Method of and apparatus for producing a film or a layer with a surface structure on both sides

Abstract

A method of and apparatus for producing a transparent film or a transparent layer with a surface structure at least on one side and, on the other side, in register with said surface structure, a structural or 2-dimensional pattern, operate with at least two rotating rollers and layer application between them and curing of a structural layer. By means of a third rotating application roller, a further layer can be applied in register to the rear side of the structural layer and can be cured. The rollers and roller nips can be set very accurately by suitable devices. The rotation of all the rollers is controlled by a master drive.

We claim:  
     
         1 . A method of producing a film or a layer with a surface structure at least on one side of a base film and, on the other side, in register with said surface structure, a structural or two-dimensional pattern, which are produced by means of a first roller and a second roller, provided with a circumferential structure, the rollers being driven in approximately equally fast, but opposite rotation, and the film or the layer being produced by applying a layer of thermoplastic polymer to a film fed to the second roller via the first roller, in which method there is a third roller, which is arranged downstream of the second roller, is driven approximately equally fast and in the opposite direction to the second roller and is likewise provided with a structural or 2-dimensional pattern, and in which method a further layer of thermoplastic, radiation-curable polymer material is applied to the other side of the base film, which has been fed to the third roller via the second roller and was already coated at least on one side, and in which method the polymer layer on the outer, other side of the base film is radiation cured.  
     
     
         2 . A method as claimed in  claim 1 , in which there is a film or a layer which has as a surface structure on one side a multiplicity of identical, parallel, elongate lenticular structures, in particular of cylindrically arched form, and is provided on the other side with mutually assigned parallel lines or grooves or ridges in register with said structures.  
     
     
         3 . A method as claimed in  claim 1 , in which there is a film or a layer which has as a surface structure a multiplicity of parallel arcuate lenses.  
     
     
         4 . A method as claimed in  claim 1  or  2 , in which there is a film or a layer which has as the surface structure on the other side a multiplicity of parallel ridges, in particular of rectangular form.  
     
     
         5 . A method as claimed in  claim 2 , wherein the lenticular structure on one side and the parallel lines, grooves or ridges on the other side are produced after each other in time, in particular immediately after each other, and in register with each other.  
     
     
         6 . A method as claimed in  claim 2  or  4 , wherein the lenses and ridges consist of a UV-curable polymer, in particular an acrylic resin.  
     
     
         7 . A method as claimed in  claim 6 , wherein the polymer, in particular the acrylic resin, contains up to 30% by weight of pigments for reducing transparency.  
     
     
         8 . A method as claimed in claims  1  and  4 , wherein the ridges are provided with optically opacifying layers, in particular said layers are printed on.  
     
     
         9 . A method as claimed in  claim 8 , wherein the at least two, preferably eight, optically opacifying layers are printed onto the ridges.  
     
     
         10 . A method as claimed in one or more of  claims 6  to  9 , wherein the maximum transparency of the ridges is about 7%.  
     
     
         11 . A method as claimed in claims  1  and  4 , wherein the width of the ridges is chosen such that the same cover and render opaque at most about 80% of the surface area of the film or of the layer.  
     
     
         12 . Apparatus for producing a film or a layer with a surface structure at least on one side of a base film and, on the other side, in register with said surface structure, a structural or 2-dimensional pattern, by means of a first roller and a second roller, provided with a circumferential structure, which rollers are driven in approximately equally fast, but opposite rotation, and by means of an application device for a layer of thermoplastic polymer to be applied to the base film fed to the second roller via the first roller and by means of a radiation source for curing through the film the polymer layer bearing against the circumference of the second roller, wherein the second roller is followed downstream by a third roller, which is also driven approximately equally fast and in the opposite direction to the second roller and is likewise provided with a structural or 2-dimensional pattern, and by means of an application device for a further layer of thermoplastic, radiation-curable polymer material to be applied to the other side of the film, which has been fed to the third roller via the second roller and was already coated at least on one side, and by means of a radiation source for curing the polymer layer on the outer other side of the base film.  
     
     
         13 . Apparatus as claimed in  claim 12 , in which there is a film or a layer which has as a surface structure on one side a multiplicity of identical, parallel, elongate lenticular structures, in particular of cylindrically arched form, and is provided on the other side with mutually assigned parallel lines, grooves or ridges in register with said structures.  
     
