudinal direction a of the endless belt 1.

The section shown in FIG. 9 shows in cross section a weld 9 with the adjoining areas of the sub-band 3 1. The weld 9 has a width b3 of 3.3 mm on the outer surface 33, which, based on the thickness di , of 2.9 mm of the sub-band 31 represents 1.15 times. An imaginary central plane 34 is shown in dashed lines symmetrically between the outer surface 33 and the inner surface 32. The weld 9 is essentially symmetrical with respect to this central plane 34; there may be notches, such as those that occur during welding. Both the outer surface layer and the inner surface layer can be machined. The inner surface layer can e.g. Show residual compressive stresses in the range of 400 MPa. 9 can be carried out electrically using a tungsten electrode and inert gas (TIG).

The cross section shown in FIG. 10 corresponds to that of FIG. 9 and differs only by the weld 9 which is rectangular in cross section and which was carried out with an Nd: YAG laser. Example 1:

Subband sections with a width of 800 mm and a thickness of 0.8 mm were welded by TIG welding with a voltage of 10 V, current strength of 29 A and as an inert gas helium. The width of the weld seam was 2.1 mm. The weld seam was V-shaped. The sheet was then deflected in a test system by 180 ° over a roller with a radius of 590 mm. Only after 2 x 10 ⁶ cycles did cracks appear in the area of the weld seam.

Example 2:

Sub-band sections with a width of 1,211 mm and a thickness of 0.8 mm, which represent parts of a sub-band, were welded by TIG welding with a voltage of 8.7 V, current strength of 16 A and as an inert gas helium. The width of the weld seam was 1.05 mm. The weld seam was double V-shaped. In addition, one side was shot-peened so that residual compressive stresses of 400 MPa could be built up. The sheet was then deflected in a test system by 180 ° with the shot-blasted surface on the roll, over a roll with a radius of 590 mm. Only after 2.8 x 10 ⁷ cycles did cracks appear in the area of the weld.

Example 3: The weld seams are produced with the aid of the welding device or method disclosed in AT516447A1 (including the clamping device disclosed there).

For the sake of completeness, it should be pointed out that each of the exemplary embodiments mentioned above and illustrated in FIGS. 1 to 10 can be combined with any other or more of these exemplary embodiments. For example, the weld seam 9 shown in FIG. 1 or FIG. 7 can additionally be combined with the application of further weld seams 17, 18, 19 or the introduction of an additional material 20 shown in FIG. 5. The combination of the illustrated and described methods is advantageous with regard to a particularly precise influence on the thermal conductivity in the weld seam 9 and / or in the area 14. According to FIG. 6, a device 22 for carrying out the method according to the invention for producing a film 23 or a film has a casting area 24. This film 23 can be a solvent-based film, such as so-called TAC films, PVOH films etc. For example, in the case of TAC films, dichloromethane (methylene chloride) or in the case of PVOH films, water can be used as the solvent - be applied.

The casting area 24, which is also referred to in the prior art as a casting chamber, can be enclosed, for example, with a sheet metal cladding. Furthermore, an endless belt 1 and at least one casting device 25 for applying a material 26 to the endless belt 1 are arranged in the casting area 24. The endless belt 1 runs between two rollers 29 and 30. One of these rollers 29, 30 can be driven and serve as a drive roller for the endless belt 1.

The material 26 can be applied to the endless belt 1 by pouring, for example by means of curtain coating, extrusion, spraying, etc. The poured-on material 26 forms a film-like layer on the endless belt 1 and undergoes a process on the endless belt 1 which leads to at least partial drying and / or hardening of the material 26. A pull-off device 27, for example in the form of a roll, can be provided to pull off the (partially) dried film 23 from the endless belt 1.

In order to achieve a high production speed, the film 23 is usually pulled off the belt in a not yet completely dry, “moist” state. In the case of solvent-based films, the term “moist” refers to the proportion of solvent still contained in film 23. For example, the solvent content would be zero for a completely dried film.

For partial drying of the material 26 or the film 23, heating devices 28 can be provided which heat an inside of the endless belt 1 opposite a product side carrying the material 26 or the film 23. The heating devices 28 can comprise, for example, nozzle boxes through which hot air is expelled in the direction of the inside of the endless belt 1. In addition to the heaters 28, one or both of the rollers 29, 30 may be heated.

By using an endless belt 1 of the type mentioned above, the visibility of weld seams of the endless belt 1 in the film 23 can be very easily avoided. In particular, the use of an endless belt 1 with a helical weld seam can avoid crossing points of weld seams. By avoiding crossing points on the endless belt, it is achieved that in a finished film wound into a roll there are no punctiform impressions of the crossing points lying exactly one above the other. Crossing points lying exactly one above the other can lead to an increased visibility of these points in the wound film.

