GB2243313A

GB2243313A - Apparatus for applying films to substrates

Info

Publication number: GB2243313A
Application number: GB9108739A
Authority: GB
Inventors: Albert Hebels
Original assignee: Pagendarm Beschichtungstechnik GmbH
Current assignee: Pagendarm Beschichtungstechnik GmbH
Priority date: 1990-04-26
Filing date: 1991-04-24
Publication date: 1991-10-30
Also published as: DE4013319A1; GB9108739D0; FR2661363A1; IT1245607B; ITMI910894A0; ITMI910894A1

Abstract

An apparatus for applying a film of adhesive coating material to one side of a running substrate has a first drum-shaped conveyor (1) which transports the substrate (3), and a second drum-shaped conveyor (7) which transports a relatively thick layer of adhesive material (9). The two conveyors are sufficiently close to each other to ensure that the layer contacts the exposed side of the substrate and the nip immediately downstream of the locus of minimum distance of the two conveyors from each other contains a splitting tool (17) which extends into the coating material to separate from the layer a film (14) which adheres to the exposed side of the substrate. The major portion of the layer (18) remains on the second conveyor. The splitting tool can include a length of thin wire or an elongated nozzle which discharges a long jet of compressed inert gas into the nip so that the jet severs or shaves the film off the layer of coating material. <IMAGE>

Description

T APPARATUS FOR APPLYING FILMS TO SUBSTRATES The-invention relates to

improvements in annaratus for ann1ving films of adherent coating material to runnina substrates of naDerr textile material, plastic foil or the like. 1111ore r)articularl,,;,, the invention relates to imurovements in apparatus wherein a first conveyor transnorts a laver of adherent coating material toward the exposed side of a substrate on a second conveyor so that the laver contacts the substrate while the substrate is caused to advance in the direction of movement of the layer.

In conventional apparatus of the above outlined character, separation of the substrate (-Nqith a film of coating material thereonl from the remainder of the laver takes place in a nip (hereinafter called outlet nip). which is located immediately downstream of the narrowest ?ortion of the ga-) between the path for the substrate on the one hand and the nath for the laver of coating material on the other hand. A drawback of conventional anparatus is that the exposed surface of the film which has been applied to the running substrate is often unsatisfactory. Thus, if the coating material is a sticky substance which contains aerosols, separation of a thin film -from the laver of coating material in the outlet nin of the two conveyors often results in the development of thin filaments which are caused to break and to release aerosols. Therefore, a ra-her large area around the film-applying station must be sealed in order to permit controlled gathering of released aerosols by suction. If the exposed surface of the film of coating material on the substrate is to be smooth, the annaratus must be designed to supply a relatively thick layer of coating material which entails reneated circulation of relativelv larae quantities of coating material toward and aqain away from the film forming zone. Moreover, even if the sunnlied laver of coatinq material is relatively thick, a conventional apparatus is still incanable of ensurinq the formation of a film which has a constant thickness and a satisfactory exposed surface. The situation is aggravated if a running substrate is to be coated with an expensive material, e.g., undiluted silicone. Additional expenses, which arise because the aerosols which are liberated at the film forminq station must be collected by resorting to one or moresuction qenerating devices, render the initial cost and maintenance cost of such apparatus nrohibitive.

1 z The invention is embodied in an apparatus for applying adhesive coating material to one side of a running substrate. The improved apparatus comprises means for transporting the substrate in a predetermined direction along a first path so that one side of the substrate remains exposed, and means for conveying a layer of coating material along a second path having a portion wherein the layer is advanced in or at least close to the predetermined direction and is close to the first path so that the layer contacts the exposed side of the substrate. The transporting means and the conveying means define a nip which is located downstream of the portion of the second path and extends transversely of the predetermined direction, and the apparatus further comprises means for splitting the layer in the nip so that a normally thin film of coating material is separated from the layer and adheres to the exposed side of the substrate whereas the remainder of the layer continues to advance along' the second path.

At least one of the transporting and conveying means is preferably rotatable about a predetermiend axis. For example, each of the transporting and conveying means can include or constitute a roller.

The nip is preferably located immediately downstream of the aforementioned portion of the second path.

The splitting means can include an elongated linear splitting tool having a layer-splitting portion which is parallel to the exposed side of the substrate, at least in the region of the nip. Such portion o-f the tool extends longitudinally of the nip and transversely of the predetermined direction.

The splitting tool can include a length of thin wire which is located in the nip and extends transversely of the predetermined direction in parallelism with the exposed side of the substrate at the nip.

