DK2755774T3

DK2755774T3 - KNIVCOATER for high viscosity COATINGMASSER

Info

Publication number: DK2755774T3
Application number: DK12772080.3T
Authority: DK
Inventors: Ludwig Grader; Mustafa Ay
Original assignee: Bayer Pharma AG
Priority date: 2011-09-13
Filing date: 2012-09-11
Publication date: 2016-06-20
Also published as: HRP20160620T1; SI2755774T1; RS54836B1; HUE029180T2; DE102011082630A1; EP2755774A1; PL2755774T3; WO2013037776A1; ES2575708T3; PT2755774E; EP2755774B1

Description

The present invention relates to an applicator unit for continuously applying viscous coating compositions to foil sheets, and in particular to an applicator unit for producing coatings having uniform coating thicknesses.

Applicator units for continuously coating foil sheets with viscous coating compositions generally comprise a region at which a coating composition is applied by a so-called coater in defined dosage to the foil sheet. Depending on the coating task or formulation of the coating composition, different coaters, such as, for example, extrusion coaters, slop-pad coaters, doctor blade coaters, deposition coaters, roller or roll coaters or slot coaters, and, of these, in particular metering coaters are used. As slot coaters are generally termed coaters in which the coating composition exits the coating head via a slot-shaped gap. The slot-shaped gap connects a distribution chamber, formed inside the feeder head and provided with an inlet, to the outer side of the feeder head and serves for the defined supply of a coating composition from the distribution chamber to the surface of the feeder head. In the case of metering coaters, the distribution chamber is additionally connected to an outlet different from the slot-shaped feed gap, whereby more coating composition flows through the distribution chamber than exits via the feed gap.

Coatings for producing active substance depots for transdermal therapeutic systems (TTS) require a particularly even coating application, since this, in addition to a homogeneous active substance distribution in the coating composition, is a precondition for a targeted dosage of transdermally administered active substances. Metering coaters enable a precisely dosable, even application of coating compositions to foil sheets and are therefore frequently used to produce active substance depots for transdermal therapeutic systems.

Metering coaters have as the core element a feeder head comprising a tubular distribution chamber which is arranged inside and which along its length, via a slot-shaped gap, is open towards one side of the feeder head. For coating, the distribution chamber in standard metering coaters is flowed through lengthwise by the coating composition or the coating material, wherein the coating composition, for this purpose, is fed to the distribution chamber at an end formed as the inlet, and is led off via the other end formed as an outlet. The pressure of the coating composition in the distribution chamber is higher than the ambient pressure of the feeder head, so that a part of the coating composition supplied via the inlet is guided via the slot-shaped gap to the outer side of the feeder head. The coating composition which exits the feeder head via this feed gap wets the foil sheet which is guided along adjacent thereto, so that it is carried along by this foil sheet and subsequently forms on this a layer of coating material. The length of the feed gap here determines the width of the coating layer applied to the foil.

The thickness of a coating layer applied as described is substantially determined by the flow of the coating material through the feed gap, the distance between the feed gap and the foil sheet, the viscosity of the coating material and the velocity of the foil sheet relative to the feed gap or the metering coater.

The flow of the coating material through the feed gap is, for its part, a function of the pressure prevailing in the distribution chamber and of the height and width of the feed gap. An analytical determination of the parameters necessary for a specific coating thickness is possible in principle, yet in practice is supplemented or replaced by an experimental determination, frequently with the use of empirical values. A coating thickness which is uniform over the width of the foil sheet requires a material flow of the coating composition that is uniform over the length of the feed gap. This is given when the pressure drop along the flow direction of the distribution chamber is negligible. Assuming equal flow velocity of the coating composition within the distribution chamber, the pressure drop between the inlet and outlet of the distribution chamber is a function of the distance between the inlet and the outlet and the viscosity of the coating material. The higher the viscosity of the coating material or the greater the distance between the inlet and outlet of the distribution chamber, the greater is the pressure difference. It has been shown that the pressure drop in respect of the coating widths of currently up to 1500 mm which are today used for the production of transdermal therapeutic systems, in conjunction with the new active substance-containing coating compositions which are used for this, having viscosities within the range from around 500 to around 5000 mPas, is no longer negligible and leads to changes in coating thickness over the width of the foil sheet, which changes lie outside the tolerances which are to be observed. A reduction of the coating thickness variation caused by the pressure drop along the longitudinal direction of the distribution chamber can be achieved by arranging that end of the feed gap which faces towards the inlet of the distribution chamber closer to the foil sheet than that end of the feed gap which faces towards the outlet of the distribution chamber. A compensation of the coating thickness variation by an appropriately inclined orientation of a metering coater is possible, however, only in small measure, in particular since the pressure along the distribution chamber does not fall linearly and thus also the flow of the coating composition introduced from the distribution chamber into the feed gap varies non-linearly along the length of the feeder head.

