Two sided coater

Abstract

Two side coaters and methods of coating paper on both sides are disclosed in which a web of paper to be coated is moved in a generally upward direction in partially wrapped relation to a coating roll, so that one side of the web is in contact with and supported by the roll. This one side of the web is coated by a first coating material which is applied by the coating roll. This coating material is applied to the coating roll by an applicator roll, either directly in which a puddle is formed between the applicator roll and the coating roll, or through transfer from a pair of metering rolls in which the coating puddle is formed between the metering rolls. A second coating, which may be the same as or different from the first coating, is applied by a non-contacting jet fountain coater to an area on the opposite exposed side of the web just ahead of or including the area which is in wrapped relation to the coating roll, and the excess coating is blade doctored, employing the coating roll as a back-up roll for the doctor blade. The .[.blade.]. .Iadd.web .Iaddend.side moves upwardly in view of the operator and is turned for subsequent drying or the like with the blade side up. There are also disclosed arrangements by which the lead-in and lead-out angles of the web may be controlled for the purpose of controlling the angle of contact and degree of wrap of the web with the coating roll. The method further contemplates conventional blade doctoring, bent-blade doctoring, and zero-angle blade doctoring.

What is claimed is: 
     
       1. Apparatus for coating a web of paper which is adapted to apply different coating materials to the opposite sides of the web in a single pass through the apparatus, comprising: (a) a coating roll mounted with the axis thereof in fixed position,   (b) a fixed guide roll cooperating with said coating roll to maintain an otherwise unsupported lead-in portion of the web to be coated travelling generally upwardly from said guide roll to said coating roll,   (c) a second guide roll supporting a lead-off portion of the web travelling generally upwardly from said coating roll and cooperating with said first guide roll to establish the extent of wrap of said coating roll by the web.   (d) means mounting at least one of said guide rolls for adjustment with respect to said coating roll to vary the extent of wrap of said coating roll by the web,   (e) applicator means for applying a metered quantity of a coating material to said coating roll at a location remote from the portion of said coating roll wrapped by the web for application of such coating material by said coating roll to the surface of the web which contacts said coating roll,   (f) non-contacting coating fountain means positioned to direct .[.ametered.]. .Iadd.a metered .Iaddend.quantity of a coating material against the other surface of said lead-in portion of the web, and   (g) a doctor blade mounted to engage said other surface of the web along the portion thereof wrapping said coating roll to remove excess quantities of the coating material applied to the web by said fountain means.   
     
     
       2. Coating apparatus as defined in claim 1 further comprising means for adjusting said fountain means with respect to said coating roll to vary the location at which said fountain means .[.applied.]. .Iadd.applies .Iaddend.coating material to the web. 
     
     
       3. Coating apparatus as defined in claim 1 wherein said adjustably mounted guide roll is said first guide roll and said mounting means therefor provide for varying the path and extent of said lead-in portion of the web, and further comprising means mounting said fountain means for movement with respect to said coating roll to vary the location at which said fountain means applies coating material to the web. .Iadd. 
     
     
       4.  Apparatus for applying a coating to both surfaces of a moving web comprising in combination: (a) means for advancing the web including a cylindrical horizontal back-up roll having a smooth back-up surface for receiving and supporting a first surface of a web as the web is advanced,   (b) guide roll means spaced away from said back-up roll for directing the path of the web to and from said back-up roll and establishing the degree of wrap of said back-up roll by the web,   (c) first applicator means positioned ahead of the location where the web engages said back-up roll for applying a first coating to the surface of said roll so that the coating is transferred to a first surface of the web in a coating zone,   (d) a second applicator means having means for applying a coating to the second surface of the web in said coating zone so that the web is coated on both surfaces as it leaves said back-up roll, and   (e) means for maintaining the web under tension pressing the web against said first coating on said back-up roll. .Iaddend. .Iadd.5. Apparatus constructed in accordance with claim 4 for applying coating to both surfaces of a moving web and further comprising means for adjusting said guide roll means with respect to said back-up roll to vary the extent of   
     
     
        wrap of said back-up roll by the web. .Iaddend. .Iadd.6.  Apparatus constructed in accordance with claim 4 for applying coating to both surfaces of a moving web: wherein said second applicator means has a trailing blade with the blade in pressure engagement with the web in said coating zone with means for supplying coating to the web in advance of the trailing edge of said blade so that the blade smooths the layer of coating on the second surface of the web and the blade pressure aids in the transfer of coating from the roll to the first surface of the web. .Iaddend. .Iadd.7. Apparatus constructed in accordance with claim 4 for applying coating to both surfaces of a moving web wherein said first applicator means applies a sizing to the surface of said back-up roll. .Iaddend. .Iadd.8. The method of coating both surfaces of a traveling web comprising the steps of:   (a) guiding the web into engagement with a moving back-up surface,   (i b) applying a first coating to said back-up surface in advance of the location where it is engaged by the web so that said coating is transferred from said back-up surface to the web,   (c) applying a coating to the second surface of the web while it is supported by said back-up surface and substantially simultaneously applying a resilient force to the web to aid in the transfer of the first coating from said back-up surface to the web, and   (d) driving said back-up surface at a different speed from that of the   
     
     
        traveling web. .Iaddend. .Iadd.9.  The method of coating both surfaces of a traveling web comprising the steps: (a) guiding the web into engagement with a moving back-up surface at a predetermined first location thereon,   (b) applying a first coating to said back-up surface in advance of the location where it is engaged by the web so that said coating is transferred from said back-up surface to the web,   (c) pressing the web against said coating on said back-up surface only by maintaining the web under tension during travel thereof from said first location to a second location on said back-up surface, and   (d) applying a coating to the second surface of the web at said second location and substantially simultaneously applying a resilient force to the web to aid in the transfer of coating from said back-up surface to the web. .Iaddend. .Iadd.10. The method of coating both surfaces of a traveling web in accordance to the steps of claim 9 wherein the application of coating to the second surface of the web includes the action of a trailing blade which applies a resilient force to the second web surface for smoothing the coating on said second surface and which resiliently forces the web toward said back-up surface to aid in the transfer of coating from the back-up surface to said first surface of the web..Iaddend.