Apparatus for coating a continuous web

Claim 2

In a coating apparatus for applying two fluid coating compositions to the surface of a web in superposed layer relation, the combination with a web guiding surface on which a web to be coated is adapted to be continuously advanced while being held in a smooth condition; of a hopper spaced from said web guiding surface; a downwardly inclined flexible trailing blade having one end fixed to said hopper and the other end engaging a first coating on the web on said guiding surface and deflected by such engagement to resiliently press against and trowell the first coating onto the surface of said web as the web is moved past said blade, said blade having an uppermost nontrowelling surface and a lowermost trowelling surface; means for applying said first fluid coating composition to the surface of said web in advance of said blade to be trowelled by said trowelling surface of said blade into a smooth layer; and means for continuously forming a layer of the other fluid coating composition with the aid of gravity flow and flowing it onto the top of said trowelled first layer, and comprising a cavity in said hopper for said other coating composition; and a discharge slot connecting said cavity with the non-trowelling surface of said trailing blade at a point spaced above the flexed end thereof; and means for metering said other coating composition from said cavity through said discharge slot in the form of a layer and onto the non-trowelling surface of said trailing blade, whereby the layer of coating composition formed upon moving down the non-trowelling surface of said blade under the influence of gravity flows off the deflected end thereof and onto the top of the layer of first coating composition applied by the trowelling action of said blade.

Claim 3

A coating apparatus as defined in claim 1, wherein said means for applying a first fluid coating composition to the surface of said web in advance of said blade comprises a second cavity in said hopper for said first fluid coating composition, and a second discharge slot for connecting said cavity with the trowelling surface of said trailing blade at a point spaced above the flexed end thereof; and means for metering said first fluid coating composition from said second cavity through said second discharge slot and onto the trowelling surface of said blade in a layer which flows down the trowelling surface of the blade and onto said web surface.

Claim 4

A coating apparatus as defineD in claim 1, wherein said means for applying a first fluid coating composition to the surface of said web comprises means for continuously depositing said first fluid coating composition onto said web surface ahead of said trailing blade in a plurality of separate streams spaced transversely of said web and at such a rate as to form and maintain a puddle of fluid coating composition behind and across the length of said blade.

Claim 5

A coating apparatus as defined in claim 1, wherein said means for applying a first fluid coating composition to the surface of said web comprises a reservoir for said coating composition, the bottom wall of said reservoir formed by the surface of said web supported by said guiding surface as it approaches said trailing blade, and one end wall of said reservoir formed by the free end of said trailing blade which controls the deposition of the coating composition onto the surface of said web as it passes said blade; and means for continuously feeding said first fluid composition into said reservoir at a rate at least equal to that at which said composition is coated out onto said web.

Claim 6

A coating apparatus as defined in claim 1, characterized in that the end of said trailing blade that is trowelling said first coating is tapered to a rounded point having a thickness less than half the thickness of the blade proper and wherein the upper surface of the tapered end joins the upper surface of the blade in a large radius so that the layer of coating flowing down the blade is not subjected to a sudden change of direction.

Claim 7

A coating apparatus as defined in claim 1 characterized by the inclusion of means for applying a third layer of fluid coating composition along with said two layers mentioned, said means including a second cavity in said hopper; a downwardly inclined slide surface intersecting said discharge slot at an acute angle, whereby a layer of fluid coating composition flowing down said surface under the influence of gravity is adapted to combine in surface relationship with the layer issuing from said discharge slot and flow down the surface of the trailing blade in such strata relationship and flow off the end of said blade onto the surface of the web in strata relationship with the layer of coating applied thereto by said blade; an elongated layer forming duct connecting said second cavity with said slide surface at a point located above said discharge slot, and means for continuously feeding the coating composition into said second cavity at a rate commensurate with the thickness desired in the third layer after coating.

Claim 8

In a coating apparatus for applying a plurality of fluid coating compositions onto the surface of a web in superposed distinct layer relationship, the combination with a web guiding surface on which a web to be coated is adapted to be continuously moved while being held in a smooth condition; of a multiple coating hopper spaced from said web guiding surface; a downwardly inclined flexible trailing blade having a trowelling surface and a non-trowelling surface and further having one end fixed to said hopper and the other end engaging a first coating on the exposed surface of the web on said guiding surface and deflected by such engagement to press against and trowell the first coating onto the surface of said web as it is moved past said blade; means for applying said first fluid coating composition to the surface of said web in advance of said blade to be trowelled by said trowelling surface of said blade into a smooth layer; and means for continuously forming each of the other fluid coating compositions into individual layers, bringing them into superposed and distinct layer relationship with one another and then with the aid of gravity flow depositing them in superposed and distinct layer relationship on the layer of the first fluid coating composition applied to the web; said last-mentioned means comprising a separate cavity in said hopper for each of said other coating compositions; a duct connectinG the first of said cavities with the non-trowelling surface of said trailing blade at a point spaced above the flexed end thereof; means for continuously metering one of said other coating compositions from said cavity and through said duct from which it emerges in the form of a layer which is deposited onto the non-trowelling surface of said trailing blade; and means for continuously metering the remaining coating compositions from their respective cavities in the form of layers and combining said layers in strata relationship with each other and then with the layer of first coating composition as it is trowelled on the surface of said web.