For the reduction of a variation in coating thickness caused by the pressure drop in the distribution chamber, also a plurality of coating material streams can be produced in the distribution chamber. For instance, the coating composition can be fed in centrally to the distribution chamber and can then be led off at its two face ends. The reverse case, with a two-sided feed-in and a central evacuation of the coating composition, is likewise possible. Since each substream of the coating composition in such multi-stream feeder heads covers only half the path length, the pressure drops in the distribution chamber are reduced to half. Through the use of a plurality of inlets and outlets, the pressure drops along the length of the distribution chamber can be further reduced. However, appropriate designs are not only very complex in terms of production, but call for a precise matching of the individual substreams during use. Moreover, although fluctuations in the coating thickness with multi-stream feeder heads can be lessened, they cannot be totally avoided due to the pressure drops in the distribution chamber, which, even though reduced, are nevertheless still present.

It is therefore desirable to define metering coaters which with simple means enable an even coating of foil sheets.

In addition, it is desirable to define a feeder head which can be produced cheaply. It is also desirable to define a feeder head whose slot width can be varied in dependence on the coating composition. Furthermore, it is desirable to define a feeder head which can be easily and cheaply cleaned and can thus be used for different coating compositions. It is also desirable to define a feeder head in which the length of the feed gap, and thus the width of the coating layer applied to a foil, can be easily varied.

Embodiments of appropriate metering coaters comprise a feeder head having a tubular distribution chamber, extending from at least one inlet opening to at least one outlet opening, and having a feed gap which connects to the side of the distribution chamber, at least along part of the length of the said distribution chamber arranged within the feeder head. The feed gap here extends from the distribution chamber to a surface of the feeder head in order to form an opening in the distribution chamber to the said surface, wherein the cross section of the feed gap varies along the length of the feed gap.

Document CH 597 928 A5 discloses a feeder head according to the preamble of Claim 1.

In embodiments of feeder heads according to the invention, the at least one inlet opening, the at least one outlet opening and the distribution chamber are arranged such that basically no neutral zones can be formed. By the term "neutral zones" are here understood regions in the distribution chamber which, during operation of the feeder head, are not flowed through by the coating composition, or not such that they can be regarded as part of the principal flow, directed from the inlet opening to the outlet opening and the feed gap, of the coating composition. By the term "basically no neutral zones" should be understood that the volume of neutral zones which may be present, for instance in the region around an inlet and outlet opening, is so small that they do not lead to the formation of deposits of the coating composition and do not adversely affect the principal flow of the coating composition. In some configurations, a portion of the distribution chamber which is located outside the portion of the distribution chamber connecting the outlet opening and the inlet opening is arranged between the inlet-side end of the distribution chamber and the inlet opening and/or between the outlet-side end of the distribution chamber and the outlet opening respectively, the extent of which portion is a maximum of 5 mm in the direction connecting the outlet opening and the inlet opening.

The feeder heads are designed such that the inlet opening, the outlet opening and the distribution chamber are arranged in such a way that a coating material which exits the outlet opening has passed through the feeder head in a substantially U-shaped manner. By "U-shaped" should here be understood an, at least in first approximation, plane geometry, in which a straight or curved leg region respectively connects to each of the two ends of a straight or curved middle region, wherein both leg regions extend away from the middle element towards the same side.

Versions of the feeder head can comprise two non-identical plates and optionally at least one shim foil in between said plates. By "plate" should here be understood a planar, in first approximation flat component, the thickness dimensions of which are substantially smaller than its dimensions transversely to the thickness direction. The thickness of the plate can however be different at different places on the plate, for instance due to recesses formed in the plate or due to projections. By shim foil should be understood a thin, planar item which is used as an interlay.

In some embodiments of the feeder head, one of the two plates comprises neither an outlet opening nor an inlet opening, so that both openings are formed on the other of the two plates and thus a particularly simple and easy-to-clean structure of the feeder head is obtained.

In some embodiments of appropriate feeder heads, the variation of the cross section of the feed gap is preferably designed as a variation of the height-to-width ratio of the feed gap along its longitudinal direction, whereby a flow resistance which varies with respect to the longitudinal direction of the feed gap is obtained.