Crossing points of welded seams can also be avoided when using a substantially straight longitudinal welded seam if the transverse ends of the band welded to each other are slightly offset when producing a transverse welded seam connecting the ends of the strip to the endless strip, so that the two ends of the longitudinal welded seam do not meet. The longitudinal weld seam, which initially runs in a straight line, becomes a helical longitudinal weld seam with a very flat pitch angle by displacing the strip ends to be welded to one another. This results in two T-shaped "crossing points" lying next to each other instead of a real crossing point.

According to the method according to the invention, the material 26 is applied to the moving surface of the endless belt 1 in step a). In this case, the material 26 is applied over a width of more than 1.9 m, in particular more than 2 m, preferably more than 2.5 m, particularly preferably more than 4 m wide, applied to the endless belt and distributed uniformly . In order to be able to use as much of the width of the endless belt as possible, the circumferential weld 9 and all other welds can also be covered by the material 26 in step a). In step b) the material is at least partially dried and / or at least partially cured. Evaporation of a solvent results in drying and / or curing of the material 26. In a step c), the at least partially dried and / or at least partially cured material is pulled off the surface of the endless belt. After step c), a section of more than 1.9 m, in particular of more than 2 m in width, preferably of more than 2.5 m, particularly preferably of more than 4 m in width, of that in step a) over a width of over 1.9 m, in particular over 2m, preferably over 2.5m, particularly preferably over a width of over 4m, of material applied to the endless belt after further drying and / or hardening of the material to the finished film or to the finished film in leave the film or film. In other words, a very large part of the material 26 applied in step a) remains in the resulting film 26 across the width 2 of the endless belt 1.

It is particularly preferred here that in step a) the material is uniformly distributed on the endless belt over at least one of the widths corresponding to the width of the dried or hardened film or the width of the dried and hardened film. This completely eliminates the need to stretch the film 23 to its final width.

The material 26 can be distributed in step a) to a uniform layer thickness, which corresponds to the layer thickness of the film or film in the finished state after evaporation of the solvent. As a result, the uniformly distributed material 26 changes its thickness at most during production during curing, but its dimensions in an area parallel to the process surface of the endless belt 1 remain essentially unchanged until the film is finished.

After the film has been pulled off the endless belt (step c)) and before the film 23 has been finished, the film 23 can be brought to a width of the finished film or film 23 by removing material 26 along parallel leading edges. The edges of the film 23 can be trimmed (trimmed) with scissors or knives in order to obtain the smoothest possible edges that run parallel to one another.

Preferred production variants and materials for the endless belt are described below. The production of the endless strip 1, which is a metal strip, is usually carried out in such a way that the intended material is cast into a metal block in a casting process, which is then formed, in particular rolled, in a rolling process into the corresponding sheet. Depending on that for sheet metal rolling The available width of the system is also determined or limited to the maximum width of the sheet that can be produced with it. In currently known and customary rolling plants for such high-quality sheets, a sheet width of approximately 2000 mm can be produced.

As an alternative to the stringing together of two sub-bands shown in FIG. 1, a wider middle band section can also be supplemented by two side band sections, as is described, for example, in WO2013 / 177604A1. Depending on the length of the strip to be manufactured, more than two sub-strips can also be welded together.

Depending on the intended use of the endless belt 1, this or the sub-belts from which it is constructed can be formed from a wide variety of stainless steel materials, carbon steels or titanium and this can be made in different qualities. The metal belts can be used as process or conveyor belts.

The following examples of materials for the belt body refer to the standard designations according to EN 10027 Sheet 1 and Sheet 2. As examples here are the materials X10CrNil8-8 with the material number 1.4310, X5CrNil8-10 with the material number 1.4301, X5CrNiMol7-12-2 with the material number 1.4401, X3CrNiMol3-4 with the material number 1.4313, CrNiCuTil5-7 or similar materials, Ck67 with the material number 1.1231, and Ti-II with the material number 3.7035, XlNiCrMoCu25- 20-5. The material Ck 67 is also designated with a protected factory designation "Ti 994-Tigrade2".

With the different materials mentioned above and in Table 1, the structure of the structure must also be taken into account. For the grain size, especially the grain size number (grain size code) according to the ASTM E 112-84 standard, the characteristic value "G"> (greater than or equal to) should be 9.0. The grain size number (grain size number) is to be determined in accordance with the “Rule Intercept Procedure” according to points 11.6, 11.6.1 and 11.6.2 of the standard in compliance with all other relevant regulations with an accuracy of at least Vi ASTM number. The structural state is fully austenitic without delta ferrite in the cold-rolled starting material of the metal strip 1. Forming martensite is only permitted to such a small extent that cold rolling to strength level 1 according to Table 2 below permits the permissible level magnetic permeability is not exceeded. The surface subsequently polished to a high gloss must not have any orange peel-like structure or cell structure.