L_ The transpo.rting means and the conveying means can define a second nip which is located at the aforementioned portion of the second path. upstream of the splitting means in the first mentioned nip and is filled with coating material. The splitting means is wedged between the film which adheres to the exposed side of the substrate and the remainder of the layer in the second path. The apparatus can comprise means for operating the transporting means and the conveying means at a plurality of different speeds including a nominal speed, and the layer preferably fills the nip between the aforementioned portion of the second path and the splitting means at least when the transporting means and the conveying means are operated at the nominal speed.

The apparatus can further comprise means for supporting or propping the splitting means against movement relative to the aforementioned portion of the second path and the nip under the action of coating material in the nip. If the splitting means includes a linear splitting tool which extends transversely of the predetermined direction and is parallel to the exposed side of the substrate, the supporting or propping means can be provided with a supporting surface which engages at least certain portions of the tool, namely portions which are spaced apart from each other in the longitudinal direction of the tool. If the tool is a wire having a circular cross-sectional outline and a longitudinal axis which extends transversely of the predetermined direction, the supporting surface can be inclined relative to the predetermined direction in such a way that a line which is normal to the supporting surface and intersects the axis of the tool also intersects the second path downstream of the nip.

The propping means can include a source of compressed gaseous fluid (particularly an inert gas) and a nozzle which is connected with the source and serves to discharge at least one jet of compressed fluid against the splitting means.

If the splitting means includes a length of wire which is disposed in the nip at a predetermined distance from and in parallelism with the exposed side of the substrate at the nip, the apparatus preferably further comprises means for maintaining the wire under tension so that one can dispense with the propping means or that the propping means merely assists the tensioned wire in resisting undue displacement under the action of coating material in the nip. The tensioning means can include a supply reel at one end of the nip, a takeup reel at the other end of the nip, means for winding the wire onto one of the reels, and means for braking the other reel.

The splitting means can comprise or constitute a source of compressed gas (particularly an inert gas) and a nozzle which is connected with the source and has means for discharging into the nip a narrow elongated jet of compressed gas between the film and the remainder of the layer of coating material. The discharging means can comprise an elongated orifice (which can be composed of one or more rows of narrower orifices) extending transversely of the predetermined direction in parallelism with te exposed side of the substrate at the nip.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be be.st understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawing.

FIG. 1 is a partly end elevational and partly transverse vertical sectional view of an apparatus which embodies one form of the invention, the section being taken in the direction of arrows as seen from the line I-1 in FIG. 4; 3FIG. 2 is an enlarged view of a detail within the phantom line circle A in FIG. 1 but turned through 180'; FIG. 3 is a view similar to that of FIG. 2 but showing a portion of a modified annaratus; and FIG. 4 is a side elevational view substantially as seen in the direction of arrow IV in FIG.' 1.

1 Referring first to FIGS. 1 and 4, there is shown an apparatus which comprises a first rotary conveyor 1 driven at a preferably variable speed bv a suitable drive including a horizontal shaft 12 and serving to transport a flexible web-shaped or stripshaped substrate 3 along an elongated first path in the direction of arrow 2 so that the exposed side of the substrate faces downward1v at the six o'clock position of the conveyor 1. The means 4 for conveying a continuous laver 9 of adherent coating material along an elongated second path in the direction of arrow 6 comprises a second rotary conveyor 7 which is rotated (.preferablv at a variable siDeed) bv a drive including a second horizontal shaft 13. The illustrated shafts 12, 13 are narallel to each other and are spaced apart a distance such that the twelve o'clock position of the conveyor 7 is sufficient1v close to the six-o'clock position of the-conveyor'l to ensure that successive increments of the exposed side of the substrate 3 are contacted by successive increments of the layer 9 at the X location 11, namely in that portion of the path for the laver 9 which is immediately adjacent and is located upstream of an outlet or exit nip 16 of the convevors 1 and 7. The manner in which the layer 9 is supplied to the periphery of the conveyor 7 (at 8 in PIr,. 1)- is known and forms no Dart of the iDresent invention.

The exnosed side of the laver 9 which is advanced toward the location 11 is pressed against the exposed side of the substrate 3 so that the latter accepts and entrains a thin film 14. The remainder or surnlus 18 of the material of the laver 9 continues to advance along the second path (which is defined by the conveyor 7) and is senarated from the peripheral surface of the conveyor 7 by a suitable scraTDer 19 or in any other acceptable way for renewed use or for delivery to another destination.