Configurations of such embodiments advantageously have a constant width of the feed gap and a height of the feed gap which varies along the longitudinal direction of the feed gap, whereby the feed gap can be produced in a particularly simple manner. Preferred configurations hereof have a profile of the height of the feed gap which decreases in the direction of the outlet of the distribution chamber, whereby the pressure drop in the distribution chamber can be easily compensated.

Solutions to the above objectives comprise a plate, partially covered with a shim foil, for producing a feeder head as referred to above, wherein both the shim foil and the plate respectively have an inlet opening and an outlet opening, and wherein the arrangement of the shim foil and of the said openings enables the production of a feeder head, the feed gap of which has a height having a profile which decreases in the direction of the outlet of the distribution chamber.

Solutions to the above objectives further comprise a plate, partially covered with a shim foil, for producing a feeder head as previously referred to, wherein the plate has an elongate depression for the purpose of forming the distribution chamber, and wherein the depression and the shim foil are arranged such that, following production of the feeder head, a feed gap, the height of which has a profile which decreases in the direction of the outlet of the distribution chamber, can be formed. By an "elongate depression" should here be understood a recess which forms none of the two main side faces of the plate and the longitudinal extent of which is substantially greater than its latitudinal extent.

Solutions to the above objectives comprise, furthermore, a plate as previously referred to and partially covered with a shim foil, or a feeder head, as previously defined and comprising two non-identical plates and optionally at least one intervening shim foil, in which the shim foil has a thickness of less than 3 mm, preferably of less than 2 mm, and most preferably of less than 1 mm.

Solutions to the above objectives additionally comprise a plate as previously referred to and partially covered with a shim foil, or a feeder head, as previously defined and comprising two non-identical plates and optionally at least one intervening shim foil, in which the shim foil is insoluble in a solvent suitable for the production of transdermal therapeutic systems (TTS) and the solvent is preferably heptane. By "a solvent suitable for the production of transdermal therapeutic systems (TTS)" should be understood all solvents which are suitable for dissolving the matrix material respectively used to form a TTS, and of which the residual quantities remaining in the matrix material during the production of a TTS do not give rise to any significant skin irritations amongst users.

Solutions to the above objectives also comprise a feeder head which has a plate partially covered with a shim foil and having openings formed therein for the inflow and outflow of coating composition.

Other configurations of embodiments of feeder heads, as previously referred to, advantageously have a constant height of the feed gap combined with a width of the feed gap which varies along the longitudinal direction of the feed gap, wherein the width of the feed gap can here change also along the direction pointing from the distribution chamber to the surface of the feeder head. Such feed gap geometries can be easily produced by means of traditional material removal methods, such as, for example, milling. Preferably, the width of the feed gap here has a profile which increases in the direction of the outlet of the distribution chamber. In specific configurations hereof, the width of the feed gap on the surface of the feeder head is constant and widens, possibly apart from the inlet-side end of the feed gap, both in the direction of the distribution chamber and in the direction of the outlet-side end of the feed gap. Such a geometry enables a variation of the flow resistance along the feed gap without changing the wetting conditions along the outlet opening of the feed gap.

For the compensation of a non-linear pressure drop in the distribution chamber, preferred embodiments have a non-linear characteristic of the profile of the height-to-width ratio of the feed gap. Preferably, such a non-linear characteristic is established using a calculation according to a mathematical model of the fluid mechanics of a coating material in the feeder head, wherein experimental determinations can be called upon. Alternatively, the non-linear characteristic is determined purely experimentally.

In some embodiments, the feeder head comprises two nonidentical plates and an intervening shim foil, wherein the width of the feed gap is determined by the dimensions of the shim foil. By "dimension" of the shim foil should here be understood the thickness extent thereof, which can assume different values at different places, for instance in order to realize a feed gap width which varies in the longitudinal direction and/or height direction of the feed gap.

In further embodiments of the feeder head, the at least one inlet opening and/or the at least one outlet opening and/or the at least one tubular distribution chamber and/or the feed gap is at least partially filled with an active substance-containing coating material.

Solutions to the above objectives additionally comprise a device comprising a feeder head as referred to above, wherein the outlet opening is connected to a collecting vessel such that the coating composition which exits the outlet opening can make its way into the said collecting vessel.