The magnetic permeability of the strip rolled to the strength levels given in Table 2 is measured in accordance with ASTM A-342. For example, for the material X5CrNi 18-10 (1.4301), strength level 1:

Relative permeability m, <1.15 with an excitation of 200 Oersted (Oe).

This value specified in Oersted (Oe) can be expressed in A / m (Ampere / m) using the following formula in a SI unit.

1 Oe = 1000 / (4 _* p)

Table 2:

The individual sheets can be subjected to different and, if necessary, multiple quality tests, starting from their condition as primary material up to the finished metal strip 1. One of the many tests is the "Metallographic test of the content of non-metallic inclusions in steels with image series", which is carried out based on the standard DIN EN10247 - July 2007 edition. As a modification of this standard, an even finer test or test is carried out, which differs from this in the points listed below. According to points 4.1.4 and 6.3 regarding the measuring surface, the standard stipulates that the measuring surface should have a size of at least 200 mm ² . In contrast to this, the measuring area is enlarged to a size of 625 mm ² , whereby due to the high purity of the materials used, a complete scanning takes place with this area size and the ascertained inclusions are completely counted. This area of 625 mm ² can be achieved, for example, by a square with a side length of 25 mm. The respective measuring surface or the measuring surfaces are always aligned parallel to the rolling surface or sheet surface, whereby multiple arrangements of the measuring surfaces are also used over the entire surface of the strip. The sheets to be tested have a wall thickness between 1.0 and 3.0 mm, preferably between 1.5 mm and 2.0 mm.

Since the entire endless belt 1 or the sub-belts forming the endless belt 1 each form components that belong together, the individual measuring surfaces are to be arranged distributed on their surface. A magnification of 200x should be selected for the evaluation, although this must not be changed during the evaluation process. This is defined in the EN 10247 standard under item 7.1 "Magnification". The evaluation and complete scanning of the measuring area described above is carried out independently of the magnification factor. Due to the high quality requirements, all the inclusions found per measuring field are divided into different size classes. The following classifications are selected: 2 mm to less than 5 mm, 5 mm to less than 10 mm, 10 mm to less than 15 mm, 15 mm to less than 20 mm, 20 mm to less than 25 mm. An example of a counting of inclusions on a metal sheet is given below, the measuring area being 625 mm ² and the material X5CrNil8-10 (1.4301) used to form the metal strip 1.

On the basis of this overview it can be seen that only a larger number of inclusions in the first size class between 2 mm and less than 5 mm have been determined.

A number of inclusions in this first size class between 2 mm and less than 5 mm lies in a lower limit of no inclusion up to 15 inclusions and an upper limit of 25 inclusions. In the second, next size class between 5 mm and less than 10 mm, the number of non-metallic inclusions is significantly lower, with the lower limit being no inclusion and the upper limit being 6 inclusions. In the third size class between 10 mm and less than 15 mm, the number of inclusions is in a lower limit of no inclusion and an upper limit of 4 inclusions. For the fourth size class between 15 mm and less than 20 mm and the fifth size class between 20 mm and less than 25 mm, the lower limit is no inclusion and the upper limit is 3 inclusions.

The determined inclusion numbers of the respective different measuring points 1 to 6 result in different mean values or average values for each size class, which in the first size class between 2 mm and less than 5 mm for 19.16 inclusions, for the second size class (5 mm to less than 10 mm) for 2.33 inclusions, for the third size class (10 mm to less than 15 mm) for an inclusion for the fourth size class (15 mm to less than 20 mm) for 0.16 inclusions and finally for the fifth Size class (20 mm to less than 25 mm) are 0.33 inclusions.

Since in many applications of the method according to the invention a very high surface quality of the endless belt used is required, the material for applying a structureless mirror polish should have a roughness depth Ra (arithmetic mean roughness value) or Rz (average roughness depth) Ra <0.02 mm; Rz <0.1 mm should be suitable. This not only in the area of the surfaces of the endless belt 1 but also in the area of connection points between the individual sub-belts. The area of larger tapes can also be several 100 m ² . A prerequisite for this is a very high degree of purity of the primary material (low phosphorus, sulfur and aluminum content), a very dense material without pores as well as the absence of hard phases, as can be caused by stabilizing elements or elements that increase hardness (eg titanium, cobalt, tantalum , Nitrogen).