In order to facilitate the formation of a predictable film 14, the improved apparatus further comnrises an elongated linear tool 17 which serves to split the film 14 off the remainder 18 of the laver 9, i.e., to actuallv shave the film 14 off the normallv much thicker remaining portion 18 of the layer 9. The illustrated splitting or shaving tool 17 is an elongated piece of thin metallic or other wire which is stretched to extend transversely of the direction (.arrow 2) of movement of the substrate 3, at a selected distance from and in parallelism with the exposed surface of the substrate, and longitudinally of and deep in the outlet nip 16, i.e., close or verv close to the six o'clock position of the conveyor 1. If the conveyors 1 and 7 are circular cylinders, the lenath of the wire 17 in the nip 16 is parallel to the axes of the shafts 12 and 13. The wire 17 is or can be extremely thin (-the diameter of this wire as well as the thicknesses of the substrate 3, film 14, laver 9 and surnlus or remnant 18 are exaggerated in FIGS. 1 and 4 for the sake of claritvl to ensure that the anDaratus can provide the substrate with a very thin or extremely thin film 14 of coating material, e.g., an adhesive substance which is thereuTDon dried and/or otherwise treated to acquire optimum characteristics for ultimate use.

FIG. 4. shows means for tensioning and for simultaneouslv moving the wire 17 lengthwise (-lonaitudinallv of the nip 161 to enhance the severing, splitting or separating action. The wire - 9 17 is trained over pulleys 21, 22 which are installed at opposite ends of the nin 16. One end of the wire 17 is connected to the core of a supply reel or drum 23 upstream of the nullev 21, and the other end of the wire is connected to the core of a takeup reel or drum 24. The reel 24 can he driven by a suitable electric motor 26 or another orime mover, and the reel 23 is braked bv a suitable braking device 27 to offer requisite resistance to advancement of the wire 17 toward the takeup reel 24 as well as to ensure that the length of wire between the pulleys 21, 22 is properly tensioned in order to withstand the pressure of coatina material in the nin 16.

The speed of movement of the wire 17 from the sunnlv reel 23 to the takeup reel 24 can be low or extremely low. In fact, the motor 26 and the brake 27 can be replaced with suitable clamping devices (.not shown)- which simply grip the respective ends of the wire 17 and at least one of which can be adjusted to increase or reduce the tensional stress unon the wire between the nulleys 21 and 22. An advantage of the means for movinq the wire 17 longitudinally of the nip 16 is that the splitting or shaving action of a moving wire is more satisfactory than that of a fixedlv installed wire.

FIG. 2 shows, drawn to a much larger scale, that nortion of the aDnaratus of FIG. 1 which is located within the phantom-line circle A, and the structure is turned around throuqh 180' about an axis which crosses the axes of the shafts 12, 13 (not shown in FIG. 2) and intersects the peripheries 7 at the six o'clock and twelve resnectivelv. The diameter of the exaggeraiLed to more clearly show an inclined suT)porting or propping of the convevors 1 o'clock positions, wire 17 is areatlv the orientation of - 10 surface 29 forming part of an elongated slender mechanical nropning or supporting device 28 for the length of the wire in the nip 16. The inclination of the supporting surface 29 is such that a line N which is normal thereto and intersects the axis of the wire 17 slopes away from the path for the substrate 3 and intersects the path for the layer 9 of coating material, i.e., such line N can be said to Denetrate into the convevor 7. This is desirable and advantageous because the thickness of the film 14 on the exposed side of the substrate 3 can be varied by the simple expedient of moving the propping device 28 in a substantially horizontal plane, namely in a plane which halves the outlet nip 16 downstream of the location of minimum distance of the conveyors 1 and 7 from each other. The surface 29 need not contact the wire 17 all the wav from the one end to the other end of the nin 6; it often suffices if the surface 29 is configurated in such a way that it merelv contacts selected longitudinally sDaced-apart portions or sections of the wire 17 (-as seen in the lonqitudinal direction of the nip 161.

That nortion of the propping device 28 which extends into the nip 16 is or can be unsupported, i.e., the device 28 can be mounted in cantilever fashion to ensure that it does not contact the film 14 and/or the surplus 18 of the laver 9.