Solutions to the above objectives further comprise a method for evenly applying a non-Newtonian coating composition to a foil sheet, wherein a feeder head as referred to above is flowed through with the non-Newtonian coating composition during the coating process. By a "non-Newtonian coating composition" should be understood a liquid fluid which has a behaviour that differs from a Newtonian fluid, i.e. a fluid with linear, inelastic flow behaviour, in which the shear rate is proportional to the shear stress.

In some embodiments of the method, the non-Newtonian coating composition is an active substance-containing material for producing transdermal therapeutic systems (TTS).

If a feeder head having a shim foil is used, the method for varying the width of the feed channel along its longitudinal extent can comprise a step for applying to the shim foil pressure forces which vary along the longitudinal extent of the feed channel.

Solutions to the above objectives also comprise use of a feeder head, as previously defined, in the production of transdermal therapeutic systems (TTS).

Further features of the invention emerge from the following description of illustrative embodiments in conjunction with the claims and the accompanying figures. It should be pointed out that the invention is not limited to the embodiments of the described illustrative embodiments, but is defined by the scope of the accompanying patent claims. In particular, in embodiments according to the invention, the features which are cited in the illustrative embodiments set out below can be realized in a number and combination which differ from the examples. In the following elucidation of some illustrative embodiments of the invention, reference is made to the accompanying figures, of which

Figure 1 illustrates a feeder head for a metering coater with a cross-sectional representation within a schematized perspective view of the feeder head,

Figure 2 shows an applicator unit having a feeder head according to Figure 1 in a schematized cross-sectional representation,

Figure 3 shows a longitudinal section through an embodiment of a feeder head with varying height of the feed gap in a schematized representation,

Figure 4 shows a schematic illustration of a feeder head having a gap width which varies in the longitudinal direction,

Figure 5 shows a schematic illustration of a feeder head with a feed gap whose width on the surface of the feeder head is constant and increases into the inside of the feeder head and towards the outlet side thereof,

Figure 6 shows in a perspective exploded representation a schematic illustration of the feeder head of the present invention with a feed gap, which feeder head is formed of two plates with an intervening shim foil, and

Figure 7 illustrates the feeder head of Figure 6 in the assembled state in a schematic perspective representation.

In the figures, same or similar reference symbols are used for functionally equivalent or similar characteristics, irrespective of specific embodiments.

Figure 1 illustrates a feeder head 10 for a metering coater (not represented in detail) in a schematized perspective view, containing a cross-sectional representation 11, of the feeder head. Inside the housing 3 of the feeder head 10 is formed a tubular distribution chamber 1. By tubular distribution chamber should in this document be understood a configuration of the distribution chamber as an elongate cavity. A limitation to specific cross-sectional geometries of the distribution chamber does not here exist. The longitudinal direction of the distribution chamber extends substantially in the direction of the longitudinal extent 1 of the feeder head 10. On one of the end faces of the feeder head is found the inlet opening 4, on the end face opposite thereto the outlet opening 5. Towards the side face 6 of the feeder head 10, the distribution chamber 1 is open via a feed slot 2. In the represented embodiment, an opening in the distribution chamber to one of the other side faces of the feeder head does not exist, yet in principle is possible, for example for the purpose of coating of a plurality of foil sheets simultaneously. The feed slot 2 of the feeder head 10 depicted in Figure 1 has a width b which is constant over its length and at the inlet end a height h. As the height of the feed slot is understood, in general terms, the distance between the distribution chamber 1 and the coating surface 6 of the feeder head 10, respectively at the transition to the feed slot 2. As the width of the feed slot 2 is termed in this document the distance b between its two opposing side faces, wherein this distance can be designed to be variable by non-parallel orientation of the two side faces both in the longitudinal direction and in the direction from the distribution chamber to the surface 6 of the feeder head.

During a coating process, the coating composition flows through the distribution chamber 1 from its inlet opening 4 to its outlet opening 5 in the direction indicated by the arrow 7 of Figure 1. The pressure of the coating composition in the distribution chamber 1 here exceeds the ambient pressure of the feeder head, so that, through the feed gap 2, a part of the coating composition flowing through the distribution chamber escapes from the distribution chamber 1 towards the surface 6 of the feeder head 10 and generates there a coating composition stream which exits the gap 2 and is illustrated in the figure by arrows 21. For the maintenance of a flow through the distribution chamber, the pressure pi of the coating material at the inlet-side end 4 of the distribution chamber 1 is greater than the pressure p2 at its outlet-side end 5. Given egual flow velocity, this produces a pressure differential, which increases with the viscosity of the coating composition, between the inflow and outflow of the distribution chamber 1. This pressure differential gives rise to a pressure gradient of the coating composition along the intake opening of the feed gap 2, which intake opening adjoins the distribution chamber 1, wherein the pressure decreases from the inlet-side end to the outlet-side end of the intake opening.