Claim 9

In a coating apparatus for applying a plurality of fluid coating compositions onto the surface of a web in superposed distinct layer relationship, the combination with a web guiding surface on which a web to be coated is adapted to be continuously moved while being held in a smooth condition; of a multiple coating hopper spaced from said web guiding surface; a downwardly inclined flexible trailing blade having a trowelling surface and a non-trowelling surface and further having one end fixed to said hopper and the other end engaging a first coating on the exposed surface of the web on said guiding surface and deflected by such engagement to press against and trowell the first coating onto the surface of said web as it is moved past said blade; means for applying said first fluid coating composition to the surface of said web in advance of said blade to be trowelled by said trowelling surface of said blade into a smooth layer; and means for continuously forming each of the other fluid coating compositions into individual layers, bringing them into superposed and distinct layer relationship with one another and then with the aid of gravity flow depositing them in superposed and distinct layer relationship on the layer of the first fluid coating composition applied to the web; said last-mentioned means comprising a separate cavity in said hopper for each of said other coating compositions; a duct connectinG the first of said cavities with the non-trowelling surface of said trailing blade at a point spaced above the flexed end thereof; means for continuously metering one of said other coating compositions from said cavity and through said duct from which it emerges in the form of a layer which is deposited onto the non-trowelling surface of said trailing blade; and means for continuously metering the remaining coating compositions from their respective cavities in the form of layers and combining said layers in strata relationship with each other and then with the layer of first coating composition as it is trowelled on the surface of said web.

Claim 10

In a coating apparatus for applying three fluid coating compositions onto the surface of a web in superposed distinct layer relationship, the combination with a web guiding surface on which a web to be coated is adapted to be moved while being held in a smooth condition; of a multiple coating hopper spaced from said web guiding surface; a downwardly inclined flexible trailing blade having a trowelling surface and a non-trowelling surface and further having one end fixed to said hopper and the other end engaging a first coating on the exposed surface of the web on the guiding surface and deflected by such engagement to press against and trowell the first coating onto the surface of said web as it is moved past said blade; means for applying a first fluid coating composition to the surface of said web in advance of said blade to be trowelled by said trowelling surface of said blade into a smooth layer on the web surface; and means for continuously forming each of the other two fluid coating compositions into individual layers, bringing them into superposed and distinct layer relationship with one another and then with the aid of gravity flow depositing them in superposed and distinct relationship with the layer of the first coating composition applied to said web; said last-mentioned means comprising, a separate cavity in said hopper for each of the other two coating compositions; an elongated discharge slot communicating with one of said cavities and directed downwardly onto the non-trowelling surface of said trailing blade at a point removed from the deflected end thereof; means for continuously metering one of the other two coating compositions from its cavity through said discharge slot in the form of a layer; a downwardly inclined slide surface intersecting said discharge slot an an acute angle; an elongated duct leading from the last cavity onto said slide surface at a point above said discharge slot; and means for continuously metering said third coating composition from said last cavity through said duct and onto said slide surface in the form of a layer which flows down said slide surface and onto the top of the layer issuing from said discharge slot and after which the two layers flow down said trailing blade and off the end thereof onto the layer of coating composition trowelled on the web by said trailing balde.

Claim 11

In a coating apparatus for applying three fluid coating compositions onto the surface of a web in superposed distinct layer relationship, the combination with a web guiding surface on which a web to be coated is adapted to be moved while being held in a smooth condition; of a multiple coating hopper spaced from said web guiding surface; a downwardly inclined flexible trailing blade having a trowelling surface and a non-trowelling surface and further having one end fixed to said hopper and the other end engaging a first coating on the exposed surface of the web on the guiding surface and deflected by such engagement to press against and trowell the first coating onto the surface of said web as it is moved past said blade; means for applying a first fluid coating composition to the surface of said web in advance of said blade to be trowelled by said trowelling surface of said blade into a smooth layer on the web surface; and means for continuously forming each of the other two fluid coating compositions into individual layers, bringing them into superposed and distinct layer relationship with one another and then with the aid of gravity flow depositing them in superposed and distinct relationship with the layer of the first coating composition applied to said web; said last-mentioned means comprising, a separate cavity in said hopper for each of the other two coating compositions; an elongated discharge slot communicating with one of said cavities and directed downwardly onto the non-trowelling surface of said trailing blade at a point removed from the deflected end thereof; means for continuously metering one of the other two coating compositions from its cavity through said discharge slot in the form of a layer; a downwardly inclined slide surface intersecting said discharge slot an an acute angle; an elongated duct leading from the last cavity onto said slide surface at a point above said discharge slot; and means for continuously metering said third coating composition from said last cavity through said duct and onto said slide surface in the form of a layer which flows down said slide surface and onto the top of the layer issuing from said discharge slot and after which the two layers flow down said trailing blade and off the end thereof onto the layer of coating composition trowelled on the web by said trailing balde.