The -mechanical Dropping evice 28 can he used jointly with or in lieu of a pneumatic propping device which is indicated in FIG. 2 bv broken lines. This pneumatic Dropping device comprises a source 32 of comnressed aas (e. a., an inert gas such as nitrogen) and a nozzle 31 having one or more orifices to discharge a narrow but long and strong jet of gaseous fluid against the adjacent portion of the peripheral i surface of the wire 17 in the nip 16. The nozzle 31 can be provided with a single elongated orifice or with one or more elongated rows of round or otherwise configurated orifice's, as long as the jet of compressed gas which issues from the nozzle 31 suffices to adequately prop the wire 17 in the nip 16. In addition, neutral gas which penetrates into the nin 16 prevents entry of air if contact of the exposed sides of the film 14 and/or surplus 18 in the nin 16 with air is undesirable or detrimental. The mechanical propping device 28 of FIG. 2 is assumed to he provided with a suitable slot to receive the front portion of the nozzle 31. However, and as mentioned above, it is eauallv within the Durview of the invention to use the mechanical propping device without the pneumatic Dropping device or vice versa.

It will be seen that the deeDmost -oortion of the nip 16 of FIG. 2 is completely or nearly completely filled by the wire 17, b-,;, the film 14, by the substrate 3 and by the surplus 18. In addition, and if the apparatus of FIG. 2 employs the nneumatic pronping device 31, 32, the space immediatelv to the left of the wire 17 is completely filled with inert gas to thus prevent penetration of air all the way to the wire 17. The ni-D of the convevors 1, 7 uTDstream of the outlet nip 16 (immediately to the right of the wire 17)_ is completely, filled with the coatinq material of the layer 9 and with the substrate 3.

FIG. 3 shows a portion of a modified apparatus wherein the splitting or shaving means -for the laver 9 of coating material comprises a pneumatic splitting tool including an elongated thin nozzle 33 connected to a source 34 of compressed gas (preferably an inert gas) and serving to direct a long, strong and narrow jet or stream of gas into the nip' 16 in order to predictably separate the film 14 from the surDlus 18 of the laver 9 as well as to prevent penetration of atmospheric air into the deenmost portion of the nip 16, i. e., close to the six o'clock nosition of the convevor 1 and the twelve o'clock position of the conveyor 7. The pneumatic splitting tool 33, 34 prevents the development of aerosols in the nip 16. It has been found that the FIG. 3 is also capable of Dneumatic splitting tool o ensuring the formation of a film 14 with a highly satisfactory external surface and of desirea thickness, even if the conveyors 1 and 7 are driven at an elevated speed.

The development of aerosols is prevented or reduced, and the quality of the exposed surface of the film 14 is more satisfactory, if the splitting tool (be it the wire 17 or the jet of compressed gas which issues from the nozzle 331 acts upon the laver 9 in or close to the deepMost portion of the outlet nip 16.

It goes without saying that the improved apparatus is or can be provided with suitable means for adjusting the nozzle 33 relative to the conveyors 1, 7 and/or for adjusting the wire 17 relative to such conveyors in order to ensure that the selected tool will snlit or shave off the 14yer 9 a film 14 of desired thickness. A wire-like splitting tool is preferred in many instances because its thickness can be selected practically at will and because it can be installed deep in the outlet nip 16 with the aforediscussed advantages as regards the development of aerosols and the quality of the exposed surface of the film 14. Moreover, and especially if the wire 13 17 need not be propped and need not be moved lengthwise as described Nqith reference to FIG. 4, the improved apparatus is extremely simple, compact and inexpensive. When the wire 17 is very thin, it acts not unlike a sharpened cutting edge which can be positioned at a desired distance from and in parallelism with the exposed surface of the substrate 3 to thus ensure the formation of a high-quality film 14. Propping of the wire 17 is desirable and advantageous when the apparatus is to process certain types of coating materials and/or when the conveyors 1, 7 are driven at an elevated speed so that the tendency of coating material which fills the space between the conveyors 1 and 7 immediately upstream of the nip 16 to displace the wire 17 is rather pronounced. Such elevated speeds are desirable because this renders it possible to coat long stretches of a running substrate per unit of time. The (preferablyl variable speed of the means (-including the shafts 12 - and 13). for rotatina the convevors 1, 7 is vreferablv selected in such a wav that the space between the conveyors 1, 7 immediately upstream of the nip 16 is at least substantiallv filled with coating material, at least wh-en the conveyors are driven at the nominal or rated speed. Such complete or practically complete filling of the nip 16 with coating material in the region of the wire 17 areatlv reduces the likelihood of the development of aerosols (to keen the losses in the course of the coating operation to a minimum) and also prevents penetration of air into the nin or into that portion of the nin which receives the wire 17. Prevention of the development of aerosols ticularly desirable if the coating material is part. is exnensive (e.g., if such material is an undiluted 14 - silicone).

t 1 - 15 Without further analvsis, the foregoing will so fully reveal the gist Of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptati6ns should and are intended to be comprehended within the meaning and range of eauivalence of the appended claims.