In Figure 2 is illustrated an applicator unit 30 using a feeder head 10. In the represented applicator unit 30, a foil sheet 32 to be coated is guided around a partial circumference of a rotating roller or roll 31. The rotational direction of the roller 31 and the motional direction of the foil sheet 32 are illustrated in the figure by corresponding arrows. In that region of the roll 31 which is enveloped by the foil sheet 32, the feeder head 10 is arranged at a distance to the foil sheet 32, wherein the coating surface 6, in the represented embodiment of the feeder head 10, is realized in a curve tailored to the diameter of the roll 31. In other embodiments, the coating surface 6, also referred to in technical jargon as the coater lip, can be realized without such a curvature, in other words flat. A part of the coating composition 20 flowing through the distribution chamber 1 makes its way through the feed gap 2 into the region which is formed between the coating surface 6 and the thereto opposing surface of the foil sheet 32. Depending on the velocity of the foil sheet, the viscosity of the coating composition 20, the pressure of the coating composition 20 in the distribution chamber and the geometry of the feed gap 2, the region between the surface 6 and the foil sheet 32 is here filled only partially, or, as represented in Figure 2, completely, by the coating material 20. Correspondingly, the wetting meniscus 22 of the coating composition 20 can extend from the outer edge of the surface 6 in the direction of the supplied foil sheet, or can be arranged, as shown, within the regions between the surface 6 and the foil sheet 32. On that side edge of the surface 6 which faces towards the led-off foil sheet 32, the thickness of the coating material 20 generally tapers to the resulting thickness d of the coating layer 24, so that the coating material 20 on this edge likewise forms a meniscus 23. The width of the coating layer 24 substantially corresponds to the length of the feed gap 2, wherein the length of the feed gap 2, as is represented in Figures 1, 4 and 5, can be shorter than the length of the distribution chamber between the inlet opening 4 and the outlet opening 5.

The working distance of the feeder head 10, i.e. the distance between its coating surface 6 and the thereto opposing side of the foil sheet 32, generally has in the production of active substance depots for transdermal therapeutic systems values between 100 ym and 1 mm, wherein working distances from a range from around 100 to around 300 ym are most frequently used. In the case of the coating materials 20 used to form active substance depots, the coating thicknesses d obtained with an arrangement as illustrated in Figure 2 generally have values of around 50 to 100 % of the working distance.

Figure 3 shows a longitudinal section through an embodiment of a feeder head 10 according to Figure 1, in which the distance of the distribution chamber 1 to the surface 6, and thus the respective height h of the feed gap 2, diminishes in the direction of the outlet opening 5. In the embodiment illustrated in Figure 3, the distribution chamber 1 is of curved construction, so that the height of the feed gap 2 decreases non-linearly from the inlet side 4 to the outlet side 5. In configurations of feeder heads 10 as shown in Figure 3, the height pattern hx or h(x) of the feed gap 2 is tailored to the pressure pattern of the coating composition 20 along the intake opening of the feed gap 2, so that the following relationship (1) between the height h(x) of the feed gap at a longitudinal position x and the pressure of the coating material px at the intake opening at the longitudinal position x is obtained:

(1)

Since a part of the coating composition 20 flowing through the distribution chamber 1 exits via the feed gap 2 to the coating surface 6 and is there carried along by the foil sheet 32 which is led past, the pressure drop along the intake opening of the feed gap has a non-linear pattern, so that the height pattern h(x) has a non-linear characteristic. A linearization of the pressure drop along the intake opening of the feed gap 2, and thus of its height pattern h(x), can be achieved in some embodiments by changing the cross section of the distribution chamber 1 in the flow direction of the coating composition 20, wherein the distribution chamber cross section must be realized such that, to this effect, it constantly varies between the inlet opening 4 and the outlet opening 5.

If the cross section of the distribution chamber 1 remains constant in the longitudinal direction x or 1 in area and geometry, the contour of the edge 8 formed at the transition from the distribution chamber 1 to the feed gap 2 can be calculated with the aid of mathematical models for the fluid mechanics of the coating composition 20 in the feeder head, wherein known methods of numerical fluid mechanics, such as, for instance, the Finite-Elements-Method (FEM), can be used for this. The numerical calculations can here be conducted with the aid of quantitative experiments. Alternatively, the characteristics of the height pattern h(x), which in the present case of a uniform width of the feed gap 2 are determined by the contour of the edge 8, can be determined by means of experimental approximation.

