Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C11/00—Component parts, details or accessories not specifically provided for in groups B05C1/00 - B05C9/00
  • B05C11/02—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface ; Controlling means therefor; Control of the thickness of a coating by spreading or distributing liquids or other fluent materials already applied to the coated surface
  • B05C11/04—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface ; Controlling means therefor; Control of the thickness of a coating by spreading or distributing liquids or other fluent materials already applied to the coated surface with blades
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C11/00—Component parts, details or accessories not specifically provided for in groups B05C1/00 - B05C9/00
  • B05C11/02—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface ; Controlling means therefor; Control of the thickness of a coating by spreading or distributing liquids or other fluent materials already applied to the coated surface
  • B05C11/04—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface ; Controlling means therefor; Control of the thickness of a coating by spreading or distributing liquids or other fluent materials already applied to the coated surface with blades
  • B05C11/045—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface ; Controlling means therefor; Control of the thickness of a coating by spreading or distributing liquids or other fluent materials already applied to the coated surface with blades characterised by the blades themselves
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
  • D21H25/08—Rearranging applied substances, e.g. metering, smoothing; Removing excess material
  • D21H25/10—Rearranging applied substances, e.g. metering, smoothing; Removing excess material with blades

Definitions

• This invention relates to a coating apparatus for applying a coating onto a web. More specifically, this invention relates to a coating apparatus in which the blade includes a metallic layer and a contiguous compressible layer disposed upstream relative to the metallic layer.
• One method of applying coating material includes applying pressurized coating material to the web with the web disposed between the coating material and the backing roll. Excess coating material is removed from the web by a trailing metering blade. Such an arrangement is known in the art as "short dwell coating”.
• flooded nip coating includes dipping an applicator roll into a container supplied with the coating material such that the applicator roll rotates and applies a relatively thin layer of coating material to the web.
• a blade is disposed downstream relative to the applicator roll for smoothing and removing excess coating material from the coated web.
• a resilient metallic metering blade is disposed downstream relative to the application of coating material onto the web.
• such blades tend to wear thereby causing streaking of the resultant coating.
• a typical blade includes a distal end disposed adjacent to the web.
• the distal end includes a tip and a heel disposed upstream relative to the tip.
• the distal end is machined such that a wedge-shaped space is disposed between the distal end of the blade and the web, the wedge-shaped space being defined by the web and the distal end of the blade between the tip and the heel.
• the wedge-shaped space decreases until the distal end of the blade between the tip and the heel is disposed substantially tantigally relative to the web and backing roll. Such wear causes turbulence of the coating material and nonuniform coating and streaking of the resultant coated web.
• the present invention overcomes the aforementioned problem by providing a compressible layer disposed contiguously with and upstream relative to the metallic layer of the blade.
• the compressible layer effectively increases the thickness of the blade and consequently increases the length of the wedge-shaped space such that the wedge-shaped space extends from the tip of the metallic layer to the heel of the compressible layer.
• the compressible layer is compressed due to the build-up of coating within the wedge-shaped space.
• Such compression of the compressible layer maintains the wedge-shaped space thereby minimizing the flow turbulence in the vicinity of the distal end of the blade so that a smooth layer of coating is applied to the web and the life of the blade is prolonged.
• the apparatus includes a smoothing blade which is disposed adjacent to the web for. smoothing and metering the coating onto the web.
• the blade includes a metallic layer having a distal end disposed adjacent to the web.
• the blade also includes a compressible layer which is disposed contiguously and upstream relative to the metallic layer.
• the compressible layer has a distal end such that during use of the apparatus, as the distal end of the metallic layer wears away, the distal end of the compressible layer is compressed by the coating so that a wedge of the coating is disposed between the web and the blade.
• the wedge is defined by the web, the distal end of the metallic layer and the compressed distal end of the compressible layer thereby maintaining a smooth application of the coating onto the web and a prolonging of the life of the blade.
• the coating apparatus of the present invention is applicable to a short-dwell coater.
• the coating apparatus of the present invention is applicable to a flooded nip coater.
• the metallic layer is of spring steel plate and the compressible layer is of a polymeric material.
• the polymeric material is rubber and the ratio of the thickness of the metallic layer to the thickness of the compressible layer is 1:2.
• the metallic layer has a thickness within the range .3 to .7 millimeters and the compressible layer has a thickness within the range .8 to 1.2 millimeters.
• the hardness of the web is greater than the hardness of the compressible layer and the compressible layer is fabricated from a material which is compatible with the color of the web to be coated.
• Figure 1 is a perspective view of a prior art short dwell coater
• Figure 2 is a perspective view of a prior art flooded nip coater
• Figure 3 is an enlarged sectional view showing the distal end of a prior art metallic metering blade showing the tip, the heel and the wedge-shaped space between the blade and the web;