Claims

CIAIMS

1. Apparatus for applying adhesive coating material to one side of a runnina substrate, comprising means for.transporting the substrate in a predetermined direction along a first path so that the one side of the substrate remains exposed; means for conveying a layer of coating material along a second path having a portion wherein the layer is advanced in said direction and which is close to said first path so that the laver contacts the exposed side of the substrate, said transporting means and said conveying means defining a nip which is located downstream of said portion of said second nath and extends transverselv of said direction; and means for splitting the layer in said nip so that a film of coating material is separated from the laver and adheres to the exposed side of the substrate while the remainder of the layer continues to advance along said second path.

2. The apparatus of claim 1, wherein at least one of said transporting means and said conveying means is rotatable about a predetermined axis.

3. The apparatus of claim 1, wherein said ni.p is located immediately downstream of said portion of said second path.

4. The apparatus of claim 1, wherein said splitting means includes a linear splitting tool having a layer-splitting portion which is parallel to the exposed side of the substrate at said nip.

5. The aDnaratus of claim 4, wherein said portion of said tool extends longitudinally of said niD and transversely of said direction.

6. The apparatus of claim 4, wherein said splitting tool includes a length of wire which is located in said nip and extends transversely of said direction in parallelism with the exposed side of the substrate at said nin.

7. The apparatus of claim 1, wherbin said transporting means and said conveying means define a second nip which is located at said portion of said second path upstream of said splitting means and is filled with coatina material.

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8. The apparatus of claim 1, wherein said laver fills said nin between said portion off said second path and said splitting means, said splitting means being wedged between the film which adheres to the exposed side of the substrate and the remainder of the layer in said second path.

9. The apparatus of claim 8, further comprising means for operating said transporting means and said conveying means at a plurality of speeds, including a nominal speed, and said layer fills said nip between said portion of said second path and said splitting means at least when said transporting means and said conveying means are operated at said nominal speed.

10. The apparatus of claim 8, further comprising means for proppinq said splitting means against movement relative to said portion of said second path and said nip under the action of coating material in said nip.

11. The apparatus of claim 10, wherein said s-olittinq means includes a linear splitting tool which extends transversely of said direction and is parallel to the exposed side of the substrate, said propping means having a supporting surface which engages at least certain portions of said tool, such portions of the tool being spaced apart from each other in the longitudinal direction of said tool.

12. The apparatus of claim 11, wherein said tool has a substantiallv circular cross-sectional outline and a longitudinal axis extending transversely of said direction, said supporting surface being inclined relative to said direction so that a line which is normal to said suDportinq surface and intersects said axis also intersects said second path downstream of said nip.

13. The apparatus of claim 10, wherein said propping means includes a source of compressed gaseous fluid and a nozzle connected to said source and arranged to discharge at least one jet of compressed fluid against said splitting means.

14. The apparatus of claim 13, wherein said source contains an inert gas.

15. The apparatus of claim 1, wherein said nip is elongated and said splitting means includes a length of wire disposed in said nip at a Predetermined distance from and Parallel with the exposed side of the substrate, and means for maintaining the wire in said nip under tension so that the wire can resist displacement relative to the nip under the action of coating material in said nip.

16. The anparatus of claim 15, wherein said means for maintaining the wire under tension includes a supply reel az one end of said nip, a takeup reel at the other end of said nip, means for windinq the wire onto one of said reels and means for braking the other of said reels.

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17. The a-D-Daratus of claim 1, wherein said splitting means comprises a source of compressed gas and a nozzle connected with said source and having-means for discharging into said nip a narrow elongated jet of compressed gas between the film and the remainder of the laver of coating material.

18. The apparatus of claim 17, wherein said discharging means comprises an elongated orific which extends transversely of said direction and in parallelism with the exposed side of the substrate at said nip.

19. The apparatus of claim 17, wherein said source contains a supply of inert gas.

20. Apparatus for applying adhesive coating material to one side of a running substrate, substantially as herein described with reference to the accompanying drawings.

Published 1991 at The Patent Office. Concept House. Cardiff Road. Newport. Gwent NP9 IRH. Further copies may be obtained from Sales Branch. Unit 6. Nine Mile Point. Cwrafelinfach, Cross Keys, Newport. NPI. 7HZ. Printed by Multiplex techniques ltd, St Mary Cray. Kent.

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