The reduction of the feed gap height h (x) in the direction of the outlet side of the feeder head 10 derives from the fact that the flow resistance of a flow passage formed between two parallel walls becomes lower with a shortening of the flow passage. For the lower flow resistance at one place in the feed channel ensures that, despite the lower pressure of the coating composition 20 which prevails there, upon entry into the feed channel 2, the same quantity of coating material 20 per unit of time can flow through this place in the feed channel as at another place at which the coating composition penetrates into the feed gap 2 under a higher pressure, but the latter, in return, has a greater height.

Alternatively to the configuration of the feed gap 2 with a height profile which decreases towards the outlet side 5, the local flow resistance of the feed gap 2 can also be varied via its gap width b.

In the case of a feed gap 2 which is bounded by side walls, the distance apart of which is constant with respect to the direction y (denoted in Figure 3) from the distribution chamber 1 to the coating surface 6, the width of the feed gap 2 here continuously increases in the direction of the outlet side of the feeder head 10. The pattern of the feed gap width b(x) is then characterized by the following relationship (2):

(2) A corresponding embodiment of a feed gap 2 is illustrated in Figure 4.

In other embodiments, the width of the feed gap 2 on the coating surface 6 is constant, but increases differently strongly in the direction of the distribution chamber, related to the relative position between inlet and outlet side. The pattern of the feed gap width b (x, y) is then (3) characterized by the following relationship:

(3)

In relationship (3) , bo denotes a constant value and yo the position of the discharge opening of the feed gap 2 on the coating surface 6. An example of a feed gap 2 of wedge-shaped configuration in accordance with relationship (3) is illustrated in the schematic representation of Figure 5.

Due to the non-linear pressure drop along the longitudinal direction 1 of the distribution chamber, the side walls, for the formation of a coating composition stream 21 which is uniform along the length of the discharge opening of the feed gap 2, are generally of curved configuration. For simpler production, the curvature of the side walls can be approximated by short mutually adjoining flat portions. The shape of the side walls for the formation of a feed gap 2 of variable gap width can likewise be determined with a numerical modelling as specified above, or experimentally.

Of course, in some embodiments of a feeder head 10, a varying design of the gap height pattern h(x) can be combined with a varying design of the gap width pattern b (x) or b(x,y), so that a variation of the height-to-width ratio of the feed gap along its longitudinal direction is obtained.

Preferably, a feeder head 10 is made up of two housing parts 3a and 3b, which are constructed in mirror symmetry with respect to the distribution chamber 1 and the feed gap 2, so that the variation of the height-to-width ratio of the feed gap 2 can be easily realized by, for example, appropriate milling of side walls belonging to the distribution chamber and to the feed gap.

In Figures 6 and 7, a particularly cheaply producible feeder head 10 is illustrated. The schematic perspective representation of Figure 6 shows the basic components of the feeder head in an exploded representation; the perspective representation of Figure 7 shows the feeder head in the assembled state.

The feeder head has a first plate-like element 60, a second plate-like element 61 and an interlay element 62 referred to in technical terms as a shim foil. The two plate-like elements 60 and 61 are hereinafter respectively referred to as a plate. In the represented embodiment, the second plate has a recess 70, the longitudinal ends of which are respectively disposed at a place which enables a fluidic connection to openings 71 or 72, which are formed in the plate 61 and penetrate this same, over the whole of their cross section. One of the two openings acts as an inlet opening, the other as an outlet opening. The elongate recess 70 forms the distribution chamber. The distance of the distribution chamber 70 to the front edge 73 of the second plate 61 varies along the length of the distribution chamber 70. As described above, the variation can be linear, linear in some sections, or nonlinear. In the first case, that edge of the distribution chamber 70 which faces towards the plate front edge 73 forms in the region provided for the slotted spout a straight line, in the second case a line composed of a plurality of straight line segments which meet at an angle, in the last case a curved line. The distance of the distribution chamber 70 to the front edge 73 of the second plate has a profile which decreases in the direction of the outlet opening.