• Figure 4 is an enlarged sectional view of a smoothing blade according to the present invention showing the wedge-shaped space extending from the tip of the metallic layer to the heel of the compressible layer. The blade shown . in figure 4 is shown before wearing down of the metallic layer has occurred;
• Figure 5 is a similar view to that shown in figure 4 but shows the metallic layer having worn down during use .of the apparatus but with the compressible layer maintaining a wedge of coating;
• Figure 6 is a perspective view similar to that shown in figure 1 but using the smoothing blade of the present invention thereby inhibiting streaking of the web as indicated in figure 1;
• Figure 7 is a perspective view similar to that shown in figure 2 but using a smoothing blade according to the present invention thereby inhibiting streaking of the web as shown in figure 2.
• FIG. 1 is a perspective view of a typical prior art short dwell coater in which a web 10 extends around a backing roll 12.
• a short dwell coater generally designated 14 supplies pressurized coating material 16 to the web 10
• SUBSTITUTESHEET and a metering blade 18 removes excess coating material from the coated surface of the web. As shown in figure 1, after prolonged usage of the blade 18, there exists a tendency for the coating to become streaked as indicated by 20. Additionally, figure 1 shows a doctor 22 and cleaning fluid 24 disposed upstream relative to the short dwell coating apparatus 14.
• FIG 7 shows a typical prior art flooded nip coater generally designated 14A for coating a web 10A movably extending around a rotatable backing roll 12A.
• the flooded nip coater 14A includes a supply of coating material 16A and a rotatable applicator roll 30.
• a metering blade 18A is disposed downstream relative to the applicator roll 30.
• a doctor 22A and cleaning fluid 24A are shown disposed upstream relative to the flooded nip coater 14A.
• FIG 3 is an enlarged sectional view of a typical metallic metering blade 18B.
• the blade 18B includes a distal end 32 having a tip 34 and a heel 36.
• a web 10B is disposed between the distal end 32 and a backing roll 12B such that a wedge-shaped space 38 is disposed between the web 10B and the distal end 32.
• the wedge-shaped space 38 is defined by the web 10B and the distal end 32 of the blade 18B between the tip 34 and the heel 36.
• the tip 34 of the blade 18B tends to wear until the distal end 32 between the tip 34 and the heel 36 becomes substantially tangential relative to the surface of the web 10B.
• Figure 4 is an enlarged sectional view of the smoothing blade generally designated 18C according to the present invention and shows the blade 18C as including a metallic layer 50 having a distal end 52 and a compressible layer 54 disposed contiguously with and upstream relative to the metallic layer 50.
• the compressible layer 54 includes a distal end 56 such that a wedge-shaped space 38C is disposed between the web 10C and the blade 18C.
• the wedge-shaped U BSTITU TESHEET space 38C is defined by the web IOC and the distal ends 52 and 56 of the metallic layer 50 and the compressible layer 54 between the tip 34C of the metallic layer 50 and the heel 36C of the compressible layer 54.
• Figure 4 shows the blade 18C according to the present invention before the metallic layer 50 wears down due to prolonged usage of the coating apparatus.
• the metallic layer 50 is fabricated from spring steel plate having a thickness Tl of .5mm and the compressible layer 50 is fabricated from rubber and has a thickness T2 of 1mm. Therefore the distance between the tip 34C and the heel 36C is at least three times that of a conventional blade.
• Figure 5 is a similar view to that shown in figure 4 but shows the metallic layer 50 having been worn down during prolonged usage such that the distal end 52 of the metallic layer 50 is disposed substantially tangentially relative to the web IOC.
• the compressible layer 54 during usage is compressed by the coating material within the wedge 38C such that a wedge of coating material is maintained upstream of the metallic layer 50.
• turbulence of the coating material in the vicinity of the blade 18C is minimized and streaking - of the resultant coated web is inhibited.
• the compressible layer 54 is always compressed by the coating material and not worn away by the same, the life of the blade according to the present invention is substantially prolonged.
• Figures 6 and 7 show the blade 18D and 18E according to the present invention applied to a short dwell coater and to a flooded nip coater respectively for inhibiting streaking of coated webs.
• the hardness of the web 10C is greater than the hardness of the compressible layer 54 and the compressible layer 54 is fabricated from white rubber so as to avoid marking of the web in the event of the rubber layer 54 coming into contact with the surface of the web IOC.
• the web IOC is ovably supported by a rotatable backing roll 12C such that the web IOC moves past the wedge-shaped space 38C between the web IOC and the blade 18C.
• Coating material is smoothed and metered onto the web IOC by the blade 18C and even after prolonged usage of the blade 18C the wedge-shaped space 38C is maintained between the blade 18C and the web IOC so that turbulence of the coating is minimized thereby inhibiting streaking of the coating and prolonging the life of the blade.
• coating rates were increased to 2,400m per minute before streaking occurred whereas only 800m per minute were possible before streaking using prior art blades.

Landscapes

• Paper (AREA)
• Coating Apparatus (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Inking, Control Or Cleaning Of Printing Machines (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

Family

ID=14177140

Family Applications (1)

Country Status (5)

Cited By (4)

Families Citing this family (1)

Family Cites Families (4)

• 1987
  • 1987-06-24 JP JP1987096896U patent/JPS641778U/ja active Pending
• 1988
  • 1988-06-24 WO PCT/US1988/002166 patent/WO1988010155A2/en unknown
  • 1988-06-24 AU AU24831/88A patent/AU2483188A/en not_active Abandoned
  • 1988-06-27 CA CA000570459A patent/CA1305855C/en not_active Expired - Lifetime
• 1989
  • 1989-02-24 KR KR1019890700342A patent/KR890701229A/ko not_active Withdrawn

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