     
         14 . Apparatus as claimed in  claim 12 , wherein the second roller has a surface structure with a multiplicity of identical, parallel arcuate grooves.  
     
     
         15 . Apparatus as claimed in  claim 12  or  14 , wherein the first roller has a smooth surface.  
     
     
         16 . Apparatus as claimed in  claim 12  or  claims 12  to  15 , wherein the third roller has as a surface structure a multiplicity of parallel grooves, in particular of rectangular form.  
     
     
         17 . Apparatus as claimed in  claim 15 , in which there is at the first roller a contact roller, by means of which the base film for the production of a film or a layer is fed to the circumference of the first roller.  
     
     
         18 . Apparatus as claimed in  claim 12  and one or more of  claims 13  to  17 , wherein the first roller serves as a master drive roller, for controlling the rotational speed of the second and third rollers.  
     
     
         19 . Apparatus as claimed in one or more of  claims 12  to  18 , wherein the second roller is designed to be axially adjustable by means of an adjusting device, in particular an eccentric adjusting device, with respect to the first and third rollers.  
     
     
         20 . Apparatus as claimed in  claim 19 , wherein the adjusting device substantially comprises a thrust element which is connected to the axially adjustable roller and with which an eccentric shaft is in contact (FIG. 4).  
     
     
         21 . Apparatus as claimed in  claim 12  and one or more of  claims 13  to  20 , wherein the not respectively axially adjustable rollers are mounted by means of a swivelling away or drawing away device (FIG. 5) for threading in the base film.  
     
     
         22 . Apparatus as claimed in  claim 12  and one or more of  claims 13  to  21 , wherein the application device is a coater with at least one metering device, and a lifting-off device is provided for threading in the carrier film.  
     
     
         23 . Apparatus as claimed in  claim 21 , wherein the swivelling mechanism comprises an eccentric mounting.  
     
     
         24 . Apparatus as claimed in  claim 12  and one or more of  claims 13  to  23 , in which there are bearing means, in which two of the first to third rollers can be set with respect to the other roller in their axial parallelism to the respectively other roller.  
     
     
         25 . Apparatus as claimed in  claim 12  and one or more of  claims 13  to  24 , wherein, for driving each of the three rollers, there is provided a drive motor with an interposed gear transmission and an electronic synchronism control.  
     
     
         26 . Apparatus as claimed in  claim 12  and one or more of  claims 13  to  25 , wherein the application device is a curtain coater which has a housing with light shielding devices, the latter including elements made of polytetrafluoroethylene.  
     
     
         27 . Apparatus as claimed in  claim 12  and one ore more of  claims 13  to  25 , wherein the application device consists of fine feed regulation elements which have a housing with light shielding devices, the latter including elements made of polytetraflouroethylene.  
     
     
         28 . Apparatus as claimed in  claim 12  and one or more of  claims 13  to  27 , wherein a nip setting device for the first nip between the first roller and the second roller and a further nip setting device for the second nip between the second and third rollers are provided.  
     
     
         29 . Apparatus as claimed in  claim 12  and one or more of  claims 13  to  28 , wherein an unwinding station for the base film with compensating roller control is provided upstream of the production device of the film or the layer.  
     
     
         30 . Apparatus as claimed in  claim 28 , wherein a further drive station with compensating roller control ( 8 ) is provided downstream of the production device of the film or the layer in the running direction of the film or the layer.  
     
     
         31 . Apparatus as claimed in claims  28  and  29 , wherein a printing station for printing onto the ridges on the other side of the film or the layer is provided downstream of the further drive station in the running direction of the film or the layer.  
     
     
         32 . Apparatus as claimed in claims  28  and  29 , wherein a station for applying an adhesive to the film or the layer is provided downstream of the printing station in the running direction.  
     
     
         33 . Apparatus as claimed in claims  28 ,  29  and  32  wherein a laminating station for laminating a screening film onto the adhesive layer of the film or the layer is arranged downstream of the adhering station in the running direction.  
     
     
         34 . Apparatus as claimed in  claim 31  co  32  or  33 , wherein the winding-up station for the film or the layer is provided downstream of the printing station or adhering station or laminating station.