As shown, the shim foil 62 is formed in a U-shape such that it covers the region of that side of the second plate 61 which is directed to the first plate 60, which region is not utilized as the side wall of the feed gap 2. In particular, the shim foil therefore covers those regions of the distribution chamber 70 which extend from the inlet opening 71 or 72 or the outlet opening 72 or 71 up to a border of the feed gap. In order to enable the flow of coating composition through the inlet and the outlet opening, appropriate openings 71 and 72 are provided in the shim foil. In the represented embodiment, the first plate has no structuring of the surfaces with regard to a formation of a part of the distribution chamber. In other embodiments, however, also a part of the distribution chamber can be provided in the first plate 60. Similarly, in the second plate at least an inlet opening or an outlet opening can be arranged. Thus, in some embodiments, the coating composition can be supplied via an opening in one of the two plates 60 or 61 and led off via an opening in the other plate. In other embodiments, both plates respectively have an inlet and an outlet opening, so that the inflow and outflow of the coating composition can respectively take place through both plates .

As materials for the formation of the two plates, steels, such as, for example, plastic mould steels, can be considered. For the formation of the shim foil, plastics, such as, for example, high density polyethylene or polyester, are preferred.

The connection of the two plates 60 and 61 to the intervening shim foil 62 is preferably made with the aid of releasable fastening means, such as, for example with the screws 66 illustrated in Figure 6, which, through holes 65 appropriately formed in the first plate 60 and the shim foil 62, engage in threads 67 formed in the second plate 61. It should be pointed out that in Figures 6 and 7 only those components of the feeder head 10 which are necessary to an understanding of the present invention are represented. The representation of further components which are necessary, for example, for the adjustment of the components one to another or for the operation of the feeder head 10 has been waived in the interest of a clear representation. However, such advantageous or necessary components are assumed to be present.

Figure 7 shows the feeder head 10 of Figure 6 in the assembled state. In this representation can clearly be seen the two openings 71 and 72 which open out into the distribution chamber 70 and via which a coating composition is led through the distribution chamber. As a result of this arrangement, a U-shaped course of the coating composition through the feeder head 10 is produced. Preferably, the openings 71 and 72 are made exactly at the respective ends of the distribution chamber 70. In other embodiments, the openings 71 and 72 are arranged offset to the respective ends of the distribution chamber 70 in the direction of its middle. The offset can measure up to 5 mm, without cavities being formed which would adversely affect the coating behaviour.

Regardless of the design of a feeder head, its outlet opening can be connected to a collecting vessel (not represented in the figures) in such a way that the coating composition exiting the outlet opening can make its way into this collecting vessel. In some embodiments, the coating composition is circulated, so that it is conveyed from the collecting vessel back to the storage tank, or the storage tank simultaneously forms the collecting vessel.

In the detailed representation A of Figure 7, a cross section through the front edge of the feeder head is shown, at which front edge the feed channel 2 enables a discharge of coating composition from the feeder head. As shown, in the represented embodiment both plates have at the exit of the feed channel 2 a projection which extends along the length of the feed channel and the width of which is less than the thickness of the respective plate at the front edge. As a result, the coater lip 6 can be designed in accordance with the application conditions of the coating composition. The formation of appropriate projections does not however constitute an essential configuration of a coater lip.

In the embodiment represented in Figures 6 and 7, the width of the feed channel 2 is not solely determined by the thickness of the shim foil, but can also be influenced within certain limits by the tightening torques of the fastening screws or the pressure forces applied to the arrangement by other suitable fastening means. Given higher pressure forces or tightening torques, the shim foil is more strongly pressed and thus results in a relatively narrower feed channel. Through the application of different pressure forces to the shim foil along this same, the width of the feed gap 2 can be designed so as to vary along its longitudinal extent and, presuming suitably arranged fastening means, also along the flow direction of the coating means in the feed gap.

That design of a feeder head 10 which is illustrated in Figures 6 and 7 enables a change of slot length and slot width of the feed gap 2 by plain and simple exchanging of the shim foil. In the case of smaller slot lengths, the cutout in the shim foil is chosen shorter, in the case of larger slot lengths correspondingly larger, wherein the maximum length of the slot that is given by the design of the distribution chamber 70 must not be exceeded. For the formation of wider feed slots, thicker shim foils are used, or two or more shim foils are laid one on top of another. In other words, the width of the feed gap can be determined by the dimension of the shim foil. The thickness of the shim foil or the thickness of a shim foil stack is in some embodiments less than 3 mm, in preferred embodiments less than 2 mm, and in particularly preferred embodiments less than 1 mm.

That feeder head 10 represented in Figures 6 and 7 can be quickly dismantled and cleaned, so that the changeover time which is necessary upon a change of coating composition can be small.