A further quality criterion can also be the final thickness or thickness of the endless belt 1. This requires a large number of measurements in order to obtain a meaningful measurement result over the entire belt surface. For this measurement, a predetermined distance in the transverse direction of the longitudinal extent of the metal strip 1 from its longitudinal side edges is maintained. This distance can e.g. between 5 mm and 15 mm. In the longitudinal extension of the metal strip 1, several measurements are also carried out. A grid of measuring points distributed over the surface is thus achieved.

If the total width 2 of the endless belt 1 is given in cm, at least half the value of the total width 2 in cm is to be selected as the number of measuring points in the transverse direction, in particular in the vertical direction with respect to the longitudinal side edges. For example, if the total width is 200 cm, the thickness must be measured in the transverse direction with a number of at least 100 measuring points. The wider the metal strip, the higher the number of measuring points that can be selected transverse to the longitudinal extent. This number of measuring points can also correspond to the total width 2 in cm or even larger. In this case, a transverse distance between the individual measuring points is preferably chosen to be equal to one another, and thus the measuring points are divided evenly over the measuring width.

For example, the deviations from the average thickness of the endless belt 1 should be between ± 5% in an edge region of the endless belt 1 and between ± 5% in a central region of the endless belt 1. A high level of accuracy is also achieved with regard to the waviness and flatness of the endless belt 1.

As already mentioned in the introduction, very high demands are made on the surface quality and purity of the material of the endless belt 1 for the film production. Due to the small inclusions in the material, this leads to an almost universal, uniform Surface quality, which means that the film material produced thereon is just as good.

For the sake of order, it should finally be pointed out that, for a better understanding of the structure, elements have been partially shown to scale and / or enlarged and / or reduced.

List of reference symbols endless belt 31 partial belt

Overall width 32 inner surface sub-belt 33 outer surface sub-belt 34 median plane

Forehead

Weld

Long side edge

Weld

Long side edge

Distance from front end

material

Band body

Area

deepening

material

Weld

material

deepening

contraption

Movie

Pouring area

Pouring device

material

Puller

Heater

role

Claims

Patent claims

1. A method for producing a solvent-based film or a solvent-based film (23), the film or film (23) having a finished state being over 1.9 m wide, in particular over 2 m wide, preferably has a width of more than 2.5 m, particularly preferably more than 4 m, with in one step a) at least one material (26) being applied to a moving surface of an endless belt (1) and in one step b) is at least partially dried and / or at least partially cured, with evaporation of a solvent resulting in drying and / or curing of the material (26), and the at least partially dried and / or at least partially cured Material is withdrawn from the surface of the endless belt in step c), characterized in that in step a) the material (26) is preferably over a width of more than 1.9 m, in particular more than 2 m more than 2.5 m, particularly preferably of more than 4 m width, is applied to the endless belt (1) and distributed evenly, with a step of more than 1.9 m after step c) to complete the film or film (23) Width, in particular of more than 2 m in width, preferably of more than 2.5 m in width, particularly preferably of more than 4 m in width, of that in step a) over a width of more than 1.9 m, in particular of more than 2 m, preferably of more than 2.5 m, particularly preferably more than 4 m wide, of material (26) applied to the endless belt (1) after further drying and / or hardening of the material to form the finished film or film (23) in the Foil or the film is left.

2. The method according to claim 1, characterized in that in step a) the material (26) at least over one of the width, such as the width of the dried or hardened film or the width of the dried and hardened film (23) corresponds, is evenly distributed on the endless belt (1).

3. The method according to claim 1 or 2, characterized in that the material (26) in step a) is distributed to a uniform layer thickness, the layer thickness of the applied material, by evaporation of the solvent to the layer thickness of the film or film in the finished condition is reduced, in particular the Layer thickness of the applied material, reduced to the layer thickness of the film or film in the finished state exclusively by evaporation of the solvent.

4. The method according to any one of claims 1 to 3, characterized in that the endless belt (1) has at least one circumferential weld seam (9) on an outer surface of the endless belt (1), wherein in step a) at least a portion of the at least one circumferential weld seam (9) is covered by the material.

5. The method according to any one of claims 1 to 4, characterized in that the endless belt has a width of over 2m, preferably greater than 2.5m, particularly preferably greater than 4m.

6. The method according to any one of claims 1 to 5, characterized in that the endless belt (1) has a circumferential length of 10m - 300m, in particular 50m - 150m.

7. The method according to any one of claims 1 to 6, characterized in that after step c) before completion of the film or film (23), the film or film (23) by removing material (26) along parallel longitudinal edges a width of the finished film or film (23) is brought.