For the production of coated foil sheets for the formation of transdermal therapeutic systems, a feeder head as previously described is flowed through with a coating composition. Preferably, the coating composition fills the cavity in the feeder head, which cavity is connected to the openings for the inflow and outflow of the coating composition, completely, or at least as far as possible, in order to prevent blistering in the coating. For the coating, the coater lip of the feeder head is arranged at a distance, as previously described, to the foil sheet surface. The coating composition generally consists of an active substance-containing matrix material, which is diluted in a suitable solvent, for instance heptane. The coating composition can constitute a Newtonian or non-Newtonian liquid. In some embodiments of the method, the feeder head 10 is flowed through by a non-Newtonian coating composition in order to achieve an even application of the non-Newtonian coating composition. A feeder head 10 formed in accordance with the features of an embodiment as described above, and a metering coater equipped with a corresponding feeder head, enable the realization of a coating composition stream 21 which is uniform over the length of the discharge opening of the feed gap 2. The precise pattern of the height-to-width ratio is here dependent on the flow behaviour of the respective coating composition 20, so that a feeder head 10 respectively has a pattern of the height-to-width ratio which is tailored to the viscosity range or the flow behaviour of a coating composition 20 to be used herewith. Feeder heads which are formed as described are preferably used in the production of transdermal therapeutic systems (TTS) .

Claims

A coating head with a tubular distribution chamber (1) extending from at least one inlet opening (4) to at least one outlet opening (5) and an inlet slot (2) extending at least along a portion of the length of the the distribution chamber (1) disposed in the inner part of the coating head (10) joins laterally thereto and in order to form an opening in the distribution chamber (1) extends to a surface (6) of the coating head (10) from the distribution chamber (1). to this surface (6), where the cross section of the supply gap (2) varies along the length of the supply gap, characterized in that the inlet opening (4), the outlet opening (5) and the distribution chamber (1) are arranged such that a coating material exiting the outlet opening (5) ), has flowed through the coating head substantially U-shaped.

The coating head according to claim 1, wherein the at least one inlet opening (4), the at least one outlet opening (5) and the distribution chamber (1) are arranged such that substantially no dead zones can be formed.

A coating head according to claim 2, wherein between the end of the distribution chamber (1) on the inlet side and the inlet opening (4) and / or the end of the distribution chamber on the drain side (1) and the outlet opening (5) is arranged each time outside that part of the distribution chamber. (1) connecting the outlet opening (5) and the inlet opening (4), located part of the distribution chamber (1), which in part in the direction connecting the outlet opening (5) and the inlet opening (4), is a maximum of 5 mm.

Coating head according to one of claims 1 to 3, wherein the coating head comprises two non-identical plates and at least one U-shaped shim foil for defining the supply gap, wherein the width of the supply gap is determined by the change in pressure, if required. thickness of the shim foil which is less than 3 mm, preferably less than 2 mm and most preferably less than 1 mm, and wherein the shim foil is insoluble in a solvent contained in the coating mass.

The coating head of claim 4, wherein one of the two plates comprises neither a drain opening (5) nor a feed opening (4).

Coating head according to one of claims 1 to 5, wherein the variation of the cross-section of the supply gap (2) is designed as variation of the height-to-width ratio of the supply gap (2) along its longitudinal direction.

The coating head according to claim 6, wherein the width of the supply gap (2) is constant and the height of the supply gap (2) varies along the longitudinal direction of the supply gap.

The coating head according to claim 7, wherein the height of the supply gap (2) has a gradient shape which decreases in the direction towards the outlet (5) of the distribution chamber (1).

The coating head according to claim 6, wherein the height of the supply gap (2) is constant and the width of the supply gap (2) varies along the longitudinal direction of the supply gap.

The coating head according to claim 9, wherein the width of the supply gap (2) has a gradient shape which increases in the direction towards the outlet (5) of the distribution chamber (1).

A coating head according to any one of claims 6 to 10, wherein the embodiment of the variation of the cross-section of the feed gap has a non-linear characteristic

A device comprising the coating head according to any one of claims 1 to 11, wherein the barrel opening (5) is connected to a collection container so that the coating mass exiting the drainage opening (5) can reach said collection container.

A method for uniformly applying a non-Newtonian coating composition to a film web, characterized in that a coating head according to one of claims 1 to 11 during the coating process is flowed with the non-Newtonian coating composition.

The method of claim 13, wherein the non-Newtonian mass is an agent-containing mass for the preparation of transdermal therapeutic systems (TTS).

Use of a coating head according to any one of claims 1 to 11 in the manufacture of transdermal therapeutic systems (TTS).